M9/A90/M90 Edinburgh to Fraserburgh Trunk Road. A90 Tealing. Moving Cursor Programme Junction Study

Transcription

1 A90 Tealing Moving Cursor Programme Junction Study This is an unpublished report prepared for the Transport Scotland, Trunk Road and Bus Operations Division (TRBO) and must not be referred to in any publication without the permission of TRBO. The views expressed are those of the author(s) and not necessarily those of TRBO CLIENT: Transport Scotland Buchanan House 58 Port Dundas Road Glasgow G4 0HF PREPARED BY: BEAR Scotland Ltd. Inveralmond Industrial Estate Inveralmond Road Perth PH1 3TW March 2012

2 Page: 1 Name Organisation Signature Date Prepared By Ross Fletcher BEAR Scotland Ross Fletcher 02/04/12 Checked By Bob Blair BEAR Scotland Bob Blair 16/04/12 Authorised By Alan Campbell BEAR Scotland Alan Campbell 23/04/12 REVISION STATUS REV. Date Revision Details Checked Authorised CONTROLLED DOCUMENT HOLDERS Ref. Name of Holder 1 BEAR 2 Transport Scotland

3 Page: 2 Contents Page 1 Introduction 3 2 Background 3 3 Site Description / Existing Environment 4 4 Accident History / Analysis 7 5 Improvement Options 10 6 Inveraldie Junction 15 7 Recommendations 17 8 Conclusion 18 Appendices Appendix A Injury Accident Details Appendix B Damage Only Accident Details Appendix C Accident Drawings Appendix D Chi 2 Analysis Appendix E Standard Drawing Central Reserve Treatments Appendix F First Year Rate of Return Calculation

4 Page: Introduction 1.1 Bear Scotland has been commissioned by Transport Scotland to undertake a safety review of the A90 trunk road at Tealing Junction. 1.2 The study will analyse accident records within the study area and the existing road network infrastructure to identify issues which are adversely affecting road safety within the study area. 1.3 The study aims to identify accident trends within this junction. These can then be used to identify possible remedial measures to help to reduce the number of accidents occurring. A prioritised list of road safety improvements will then be identified and recommended to Transport Scotland. 2.0 Background The Moving Cursor Program, operated by Transport Scotland, identified this location on the A90 trunk road at Tealing Junction as meeting the minimum criteria for investigation.

5 Page: Site Description & Existing Environment The A90 in this location is a strategic traffic route linking Tayside and Central Scotland with Aberdeen and the North East of Scotland. This is a staggered junction on the A90 trunk road approximately 4 kilometres north of the city of Dundee. A local road (C6) crosses through the A90 in this location linking the settlement of Tealing on the west side of the A90 with the travelling peoples site and Tealing Garage on the east side of the A90. Location Plan The northern junction within the stagger is known locally as the Tealing junction. The southern junction within the stagger is known locally as the Newbigging junction. For clarity this report will therefore address the northern junction as the Tealing junction and the southern junction as the Newbigging junction. The speed limit in this section is 70mph and the alignment and visibility on the A90 within this section is good. There are two bus lay-bys within the site. One on the northbound A90 just north of the staggered junction and one on the A90 southbound in the middle of the staggered junction. Both bus stops have raised bus boarder kerbing and a bus shelter.

6 Page: 5 There is a footway on the northbound A90 for the full length of the staggered junction. This is link to the bus lay-by on the southbound A90 with an uncontrolled crossing with dropped kerbs and a staggered barrier layout to negotiate the central reserve barriers. There is no property with direct access onto the A90 in this location. The traffic flows on this section of the A90 are approximately 12,000 (AADF) in each direction (Total two way AADF 24,000). The percentage of HGV is approximately 17%. The map overleaf gives a summary of all the features described above:

7 Page: 6 Forfar N Tealing Travelling People Site C6 Tealing junction A 90 C6 Tealing Garage Newbigging junction Dundee

8 Page: Accident Analysis 4.1 Injury accident details from 2007 to 2011 have been reviewed and are contained in Appendix A and B. The time period analysed has been extended to 5 years from the 3 year period which was initially used to identify this location in the moving cursor programme. This is because the accident patterns have continued over the subsequent two years and it is thought to be prudent to include these additional accidents and give a more holistic view of the accident patterns in this location. Of the 8 accidents that occurred in the vicinity of this junction, 75% (6) involved a vehicle emerging from a side road and turning right. Five of these accidents were involving vehicles emerging from the C6 on the east side of the A90 and turning right onto the northbound A90. 38% (3no.) of the accidents within the scheme extents involved drivers that were aged This is higher than the national average which is 25% (Reported Road Casualties Scotland 2010, Table 18a.) 38% (3no.) of the accidents within the scheme extents involved drivers that were aged 60 and over. This is higher than the national average which is 11.8% (Reported Road Casualties Scotland 2010, Table 18a.) Of the 8 injury accidents that occurred in the vicinity of the junction, 2 (25%) occurred during wet road conditions. This is far less than the national average proportion of wet road injury accidents (38% - Reported Road Casualties Scotland 2010, Table 7.) One of the 8 injury accidents (13%) occurred during the hours of darkness. This is a lower than the national average proportion of darkness injury accidents (28%) - Reported Road Casualties Scotland 2010, Table 7.) 4.2 Chi2 tests were carried out on possible patterns identified through analysis of the injury accident records. This statistical test helps to identify whether an overrepresentation of an accident type, against control data, is due to site specific issues or random fluctuation. The control data used for this particular analysis was taken from Reported Road Casualties Scotland Tests identified a very high level of confidence that there are site specific reasons for accidents involving right turning manoeuvres and an acceptable level of confidence that there are site specific reasons for accidents involving drivers aged 60 and over. No other relevant trends were highlighted by the analysis. A summary of the analysis undertaken is presented in Appendix C.

9 Page: 8 The accident times have been analysed and plotted to show any trends. This, as expected, has shown that the accidents are more likely to occur around peak times when traffic flows are at their highest. At this time drivers will have to show more patience to wait for a safe gap in the traffic and are more likely to take risks and turn right onto the A90 when there is not a safe gap in the traffic. Accident Times 00:00:00 22:00:00 20:00:00 18:00:00 EVENING PEAK 16:00:00 Time of Accident 14:00:00 12:00:00 10:00:00 08:00:00 Series1 06:00:00 MORNING PEAK 04:00:00 02:00:00 00:00: Accident Number 4.3 It is clear from the accident analysis that there is an issue at this location with vehicles making the right turn manoeuvre. From the accident plot in appendix B it is clear that vehicles emerging from the Newbigging junction present most significant road safety risk. For consistency however, it is recommended that any treatment provided is also provided to the Tealing junction. The accident analysis also indicates that there may be an issue with elderly drivers using these junctions. This should be considered when implementing any accident remedial measures.

10 Page: SCRIM data has been obtained from webseris. This shows that generally the carriageway skid resistance is above investigatory levels other than the northbound approach to the Tealing junction and the southbound approach to the Newbigging junction: A plan showing the processed SCRIM summary None of the 8 injury accidents involved a vehicle skidding. This demonstrates that the skid resistance of the carriageway is not a contributory factor in the accidents that are occurring at this location. Improvement of the skid resistance would therefore not provide a return in accident savings in this location. On visual investigation of the road surface at this location there does not appear to be any polishing in the wheel tracks or other signs that there is a skidding resistance issue in this area. Surface course treatment is therefore not recommended at this time. The site will, however, continue to be monitored through the annual moving cursor programme.

11 Page: Improvement Options 5.1 Problem Identified: There is a traffic sign in the central reserve immediately to the south of the Newbigging junction that is blocking visibility for traffic emerging form the side road and turning right on the northbound A90. The location of this issue coincides with the majority of the accidents involving right turning vehicles (6 / 7). A photograph looking south and showing the sign. Possible Solution: The sign should be removed and relocated out with the visibility splay for this junction. This will improve the visibility for vehicles emerging from the Newbigging junction and turning right.

12 Page: Problem Identified: The advanced directional signing (ADS) on approach to the junction from both north and south on the A90 does not give warning to drivers that they are approaching a staggered junction where there is likely to be right turning traffic emerging. Existing ADS on approach to this junction Possible Solutions: a. Provision of new map type ADS showing the true staggered junction layout. Example of map type ADS that could be used b. Provision of Vehicle Activated Signs on the A90 on approach to the junction warning road users when there is a vehicle emerging onto the A90 from a side road*. Example of VAS signage that could be used c. Provision of a standard hazard marker post / bollard layout at both of the gaps in the central reserve to highlight the presence of the junction to road users (See Appendix D). *This option would be subject to approval of a non-standard sign by Transport Scotland.

13 Page: Problem Identified: Signing on approach to the A90 from Tealing on the C6 local road is poor and does not give drivers a clear indication that they are approaching a high speed dual carriageway. Photograph from the C6 local road looking east towards the A90. Possible Solution: a. Replace the existing give way signs with new signs of a consistent size and to correct mounting height with advanced warnings that drivers are approaching a dual carriageway. Examples of revised give way signage b. Install a cross with care sign opposite the junction to encourage drivers to wait for a safe gap before turning right onto the A90*. Example of cross with care sign *This option would be subject to approval of a non-standard sign by Transport Scotland.

14 Page: Problem Identified: Similar to the issue described above, signing on approach to the A90 from Newbigging on the C6 local road is poor and does not give drivers a clear indication that they are approaching a high speed dual carriageway. Photograph from the C6 local road looking west towards the A90 Possible Solution: a. Replace the existing give way signs with new signs of a consistent size and to correct mounting height with advanced warnings that drivers are approaching a dual carriageway. Examples of revised give way signage b. Install a cross with care sign opposite the junction to encourage drivers to wait for a safe gap before turning right onto the A90*. Example of cross with care sign *This option would be subject to approval of a non-standard sign by Transport Scotland.

15 Page: Problem Identified: Two diagram 610 keep left arrows are not lit. These should be lit as per the Traffic Signs Regulations and General Directions. Existing diagram 610 sign not lit Possible Solution: Replace sign and provide lighting supply and lighting unit to sign. 5.6 Problem Identified: Various signs are at incorrect mounting height. Most notably the signs in the vicinity of a junction which should be mounted at a minimum of 2 metres to maximise visibility for road users. Example of incorrect mounting height Possible Solution: Replace signage at incorrect mounting height with new signs to correct mounting height and with high reflectivity (micro prismatic) to ensure they are clearly visible and no not impede visibility at these junctions.

16 Page: Inveraldie Junction 6.1 Concerns have been raised by the local community regarding road safety on the A90 at Inveraldie. Alan Campbell (BEAR Scotland Ltd.) met representatives of the local community and Insp. Grant Edward of Tayside Police on the XXXXXX to discuss this issue. As a result this study has been extended to include the Inveraldie junction. 6.2 A further meeting was then held on the 19 th April 2012 between Ross Fletcher (BEAR Scotland Ltd.) and Insp. Grant Edward of Tayside Police to discuss which improvements would be practical, affordable and beneficial in this area. The main discussion points and recommendations are summarised below: 6.3 On approach from the south on the northbound A90 the junction is not very visible. There are large trees adjacent to the junction on the west side which block visibility of the junction and the directional sign for northbound traffic. Photographs looking north showing the poor visibility of the junction It is therefore proposed to replace the existing signs with larger signs with a more appropriate x-height for this location. The signs will also be re-located into the correct positions in the central reserve. This will prevent future issues with the tree growth obstructing visibility of the signs.

17 Page: The existing advanced directional signage for southbound traffic on the A90 is not well positioned. It is too close to the junction and does not give drivers enough prior warning that they are approaching a junction. It is also at the wrong mounting height. Photograph looking south showing ADS and its close proximity to the junction It is proposed to replace the southbound advanced warning sign with a new sign in a more appropriate location at the correct mounting height. The sign will be moved further north and located in the verge. This will give southbound road users more advanced warning that they are approaching a junction. 6.5 To highlight the presence of the junction further it is recommended to install a standard bollard and hazard marker post layout. These are shown in appendix D. 6.6 The recent accident history ( ) for this location has been researched. This has highlighted only one injury accident at the Inveraldie junction (25/05/2009). This was on the southbound A90 and involved a vehicle striking an animal therefore it cannot be attributed to the junction layout. The improvements will not therefore provide a measurable accident saving in this location, however the improvements are relatively minor (approximate cost 3,000) therefore it would be prudent to implement these improvements at the same time as the Tealing junction improvements. This will provide consistency in signing on this section of the A90 and address the concerns of the local community.

18 Page: Recommendations It is recommended that a complete sign revision is carried out at this location. This will include: Removal of the sign discussed in 6.1 from the central reserve. This will improve visibility for road users emerging from the Newbigging junction and turning right. Provision of map type ADS as part of the overall sign revision as discussed in 6.2b. This will give A90 road users a clear indication of the road layout ahead. Provision of a standard central reserve gap treatment as discussed in 6.2c. This will highlight this junction and the gap to road users on the A90. Provision of improved give way signage as part of the overall sign revision as discussed in 6.3a and 6.4a. This will ensure that drivers on the C6 from both directions are well informed of the road layout ahead. Provision of a CROSS WITH CARE sign opposite the side roads at both the Tealing junction and the Newbigging junction. This will give a strong message to road users wishing to turn right that they should wait for a safe gap and cross with due care (as part of the overall signing revision). Replacement of the existing diagram 610 signs at the central reserve gaps and ensuring that they are all lit as per the current legislative requirements (as part of the overall signing revision). Replacement of all signs that are in the vicinity of the junction and are not at the correct mounting height. This will ensure that all traffic signs are at a consistent mounting height and are not blocking the visibility of road users. The estimated cost of these proposals is 36,000 for construction and the first year rate of return is 143%. The revision of signage throughout the staggered junction will also aid elderly drivers in this location (drivers over 60 was one of the common trend identified in the accident analysis). It is known that drivers over the age of 60 can often take longer to process the information available through traffic signage. It will therefore be of great benefit to clarify the signage provided and ensure it si of a consistent standard. The proposal for VAS on the A90 on both approaches to this location has been considered. It is thought that since there are significant other signing improvements that can be made in this location, the VAS should not be included at this time. It is recommended that the VAS is retained as a further option if the above recommendations do not yield that desired accident reductions. It is proposed to install the improvements at Inveraldie junction as discussed in section 6 of this report.

19 Page: Conclusion It is recommended that the proposals discussed in 7.0 are implemented in 2012/13. It is believed that these proposals will give clarity on the road layout ahead to road users on the A90 and also ensure that road users on the side road approaches to the A90 are well informed of the dual carriageway ahead. The site will continue to be monitored through the Moving Cursor Programme and should the desired accident savings not be achieved then a further review should be carried out with a view to installing Vehicle Activated Signage.

20 Appendix A Injury Accident Details

21 Appendix B Damage Only Accident Details

22 Appendix C Accident Drawings

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25 Appendix D Chi Squared Analysis

26 Ross Fletcher 09/03/12 11/NE/0805/278 A90 Tealing Chi Squared Analysis All NE Dual Carriageway Accidents as Control Site single Control Chi Sq significance Confidence Interpretation All Accidents Serious/Fatal Slight Dark Non Dark Single Vehicle Non Single Vehicle Casualty age Non Casualty age Casualty age Casualty age Pesdestrian casualty collisions Non Pesdestrian casualty collisions Pesdestrian casualty 0 35 collisions (0-16 child) Non Pesdestrian casualty collisions (0-16 Involving Agricultural 0 40 vehicles Non Involving Agricultural vehicles Involving All goods vehicle Non Involving All goods vehicle Involving All moped and motorcylce Non Involving All moped and motorcylce Involving Pedal Cycle 0 59 Non Involving Pedal Cycle Road surface wet/damp Non Road surface wet/damp Involving Right Turn manouvres Non Involving Right Turn manouvres not significant # # 0.38 not significant # # 0.85 not significant # # 0.03 not significant # # % 95% Acceptable 0.00 not significant # # 1.16 not significant # # 0.92 not significant # # 0.85 not significant # # 0.05 not significant # # 0.42 not significant # # 0.49 not significant # # % 100% Definite!!!

27 Ross Fletcher 09/03/12 11/NE/0805/278 A90 Tealing Chi Squared Analysis All NE Accidents as Control Site single Control Chi Sq significance Confidence Interpretation All Accidents Serious/Fatal Slight Dark Non Dark Single Vehicle Non Single Vehicle Casualty age Non Casualty age Casualty age Casualty age Pesdestrian casualty collisions Non Pesdestrian casualty collisions Pesdestrian casualty 0 28 collisions (0-16 child) Non Pesdestrian casualty collisions (0-16 Involving Agricultural 0 37 vehicles Non Involving Agricultural vehicles Involving All goods vehicle Non Involving All goods vehicle Involving All moped and motorcylce Non Involving All moped and motorcylce Involving Pedal Cycle 0 45 Non Involving Pedal Cycle Road surface wet/damp Non Road surface wet/damp Involving Right Turn manouvres Non Involving Right Turn manouvres not significant # # 0.61 not significant # # 0.91 not significant # # 0.03 not significant # # 1.14 not significant # # 0.02 not significant # # 1.97 not significant # # 1.30 not significant # # 0.91 not significant # # 0.01 not significant # # 0.94 not significant # # 0.99 not significant # # % 100% Definite!!!

28 Appendix E Central Reserve Treatment Drawings

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30 Appendix F FYRR for Recommended Treatment Treatment: Revision of junction signage and provision of central reserve treatment at Tealing junction. No of injury accidents at this location: 8no. ( ) Cost of proposals: 36, Cost of Design: 5, Total Scheme Cost: 41, %FYRR = Annual Collision Savings * 100 Scheme Cost Annual Collision Reduction = 30% (Table 5.1 RoSPA Road Safety Engineering Manual) = 0.3 * 8 accidents = 2.4 accidents => Accidents saved per year = 2.4 / 5 = 0.48 accidents. Average Injury Accident Cost = 122,490 (Table 10 of Reported Road Casualties Scotland 2010) => Annual Collision Savings = 0.48 * 122,490 = 58, %FYRR = * = 143%