Meeting documents

EEC/10/125/HQ

North Devon Highways and Traffic Orders Committee

29 June 2010

Report on Proposed Speed Limit at Portmore Roundabout

Report of the Area Engineer (North)

Recommendation: It is recommended that no speed limit is advertised at this time.

1. Summary

The report outlines alternatives considered to the proposal for a 40mph buffer speed limit on the A361 North Devon Link (NDL) approach to Portmore roundabout at Barnstaple.

2. Background

A report recommending approval to advertise a 40mph speed limit was considered by the North Devon Highways and Traffic Orders Committee on 3 December 2009. Members did not support the proposed Traffic Order and the resolution of the Committee was for the Area Engineer (North) to investigate and report back on alternatives to the proposed scheme.

3. Alternatives

The proposal for a 40mph buffer speed limit to Portmore Roundabout was recommended to help reduce a record of shunt related casualties caused by vehicles approaching the roundabout along the North Devon Link road. Existing casualty reduction measures at this location include a fixed safety camera site for traffic heading north towards Portmore and also a "queue warning" electronic traffic sign that is activated by a combination of approach speed detectors and in-carriageway queue detectors.

Prior to the consideration of a buffer speed limit, the recommended treatment involved introducing transverse yellow bar markings to increase a driver's perception of speed and to encourage early deceleration. This treatment has already been used effectively at the southern end of the NDL at its junction with the M5 and more recently through the Country Mile Project at the end of the dual carriageway section of the NDL near Tiverton. To implement transverse bar markings, special authorisation is required from the Department for Transport. An application for authorisation was not approved for use on any single carriageway section of the NDL including this approach to Portmore.

Following the North Devon Highways and Traffic Orders Committee in December 2009 consideration has been given to two suggestions. Firstly, extending the proposed 40mph limit to encompass Landkey junction and secondly, no further safety engineering measures at this time.

The original proposal for a 40mph buffer considered approach speeds on the NDL and the type and location of recorded shunt incidents. Measured approach speeds to the proposed 40mph gateway area were typically in the order of 52mph. And at peak times speeds within the proposed buffer zone were in the region of 48mph. Typical approach speeds to the Landkey junction area were found to be higher at around 62mph.

The original proposal for a 40mph buffer was aimed at reducing shunt incidents by targeting driver awareness and deceleration at the key location in advance of the roundabout. Based on measured approach speeds it is recommended that an extended 40mph limit would not be a realistic limit to be introduced in advance of Landkey junction and one that could not be justified in terms of casualty reduction benefits.

Justification for extending the 40mph limit is reduced further by the location of the existing safety camera at Landkey. Fixed safety camera sites are identified and evidenced through speed related casualty records and from high measured levels of non compliance with the prevailing speed limit. Maintaining an active camera site within a reduced limit of 40mph could not be justified on casualty grounds and could have a negative impact on the reputation of camera sites across the county. Decommissioning this camera site would have a negative impact on the overall enforcement work of the safety camera partnership and police along the NDL. The enforcement activity as part of the Country Mile project identified a positive month on month reduction in typical vehicle speeds along the NDL. Speeding is one of the major contributory factors in casualties along the route.

A second alternative is to maintain the existing highway safety measures. Recent monitoring of crash records indicate that the frequency of speed related shunt accidents is reducing. Whilst the existing safety engineering measures play a part in this, the historical issue of traffic queuing has reduced significantly with traffic pattern changes associated with the western bypass. The latest available data shows that during the last three years there have been only two injury crashes in the location.

4. Sustainability Considerations

There are no sustainability implications to be considered.

5. Equality Considerations

There are no equality implications to be considered.

6. Reason for Recommendation

Following further investigation and monitoring of recent crash data it is recommended that no speed limit is advertised at this time.

Joe Deasy

Electoral Division: Chulmleigh & Swimbridge

District Ward: North Devon

Local Government Act 1972: List of Background Papers

Contact for enquiries: James Anstee

Room No: Barnstaple Civic Centre, Room 511

Tel No: (01271) 388500

jd040610ndh

sc/portmore roundabout

4 220610