Christchurch City Council Assets & Network Unit Transport Technical Services & Design

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1 Date: 6 th May 2014 From: To: Bill Homewood Transportation Engineer TOC Subject: Main South Road / Carmen Road Optimisation Budget Category: Network Optimisation Appendices Appendix 1 - Turning Counts Appendix 2 - Christchurch Risk Map Output Appendix 3 - CAS Analysis (Diversion) Appendix 4 - Scheme Plan Option 1 (Trim 15/647442) Appendix 5 - Scheme Plan Option 2 (Trim 15/647442) Appendix 6 - Scheme Plan Option 3 (Trim 15/647442) Appendix 7 - Scheme Plan Option 4 (Trim 15/647442) Appendix 8 - Scheme Plan Community Board Option 1 (Trim 15/647442) Appendix 9 - Scheme Plan Community Board Option 2 (Trim 15/647442) Appendix 10 - Modelling Report Appendix 11 - Safety Audit (Trim 15/646563) Appendix 12 - Preferred Design (Trim 15/647442) Appendix 13 - Lighting Assessment (Report Awaited) Purpose of this memo This memo details the options considered to upgrade the existing intersections of Main South Road with Carmen Road. Objectives The objective, as set out in the project brief, are to: Increase capacity for west bound vehicles on Main South Road, through the Main South/Carmen/Shands Road intersection. Improve stacking capacity for Right turning vehicles into Carmen Road. Provision for safe access to/from Brynley / Tower Street and the Clock Tower site. Improve safety on the west bound approach to the Carmen / Main South intersection. Background A section of Main South Rd from Carmen Rd/Shands Rd to the Sockburn Roundabout was transferred to the Council's ownership following the completion of Christchurch Southern Motorway stage 1 (CSM1) by the New Zealand Transport Agency (NZTA). 1

2 This road transfer has resulted in Council staff reviewing traffic operation of the Main South Rd/Carmen Rd/Shands Rd intersection. The review showed that the number of drivers turning right from Main South Rd onto Carmen Rd (SH1) creates a long queue that extends beyond the formed right turn bay. This queue extends into the straight through lane at PM peak times and reduces the capacity of the intersection substantially. Because of short distance between the Main South Rd/Brynley/Tower St access and Main South Rd/Carmen Rd/Shands Rd intersection, creating a longer turning bay onto Carmen Rd needs closure of the access from Main South Rd eastbound from/to Brynley/Tower St. It is understood that the proposal requires public consultation. A resource consent (RMA ) was issued by CCC for a fast food development (Carl's Junior) on the southern side of Main South Rd. As a condition of resource consent, this development was required to develop a turning bay on Main South Rd to mitigate its traffic generation issues and its impact on Main South Rd/Brynley St/Tower St access. Incorporating the objectives of that resource consent document is also another objective for this study. In order to enhance the efficiency, CCC staff advised to combine the two projects of optimising the segment of Main South Rd and improving access to the consented fast food development into a single project. Carmen Road Main South Road Tower Street Shands Road Brynley Street Figure 1: Existing Road Layout Police Station Surrounding Land Use Main South Road is predominantly commercial in nature for this section. There is a large retail park on the north side of Main South Road, which is served by access from Chappie Place. This incorporates a Mitre 10, Countdown and several smaller units. On the south side of Main South Road there are two retail areas, either side of the Tower Street intersection. There is a police station located on Tower Street, which will be affected by any alterations to access onto the Main South Road. To the west of the intersection of Main South Road with Carmen Road are two further retail 2

3 areas, one on the north side of Main South Road (The Hub) and one on the southern side. Surrounding Transport Environment Between the Chappie Place and Carmen Road intersections, Main South Road is a median divided two way, four lane, road, with two lanes in either direction. There is an existing right turn provision in this median for vehicles to turn into Tower Street and Brynley Street. This gap also provides for vehicles right turning out of Tower Street and Brynley Street onto Main South Road. Main South Road is a very busy congested road that carries over 28,000 vehicles per day and 2,300 in the peak hour, as shown in Figure 2. Figure 2 is based on 2008 count data and is now 7 years old. However turning counts were carried out in April 2015 at the Main South Road / Carmen Road intersection, the Main South Road / Tower Street intersection and the Main South Road / Chappie Place intersection, which broadly reflect the 2008 data, these counts are attached in Appendix 1. Figure 2: Main South Road Traffic Volumes (2008 Count Data) The right turn lane on the eastern approach the Main South Road / Carmen Road intersection is noted to experience problems with capacity, with the right turn queue often extending past the start of the right turn lane and into the through lane. This right turn lane is limited in size by the adjacent right turn lane to the east, which provides for eastbound vehicles to turn right into Tower Street. Public Transport Bus stops are located on Main South Road between the intersections with Tower Street and with Chappie Place, as shown in Figure 3. These stops service the 'yellow line' bus route, which travels between New Brighton and Rolleston with a service every 15 minutes. There is an existing bus lane on the south side of Main South Road which extends from Chappie Place to approximately 60 metres east of Tower Street. 3

4 Figure 3: Bus Stops Route 125 Halswell to Westlake, route 140 Mt Pleasant to Russley and route 130 Avonhead to HeiHei, also use the Main South Road / Carmen Road intersection. Cycle Network On the north side of Main South Road there is no provision for cyclists between the intersections of Carmen Road with Chappie Place. On the southern side there is a bus lane which starts 150 metres to the east of Chappie Place and continues through the Chappie Place intersection before ending approximately 100 metres to the west. This bus lane can be used by cyclists. Where the bus lane end on the southern side of Main South Road, a cycle lane continues to the intersection of Main South Road with Carmen Road. Road Safety The CCC Christchurch Risk Map developed by Abley Transportation, has been used to determine the collective and personal risk at intersections within the vicinity of the scheme and along surrounding roads. The Risk Maps are contained in Appendix 2, and their output is summarised in Table 1. 4

5 Personal Collective Corridor Main South Road Low Medium Tower Street Low Low Ameys Road Medium Low Medium Shands Road Medium Medium Brynley Street Low Low Intersection Carmen Street / Main South Road Medium High Actual High Tower Street / Main South Road N/A Low Chappie Place / Main South Road N/A Low Tower Street / Ameys Road N/A Low Ameys Road / Shands Road Medium high Medium Definitions Personal Risk Collective Risk This is measure of the risk of death or serious injury per 100 million vehicle kms travelled within 50 metres of an intersection. Collective risk is a measure of the risk of deaths and serious injuries within 50 metres of an intersection in a crash period. Table 1: Risk Map Outputs for Personal and Collective Risk Main South Road (Chappie Place - Carmen Road) Reported crashes at and within 50 metres of this section of Main South Road, excluding the Carmen Road / Main South Road intersection which will be considered separately, were retrieved from the Crash Analysis System (CAS) for the five years period from The locations of crashes are shown in Figure 4. 5

6 Pedestrians Cyclist Right Turn Out Right Turn In Figure 4: CAS Diagram Main South Road (Chappie Place - Carmen Road) The number and severity of crashes varies each year ranging between two and seven crashes. There have been 2 serious injury, 4 minor injury and 18 non-injury crashes recorded in the study area over the past five years, there were no fatal crashes during the study period (Figure 5). Figure 5: CAS Analysis Crash Severity

7 Pedestrian crashes There was one pedestrian collision in this 5 year study period, where a pedestrian was hit crossing the Main South Road from the north side by a vehicle travelling eastbound. The pedestrian was crossing mid-block, where there is no pedestrian facilities, and was considered to be crossing 'heedless of traffic'. Cycle crashes There were two cycle crashes recorded in the study area in the 5 year period assessed. One of the collisions involved an eastbound cyclist who was hit by an overtaking truck, which was positioned too far left. This crash was in the left turn lane approaching the Chappie Place intersection, where there is no cycle lane. The other collisions involved a cyclist travelling westbound who was hit by a vehicle turning right out of Tower Street, there is a cycle lane in this location however there is no green pain across the intersection to highlight to drivers the need to be aware of cyclists. Motor vehicle crashes There are five right turning collisions at the intersection of Tower Street with Main North Road, 2 of these were a result of vehicles turning out of Tower Street and three a result of vehicles turning into Tower Street, these are identified in Figure 4. The two right turn out collisions were due to a failure to give way and a failure to look when required. In one of these instances visibility was obscured by other vehicles. The three right turn in collisions were all due to a failure to give way. In two of these three collisions one of the crash factors was identified as 'failed to give way when waved through by another driver'. This type of collisions is not uncommon where vehicles need to turn across congested two lane roads. There were no patterns or common factors other than the failure to give way, which would indicate a trend in the collisions, with collisions occurring at different times of the day and in different conditions. There have been two rear end collisions to the east of the Tower Street / Main South Road intersections. Both of these occurred within the lunch period (12:00 & 12:45) and happened on a Friday and Saturday. These types of collisions are to be expected on the approaches to busy intersections such as the Main South Road / Carmen Road intersection. Apart from these right turning collisions and the two rear end crashes there are no other repeated crash types, the crashes occur at different locations, in different conditions and at different times of the day. Main South Road / Carmen Road Intersection Reported crashes at and within 50 metres of this intersection were retrieved from the Crash Analysis System (CAS) for the five years period from The locations of crashes are 7

8 shown in Figure 6. Figure6: CAS Diagram Main South Road/ Carmen Road Intersection Pedestrian Cyclist Right Turn Against The number and severity of crashes varies each year ranging between 5 and 9 crashes per year. There have been 3 serious injury, 11 minor injury and 23 non-injury crashes recorded in the study area over the past five years, there were no fatal crashes during the study period (Figure 7). Figure 7: CAS Analysis Crash Severity

9 Pedestrian crashes There were three pedestrian collision in this 5 year study period, resulting in 2 minor injuries and one serious injury. Two of these collisions happened on Carmen Road, north approach. One was where a pedestrian was crossing 20m north of the signalised pedestrian crossing and was not crossing on a pedestrian phase. The other involved a pedestrian on the crosswalk however they did not cross in accordance with the signals. The other pedestrian collision involved a pedestrian using the Shands Road crosswalk, southern approach. In this instance the pedestrian did not cross in compliance with the signals. All three of these pedestrian crashes occurred due to inappropriate crossing by pedestrians, who were crossing heedless of traffic. The collisions are therefore not a result of the intersection design. Cycle crashes There was one cycle crash recorded in the study area in the 5 year period assessed. This crash was a result of the right turning cyclist failing to give way, when turning from the Shands Road approach (south) to the Main South Road (east) approach. Motor Vehicles Crossing and turning collisions make up 22 of the 37 crashes within 50 metres of this intersection. 17 of these were right turn against collisions at the intersection. These right turning crashes have been considered based on the approach the vehicle is right turning from. Right turn from east approach Right turn from south approach There were 8 collisions involving vehicles right turning from the eastern approach. 7 of these were a result of right turning vehicles failing to give way to nonturning traffic, and were therefore during a filter right turn phase. Three of these collisions were also noted as failing to look when required. One did not notice the intersection and one failed to stop on a steady amber light. The other 1 of the 8 collisions was a result of the right turning vehicle intentionally driving through the red light. There were 4 collisions involving vehicles right turning from the southern approach. All 4 of these were a result of right turning vehicles failing to give way and were during a filter right turn phase. 2 of the collisions were also noted to have misjudged the intentions of other drivers and one was noted to have misjudged the speed of an approaching vehicle. 9

10 Right turn from west approach Right turn from north approach There was a single collisions involving vehicles turning right from the western approach, the right turning vehicle failed to look and failed to give way when turning to non-turning traffic. There were 4 right turning collision involving vehicles turning right from the northern approach. All of these were due to a failure to give way, however 1 was also noted as 'didn't see/look when required' and another 1 was noted to have had inadequate headlight. These right turn against crashes are clearly a trend in the crash data. The times of the collisions are not limited to the peak hours, or set times of the day. The crashes occur more frequently when it is dark, 10 out of 17. A lighting assessment will therefore be required for any work at this intersection, to ensure the existing lighting provision complies with current standards. The signal phasing is likely to be the primary reason for this volume of right turn against collisions. The existing signal phasing is shown in Figure 8. While the right turn from Main South Road (east) does benefit from a dedicated right turn phase, this is only accommodates some of the vehicles making this turn and the rest need to turn during the filter phase. All of the other right turn movements are filter right turns. Figure 8: Existing signal Phasing There is one other right turn against collision which happened north of the intersection, with a 10

11 vehicle right turning into a private access. There were four crossing and turning crashes, where one of the vehicles failed to stop at a red light in each crash. These collisions happened on different approaches, at different times of the day and in various conditions. Therefore they do not constitute a trend in. There are 8 rear end collisions at the intersection during the 5 year study period. There is no more than three on any approach, and they are concentrated during the intersections busiest times as would be expected. This volume of rear end collisions is typical for an intersection which experiences this volume of traffic flow. 4 of the crashes were due to over taking / lane changing. Only two of these were at the intersection, with the other two being on exit lanes after the intersection. One of those 2 was at a merge location for vehicles travelling southbound on Shands Road. The other two, which happened at the intersection, do not indicate a trend as they were on separate approaches and over a five year period. One of these did occur on the eastern Main South Road approach and the report does suggest that it was a result of a driver moving around the right turn queue which had extended into the through lanes. Options Assessment Objectives Based on the Project Initiation Brief and information provided by the sponsor, the primary objectives of the project are to: Increase capacity for west bound vehicles on Main South Road, through the Main South/Carmen/Shands Road intersection. Improve stacking capacity for right turning vehicles into Carmen Road. Provision for safe access to/from Brynley / Tower Street and the Clock Tower site. Improve safety on the west bound approach to the Carmen / Main South intersection. Options Four preliminary options have been considered for meeting the objectives, as set out by the sponsor, these are outlined below. A further two options have been identified by the community board, during a seminar and these have been included in the assessment. Option 1 - Do Minimum The Do Nothing option maintains the status quo and as such there is no benefit. However, the additional traffic forecast to use this corridor, the Main South Road / Carmen Road intersection and the Main South Road / Tower Street Intersection, will result in the capacity and safety of the intersection deteriorating in the long term, with longer delays and more collision expected over the next years. There is also a question over what would happen with the Carls Junior resource consent, it is presumed for the purpose of this assessment that the Carls Junior would still go ahead without the right turn lane in the 'Do Minimum' scenario. This will increase the volume of right turning 11

12 movements from Main South Road eastbound into Tower Street / Brynley Street. Figure 9 - Option 1 Option 2 - Provide Right Turn for Carls Junior, maintain existing right turn from Main South Road to Carmen Road. This option provides the right turn lane required by the Carls Junior resource consent (RMA ), however makes no other alterations to the road layout. The right turn bay is shown to be 50 metres long in Figure 10, as shown to be required by the SIDRA model completed by Flow Transportation on behalf of Carls Jr Figure 10 - Option 2 12

13 Option 3 - Close central median at Tower Street so that it is left in left out only. Provide longer right turn lane at Carls Junior access to accommodate U turning traffic. Extend right turn lane on Main South Road approach to Carmen Road intersection. Option 3 provides the right turn into Carls Junior however closes the central median at the Tower Street intersection. The right turn lane will need to be longer than that shown in option 2 to accommodate U turning vehicles that are travelling eastbound and want to enter Tower Street. The right turn into Carmen Road from Main South Road has been extended to allow for increased stacking. Figure 11 - Option 3 Option 4 - Close central median between Carmen Road and Chappie Place and require vehicles to U turn at Chappie Place This option will make all access between Chappie Place and Carmen Road left in left out. There are no accesses on the north side so this only applies to the southern accesses. All vehicles that need to enter Tower Street, Clocktower Lane, or Carls Junior would therefore be diverted to the Chappie Place intersection, where they will need to complete a U turn. A U turn phase will need to be added to enable this manoeuvre to be undertaken safely. Community Board Option 1 - Hatch the Tower Street intersection. This option would hatch the tower street intersection, this is the only alteration which would be made. The idea behind the hatching is to discourage vehicles from parking over the intersection, which would allow vehicles to turn into and out of Tower Street while vehicles were queuing for the Carmen Road Main South Road intersection. 13

14 Community Board Option 2 U turn at Canterbury Street. The second community board option is to perform a U turn at the Canterbury Street intersection, figure 12, the Community Board have identified that this will provide improved visibility. This will enable the right turn into Tower Street to be blocked off and the right turn lane from Main South Road into Carmen Road to be extended. Figure 12 Community Board Option 2 14

15 Options Assessment Matrix Each of the six options has been considered against the objectives and against additional considerations in a matrix, Pages?? to??. For the purpose of this assessment the matrix provides a brief explanation and assessment of how each option matches the desired outcomes, in addition to this written assessment the following colour grading has been used for ease of comparison. Contributes to achieving desired outcome Could detract from achieving desired outcome, but can be managed through design Detracts from achieving desired outcome, and cannot be reasonably overcome through design. This includes cost prohibitive measures that fall outside the projects budget. 15

16 Objectives Increase capacity for west bound vehicles on Main South Road, through the Main South/Carmen/Shands Road intersection. Improve stacking capacity for Right turning vehicles into Carmen Road. Provision for safe access to/from Brynley / Tower Street and the Clock Tower site. Improve safety on the west bound approach to the Carmen / Main South intersection. Brynley / Tower Clock Tower Option 1 As Option 1 Do Minimum requires no alterations to existing layout, the option can only contribute or detract from the objectives. There is no provision to manage through design. No Improvements to Capacity through this option. However additional vehicle will right turn into Tower Street as a result of the Carls Jr Development. This will have the potential to impact on the capacity of east bound vehicles as the stacking space for this manoeuvre is limited (Approx 25 metres) No additional right turn queuing provided. Existing access arrangements will be maintained. There have been 5 accidents involving vehicles turning into and out of this intersection in the past 5 years. This is likely to increase with the creation of the Carls Junior as more vehicles would be making these manoeuvres. The existing turning movements at this intersection are relatively low, with 76 vehicles right turning in and 28 vehicles right turning out in the PM peak. The addition of the Carls Jr development these will increase to 92 right turning in and 48 right turning out. This is an increase of 21% and 71% respectively. While the numbers are low, considering them in context of percentage increase in turning movements, would suggest a potential for a corresponding increase in the potential for collision to occur. No alterations to the existing access arrangement are proposed for this option, and the existing left in left out provision is maintained. No improvements to safety will be provided by this scheme. Additional right turning movements generated from Main South Road into Tower Street by the Carls Junior Development. The Carls Junior will increase the number of vehicles right turning which will increase the potential for crashes to occur. Outisde of the PM peak there will be an increase of 10 vehicles right turning in (23%) and an additional 11 vehicles right turning out (44%) Option 2 Provide Right Turn for Carls Junior, maintain existing right turn from Main South Road to Carmen Road. Capacity is not improved with this option. No additional right turn queuing provided Existing access arrangement will be maintained, however the provision of the right turn into the Carls Junior site will mean that there is no increase in right turning in vehicles at the Main South Road / Tower Street intersection, shown in the modelling. There will still be an increase of 8 vehicles right turning out in the PM peak (28%) and an additional 11 vehicles in the inter peak (44%). It should be noted that these additional movements were found to be acceptable as part of the resource consent. The right turn into the Clock Tower site has already been secured as part of a resource consent. This design has been completed and agreed as part of the resource consent process. There has been no safety audit completed for the existing Carls Junior design at this stage, but one is required as a condition of consent. No improvements to safety will be provided by this scheme for west bound traffic. The creation of an additional right turn bay will increase the number of locations where vehicles come into conflict, and the Carls Junior will increase the number of vehicles crossing / turning, which will increase the potential for crashes to occur. 16

17 Objectives Increase capacity for west bound vehicles on Main South Road, through the Main South/Carmen/Shands Road intersection. Improve stacking capacity for Right turning vehicles into Carmen Road. Provision for safe access to/from Brynley / Tower Street and the Clock Tower site. Improve safety on the west bound approach to the Carmen / Main South intersection. Brynley / Tower Clock Tower Option 3 Close central median at Tower Street so that it is left in left out only. Provide longer right turn lane at Carls Junior access to accommodate U turning traffic.. Extend right turn lane on Main South Road approach to Carmen Road intersection. Capacity for west bound vehicles will be improved with the extended right turn lane. The additional right turn lane length will make it less likely that the right turn queue will extend out into the through lanes, as it currently does blocking traffic flow. Length of right turn lane will be increased as part of this proposal, by turning the Tower Street intersection into a Left in Left out arrangement. The right turn into Carmen Road will be back to back with the right turn / u turn facility for Carls Jr. The exact length of each lane will be determined using modelling if this is considered as the preferred option Existing intersection will be turned into left in left out arrangement. This will remove the potential for right turn against collisions at this intersection. The existing right turn in movements will be relocated to the Carls Junior right turn / u turn bay which will be created in the central median (see Provision for safe access to/from Clock Tower Site) Altering the central median so that Tower Street is left in left out will result in the right turn out movements having to divert. The implication of this are considered in Table 3 'Additional Consideration'. A right turn into the Clock Tower site is a condition of the Carl Junior resource consent. This right turn is only proposed to be 50 metres in length which is not sufficient to accommodate the Carls Junior right turning movements and the U turning movements generated by the demand for access to Tower Street and Brynley Street. The proposed right turn bay will need to be extended to accommodate the U turning movements, and modelling will be used to determine the appropriate length. The history of right turn accidents at the intersection of Main South Road and Tower Street (3 in 5 years), indicates that this right turn could be a difficult manoeuvre. U turning takes a longer amount of time and requires vehicles to drive at a lower speed, and therefore increases a vehicles exposure to oncoming traffic. The U turn bay will need to be designed to current standards with adequate visibility and this will be considered at a more detailed design stage, if this option is taken forward. Extending the right turn from Main South Road to Carmen Road will improve safety by reducing the likelihood of right turning vehicles blocking one of the through lanes. However the U turn bay will need to meet current design standards and provide a safe provisions for vehicles undertaking this manoeuvre, with clear lines of sight provide to approach vehicles (westbound). A safety audit will be required. 17

18 Objectives Increase capacity for west bound vehicles on Main South Road, through the Main South/Carmen/Shands Road intersection. Improve stacking capacity for Right turning vehicles into Carmen Road. Provision for safe access to/from Brynley / Tower Street and the Clock Tower site. Improve safety on the west bound approach to the Carmen / Main South intersection. Brynley / Tower Clock Tower Option 4 Close central median between Carmen Road and Chappie Place. Requires right turning vehicles into Tower Street to U turn at Chappie Place. Capacity for west bound vehicles will be improved at the Carmen Road / Main South Road intersection, with the extended right turn lane. However providing a U turn at the Chappie Place intersection would require alterations to the signal phasing, with an additional phase being added to allow vehicles to safely carry out a U turn. At this stage modelling shows that this U turn phase can be provided by removing a phase for vehicles using the eastern approach (west bound). Creating this provision will increase the queue length from 60 vehicles to 111 during the weekday PM peak hour, and from 47 to 72 during the weekend peak. This is a substantial increase and equates to a queue length of over half a kilometre in the PM peak hour. The objective is very specific in stating improving travel time for westbound vehicles at the Main South Road / Carmen Road intersection, and therefore this option in theory meets that objective. However in practice the improvements in capacity at that intersection would come at the expense of capacity at the Chappie Place intersection. Therefore this has been put as could detract, and this will need to be discussed with the project sponsor. Right turn lane will be increased in length, unlike with option 3 there is no right turn into Carls Junior which allows for a longer right turn lane into Carmen Road if required. Existing intersection will be turned into left in left out arrangement. This will remove the potential for right turn against collisions at this intersection. This option does not provide for a U turn at the Clock Tower site, and therefore any vehicles which would have turned right into Tower Street will now need to perform a U turn at the Chappie Place intersection. The signal phasing at Chappie Place would have to be altered to provide a safe U turn provision at the signals, and therefore this manoeuvre could be undertaken safely. Altering the central median so that Tower Street is left in left out will result in the right turn out movements having to divert. The implication of this are considered in Table 3 'Additional Consideration'. No alterations to the existing access arrangement are proposed for this option, and the existing left in left out provision is maintained. The resource consent granted to Carls Junior provides for a right turn bay. If this right turn provision is not provided vehicles will perform U turns at the Chappie Place intersection. Which could be undertaken safely with a dedicated U turning phase. This will create additional queuing to the east of Chappie Place intersection, which could result in additional crashes. Additional queuing and delays caused by adding a U turn phase at the Chappie Place intersection, which doubles the queue length, will result in an increased potential for crashes to occur and will have a detrimental impact on the safety of road users. It should be noted that if the objective was less specific and stated the objective was to improve travel times for westbound vehicles, which is the intention of the scheme, then this would be rated as Detracts from the desired outcome. 18

19 Objectives Increase capacity for west bound vehicles on Main South Road, through the Main South/Carmen/Shands Road intersection. Improve stacking capacity for Right turning vehicles into Carmen Road. Provision for safe access to/from Brynley / Tower Street and the Clock Tower site. Improve safety on the west bound approach to the Carmen / Main South intersection. Brynley / Tower Clock Tower Community Board Option 1 Hatch Tower Street intersection. This option significantly detracts from achieving the desired outcome. Providing sufficient hatching to create adequate visibility for both approach lanes (90m splay in 50km zone, driver eye height to driver eye height) will require approximately 75 metres of hatching. Providing this visibility is essential, to ensure that a queue in one lane does not block the visibility of approaching vehicles in the other. This is a loss in queuing/stacking space, and splits the queue by a significant distance, reducing the volume of vehicles which can get through on a green phase. Figure 13 shows the approximate area of hatching required in yellow and the approximate visibility splay in green. No additional right turn queuing provided, in fact this option reduces the right turn capacity. Where there are two lanes that the hatching extends over, as there would be in this instance (plus a bus lane), the hatching creates a significant risk of a side on collision. If the queue, in the near side lane to the right turn bay extends beyond the right turn lane, however the queue on the far side lane (footpath side) does not, then vehicles queuing in the near side lane will block the visibility of approaching vehicles. This will result in additional unnecessary crashes, which will be side one and therefore likely to result in a serious injury. There will also be cyclists and buses travelling on the kerbside that will potentially be at risk. The impacts of this can be reduced by creating a larger area of hatching, as outlined in this assessment when considering the option against objective 1. However this creates separate capacity issues and relies on drivers observing the full hatched area, something which is unlikely to happen. No alterations to the existing access arrangement are proposed for this option, and the existing left in left out provision is maintained. The resource consent granted to Carls Junior requires a right turn bay. If this right turn provision is not provided some vehicles may perform U turns at the Chappie Place intersection, this will need to be discouraged (banned?) to ensure that any Carls Junior traffic uses the Tower Street access adding to the potential safety issues. Concerns with the safety of vehicles undertaking the right turn into or out of Tower Street, as already outlined, apply to this objective. The safety of these manoeuvres relies on drivers observing the large hatched area. Figure 13 Approximate hatching required. If the hatching is not observed, as is often the case, then the right turning vehicles into Tower Street will have to wait until the vehicles clear the intersection, and this situation could repeat itself for the next phase. Given the significant extent of the hatching it is likely that some vehicles will unintentionally queue over it. 19

20 Objectives Increase capacity for west bound vehicles on Main South Road, through the Main South/Carmen/Shands Road intersection. Improve stacking capacity for Right turning vehicles into Carmen Road. Provision for safe access to/from Brynley / Tower Street and the Clock Tower site. Improve safety on the west bound approach to the Carmen / Main South intersection. Brynley / Tower Clock Tower Community Board Option 2 U turn at Canterbury Street with closure of median at Tower/ Brynley. Capacity for west bound vehicles will be improved with the extended right turn lane. The additional right turn lane length will make it less likely that the right turn queue will extend out into the through lanes, as it currently does blocking traffic flow. Length of right turn lane will be increased as part of this proposal, by turning the Tower Street intersection into a Left in Left out arrangement. The right turn could be extended as far back as chappie place in theory. Vehicles which want to right turn into Tower Street are unlikely to drive to Canterbury Street to undertake a U turn to drive back to the Tower Street access, this is a detour of approximately 850 metres. Vehicles would be more likely to try U turning at Chappie Place which would be likely to result in an increase in crashes if there is no U turning phase. Altering the central median so that Tower Street is left in left out will result in the right turn out movements having to divert. The implication of this are considered in Table 3 'Additional Consideration'. No alterations to the existing access arrangement are proposed for this option, and the existing left in left out provision is maintained. The resource consent granted to Carls Junior requires a right turn bay. If this right turn provision is not provided some vehicles may perform U turns at the Chappie Place intersection, rather than driving to the Canterbury Street intersection. This manoeuvre would be likely to result in an increase in crashes. Concerns with the safety of vehicles undertaking U Turns at Chappie Place, as already outlined, apply to this objective. These manoeuvres are likely to result in an increase in crashes. While the U turning at Chappie Place could be banned under the Community Boards delegated authority, and therefore considered an enforcement issue, the Safe System Approach outlines three key areas that need to be considered when designing road layouts which are applicable. 1. People make mistakes People make mistakes and some crashes are inevitable. 2. People are vulnerable Our bodies have a limited ability to withstand crash forces without being seriously injured or killed. 3. We need to share responsibility System designers and people who use the roads must all share responsibility for creating a road system where crash forces do not result in death or serious injury. Mindful of this guidance, relying on enforcement when there is a clear demand and high likelihood of a movement being undertaken is not an appropriate method of road design. Table 2 Options Matrix - Objectives 20

21 Additional considerations Option 1 As Option 1 Do Minimum requires no alterations to existing layout, the option can only contribute or detract from the objectives. There is no provision to manage through design. Option 2 Provide Right Turn for Carls Junior, maintain existing right turn from Main South Road to Carmen Road. Option 3 Close central median at Tower Street so that it is left in left out only. Provide longer right turn lane at Carls Junior access to accommodate U turning traffic. Extend right turn lane on Main South Road approach to Carmen Road intersection. Option 4 Close central median between Carmen Road and Chappie Place. Requires right turning vehicles into Tower Street to U turn at Chappie Place. Community Board Option 1 Hatch Tower Street intersection. Community Board Option 2 U turn at Canterbury Street with closure of median at Tower/ Brynley. Detours Required N/A N/A Detour is the same for both Option 3 and Option 4 Prohibiting vehicles from right turning out onto Main South Road will have an impact on approximately 28 vehicles in the PM peak hour and 38 in the AM peak hour, based on the most recent traffic counts. These vehicles will need to find alternate routes. CAST modelling shows that the majority of these vehicles will divert along Ameys Road, turn right onto Shands Road and then undertake another right turn onto Main south Road. This detour is 927 metres long, and is shown below in figure 14 N/A As with Option 3 & Option 4 Figure 14 Detour required A CAS analysis has been undertaken to determine if there are any existing safety concerns with this route, this analysis is attached in Appendix 3. There are no 21

22 Additional considerations Option 1 As Option 1 Do Minimum requires no alterations to existing layout, the option can only contribute or detract from the objectives. There is no provision to manage through design. Option 2 Provide Right Turn for Carls Junior, maintain existing right turn from Main South Road to Carmen Road. Option 3 Close central median at Tower Street so that it is left in left out only. Provide longer right turn lane at Carls Junior access to accommodate U turning traffic. Extend right turn lane on Main South Road approach to Carmen Road intersection. Option 4 Close central median between Carmen Road and Chappie Place. Requires right turning vehicles into Tower Street to U turn at Chappie Place. Community Board Option 1 Hatch Tower Street intersection. Community Board Option 2 U turn at Canterbury Street with closure of median at Tower/ Brynley. trends in the crash data for the intersection of Ameys Road with Shands Road or on Shands Road between that intersection and the intersection with Carmen Road and Main South Road, when considering the movements which will be undertaken by vehicle using this diversion. There is however a prevalence of right turning against crashes with vehicles turning from Shands Road into Main South Road, which could affect the vehicles which will have to detour. There were four collisions involving right turning vehicles from Shands Road in the past 5 years, which appears to be due to the right turn filter provisions and the lack of any right turn phase. The volume of right turners will increase as a result of this detour, with an approximately 19% increase in right turning movements in the AM peak and 11% increase in the PM. This will inevitably lead to an increased potential for right turn against collision. However this increase needs to be considered in context. The right turn out collisions at the Tower Street intersection resulted in 2 collisions, which is half of the total number of right turning collisions at Shands Road Main South Road, however the volumes or turning movements is significantly lower, only accounting for 11% in the AM peak and 19% in the PM peak. It can therefore be concluded that the right turning at Shands Road Main South Road is an improvement to the safety of vehicles undertaking this manoeuvre. Modelling output 1.11 Do Minimum option shows a significant increase in turning delays at Main South Rd/Carmen Rd intersection and low efficiency in future. Modelling report attached in Appendix Option 2 has very similar performance to do minimum. It, however, does not address the problem of inefficiency at Main South Rd/Carmen Rd intersection. Modelling report attached in Appendix Option 3 has been overall successful in increasing the Main South Rd/Carmen Rd/Shands Rd intersection efficiency. However, side effects of closing the Brynley St/Tower St access will degrade Main South Rd efficiency on other parts. A noticeable volume of traffic will be shifted toward Amyes Rd and Springs Rd by this option. It will not adversely impact these roads as the extra traffic would balance the reduction of traffic in the Springs Rd caused by utilisation of CSM. Modelling report attached in Appendix Option 4 does not improve the Main South Rd/Carmen Rd/Shands Rd intersection efficiency as good as option 3. In contrast it has the worst impact on Main South Road efficiency, particularly at Chappie Pl intersection. The magnitude of forecasted increase at this intersection is the highest compared to all other options. Modelling report attached in Appendix Option 5 is similar to option 4 in terms of Main South Rd/Carmen Rd/Shands Rd intersection optimisation. Compared to option 4, however, it has better performance in terms of overall efficiency of Main South Rd. Modelling report attached in Appendix Option 6 has not been examined for traffic impacts due to many problems regarding its safety, efficiency and movement priorities. The issue is further covered in safety audit report. Modelling report attached in Appendix 10 22

23 Additional considerations Option 1 As Option 1 Do Minimum requires no alterations to existing layout, the option can only contribute or detract from the objectives. There is no provision to manage through design. Option 2 Provide Right Turn for Carls Junior, maintain existing right turn from Main South Road to Carmen Road. Option 3 Close central median at Tower Street so that it is left in left out only. Provide longer right turn lane at Carls Junior access to accommodate U turning traffic. Extend right turn lane on Main South Road approach to Carmen Road intersection. Option 4 Close central median between Carmen Road and Chappie Place. Requires right turning vehicles into Tower Street to U turn at Chappie Place. Community Board Option 1 Hatch Tower Street intersection. Community Board Option 2 U turn at Canterbury Street with closure of median at Tower/ Brynley. Comments This option relies on a U turn phase being provided at the Chappie Place intersection. As far as can be determined there is no signal aspect permitting a U turn to be undertaken which is an approved traffic control device. The legality, and therefore liabilities if there is an accident associated with the phase of the signals is currently unknown and will need to be considered further if this is identified as a preferred option. Table 3 Options Matrix Additional Considerations Christchurch City Council does not use hatching for these purposes and consideration needs to be given to whether this sets a precedence. 23

24 Scheme Designs Following discussions with the Community Board it has been decided to deviate from the standard approach used by Christchurch City Council, where a preferred option is identified from the options assessment, which is then taken through the scheme design stage, and a Safety Audit then completed by an independent safety audit team. Instead it has been decided to take all 6 options through the scheme design process, and undertake safety audits on each. This section of the report details a scheme design to the same standard as would usually be completed for a preferred design. These scheme designs should be read in conjunction with the options assessment. Option 1 Do Minimum Figure 15 shows the existing road layout for Option 1, an A3 scale version is attached in Appendix 4. Figure 15: Option 1 Existing Layout The Do Minimum option requires no alterations to the existing layout, however assumes that the Carls Junior development does ahead. This will increase the right turning movements using the Tower Street intersection. The existing turning movements at this intersection are relatively low, with 76 vehicles right turning in and 28 vehicles right turning out in the PM peak. The addition of the Carls Jr development will increase these to 92 right turning in and 48 right turning out. This is an increase of 21% and 71% respectively. 24

25 Outisde of the PM peak there will be an increase of 10 vehicles right turning in (23%) and an additional 11 vehicles right turning out (44%) These additional turning movements are substantial when compared to the existing flows and need to be considered in comparison to the existing accident data. While an up to 44% increase in flows does not necessarily mean a corresponding increase in crashes, it does raise the potential for crashes to occur. Existing access arrangements will be maintained. There have been 5 accidents involving vehicles turning into and out of this intersection in the past 5 years. This is likely to increase with the creation of the Carls Junior as more vehicles would be making these manoeuvres. There are limited options to improve the safety for vehicles undertaking these manoeuvres without prohibiting them entirely, and as such it should be left for the Safety Audit team to independently consider whether this increase is acceptable. Option 2 Provide Right Turn for Carls Junior, maintain existing right turn from Main South Road to Carmen Road. Figure 16 shows an initial scheme plan for Option 2, an A3 scale version is attached in Appendix 5. Figure 16: Option 2 Proposed Layout Right turn into Carmen Road There are no alterations proposed to the right turn into Carmen Road as part of this Option. The scheme does not meet the client brief to provide additional stacking space for this manoeuvre. It should be noted that the situation will be unlikely to deteriorate as a result of 25

26 this option and any additional right turning movements generated by Carls Junior from this approach will be relatively low. While the option will have no detriment to this queuing, the typical increases in traffic flow will. The problems that are experienced here will continue to worsen due to this growth in traffic flows. Right turn into Carls Junior This proposal provides a 50 metre right turn lane into Carls Junior, which Carls Junior have modelled and identified as being the required length. This consists of 20 metres of stacking space and a 30 metre taper leading in. There are two existing advanced directional signs located within the central median, which will need to be either relocated or removed. These signs will interfere with the visibility between drivers waiting to use the U turn facility and drivers approaching from Main South Road or Chappie Place. Existing right turn into Tower Street The existing right turn into Tower Street will be maintained in this option, However the right turning movements from Main South Road will be unlikely to be increased as the Carls Junior development will be served by a separate right turn bay. However as identified in the options assessment there will be additional right turning movements from Tower Street, generated by vehicles leaving the development. There will still be an increase of 8 vehicles right turning out in the PM peak (28% increase) and an additional 11 vehicles in the inter peak (44% increase). These additional turning movements are substantial when compared to the existing flows and need to be considered in comparison to the existing accident data. While a 25 44% increase in flows does not necessarily mean a corresponding increase in crashes, it does raise the potential for crashes to occur. There are limited options to improve the safety for vehicles undertaking this manoeuvre without prohibiting them entirely, and as such it should be left for the Safety Audit team to independently consider whether this increase is acceptable. Intersection of Chappie Place The proximity of the proposed right turn to the Chappie Place intersection could increase the potential for collisions to occur, as right turning vehicles from Chappie Place accelerate into the manoeuvre. Vehicles leaving Chappie Place who are not familiar with the area would be unlikely to expect this right turn bay immediately after exiting the intersection. As such, the end of the central median, nearest Chappie Place, is shown to have been widened on the scheme plan. This widening will be undertaken to slow right turning movements from Chappie Place into Main South Road. Slower vehicle speeds will reduce the likelihood of a crash occurring and will also lower the severity of any injuries. All Planting between the U turn provision and the end of the island will be removed as part of 26

27 this scheme to ensure that adequate visibility can be achieved and that there are no distractions to vehicles when looking for hazards. It is the opinion of the project team that these measures will assist in reducing the detrimental impact caused by locating a high volume right turn provision close to the existing signalised intersection. Option 3 Close central median at Tower Street so that it is left in left out only. Provide longer right turn lane at Carls Junior access to accommodate U turning traffic. Extend right turn lane on Main South Road approach to Carmen Road intersection. Figure 17 shows an initial scheme plan for Option 3, an A3 scale version is attached in Appendix 6. The right turn bay at the Camen Road and the U turn bay at Carls Junior are shown as arbitrary lengths at this stage. On completion of the modelling they will altered accordingly. Figure 17: Option 3 Proposed Layout Right turn into Carmen Road The right turn bay into Carmen Road has been extended by closing the right turn into Tower Street. It is proposed to increase the lane length from 50 metre to 145 metres. This provides sufficient stacking space for the 85 th percentile queue. Sidra has identified that the 85 percentile queue length would be 158 metres and this has been validated on site using queue length surveys. However it has been noted, while on side that there is a metre courtesy gap provided at the Tower Street intersection. With the Tower Street intersection being closed this metre gap will not be required and therefore the 85 th percentile queue will be closer to 145 metres in length. The lane will be continued at its current width of 3.3 metres, which meets the standards as set out in Austroads. The extended right turn provision will not completely remove the existing problem of the 27

28 right turn queue extending out into the through lane, as queues above the 85%ile will not be able to be accommodate. There will still be significant improvements on the existing situation, which will offer significant improvements to travel time and help to reduce the potential for rear end and lane changing collisions. There is no survey data available at this stage and these measurements are based on Aerials. U turn The U turn into Carls Jr has been shown as 100 metres on the options plan, in accordance with the approved resource consent documents. Realistically this will not fit if a 145 metre right turn bay is provided for the Main South Road - Carmen Road intersection. At this stage it is anticipated that the U turn bay length will reduced below the 85 th percentile queue length (89 metres, as calculated in the modelling report Appendix 10). The predominant flow in the PM peak, when the queuing will be most likely to exceed the 85 th percentile, is west bound. The impact of a short lane effect at the U turn bay will only be experienced by the east bound flow, which experiences significantly less delay during the PM peak period. The width of the right turn lane is 3.3 metres which meets the standards as set out in Austroads. There are two existing advanced directional signs located within the central median, which will need to be either relocated or removed. These signs will interfere with the visibility between drivers waiting to use the U turn facility and drivers approaching from Main South Road or Chappie Place. Existing right turn into Tower Street The existing right turn into Tower Street is to be closed in this option, with a raised central median installed to prohibit this manoeuvre. With the presence of the police station on Tower Street it has been decided to reduce the height of this median to allow for police vehicles to continue to right turn out of Tower Street. This is to allow the police to easily exit the station and travel east in an emergency. However it should be noted that police can legally undertake a U turn from the Main South Road eastern approach at the intersection with Carmen Road in an emergency. It is accepted that installing this provision for the benefit of the police station could encourage other drivers to make this turn. However banning the right turn under the Community Boards delegated authority, installing no right turn signs and creating a physical barrier, albeit one which can be driven over, will discourage vehicles from making this turn. Ensuring that the section of the median that can be driven over is not clearly indicated to vehicles, will be important to limiting its use and therefore this section should be made of the same materials as the surrounding median. The location of the police station should also discourage vehicles from making this turn, as enforcement action is more likely than in most other places on the road network. The central median will be constructed so that it is 2.1 metres wide, it is intended to be constructed using kerbs and pressed concrete to provide a cobble effect in the centre. Some planting could be considered at the detail design stage. However to discourage vehicles from right turning using the provision, either side of the lowered section there will need to be made of a similar surface so that reduced height of the median is less noticeable and there is 28

29 no clear location for vehicles to turn. Intersection of Chappie Place The proximity of the proposed U turn to the Chappie Place intersection could increase the potential for collisions to occur, as right turning vehicles from Chappie Place accelerate into the manoeuvre. As such, the end of the central median, nearest Chappie Place, is shown to have been widened on the scheme plan. This widening will be undertaken to slow right turning movements from Chappie Place into Main South Road. Slower vehicle speeds will reduce the likelihood of a crash occurring and will also lower the severity of any injuries. All Planting between the U turn provision and the end of the island will be removed as part of this scheme to ensure that adequate visibility can be achieved and that there are no distractions to vehicles when looking for hazards. It is the opinion of the project team that these measures will assist in reducing the detrimental impact caused by locating a high volume right turn provision close to the existing signalised intersection. Diversions See Options Assessment, Table 3 Options Matrix Additional Considerations. Option 4 Close central median between Carmen Road and Chappie Place. Requires right turning vehicles into Tower Street to U turn at Chappie Place Figure 18 shows an initial scheme plan for Option 4, an A3 scale version is attached in Appendix 7. Figure 18: Option 4 Proposed Layout 29

30 Right turn into Carmen Road The right turn bay into Carmen Road has been extended by closing the right turn into Tower Street. It is proposed to increase the lane length from 50 metre to 186 metres. This provides sufficient stacking space for the 100 percentile queue. The lane will be continued at its current width of 3.3 metres, which meets the standards as set out in Austroads. The extended right turn provision will provide sufficient stacking space to accommodate the queues during its busiest times, above what would be experienced on a typical day. This will provide significant improvements on the existing situation, with improvements to travel time and a reduction in the potential for rear end and lane changing collisions. There is no survey data available at this stage and these measurements are based on Aerials. Existing right turn into Tower Street The existing right turn into Tower Street is to be closed in this option, with a raised central median installed to prohibit this manoeuvre. With the presence of the police station on Tower Street it has been decided to reduce the height of this median to allow for police vehicles to continue to right turn out of Tower Street. This is to allow the police to easily exit the station and travel east in an emergency. However it should be noted that police can legally undertake a U turn from the Main South Road eastern approach at the intersection with Carmen Road in an emergency. It is accepted that installing this provision for the benefit of the police station could encourage other drivers to make this turn. However banning the right turn under the Community Boards delegated authority, installing no right turn signs and creating a physical barrier, albeit one which can be driven over, will discourage vehicles from making this turn. Ensuring that the section of the median that can be driven over is not clearly indicated to vehicles, will be important to limiting its use and therefore this section should be made of the same materials as the surrounding median. The location of the police station should also discourage vehicles from making this turn, as enforcement action is more likely than in most other places on the road network. The central median will be constructed so that it is 2.1 metres wide, it is intended to be constructed using kerbs and pressed concrete to provide a cobble effect in the centre. Some planting could be considered at the detail design stage. However to discourage vehicles from right turning using the provision, either side of the lowered section there will need to be made of a similar surface so that reduced height of the median is less noticeable and there is no clear location for vehicles to turn. Intersection of Chappie Place The proposal requires vehicles that would have under taken a right turn into Chappie Place or into the Carls Junior Development to instead U turn at the signals. As requested by members of the project team this option has been considered on the basis that a U turn phase is added at the signal. It has been determined through modelling that this U turn could be included as part of the existing phasing, at the expense of one of the Main South Road westbound phases. This will 30

31 increase the Main South Road eastern approach queue from 77 metres to 117, i.e. more than 50% increase. In theory, despite this significant increase of the Westbound queue, the scheme does meet the project objectives to increase the westbound capacity at the Main South Road / Carmen Road intersection. However in practice this goes against the core intention for the scheme and the justification for the funding, which is to improve travel times for the Main South Road westbound flows. Improving the travel times at one intersection on a corridor at the expense of the corridors capacity up or down stream is contradictory and difficult to justify. While it is important to meet the objectives of the scheme, the wider implications must be taken into consideration. This option relies on a U turn phase being provided at the Chappie Place intersection. There is no signal aspect permitting a U turn to be undertaken which is an approved traffic control device. The legality and liabilities if there is an accident associated with the phase of the signals is currently unknown and will need to be considered further if this is identified as the preferred option. If this scheme is taken forward then a legal opinion will be sought on the use of a U turn signal. Diversions See Options Assessment, Table 3 Options Matrix Additional Considerations. Community Board Option 1 Hatch Tower Street intersection. Figure 19 shows an initial scheme plan for Community Board Option 1, an A3 scale version is attached in Appendix 8. Right turn Into Tower Street Figure 19: Community Board Option 1 Proposed Layout 31

32 The existing right turn into Tower Street is maintained with this option however yellow hatching would be installed to prohibit queuing over the Tower Street intersection. Where there are two lanes that the hatching extends over, as there would be in this instance (plus a bus lane), the hatching creates a significant risk of a side on collision. If the queue, in the near side lane to the right turn bay extends beyond the right turn lane, however the queue on the far side lane (footpath side) does not, then vehicles queuing in the near side lane will block the visibility of approaching vehicles. This will result in additional unnecessary crashes, which will be side one and therefore likely to result in a serious injury. There will also be cyclists and buses travelling on the kerbside that will potentially be at risk. Due to this risk, the hatching has been extended to provide the Safe Intersection Stopping Sight Distance as stated in Austroads. This creates approximately 90 metres where vehicles cannot queue. The benefit provided by this SISSD is only realised if vehicles observe the yellow hatching at all times. Where the queue extends over this hatching, which is likely given it's extent and its proximity to the Main South Road / Carmen Road intersection, the benefit would be lost. It is evident from other treatments around the City that yellow hatching at intersection is often ignored, such as at the Hereford Street Colombo Street intersection, photo 1. Photo 1: Hereford Street / Colombo Street The creation of this no Queuing area will resulted in a reduced capacity at this intersection as the available queuing space has been reduced and the queue split in two. This proposal assumes that the Carls Junior development goes ahead. Which will increase the right turning movements using the Tower Street intersection. The existing turning movements at this intersection are relatively low, with 76 vehicles right turning in and 28 vehicles right turning out in the PM peak. The addition of the Carls Jr development will increase these to 83 right turning in and 36 right turning out. This is an increase of 9% and 28% respectively. 32

33 Outisde of the PM peak there will be an increase of 10 vehicles right turning in (23%) and an additional 11 vehicles right turning out (44%) These additional turning movements are substantial when compared to the existing flows and need to be considered in comparison to the existing accident data. While an up to 44% increase in flows does not necessarily mean a corresponding increase in crashes, it does raise the potential for crashes to occur. There have been 5 accidents involving vehicles turning into and out of this intersection in the past 5 years. This is likely to increase with the creation of the Carls Junior as more vehicles would be making these manoeuvres. Community Board Option 2 U turn at Canterbury Street with closure of median at Tower/ Brynley. Figure 20 shows an initial scheme plan for Community Board Option 2, an A3 scale version is attached in Appendix 9. Figure 20: Community Board Option 2 Proposed Layout Existing right turn into Tower Street The existing right turn into Tower Street is to be closed in this option, with a raised central median installed to prohibit this manoeuvre. With the presence of the police station on Tower Street it has been decided to reduce the height of this median to allow for police vehicles to continue to right turn out of Tower Street. This is to allow the police to easily exit the station and travel east in an emergency. However it should be noted that police can legally undertake a U turn from the Main South Road eastern approach at the intersection with Carmen Road in an emergency. It is accepted that installing this provision for the benefit of the police station could encourage other drivers to make this turn. However banning the right turn under the Community Boards delegated authority, installing no right turn signs and creating a physical 33

34 barrier, albeit one which can be driven over, will discourage vehicles from making this turn. Ensuring that the section of the median that can be driven over is not clearly indicated to vehicles, will be important to limiting its use and therefore this section should be made of the same materials as the surrounding median. The location of the police station should also discourage vehicles from making this turn, as enforcement action is more likely than in most other places on the road network. The central median will be constructed so that it is 2.1 metres wide, it is intended to be constructed using kerbs and pressed concrete to provide a cobble effect in the centre. Some planting could be considered at the detail design stage. However to discourage vehicles from right turning using the provision, either side of the lowered section there will need to be made of a similar surface so that reduced height of the median is less noticeable and there is no clear location for vehicles to turn. Intersection of Chappie Place This option requires that vehicles drive past the Chappie Place intersection and continue to Canterbury Street where they will undertake a U turn. However vehicles are unlikely to drive to Canterbury Street and are likely to attempt to U turn at the Chappie Place intersection. As there is no safe phase for vehicles to undertake this manoeuvre vehicles will U turn from the eastbound lane while vehicles are approaching in the Westbound Lanes. This will result in a high potential for collisions to occur resulting in either a severe or fatal crash. Vehicles waiting for a sufficient gap in the westbound traffic flow will block one of the through lanes of traffic for east bound vehicles. This will increase queuing and create the potential for lane changing crashes to occur on this approach. Erecting a no u turn sign, as shown on the options plan, will discourage vehicles from making this manoeuvre, however it will not stop vehicles. Intersection of Canterbury Street It is proposed all of the vehicles which would have right turned into Tower Street or Carls Junior would right turn from the Canterbury Street intersection. This right turn bay would need to be extended to accommodate the U turning movements. However the right turn bay can only be extended by at most 20 metres before any extension would come at the loss of the right turn bay on Main South Road eastern approach to its intersection with Chappie Place. Mindful of the requirement for the U turn bay in Option 3 to be approximately 100 metres long, this additional 20 metres would be unlikely to be sufficient. The community board requested that this option was considered as they believe that it will provide improved visibility when compared to the other U turn options. The visibility at this intersection is sufficient, of vehicles approaching from the west (eastbound). The visibility to lane nearest the footpath is adequate, however the lane adjacent to the central median could be obscured by vehicles waiting to use the right turn into Canterbury Street north, from Main South Road eastern approach. Canterbury Street (north) is used for servicing the retail units on the old Mitre 10 site, and therefore heavy trucks could be expected to use this right turn with some frequency, which 34

35 would exacerbate the issues with visibility for vehicles waiting to U turn. Diversions See Options Assessment, Table 3 Options Matrix Additional Considerations. Options Assessment Safety Audit An options assessment safety audit has been completed for each of the 6 options. This has been included in Appendix 11. The number of issues identified for each option has been summarised below. Preferred Design Table 4: summary of options stage safety audit findings. The preferred Design has been identified as Option 3, pages 28, 29 & 30. Some minor changes have been made, to provide a 145 metre right turn lane from the Carmen Road approach to the intersection, and a 72m U turn bay at the Carl's Jr access. As discussed during the Option 3 scheme design, this is below the 85 th percentile and therefore the queue will extend out of this lane during the PM peak period. However this will only effect the eastbound flows, which experience lower volumes of traffic and less delay during this period. Broken yellow lines have also been added to enable the U turn at the fast food access. The central median has been altered so it is fully removed of planting to ensure adequate visibility between all vehicles / movements. The locations of the relocated Advanced Directional Signs have been altered to reduce the impact on the visibility of vehicles exiting Clock Tower Lane. The final location, or complete removal, of these signs will determined at the detailed design stage. Figure 21: Preferred Design. A scheme plan is attached in Appendix 12 Lighting Assessment A Lighting Assessment has been requested and will be presented project sponsor once received. Lighting assessment will attached in Appendix 13 once complete. 35

36 Safety Audit A safety audit has been completed as part of the options assessment. Designer responses will be provided to the concerns raised in the safety audit, and any alterations will be made to the scheme at the detailed design stage. The preferred design had 6 moderate issues identified, 4 minor issues and 1 comment. The project team have reviewed these risks and are satisfied that they can be addressed. The Safety Audit is attached in Appendix 11. Signatures Approved by Team Leader Approved by Sponsor Name and title of Signatories Signature Date P Burden 30/1/15 36

37 Appendix 1 Turning Counts 37

38 Appendix 2 - Christchurch Risk Map Outputs Personal Risk 38

39 Collective Risk 39