INTRODUCTION

1. At its meeting on 14 January 2004 the Chandler’s Ford and Hiltingbury Local Area Committee agreed to adopt the following motion from Councillor Mrs Wellfare: -

“In view of the concern expressed by local residents, this Area Committee requests that officers upgrade the North Millers Dale Traffic Survey, scheduled for North Millers Dale, to a full Road Traffic Management Study and provide recommendations for measures designed to deter rat running and reduce the speed of traffic using North Millers Dale Road”

2. A traffic study was completed in February 2005 and its findings were reported to Members of the Committee at a recent team meeting also held in February 2005 at which Members agreed to allocate further funding to the preparation of a feasibility study into the provision of traffic calming measures in North Millers Dale.

3. North Millers Dale is a local distributor road running between Hursley Road and Baddesley Road, serving a residential estate. The road is of a width of between 6.8m and 7.0m and is of a modern layout in keeping with the design principles of Design Bulletin 32, with many of the side roads benefiting from traffic calming measures intended to enforce a ‘slow speed’ regime. The road is a subject to a 30mph speed limit due to the presence of a system of streetlighting and footways are present along the full length of the road. There are numerous junctions along the road at regular intervals and in general little direct residential frontage.

4. This feasibility study has arisen from concerns being raised regarding the speed at which traffic travels through North Millers Dale and the amount of through traffic using the road to avoid queuing at the Baddesley Road / Hursley Road traffic lights.

5. The traffic study concluded that speeding traffic is a problem in North Millers Dale, particularly in the western half of the road where 85th percentile speeds were recorded in excess of 40mph. It also found that a high percentage of vehicles used the road as a through route during the morning peak hour with 77 per cent of vehicles from Baddesley Road to Hursley Road being through traffic and 63 per cent from Hursley Road to Baddesley Road. These figures significantly reduce in the afternoon peak hours to 30 per cent in both directions.

6. Two traffic surveys were undertaken in North Millers Dale as part of the traffic study with Speed Detection Radar recorders located to the south of the Ashbridge Rise and The Tanyards junctions. There are large discrepancies in the average 5 day weekday peak hours measurements between the two sites which makes it difficult to accurately confirm whether traffic flows are tidal, but it would appear that traffic flows are higher in the direction from Baddesley Road to Hursley Road in the morning, and in the opposite direction from Hursley Road to Baddesley Road in the afternoon. However, the overall traffic flows were found to be relatively light for the road and the low numbers of recorded personal injury accidents demonstrate that flows are not of major concern in terms of safety.

OPTIONS CONSIDERED FOR IMPLEMENTATION

Vertical Deflection Measures

7. The choice of vertical deflection traffic calming measures that can be used in North Millers Dale is restricted by several factors. The main consideration is due to the road being a bus route. Bus companies are likely to object to the use of full width road humps or road tables along the length of the road due to the possibility of discomfort being caused to passengers. Another consideration is the need to maintain unimpeded emergency access. The use of full width vertical measures causes delay to emergency vehicles and in the case of the ambulance service can be of detriment to patient care. Emergency access is particularly important in North Millers Dale as it is the distributor road for the estate and traffic can only enter and leave by the road.

8. The only vertical deflection measures that therefore would appear to be appropriate for installation in North Millers Dale are speed cushions. Their suitability is enhanced by low levels of parking occurring in the road and the carriageway being of a width that allows speed cushions to be installed whilst still maintaining appropriate width transverse gaps. The use of speed cushions forms the proposal shown as ‘Option 1’.

9. Option 1 – Speed Cushions
Drawing no. E/EC/173/001 included as Appendix A, shows a proposed traffic calming scheme comprising of speed cushions along the length of North Millers Dale. Consideration has been given to maintaining spacings between cushions of around 70m to 80m wherever possible to achieve mean speeds of approximately 26-27mph as indicated in TAL 1/98 – Speed Cushion Schemes. It would be intended to use speed cushions conforming to the Hampshire County Council standard drawing detail constructed from macadam surfacing and being of a height of 75mm overall. A width of 1.7m is proposed and to draw drivers attention to the cushion it is proposed to finish the cushions in a red coloured surfacing material.

10. To break the continuity of speed cushions throughout the length of North Millers Dale consideration could be given to the provision of junction tables in isolated locations with the spacings of the cushions amended. However, this would significantly increase costs and would be subject to the agreement of the bus operator and emergency services who may object to this type of measure.

11. A scheme consisting of speed cushions would be required to meet the requirements of the Highways (Road Humps) Regulations 1999 including illumination requirements. Being a modern estate the lighting levels in North Millers Dale are likely to meet the relevant illumination levels contained within the Regulations and observation of the site indicates that the columns are spaced within the 38m maximum spacing allowed by the Regulations. However, the final decision as to whether any upgrade to the streetlighting is necessary rests with the County Council.

12. The installation of speed cushions in North Millers Dale is likely to achieve a substantial reduction in traffic speeds, particularly in the western half of the road contributing to an environmental improvement as well as a safety improvement. Although not as effective as full width road tables speed cushions are likely to be more effective than horizontal deflection measures in terms of reducing traffic speeds over the full length of the road.

13. In addition to enabling buses to straddle the cushions, the gap between each nearside kerb and the cushion can be used by cyclists. This is advantageous as North Millers Dale may be considered for inclusion as part of an advisory cycle route between Valley Park and Hiltingbury. However the gaps also enable motorcyclists to pass between the cushions and so are less effective at slowing these vehicles, although the use of the road by motorcycles has not been raised as a problem.

14. Experience suggests that despite the speed reductions that can be achieved with speed cushions many residents remain opposed to the introduction of these types of measures simply due to the discomfort that can be caused along with other factors such as vehicle body rattle noise and ground borne vibrations.

Horizontal Deflection Measures

15. Option 2 – Chicanes
Drawing no. E/EC/173/002 included as Appendix B, shows locations in North Millers Dale where chicanes could be implemented as part of a traffic calming scheme. The areas in which chicanes can be placed are restricted by the geometry of the road which shortens forward visibility. Four locations in the road have been identified as meeting the stopping sight distance criteria of 70m corresponding to a 30mph speed limit, as stated within Design Bulletin 32.

16. Chicane design can vary enormously and for the purposes of carrying out this feasibility study and preliminary design a typical example of the layout that could be expected to be found in a local distributor road such as North Millers Dale has been illustrated. Chicanes are formed of two or more buildouts on opposite sides of the road causing a difficult route for vehicular traffic through the chicane resulting in a reduction of traffic speeds. TAL 9/94 – Horizontal Deflections, provides guidance on chicane design including the important elements of ‘free view width’ and ‘stagger length’ together with the expected traffic speeds that can be expected depending on the dimensions selected.

17. For example, to achieve a reduction in traffic speeds to approximately 20mph within a chicane a moderate design is shown with a ‘free view width’ of 0.0m and a stagger length of 12m. The ‘free view width’ is the horizontal distance between the two buildouts forming the chicane and is usually of a measurement between +/-1.0m and the stagger length is the longitudinal distance between the buildouts. It would be possible to vary these dimensions if any particular concerns were raised at consultation stage, however it is thought that this design would provide a reasonable compromise between the severity of the measure and inconvenience caused to motorists.

18. It is possible to incorporate cycle by-pass lanes within the chicane design, however the proposed positions of the chicanes will require the bus stop sited opposite Weavers Place to be re-sited northwards by approximately 20m. This will require consultation with the bus operator however as the current stop is located opposite a junction relocating the stop will actually prove beneficial on safety grounds and is not likely to cause a problem to the operator.

19. Chicanes are likely to prove very effective in reducing traffic speeds in North Millers Dale around the sites they are located. Due to the geometry of North Millers Dale chicanes or other priority working measures can not be installed in long lengths of the road and in particular around the bend between The Deanery and Weavers Place. This could lead to sustained acceleration and deceleration between the chicanes causing a nuisance to local residents and it is therefore suggested that if the installation of chicanes were to be pursued in the road that they are not implemented in isolation of other measures. Additionally, chicanes are sometimes viewed as a challenge by drivers resulting in reckless behaviour. Unlike other horizontal deflection measures, it is also recommended that pedestrian crossing facilities are not included within chicanes as drivers are likely to be concentrating on negotiating the chicane rather than looking out for pedestrians.

20. The visual appearance of chicanes can be very important in residential areas. The paving material forming the buildouts could be varied to a more attractive finish to offset the urbanisation that occurs through additional signing and roadmarkings. However, although no longer calculated in scheme evaluation, in terms of a cost benefit ratio, the rate of return lessens significantly if more costs are added to the scheme with no additional safety measures incorporated into the design. Nevertheless it would be appropriate to give careful consideration to the choice of materials in a chicane design to minimise the intrusive nature of such measures.
21. Option 3 - Priority Working
Drawing no. E/EC/173/003 included as Appendix C, shows a scheme consisting of single buildouts with priority working. These have been located in similar positions as the chicanes due to the restricted visibility in North Millers Dale. A buildout has been shown shortly after entering each end of North Millers Dale with priority for vehicles leaving the estate to persuade drivers to travel at a moderate speed along the road and this is supplemented along the straighter sections of the road by the use of buildouts in close proximity to each other to achieve reduced speeds on the approach to each bend.

22. Single sided buildouts with priority working have proved to be effective in controlling traffic speeds however their effectiveness in North Millers Dale may prove to be limited compared to more severe measures such as vertical deflection measures or chicanes. Their success relies heavily upon comparable two way flows to ensure that drivers concede priority to oncoming vehicles thereby reducing traffic speeds. A similar problem arises as ‘Option 2’ due to the road geometry limiting the positions where measures can be placed and resulting in the spacings being longer than would normally be employed with more favourable road geometry. Again this could result in sustained acceleration and deceleration between the measures.

23. Pedestrian crossing points may be incorporated into the design of single buildouts and where possible buildouts have been sited at established crossing points within the design of this option. Cycle by-pass lanes can also be included within the design. Three bus stops will require relocation to avoid stationery buses blocking the path for other vehicles past the narrowing.

Suitability of horizontal deflection measures in North Millers Dale

24. Unlike vertical deflection measures, the success of horizontal deflection measures, and particularly single sided buildouts with priority working as a traffic calming scheme is much more dependant on existing traffic conditions and the ‘after’ effects of implementation. TAL 12/97 - Chicane Schemes, provides some advice on suitable traffic flows in which horizontal measures are likely to prove effective. It recommends following Danish advice of a maximum of 3000 vehicles per day (vpd) and a maximum of 600 vehicles per hour (vph). Additionally, experience of such schemes has demonstrated that opposing traffic flows should have a difference of no more than approximately 20%. Traffic flows in North Millers Dale have been measured as part of the traffic study and record traffic flows well within the maximum flows suggested.

25. The traffic study measured the average weekday traffic flow at 1691vpd at the site south of Ashbridge Rise and 2589 vpd at the site north of The Deanery, with corresponding maximum hourly flows of 423 vph and 488vph. However it should be borne in mind that morning peak flows are substantially higher than at any other time of the day, and outside of peak hours traffic flows in the busier eastern part of North Millers Dale fall to around 110 vph and in the less busy western section of North Millers Dale flows fall to around 70 vph. Experience suggests that it is possible to achieve around a 10-20% reduction in traffic flows following the implementation of traffic calming and therefore flows could be expected to fall further. This is of concern when considering ‘Option 3’ as the success of the scheme may be limited by the lack of opposing traffic flow resulting in drivers travelling through North Millers Dale with only small reductions to their speed occurring only when passing the measure.

26. Option 4 – Pinch-Points and Pedestrian Refuges
Drawing no. E/EC/173/004 included as Appendix D, shows a scheme consisting of pinch-points placed at regular intervals along North Millers Dale and two pedestrian refuges located either side of Stratfield Drive.

27. Due to the geometry of North Millers Dale it is proposed to use the pinch-points as regular road narrowings but without priority working. A narrowing to 5m could be implemented to allow two way traffic to be maintained but require drivers to reduce their speed to negotiate the narrowing.

28. A similar scheme to this option has recently been implemented by Hampshire County Council in Maunsell Way, Hedge End, a local distributor road which has similar design characteristics as North Millers Dale. For safety purposes it would be intended to place bollards with reflective banding on the leading edge of each side of the buildout and where appropriate incorporate dropped kerbs to enable pedestrians to cross taking advantage of the reduced carriageway width.

29. Pedestrian refuges can be provided each side of Stratfield Drive utilising the extra highway width at this point that forms part of the visibility splay. Based on a 2.0m wide pedestrian refuge carriageway widening of approximately 1.2m will be required. This would leave a running lane width of 3.1m plus 150mm sideways clearance from the refuge. The widening can be formed from within the existing verge separating the footway and carriageway. Elsewhere in North Millers Dale the restricted highway width and difficult alignment does not allow pedestrian refuges or traffic islands to be implemented without the acquisition of third party land.

30. This option is unlikely to cause problems for cyclists as the 5m carriageway width at the pinch-point will allow vehicles to pass clear of cyclists. Two bus stops will require relocating a short distance away to avoid a stationery bus obstructing the pinch-point.

31. It is important to stress that this combination of measures is unlikely to achieve such a reduction in traffic speeds as ‘Option 1’ or ‘Option 2’ but should ensure that a modest reduction in traffic speeds can be realised throughout the length of North Millers Dale.

Other measures considered for implementation

32. Option 5 – Roadmarkings
A further option that could be considered is the implementation of a revised roadmarking scheme in North Millers Dale. Currently the road is marked with warning lines throughout the length of the road with lane lines marked between The Tanyards and Cranford Gardens and is typical of the arrangement that could be expected to be found on local distributor roads.

33. Drawing no. E/EC/173/005 included as Appendix E, shows a scheme that could be implemented to narrow the perceived width of the carriageway by removing the centre line throughout the road and introducing a continuous edge of carriageway line offset from each kerbline by approximately 0.65m to form a 5.5m main carriageway. It is suggested that centre warning lines are retained through each junction to provide a warning of the hazard. To segregate traffic around the bend between The Deanery and Weavers Place where visibility is reduced it is proposed to introduce central hatching leaving 3.0m wide running lanes.

34. Research has demonstrated that the narrower drivers perceive a carriageway, the greater the likelihood is that they will drive slower and more cautiously. However, it is important to stress the limitations of roadmarking only schemes and the level of speed reduction that could actually be achieved is likely to be small when compared to physical measures. It may therefore be appropriate to include this scheme as a supplement to a scheme consisting of physical measures.

35. Junction Realignment
Drawing no. E/EC/173/006, included as Appendix F shows a proposed realignment of the North Millers Dale / Hursley Road junction that could be implemented to supplement the other works along the length of North Millers Dale. It is proposed to remove the acceleration and deceleration lanes which do not conform to current design guidance and which give the impression that the road is of a higher importance than it actually is. A radius of 10m is suggested in accordance with advice contained within Design Bulletin 32. This will enable cars and light goods vehicle traffic including refuse vehicles and buses to use the junction without obstructing other road users.

36. Within the junction realignment it is proposed to realign the footway adjacent to the carriageway and convert the redundant footway to verge to improve the appearance of the junction. To reduce costs it would be possible to remove the deceleration lane only and leave the kerbline of the acceleration lane as it currently exists, hatching out the carriageway to give the impression of a reduction in carriageway space although this may be open to abuse by drivers over-running the hatching.

37. To emphasise the junction narrowing and the entry into a residential area gateway signing could be installed with a road safety message. A good example of this arrangement can be found locally at each end of Peverells Wood Avenue. To further highlight the gateway a change in road surfacing material is suggested.

38. The junction of North Millers Dale and Baddesley Road, which falls outside of the Borough boundary, although a ‘simple’ layout does not have the same kerb alignment as the Hursley Road junction. The radii of the junction would appear to measure approximately 15m and given that that the junction has a good safety record and that there is less through traffic from this end of the road it is suggested that this junction alignment remains as it currently is. However, it is recommended that gateway signing is introduced with different paving material to signal the entry into the road and a change to a residential environment from Hursley Road and Baddesley Road.

39. Displacement of Traffic
Experience suggests that traffic calming schemes achieve approximately a 10-20% reduction in traffic flows along a route. The reality is that this traffic is generally displaced onto other routes as few drivers choose to switch transport modes with the implementation of traffic calming on one road only other than possibly for very short local journeys.

40. The main reason drivers use North Millers Dale as a through route is to avoid queuing at the Baddesley Road / Hursley Road traffic lights. Given that the traffic study measured a considerable difference in times between the two routes it is possible that traffic flows after the installation of traffic calming may not be reduced as much as normally achieved. However, as the traffic study concluded that the main problem in North Millers Dale was inappropriate traffic speeds, despite the high percentages of through traffic measured from the origin and destination surveys, it would appear that if it was possible to introduce a scheme to reduce traffic speeds in North Millers Dale then the main concern would be addressed.

COST ESTIMATE

41. Estimated total scheme costs are listed below: -

42. Costs have been broken down to include separate costs for the pinch-points and pedestrian refuges shown as ‘Option 4’, and for the junction realignment and gateway / entry feature shown as ‘Option 6’. This is to allow for the possibility of either removing these measures from the scheme option or including them within another option.

43. The costs identified with ‘Options 2 and 3’, and the pedestrian refuges forming part of Option 4 have been costed based on the provision of base lit bollards. It may be possible to significantly reduce these costs if non-illuminated flexible bollards were to be used, however, this would depend on the final design of the physical measures and whether Hampshire County Council would approve their use.

44. The fees have been costed at 20% of the works plus contingency cost, with an additional £1000 added to each option due to the extensive nature of the consultation required for such schemes.

45. The costs identified do not include for the possibility of service diversions. C2 notices will be sent to statutory undertakers at design stage. An initial observation of the site indicates that service diversions are unlikely to be necessary with any of the proposals shown with the exception of the carriageway widening required for the implementation of the pedestrian refuges shown in ‘Option 4’.

46. A safety audit of the favoured scheme proposals will be required before and after installation of any of the options shown. As an Eastleigh Borough Council funded scheme, a fee of £350 will be payable for Hampshire County Council to carry out the audit.

CONCLUSIONS

47. From the options presented, it is likely that in terms of meeting the Committee’s objectives of reduced traffic speeds, ‘Option 1’ is the most likely to be effective. However, experience suggests that the more severe a scheme is and therefore the greater the speed reduction achievable, the greater the opposition may be to the scheme proposals.

48. ‘Option 2’ is also likely be an effective choice of traffic calming in terms of speed reduction although the long spacings between the measures around the bend between The Deanery and Weavers Place could result in sustained acceleration and deceleration rather than drivers travelling at a constant speed that measures placed at regular intervals would encourage.

49. ‘Option 3’ is unlikely to be as successful in reducing traffic speeds as ‘Option 2’ due to the large differences in opposing traffic flows which are likely to result in drivers rarely having to concede priority to oncoming vehicles outside of peak hours. However, the inclusion of pedestrian crossing facilities at the buildouts would improve pedestrian access around the estate.

50. Due to the large differences in opposing traffic flows which may cause priority controls to be less effective than normal, ‘Option 4’ could be pursued if horizontal deflection measures were to be prove more favourable than vertical measures with the local community. Although a scheme of this type would allow traffic to remain free-flowing the regular spacing of measures and the need to negotiate each should result in a moderate reduction in traffic speeds, although not as significant as Options 1 and 2. It is worth noting that the pedestrian refuges shown could be incorporated into other scheme options.

51. ‘Option 5’ has been included within this report as an alternative scheme to physical measures and to provide a further option should the implementation of physical measures be opposed by the local community. Realistically, the speed reduction benefits will be limited and rely heavily on drivers perceiving the road to be narrower than it actually is and therefore travelling more cautiously.

52. The realignment of the North Millers Dale / Hursley Road junction and the introduction of gateway signing would be beneficial in changing driver’s perception of the status of the road and the ease at which they can enter and exit the estate. Additionally, the gateway signing will help to reinforce the message that drivers are entering a traffic calmed residential area along which they may encounter pedestrians and cyclists and should therefore drive responsibly.

53. Comparing the costs of each scheme together with their likely effectiveness, overall it is difficult to recommend any option for progression other than speed cushions, particularly when the horizontal deflection measures ideally need supplementing with further measures in between. Speed cushions could be placed throughout the length of North Millers Dale to ensure drivers maintain a constant speed along the road avoiding excessive acceleration and deceleration and would be the least expensive scheme to implement. The scheme would not unduly compromise the bus or emergency services and also be cycle friendly. In view of these advantages it is recommended that of the proposals shown within this feasibility study investigating possible traffic calming options in North Millers Dale, then ‘Option 1’ be considered to be the favoured option.

APPENDICES

· Appendix A – Drawing no. E/EC/173/001 - Option 1, Speed Cushions
· Appendix B – Drawing no. E/EC/173/002 - Option 2, Chicanes
· Appendix C – Drawing no. E/EC/173/003 - Option 3, Priority Working
· Appendix D – Drawing no. E/EC/173/004 - Option 4, Pinch-Points and Pedestrian Refuges
· Appendix E – Drawing no. E/EC/173/005 - Option 5, Roadmarkings
· Appendix F – Drawing no. E/EC/173/006 - Junction Realignment and Gateway Signing
Dated: April 2005