A465 Heads of the Valleys Sections 5 and 6: Dowlais Top to Hirwaun

Transcription

1 A465 Blaenau r Cymoedd A465 Heads of the Valleys Adrannau 5 + 6: Dowlais Top - Hirwaun Sections 5 + 6: Dowlais Top - Hirwaun A465 Heads of the Valleys Sections 5 and 6: Dowlais Top to Hirwaun March 2018

2 Contents 1. Introduction Commissioning and Scope Terms of Reference March 2018 Addendum Key Personnel Items Raised at this Stage 1 Road Safety Audit General Local Alignment Junctions Non-Motorised Users Signing and Lighting Road Safety Audit Team Closing Comments Appendix A. RSA1 Addendum Appendix B. RSA1 Team Closing Comments ii

3 1. Introduction 1.1 Commissioning and Scope This report is a Designers response to the findings of a Stage 1 Road Safety Audit carried out on the A465 Heads of the Valley Dualling Sections 5 and 6 at the request of the Welsh Government. The scheme comprises the widening and improvement of the A465 trunk road between Abergavenny and Hirwaun. The improvements will provide a continuation of the dual carriageway from the already constructed Section 4 at Dowlais Top to merge with the existing A465 dual carriageway to the east of Rhigos Roundabout in Hirwaun. The scheme covers a distance of approximately 17km and will predominately follow the existing line of the A465 with a 1.4km offline section to the south of Hirwaun. The scheme consists of the widening and dualling of the existing A465 between Dowlais Top and Hirwaun from a three-lane single carriageway to a dual carriageway with two lanes in either direction together with grade separated junctions including the junction with the A470 trunk road to the west of Merthyr Tydfil. 1.2 Terms of Reference The terms of reference of this Road Safety Audit are as described in HD19/15 Road Safety Audit. The Road Safety Audit Team has examined and reported only on the road safety implications of the scheme as presented and has not examined or verified the compliance of the designs to any other criteria. 1.3 March 2018 Addendum Following publication of Draft Orders for the A465 Sections 5 & 6 Scheme, a number of objections have been received. A number of these objections required the design team to produce and assess alternative design proposals. To consider road safety when preparing one of the alternative designs, the Welsh Government has requested an additional Stage 1 Road Safety Audit be undertaken supplementary to the original Audit undertaken. Additionally, where an objection was received and explicitly related to an issue of roads safety; observations were sought from the Road Safety Audit team. This additional phase of Stage 1 Road Safety Audit is summarised in Stage 1 Road Safety Audit Designer s Response Addendum included as Appendix A of this report. 1.4 Key Personnel Overseeing Organisation Project Sponsor Mark Dixon (Welsh Government) Road Safety Audit Team Audit Team Leader Kate Yeo (Jacobs UK Ltd, Operational Safety) Audit Team Member Daniel Trump (Jacobs UK Ltd, Operation Safety) Audit Team Member - Renata Barnes-Wright (Jacobs UK Ltd, Operation Safety) Design Organisation Design Team Leader Martin Sandwell (Jacobs UK Ltd, Principal Engineer) 1

4 2. Items Raised at this Stage 1 Road Safety Audit 2.1 General PROBLEM Location: Westbound A465 diverge and minor unnamed road linking to Merthyr Tydfil Road to south of Baverstock junction. Drawing reference: JAC-GEN-DR-HE Rev P02 Vicinity of Ch8,100. Summary: Proximity of roads could confuse drivers, and result in unexpected manoeuvres leading to collisions. The westbound A465 diverge runs adjacent to a minor unnamed road linking to Merthyr Tydfil Road to the south of Baverstock junction. During hours of darkness opposing drivers on the two roads will see headlights on their left-hand side. Drivers may not expect this when driving in the dark in the UK; approaching headlights are usually on the right. This could lead to driver uncertainty, swerving, or sharp braking if they believe drivers could be approaching on the wrong side of the road, which could result in rear end shunt or loss of control type collisions. Install appropriate measures to block opposing headlights, particularly between Chainages 8,075 and 8,500 and any other locations where roads run close, and parallel to each other. Agree: Installation of appropriate antiglare screening will need to be considered in Key Stage 6 during detailed design to mitigate any such occurrence as outlined in the above summary. It should be noted that for a significant length up to approximately Ch.8200 the proposed local connector road that runs parallel to the westbound diverge is 3m to 4m lower than the diverge, this is the case at the point where the two roads are at their closest, so the severity of the glare will be partly offset by the level difference. Where the two roads are at similar level the distance between the roads is approximately 18m minimum, which can be further mitigated by more sympathetic landscape screening or similar between the opposing roads PROBLEM Location: Westbound merge, to the west of the Hirwaun junction, at Chainage 1,310 Drawing reference: JAC-HRR-DR-HE Rev PO1 Summary Provision of a P1 road restraint terminal at the junction merge could result in vehicles breaching the vehicle restraint system (VRS), which could increase the severity of any collisions which occur. The drawings show the provision of a P1 terminal at the start of the VRS on the westbound carriageway, facing oncoming traffic at the slip road merge point. In the event of a vehicle failing to merge, or losing control of a vehicle on the mainline at this location, there is a risk that the P1 terminal will fail to protect any hazards and the design may cause an errant vehicle to breach the barrier; potentially causing it to launch, or overturn. Provide P4 terminals in this location. 2

5 Agree: All approach terminals on the trunk road network will be P4 to reflect the national speed limit applicable to the mainline, irrespective of the signed speed limit potentially being signed as 40mph on slip roads. Despite the slip road connector roads being designed to a design speed of 70kph, the positioning of signed speed limits do not necessarily correspond to the change in design speed criteria used for geometrical alignment. Therefore, using P4 terminals introduces a factor of safety to mitigate the potential lack of correlation in positioning the signed speed limit and or the higher anticipated transitional speed on both a merge and diverge connector slip road, where vehicle speeds are either gaining speed or decelerating when joining or departing from the mainline carriageway respectively. As part of the detailed design in Key Stage 6, the start of the VRS at this location should be reviewed in accordance with the requirements of TD 19 and the associated risk assessment process and if appropriate it should be extended further upstream from the merge point to mitigate against any potential breach of the VRS PROBLEM Location: Westbound carriageway of the A465, to the east of the Hirwaun junction Drawing reference: JAC-HRR-DR-HE Rev PO1 Summary: Insufficient protection of the water course may increase the risk of drowning in the event of a driver leaving the carriageway. From plans provided, the proposed VRS appears to commence at Chainage 2,400, although the water course appears to be still relatively close to the carriageway at this location. The alignment of the carriageway here takes the form of a shallow right hand bend, and there is concern that a vehicle leaving the carriageway here may be able to do so before the VRS commences, which could increase the severity of any loss of control collision, and could result in drowning if the water hazard is reached. Ensure that the VRS is sufficient to protect against the hazards in this location. Agree: The VRS provided will need to be sufficient to protect against the hazards at this location, which will be determined by the risk assessment process set out in TD 19 and refined to reflect the finalised detailed design during Key Stage 6. The containment level is N2, with an anticipated available Working Width between 1.0m to 1.3m (W3 to W4). The minimum full height length in advance of the hazard for N2 containment is 30m, which is currently achieved as illustrated in the preliminary design extract above. To clarify, the watercourse shown running parallel with the mainline on the plans, known locally as the Nant-Y-Bwlch, will be realigned in conjunction with the proposed drainage proposals, which currently 3

6 indicate that a trapezoidal cut off drain is located at the top of the proposed cut slope. The cut slope varies in height and is on average 2m to 3m high. The length of need over and above the minimum 30m will be assessed at detailed design during Key Stage PROBLEM Location: Baverstock Junction underbridge, to the north of the A465, and southern roundabout, on the two-way eastern arm to the east of the roundabout Drawing reference: JAC-HRR-DR-HE Rev PO1 Summary: VRS terminal may fail to protect road users sufficiently; which could increase the likelihood of overturning collisions in the event of a loss of control whilst exiting the roundabout. P1 terminals are proposed at the entry to the A465 eastbound merge at the northern roundabout, and on the nearside of the two-way link road to the east of the southernmost roundabout. In the event of a vehicle losing control whilst circulating or exiting at these locations, this VRS may fail to protect the vehicle occupants sufficiently, and may result in overturning and serious injury. Provide P4 terminals at these locations. Agree: Whilst P1 terminals are permissible in accordance with TD 19 on roads with a signed speed limit less than 50mph, each location needs to be risk assessed for need based upon the unique factors that influence the determination and or choice of provision required. In this instance and in the majority of situations it is highly likely that the decision to incorporate P4 terminals as a direct replacement for P1 terminals will prevail in order to minimise the potential risk of overturning. Provision of VRS on local authority highways is not necessarily provided strictly in accordance with the predominant risk based approach described and used in TD 19. Whilst TD19 is used as the Parent document and guidance for consistency the provision on the local highway network is usually carried out using a less onerous process as set out in Appendix 2 of TD 19 or as set out in alternative bespoke guidance adopted by the Local Highway Authority using a Risk Ranking process or similar. At some of these locations the provision is in close proximity to the boundary between trunk road and what effectively will be the adoptable section of highway by the Local Authority. The ultimate decision and choice will be determined in Key Stage 6 as part of the detailed design PROBLEM Location: A465 between Chainages 8,550 and 9,750 Drawing reference: JAC-HRR-DR-HE Rev PO1 Summary: Failure to provide VRS may result in vehicles leaving the road in the event of a loss of control, which could result in overturning collisions. From plans provided, it appeared that VRS is proposed on the south side of the A465 only, but the level difference appears greater on the north side. Failure to provide adequate protection for road users could result in vehicles leaving the road following a loss of control; resulting in overturning incidents and higher severity injuries. Provide adequate protection from roadside hazards. 4

7 Agree: The north side of the proposed A465 is indicating that the mainline is on embankment, which will undoubtedly require VRS following a detailed risk assessment. For the majority of the length quoted above there is a Private Means of Access (PMA), that is located parallel to the north of the proposed A465 and is at a lower elevation. In order to mitigate risk of an errant vehicle leaving the proposed mainline A465 and causing a secondary incident on the PMA a VRS will be provided at this location PROBLEM Location: Northernmost roundabout on the A470 at its junction with the A465: at and to the south of the eastbound A465 merge arm of the roundabout, and at and to the north of the westbound merge slip at the southernmost roundabout. Drawing reference: JAC-HRR-DR-HE Rev PO1 Summary Risk of vehicle launch or overturn in the event of a vehicle strike whilst circulating or exiting. It was noted that pairs of P1 terminals are proposed at each of the roundabout arms which form merges or diverges with the A465. However, the pair on the eastern side of the northernmost roundabout, and on the western side of the southern roundabout are located where they will be approached and passed by s circulating traffic, and vehicles exiting onto the A465 eastbound or westbound merge slips. In the event of a vehicle losing control in this area of the roundabout and striking the VRS, there is a risk of the vehicle launching or overturning, which could increase the severity. Provide a VRS which minimises the potential for vehicle launch or overturn in these locations. Agree: Whilst P1 terminals are permissible in accordance with TD 19 on roads with a signed speed limit less than 50mph, each location needs to be risk assessed for need based upon the unique factors that influence the determination and or choice of provision required. In this instance and in the majority of situations it is highly likely that the decision to incorporate P4 terminals as a direct replacement for P1 terminals will prevail in order to minimise the potential risk of overturning. Provision of VRS on local authority highways is not necessarily provided strictly in accordance with the predominant risk based approach described and used in TD 19. Whilst TD19 is used as the Parent document and guidance for consistency the provision on the local highway network is usually carried out using a less onerous process as set out in Appendix 2 of TD 19 or as set out in alternative bespoke guidance adopted by the Local Highway Authority using a Risk Ranking process or similar. At some of these locations the provision is in close proximity to the boundary between trunk road and what effectively will be the adoptable section of highway by the Local Authority. The ultimate decision and choice will be determined in Key Stage 6 as part of the detailed design PROBLEM Location: At the commencement of the A465 westbound merge slip, in the vicinity of Dowlais Top roundabout Drawing reference: JAC-HRR-DR-HE Rev PO1 Summary Risk of vehicle launch or overturn in the event of a vehicle strike whilst circulating or exiting. P1 terminals are proposed at the entry to the westbound merge, on both sides of the slip road. There is concern that these terminals may not perform as expected, and the risk of overturning a vehicle may be increased as a result of the ramp design of P1 terminals. 5

8 Provide a VRS which minimises the potential for vehicle launch or overturn in this location. Agree: Whilst P1 terminals are permissible in accordance with TD 19 on roads with a signed speed limit less than 50mph, each location needs to be risk assessed for need based upon the unique factors that influence the determination and or choice of provision required. In this instance and in the majority of situations it is highly likely that the decision to incorporate P4 terminals as a direct replacement for P1 terminals will prevail in order to minimise the potential risk of overturning. Provision of VRS on local authority highways is not necessarily provided strictly in accordance with the predominant risk based approach described and used in TD 19. Whilst TD19 is used as the Parent document and guidance for consistency the provision on the local highway network is usually carried out using a less onerous process as set out in Appendix 2 of TD 19 or as set out in alternative bespoke guidance adopted by the Local Highway Authority using a Risk Ranking process or similar. At some of these locations the provision is in close proximity to the boundary between trunk road and what effectively will be the adoptable section of highway by the Local Authority. The ultimate decision and choice will be determined in Key Stage 6 as part of the detailed design. 2.2 Local Alignment PROBLEM Location: A465 Eastbound diverge arm, on the approach to the Dowlais Top roundabout Drawing reference: JAC-GEN-DR-HE Rev P02 Ch 15,950 16,100 Summary: Realignment of the eastbound entry to the Dowlais junction reduces deflection on entry to the roundabout, which could increase the potential for inappropriate entry speeds, junction overshoots and loss of control collisions. The proposals include reconfiguration of the existing A465 eastbound carriageway such that the new mainline continues over the existing roundabout, and the existing A465 forms the eastbound diverge and eastbound entry arm to the Dowlais Top roundabout. To accommodate the eastbound, diverge, the entry arm to Dowlais Top roundabout is being relocated northwards. This change to the alignment results in a reduction in deflection on entry. When combined with a downhill approach to the roundabout, the potential for drivers to approach the junction at higher speeds than might otherwise be the case may be increased. This combination may increase the likelihood of junction overshoots or inappropriate entry speeds which may increase the potential for collisions, including loss of control, within the circulatory area. Provide an alignment which includes sufficient deflection to discourage high approach and entry speeds. Disagree: There are several influential factors that have dictated the line and level of the proposed Dowlais Top eastbound diverge. When the first section of the A465 (Section 4) was constructed circa 2004, the designer was instructed through the contract to develop and design an interim at grade junction to accommodate capacity for a defined Design Year post opening. As part of that design process and submission the designer was also required to demonstrate and evidence the future proofing of their interim layout to be reconfigured to facilitate full movement grade separation upon subsequent phased completion of the over A465 improvements. The layout that we are now trying to tie into is constrained by the design that was developed to current standards circa Whilst the principles of TD 16 have not changed significantly, there are a lot more mandatory requirements, however, the practice of good roundabout design using the philosophy 6

9 of Slow in Fast out are still relevant and every effort to meet these principles is always adopted where practicably possible. There is very little lateral flexibility for positioning the line of the diverge between the proposed A465 mainline and the existing boundary of Asda. Currently the design is based upon minimising the need for retainment between the mainline and the diverge. There is also the assumption that the proposed underbridges will have splayed wingwalls. There is scope to pull the diverge southwards closer to the mainline and lengthen the wingwalls along a line that follows the back of the proposed verge, which in turn would act as a retaining wall between mainline and diverge slip road, which would improve deflection and entry angle. The ability to arrive at a good roundabout design is all about achieving a balance of the influencing factors, not just in terms of design, environmental impact and cost, but primarily in respect of capacity and not least safety to achieve effective and efficient operational performance throughout the design life and beyond. Irrespective of forward visibility and circulatory visibility, the provision of approach visibility and visibility to the right at roundabouts is quite generous in accordance with TD 16. Excessive visibility with good deflection can also encourage high entry speeds. Whilst the horizontal and vertical alignment of the eastbound diverge is not conducive to reducing vehicular speeds the fact that the mainline alignment continues over the proposed Dowlais roundabout, means that the diverge elevation is at the lower level. The embankment from the mainline and location and aperture of the underbridge act as mitigation to slow vehicles speeds on the immediate approach as visibility to the right is completely physically blocked until vehicles reach the point where visibility is measured at 15m back from the give way line. We consider that the design achieves a good balance of the influencing factors and incorporates sufficient mitigation to regulate vehicle approach speeds PROBLEM Location: Prince Charles Hospital Junction, at the eastbound A465 merge. Drawing reference: JAC-GEN-DR-HE Rev P02 Chainage 13,350 13,500 Summary: Combination of horizontal and vertical alignment between the merge slip and mainline could increase the potential for merge conflicts. The eastbound A465 merge runs almost parallel to the mainline, with both approaching the merge on an uphill gradient. This may make it difficult for divers on both the slip road and the mainline to appreciate the road layout ahead and to see approaching traffic when merging. This could result in merging difficulties and side swipe type collisions whilst merging. It was noted that there are a number of Departures from Standard relating to obstructed stopping sight distance and below minimum standard horizontal and vertical curvature which are relevant to this safety concern: whilst the Audit Team acknowledged the site constraints associated with this scheme, it was considered that the combination of concerns at this particular location merits a revision to the design. Provide a merge layout which gives drivers sufficient time and visibility to merge safely. Disagree: Prince Charles Hospital junction is elevated above the mainline, and therefore the eastbound merge slip is on a downhill gradient of approximately 2% immediately on the exit from the proposed roundabout circulatory carriageway. The vertical alignment then bottoms out with a shallow sag before continuing eastbound on an uphill gradient of approximately 3% to match the mainline gradient. The vertical alignment on the mainline is compliant for the required design speed of 120kph with desirable minimum sag k=37 and crest k=182 curves. 7

10 The general arrangement drawing JAC-GEN-DR-HE contains the proposed mainline longitudinal section, which indicates that the vertical crest curve gradient does not exceed 3% in the immediate vicinity where merging manoeuvres take place. Due to the surrounding constraints and the desire to minimise the impact on the established built environment the horizontal alignment incorporates a reverse curve comprising a right hand and left hand 510mR, which would normally represent a permissible two design speed step relaxation below the desirable minimum horizontal radius of 1020m, provided desirable minimum stopping sight distance was achievable. The challenges of locating a full movement grade separated junction in such a heavily constrained corridor have resulted in a reduction in standards below the desirable minimum recommended in the Design Manual for Roads and Bridges. The objective we have adopted from the outset is consistency in any standard reduction incorporated into the scheme proposals. Where possible we have aimed to achieve a fully compliant vertical alignment with the exception of a couple of isolated locations. The compliance in vertical alignment is directly related to achieving compliance in the vertical stopping sight distance. The compromise and reduction in standard is primarily related to the achievement of stopping sight distance in the horizontal plane due to cross sectional restrictions imposed by roadside features and furniture and or the use of radii below the desirable minimum 1020m. We consider the proposals for this junction achieve a balance of reduction in standards below desirable minimum values that reflect the surrounding constraints without being potentially detrimental to the overall operational safety or performance of the improvements. Whilst the exact details of any departures from standard have not yet been fully analysed, the final acceptability of the specifics will be subject to an independent review and assessment by Welsh Governments Technical Review Panel PROBLEM Location: Prince Charles Hospital Junction, Gurnos Ring Road arms. Drawing reference: JAC-GEN-DR-HE Rev P02 Chainage 13,100 13,250 Summary: The proposed realignment of the Gurnos Ring Road to create two new roundabout arms could increase the potential for loss of control collisions on the Ring Road approaches. The proposals include the incorporation of the Gurnos Ring Road into the Prince Charles Hospital Junction. This route currently runs parallel, and to the south of, the A465, with no direct connections. The revised layout will result in two arms of the roundabout being very close together, with sharp deflection on entry. The Gurnos Ring Road is very straight along most of its length, which could increase the likelihood of inappropriate approach speed choices, and may introduce a see-through effect between the two Gurnos Ring Road arms. The combination of these three factors could result in loss of control collisions on the immediate approaches to the roundabout. Provide appropriate measures to reduce the potential for see-through between the Gurnos Ring Road arms, and encourage slow approach speeds. Agree: Enhanced mitigation will be required at this location due to the change in configuration, this will need to include signing and lining in accordance with TSRGD (2016) in conjunction with new road layout ahead signage to be installed on the approaches to warn motorists of the roundabout. Further mitigation should be considered in Key Stage 6 by the detailed designer to prevent the through visibility creating the perception to drivers that the road is continuous. This can be achieved through implementation of some soft estate planting and or landscaping. Due to the physical constraints of connecting the existing Gurnos Ring Road into the proposed circulatory carriageway, some of the recommended geometrical criteria outlined in TD 16 are not achievable, however, where departures from standard are required 8

11 these will be discussed with the relevant local highway authority before being submitted as part of the overall scheme proposals to Welsh Governments Technical Review Panel PROBLEM Location: Eastbound approach to northern roundabout at A465/A470 junction. Drawing reference: JAC-GEN-DR-HE Rev P02 Chainage 10,350 10,700. Summary: The alignment may reduce forward visibility, which could result in rear end shunt collisions at the back of any queue to enter the junction. This is the major interchange of the route, with the A470 providing the main means access to areas to the south, and as such would be expected to cater for higher volumes of traffic than other interchanges. The eastbound A465 diverge is located on a sweeping left hand curve on a downhill gradient on approach to the roundabout. When drivers enter the diverge they may be unable to see the give way line as a result of vertical and horizontal alignment. Drivers may approach the end of queue of traffic at an inappropriate speed which may result in rear end shunt collisions. It is recommended that appropriate, timely, measures are provided to alert approaching drivers to the potential presence of queueing vehicles on the slip road. Agree: Signing and lining in accordance with TSRGD (2016) will need to be incorporated on the approaches to warn motorists of the proposed roundabout. As with all grade separated junctions designed in accordance with TD 22, the design speed criteria applicable to the diverge connector road is applicable downstream from the back of the diverge nose. Careful consideration and coordination needs to be given to the siting of the corresponding signed speed limit (40mph) to reflect the change in geometrical design speed parameters. This should also include any change in the x heights for the approach signage. Notwithstanding this there may also be a need to consider a further reduction in speed to capture the lowest signed speed limit (potentially 30mph) on any of the other local highway network connector roads that enter exit the roundabout as explained in Welsh Governments Circular Roads 1/93 and DfT Circular 01/2006. This coordination will need to be carried out in Key Stage 6 during detailed design. Our current proposals include for a two lane diverge as determined by the traffic flows. The actual diverge connector road is well in excess of 0.5km in length downstream from the back of the diverge nose. The diverge vertical alignment is on a downhill gradient circa 7.5% downstream of the point it leaves the mainline, which exceeds the desirable maximum recommended in TD 9, but does not constitute a departure from standard unless it exceeds 8%. The horizontal alignment between the chainages referenced above is compliant with a design speed of 70kph. It should be noted that the 360mR is desirable minimum and to achieve the required desirable minimum stopping sight distance we have allowed for a verge width inclusive of hardstrip circa 3.5m allowing for a VRS with W2 working width. It is considered that the clear downhill visibility and length of diverge combined with compliant horizontal alignment and stopping sight distance for a 70kph design speed affords sufficient reaction time for drivers to act accordingly and appropriately should the issue of queuing traffic occur PROBLEM Location: South eastern section of the southern roundabout at the Baverstock junction. Drawing reference: JAC-GEN-DR-HE Rev P02 Vicinity of Chainage 7,850. 9

12 Summary: Successive changes in horizontal alignment on entry to the roundabout could increase the potential for poor lane discipline and side swipe conflicts whilst circulating. The geometry of this section of the roundabout is such that drivers entering the roundabout from the east on Swansea Road (linking to Merthyr Road) are required to deflect sharply to the left on entry in and then to the right in order to remain in lane whilst circulating. It is possible that drivers may take a more direct line when negotiating this section of the roundabout, resulting in poor lane discipline, inappropriate circulating speeds, and an increased risk of side swipe conflicts. The downhill approach to the roundabout from the east may exacerbate this problem, and increase the severity of any collisions which occur. Install appropriate measures on this approach to, and within the circulatory area of, the roundabout to encourage appropriate entry and circulatory speeds, and to encourage good lane discipline whilst circulating. Agree: Appropriate measures such as good signage and road markings, will need to be installed to mitigate and regulate entry and circulatory speeds. In addition, lane delineation by way of line marking and destination demarcation should be considered at Key Stage 6 during detailed design to encourage and promote good lane discipline. To clarify, the proposed roundabouts at this location have been subject to further geometric changes following subsequent revisions to the traffic model and resultant traffic flows. Swept path analysis has also been undertaken to identify any potential issues with movements at this location discussions with the relevant Local Authorities are ongoing and the details of any departures from standard are yet to be presented and discussed with the appropriate representatives within the local Highway Authority PROBLEM Location: A465: Eastbound approach to the proposed layby at Chainage 3,550 3,800 Drawing reference: JAC-GEN-DR-HE Rev PO2 Summary: Restricted forward visibility as a result of the vertical alignment on the eastbound approach to the layby exit may result in unsafe exit manoeuvres resulting in collisions. It was noted from plans that a layby is proposed along a stretch of carriageway which is downstream of a crest. The vertical alignment restricts forward visibility, and a proposed departure to reflect the one step below minimum Stopping Sight Distance (SSD) to the layby merge is included in the list of relaxations and departures submitted to the Audit Team. Although sign drawings have been provided to the Audit Team as part of this Stage 1 submission, these did not include any signs associated with laybys. In the absence of appropriate signs, drivers approaching the crest may not be aware of the upcoming layby, and drivers using the layby may have difficulties choosing safe gaps to exit because of the visibility restriction, which could increase the potential for rear end shunts between drivers exiting the layby, and following vehicles. Provide adequate visibility for drivers exiting the layby, and provide appropriate signs in advance of the layby. Agree: The physical siting of laybys on this scheme has been extremely difficult and compliance with TD 69 is almost impossible. Due to the strategic nature and prominence of this route and the likely use by long distance drivers, especially from the ports in the west heading to the midlands and onwards to the ports in the east the need for laybys is fundamental. This layby is located on the eastbound 10

13 carriageway and sandwiched between the proposed Pentwyn footbridge and the proposed Afon Cynon underbridge. Albeit the mainline vertical alignment is on a crest curve, it is a desirable minimum k=182 curve for a 120kph design speed, which directly corresponds to the achievement of the required desirable minimum stopping sight distance of 295m in the vertical plane. Whilst the crest curve is on the immediate approach to the layby, it is compliant and it is on a continuous downhill gradient on the approach to the layby, so will afford good visibility. The departure of one design speed step reduction in standard for stopping sight distance relates to the offside lane, achievable to the face of the VRS in the central reserve and relates to a reduction from 295m to 215m in the horizontal plane. This is a worst case scenario from an eye height between 1.05m and 2.0m in the centre of the offside lane to a target height of 0.26m in the centre of the offside lane at a minimum distance of 215m apart. In order to achieve this the central reserve has been widened over and above the desirable minimum 2.5m excluding hard strips. In respect of visibility for vehicles exiting the layby, this is a slightly different issue. In a worst case scenario visibility from a vehicle on the immediate approach to the layby in the offside lane to a vehicle exiting the layby in the vicinity of merge area exceeds the desirable minimum distance of 295m, therefore combined with a compliant stopping sight distance in the vertical plane, we consider that the visibility for the purposes of existing the layby and vehicles being able to see vehicles exiting meets the requirements. The issue of the reduction in stopping sight distance on the immediate approach to the layby is born from the definition that a layby is defined as a junction, hence the reduction constituting a departure from standard, which will form part of the departures submission to Welsh Governments Technical Review Panel. In support of this, we are currently preparing a detailed Technical Note to outline the proposed strategy and rationale for the provision of laybys through the entire scheme. Appropriate signing and lining in accordance with TSRGD (2016) will be provided at Key Stage 6 during the detailed design PROBLEM Location: A465: Eastbound approach to the proposed layby at Chainage 11,650 11,900 Drawing reference: JAC-GEN-DR-HE Rev PO2 Summary: Location of layby on the inside of a shallow left hand bend on an uphill gradient could make it difficult for drivers to see the layby diverge, which could result in sudden braking and rear end shunt collisions. The layby is to be located on the inside of a shallow left hand bend on an uphill section of the A465 to the east of the Taf Fechan Viaduct. There is concern that drivers approaching the layby may be unable to identify the start of the diverge in time to reduce speed sufficiently in order to enter the layby safely, which could result in sudden braking and an increased potential for rear end shunt collisions at the entrance to the layby. It was noted that a proposed Departure from Standards is reported for the approach to the layby diverge, as a result of the SSD being restricted by the nearside VRS, but it is further noted that the uphill gradient may assist with braking. Provide appropriate signs to ensure that drivers are aware of the presence of, and distance to, the upcoming layby. Agree: Appropriate signing and lining in accordance with TSRGD (2016) will need to be provided at Key Stage 6 during detailed design. The immediate approach across the Taf Fechan viaduct is relatively flat. The layby elevation immediately east of the viaduct is approximately 4m above the level of the viaduct deck. In addition, the actual parking bay area is approximately 9m higher than the viaduct deck 11

14 level and is on embankment, all these factors including compliant signing and distance signs on the immediate approach to the layby should provide drivers with sufficient information and reaction time to utilise the layby if required. It is also worth noting that further developments have been looked at in terms of the viability of retaining the existing structure and the potential future maintenance liabilities that may or may not be realised with a blended (existing and new) structure. As a result, a number of solutions have been considered and at the moment the proposal is to have an over-widened Taf Fechan viaduct structure to accommodate removal and subsequent replacement of the existing structure without compromising to the resilience of the network by having to close the A465. The over-widened structure will also afford greater stopping sight distance and visibility to the nearside on the immediate approach to the layby PROBLEM Location: A465: Westbound approach to the proposed layby at Chainage 11,870-12,200 Drawing reference: JAC-GEN-DR-HE Rev PO2 Summary: Downhill approach to the layby diverge from a crest at the Gurnos Farm underpass may result in sudden braking at the layby entrance, and rear end shunt collisions. It was noted from plans that a layby is proposed along a downhill stretch of carriageway which is downstream of a crest. Forward visibility is restricted by the nearside VRS and a proposed departure to reflect the one step below minimum SSD to the layby merge is included in the list of relaxations and departures submitted to the Audit Team. Although sign drawings have been provided to the Audit Team as part of this Stage 1 submission, these did not include any signs associated with laybys. In the absence of appropriate signs, drivers approaching the crest may not be aware of the location of the proximity of the upcoming layby, and may brake suddenly as a result. This could result in rear end shunts with following vehicles. Provide appropriate driver information signs in advance of the layby. Agree: Appropriate signing and lining in accordance with TSRGD (2016) will need to be provided at Key Stage 6 during detailed design. As mentioned previously the siting of laybys has been very challenging and the number of departures on the scheme associated with the laybys, along with the supporting Technical Note will be submitted to Welsh Governments Technical Review Panel for consideration. 2.3 Junctions PROBLEM Location: Hirwaun junction circulatory area Drawing reference: JAC-GEN-DR-HE Rev P02 and JAC-HSN-DR-HE Rev P03 Summary: Layout of the junction could enable circulating vehicles to drive at high speed whilst circulating, which could increase the potential for loss of control incidents at the northern and southern ends of the roundabout. The proposed revised Hirwaun junction is a large grade separated junction with eight arms, although these are clustered at the northern and southern ends, where the radius reduces. The size of the junction and distance between the southern and northern arms could result in drivers travelling at excess speed on the circulatory area. This could result in loss of control collisions or vehicles overturning as 12

15 they enter and try to negotiate the tighter radii at the northern and southern ends of the junction. This is more likely to affect high sided vehicles. Although the Audit Brief defined the proposed speed limits which will be applicable to the A465 mainline, slip roads and side roads, there was no confirmation of the proposed speed limits on this or other junctions within the scheme. In addition, although the proposed map-type Advance Direction Signs (ADS) suggest a non-circular layout of the roundabout, these signs do not appear to provide an accurate representation of the junction layout ahead. Implement an appropriate speed limit on the junction to enable safe circulation, along with supplementary measures to ensure drivers are aware of the change in radius in sufficient time to adjust to it. Agree: As with all grade separated junctions designed in accordance with TD 22, the design speed criteria applicable to the diverge connector roads is applicable downstream from the back of the diverge nose. Careful consideration and coordination needs to be given to the siting of the corresponding signed speed limit (40mph) to reflect the change in geometrical design speed parameters. This should also include any change in the x heights for the approach signage. Notwithstanding this there may also be a need to consider a further reduction in speed to capture the lowest signed speed limit (potentially 30mph) on any of the other local highway network connector roads that enter / exit the roundabout as explained in Welsh Governments Circular Roads 1/93 and DfT Circular 01/2006. The proposed speed limit at Hirwaun junction will be subject to agreement by the relevant Local Authority, but is expected to match that of the lowest speed connector road (30mph). Consideration of road marking lane delineation and demarcation of destinations may be beneficial to help mitigate the change in radius. This coordination will need to be carried out in Key Stage 6 during detailed design. The signing proposals have been reviewed due to ongoing changes to junctions, the point in respect of accurate representation of the roundabout ADS map sign is noted and will be refined accordingly at Key Stage 6 during detailed design PROBLEM Location: Junction leading to Gurnos Farm, Gurnos Ring Road. Drawing reference: JAC-GEN-DR-HE Rev P02 Chainage 12,300 12,350 Summary: Poor visibility in the vicinity of the proposed junction could result in side impact collisions. The proposals include the relocation of an existing priority junction south westwards, closer to an existing left hand bend. The relocated junction may not be sufficiently visible for eastbound drivers approaching from the south west on the Gurnos Ring Road as a result of the combination of the left-hand bend, and dense vegetation on the north side of Gurnos Ring Road. Although lightly trafficked, speeds may be high on this link, and the potential for side impact collisions involving drivers pulling out of the side road into the path of drivers approaching from the south west could be increased. 13

16 Locate the junction in a location where adequate visibility can be provided.. Disagree: The location of the junction is determined primarily by ability to get sufficient headroom to pass under the changes to the vertical alignment for the proposed mainline. Once this was established a suitable horizontal and vertical alignment for the private means of access to Gurnos Farm had to be developed, which presented further challenges due to the nature of the existing topography. The land between the existing access bellmouth and the proposed junction for Gurnos Farm is identified as Title on the Orders, hence there will be scope to potentially move the junction access slightly closer to its existing location if the required visibility is not achievable. Junction visibility checks to TD42/95 have yet to be finalised, but will be presented to the relevant Local Authority for comments. If there are any compliance issues these will be identified and actions agreed accordingly. Whilst the location of the junction has been fixed at this stage of the design, the potential to reconfigure it within the land taken as Title, is an option to be considered at Key Stage 6 during detailed design. In addition, there are further mitigation measures than can be considered in terms of low level planting to improve visibility on approach to the junction from the south west, localised traffic calming and signing to emphasise the presence of the junction. 2.4 Non-Motorised Users PROBLEM Location: Baverstock junction. Drawing reference: JAC-GEN-DR-HE Rev P02 Vicinity of Chainage 8,100. Summary: Alteration of equestrian route may result in inappropriate crossing movements and collisions involving equestrians. The NMU Context Report identifies a north/south conflict point for equestrians travelling to the riding area of Penmoelallt to the north of Baverstock junction. In order to access Penmoelallt from the minor road which makes up the southern arm of the southern Baverstock roundabout requires crossing the carriageway three times, increasing the risk of collision with a vehicle. The existing route used by local equestrians will be altered substantially and will no longer be safe for them to use. This could result in equestrians attempting to cross at inappropriate locations which could lead to conflicts between equestrians and traffic on the A465. It is recommended that crossing facilities are provided to allow equestrians based to the south of the A465 to access the riding areas located north of the A

17 Agree: Uncontrolled equestrian crossing facilities have been provided within the design to allow equestrians based in the south of the A465 to access the riding areas located north of the A465. The number of crossings have been minimised. The location of these crossing facilities is shown in the extract from drawing JAC-GEN-DR-HE Rev P02 below. 2.5 Signing and Lighting PROBLEM Location: Slip roads throughout the scheme. Drawing reference: Various. Summary: Failure of vehicles on the slip road to match the speed of mainline traffic may experience difficulties merging, which could result in side swipe conflicts and rear end shunts at the merge point. Section 2.4 of the audit brief states that the A465 entry slips will be subject to a 40mph speed limit, but it is unknown where the speed limit terminals will be. If these are located near the mainline it gives drivers a short distance to accelerate and match their speed to mainline vehicles. This is especially pertinent for entry slips with an uphill gradient, and where large goods vehicles are present. If drivers are unable to match the speed of mainline traffic, merging difficulties could lead to shunt type collisions on the slip road or side swipe collisions in the vicinity of the merge point. Although traffic signing would normally be considered at detailed design stage, the Audit Team were provided with a set of Series 1200 drawings which included all direction signing, and so it was considered relevant to raise this signing-related problem at Stage 1. It is recommended that the National Speed Limit/40mph speed limit terminates at the start of all entry slips. Agree: As with all grade separated junctions designed in accordance with TD 22, the design speed criteria applicable to the merge connector road is applicable downstream from the back of the merge 15

18 nose. The geometrical criteria used for the merge up to the back of the merge nose is based upon a design speed of 70kph, which equates to a signed speed limit of 40mph, which includes a small marginal factor of safety. In theory the national speed limit is not appropriate until vehicles reach the back of the nose. It is an anomaly that is inherent within the design standards, that in reality is not strictly adhered to due to physical constraints and issues highlighted in the problem above. The difficulty comes when a merge or diverge connector road utilises tighter horizontal and vertical curvature akin to a 70-kph design speed criteria, but has not got the corresponding 40mph signed speed limit appropriately placed or not signed at all. Careful consideration and coordination needs to be given at Key Stage 6 during detailed design to the siting of the corresponding signed speed limit (40mph) to reflect the change in geometrical design speed parameters and the physical constraints imposed by the scheme proposals and existing topography. This should also include any change in the x heights for the signage subject to applicable signed speed limit PROBLEM Location: Prince Charles Hospital Junction, south-western section of circulatory area. Drawing reference: JAC-GEN-DR-HE Rev P02 Chainage 13,100 13,200 Summary: The western arm of the Gurnos Ring Road and the westbound A465 merge arm of the roundabout are closely spaced in the south-western section of the roundabout, and circulating drivers may confuse the Gurnos Ring Road exit with the westbound A465 merge. Such confusion could cause sudden braking and late lane changes, resulting in side swipe conflicts and rear end shunts within the circulatory area. Beyond the roundabout, drivers who have exited incorrectly may be involved in collisions on the Gurnos Ring Road, as a result of attempting inappropriate U turning manoeuvres. Ensure that flag type direction signs provided at the exit to the Gurnos Ring Road are clearly visible to approaching drivers. Agree: Careful consideration will need to be given to the proposed signing strategy and the complexities of the junction layouts. The appropriate signage relating to this junction will need to be located so it is clearly visible to approaching drivers on the circulatory carriageway. This will need to be reviewed at Key Stage 6 during the detailed design PROBLEM Location: On both approaches to the Hirwaun roundabout junctions Drawing reference: JAC-HSN-DR-HE Rev PO3 Summary: Stack type signs may be misleading for motorists, which could result in last minute lane changes and unexpected manoeuvres resulting in rear end shunt collisions. It was noted from the 1200 series drawings provided that stack type signs are proposed for supplementary (predominantly tourist and industrial) destinations on the approaches to the Hirwaun roundabout. These are shown below. 16

19 Although corresponding flag type signs are provided on the exits from the roundabout, there may be potential for drivers to find it difficult to equate the signs to a complex roundabout layout. As a result, the potential for last minute lane changes or braking at the exits may be increased, which could result in collisions. On the eastbound approach to the junction, the highest potential for confusion may be for drivers differentiating between the two destinations signed left. A related item concerning the design of lorry route signs has been raised in the covering letter. Provide a sign layout which enables drivers to easily comprehend which exit is required for each tourist or industrial site destination. Agree: The stack signs will need to be refined at Key Stage 6 during detailed design. Again this will need careful consideration to ensure clarity for approaching drivers PROBLEM Location: Croesbychan junction: for traffic approaching the roundabout to the south of the A465 Drawing reference: JAC-HSN-DR-HE Rev PO3 Summary: Drivers following signs to the Crematorium may be unsure as to which way to turn at the second roundabout, which could result in hesitation and rear end shunt collisions. For drivers exiting the A465 towards the Crematorium at this dumbbell junction, direction signing is provided to guide motorists under the A465 to the second roundabout. However, only a flag-type sign is provided here, which may not be visible to motorists entering the roundabout. Drivers may be unsure how to proceed, which could result in hesitation and rear end shunts at the roundabout. Provide adequate signing for drivers travelling towards the crematorium. Agree: Appropriate signing in accordance with TSRGD (2016) will need to be reviewed and incorporated at Key Stage 6 during detailed design, which may include the addition of a map type ADS on the approach to the southern dumbbell roundabout as motorists pass under the proposed A465 mainline PROBLEM Location: Baverstock junction Drawing reference: JAC-HSN-DR-HE Rev PO3 Summary: Signing between the two roundabout junctions is misleading, which could result in incorrect manoeuvres, including head on collisions. 17

20 For drivers travelling towards the roundabout to the south of the A465, a stack type sign is provided (TS055 B) which directs drivers to only two of the possible exits. There are two concerns with this proposal, as follows: Drivers travelling to Llwydcoed may inadvertently attempt to take the first left, which is an exit slip. This could result in driver hesitation and rear end shunts whilst circulating, The destinations associated with the left and right arrows appear reversed: the Gellideg exit is to the left, rather than to the right of the roundabout. This could result in drivers positioning themselves inappropriately when entering the roundabout, which could result in sudden lane changes and side swipe conflicts whilst circulating. For drivers travelling towards the roundabout to the north of the junction, there is no supplementary guidance provided, other than a flag-type sign at the exit. More generally, it may not be clear to drivers using this exit that the road layout comprises two roundabouts, as this is not reflected in the map type signs provided. Provide signs which accurately reflect the road layout and destinations to be reached from these roundabouts. Agree: Stack type destinations should be reversed. There is insufficient room to fit additional map type signs and additional flag type signs to guide traffic to the appropriate exit. A double roundabout ADS was considered, but has not been used due to the number of destinations and complexity of these signs, which may be confusing to drivers. A more detailed review of the signing provision in this area will need to be carried out at Key Stage 6 during detailed design and appropriate changes incorporated accordingly PROBLEM Location: Eastbound approach to the A465/ A470 Junction, on the main A465. Drawing reference: JAC-HSN-DR-HE and Rev PO2 Summary: Lack of continuity of tourist and lorry route signing at the junction could result in inappropriate manoeuvres, sudden braking or lane changes, and rear end and side-swipe collisions. From the 1200 series of plans provided, sign references TS073 and TS077A provide advance information to drivers regarding tourist and lorry signing destinations which can be reached by exiting the A465 at the next junction. However, there is only one further lorry route sign, and no further tourist signs at all at the junction. In the absence of continuous signing, and flag type signs to indicate the correct exit for drivers, the potential for driver confusion and unexpected manoeuvres could result in collisions involving circulating drivers. A related item, concerning the connections between the A465 and the A470 south, has been raised in the covering letter which accompanies this Road Safety Audit. Provide clear and continuous signing through this junction to enable drivers to find routes to tourist and lorry route destinations. 18

21 Agree: The proposed signing strategy needs to incorporate more continuity to mitigate driver confusion. In addition to the proposed signing strategy there also needs to be continuity with regards to the consequential (existing) signing strategy, in that it reflects the proposed changes being introduced as a result of the improvements to the A465. Careful coordination and consideration for the overall signing strategy, both proposed and consequential PROBLEM Location: Roundabouts to the east of the Gurnos junction Drawing reference: JAC-HSN-DR-HE Rev PO2 Summary Sign designs may be difficult for drivers to assimilate in time, which could result in driver confusion, hesitation and an increased potential for collisions. Map type signs TS104, TS105, TS114, TS111, TS116 and TS117 suggest a roundabout layout ahead, but provide no indication that the layout comprises two closely associated roundabout junctions. There appears to be insufficient space between the junctions to provide additional directional information between the junctions, and so will be reliant on the flag type signs at exits. This could result in sudden braking and last minute manoeuvres, resulting in collisions. Provide signs which accurately reflect the road layout and destinations to be reached from these roundabouts. Agree: The layout of the proposed junction at this location presents challenges in terms of signing. It is likely that there will be departures for the reconfigured connector roads at this junction, which have yet to be discussed with Merthyr Tydfil County Borough Council. As part of the mitigation we anticipate that careful consideration will need to be given to the overall signing for the roundabout and immediate approaches, entries and exits. Further consideration will need to be incorporated at Key Stage 6 during detailed design. 2.6 Road Safety Audit Team Closing Comments Subsequent to the original issue of this report on 8 th January 2018, further comments have been received from the Road Safety Audit team in response to the above designer team responses. These comments are collated in Appendix B of this report. 19

22 Appendix A. RSA1 Addendum 20

23 Memorandum Churchill House Churchill Way Cardiff, CF10 2HH United Kingdom T +44 (0) F +44 (0) Subject Stage 1 Road Safety Audit - Project Name Designer's Response - Addendum A465 Heads of the Valley Dualling Sections 5 & 6 Attention M. Sandwell Project No. B D From S. Burke Date March 7, 2018 Copies to D. Sallis 1. Background This note provides an addendum to the A465 Heads of the Valley Dualling Sections 5 and 6 Stage 1 Road Safety Audit Designer s Response (Document Ref. B D issued by Jacobs in January Following publication of Draft Orders for the A465 Sections 5 & 6 (herein referred to as the Scheme), a number of objections have been received. A number of these objections required the design team to produce and assess altermative design proposals. To consider road safety when preparing these alternative designs, the Overseeing Organisation (Welsh Government) has requested a Stage 1 Road Safety Audit (RSA1) be undertaken supplementary to the original RSA1. Additionally, where an objection was received and explicitly related to an issue of road safety; observations were sought from the Road Safety Audit team. Information was issued to the Road Safety Audit Team piecemeal (i.e. as each of the alternative options was assessed), and responses from the Audit Team received likewise. This Road Safety Audit Designer s Response addendum summarises the additional information issued to, and observations made by, the Road Safety Audit Team subsequent to the original Stage 1 Road Safety Audit. Please select a legal entity from the Change Document Details option on the Jacobs ribbon B D

24 Memorandum Stage 1 Road Safety Audit - Designer's Response - Addendum 2. Items raised subsequent to the Stage 1 Road Safety Audit 2.1 Vale of Neath Railway Footbridge Summary The location of the published Vale of Neath (VoN) Footbridge is located at approximately Ch to Ch , approximately 0.75km south west of the proposed grade-separated junction at Croesbychan. The published version of the NMU footbridge over the Vale of Neath railway allowed for a shared use path to the north of Swansea Road which connects to and uses an existing shared driveway for the properties around Ger-y-bont. The actual footbridge crossing - square to the alignment of the VoN railway - was to be located to the east Ger-y-bont. Following objections subsequent to the publication of the draft Orders, a potential alternative location for the proposed footbridge has been explored by the design team (Ref. Figure 1 for details). The alternative proposal aligns the proposed footbridge much closer to and parallel with the proposed A465 mainline. Figure 1 Alternative Vale of Neath Footbridge Location 1 All Scheme chainage reference the mainline, centre line unless stated otherwise. Units are in metres. B D