Highways Agency - Safe roads, Reliable journeys, Informed travellers

Related pages

• Summary
• 1 introduction
• 2 traffic, congestion and safety issues
• 3 geotechnical issues
• 4 environmental constraints
• 5 option development
• 6 options considered further
• 7 engineering comparison of options
• 8 economic comparison of options
• 9 environmental appraisal of options
• 10 waste management
• 11 public open day
• 12 responses from statutory and non-statutory consultees
• 13 conclusions
• 14 recommendations
• Environmental study findings
• Environmental study findings
• Environmental study findings
• Environmental study findings
• Environmental study findings

A417 Cowley to Brockworth Bypass Improvement

2 TRAFFIC, CONGESTION AND SAFETY ISSUES

2.1 The section of the A417 from Cowley Roundabout to the Brockworth Bypass, known as the "Missing Link", suffers from severe congestion and has a poor accident record. These problems are likely to get worse if, as predicted, future traffic levels increase. This section of road is single carriageway and its layout is below the acceptable standard for a road of its type and with its high traffic flows (see Figure 2.1).

2.2 The Personal Injury Accident record for this section is provided in Table 2-1 below. The figures refer to the number of accidents, rather than the number of casualties. Anecdotal evidence also suggests that there are a large number of near misses and minor damage only accidents along this section that do not find their way into official statistics. More recently, in May 2002, there was a fatal accident on Crickley Hill involving a car and a light goods vehicle.

2.3 The national trunk road speed limit applies along the route with the exception of a 40 mph zone through Nettleton Bottom.

2.4 Congestion along the route (especially at Cowley and Air Balloon roundabouts) results in 'rat-running' on local roads and through villages including Birdlip, Elkstone and Syde. Local Parish Councils have also informed that Leckhampton is affected when problems occur on Crickley Hill and the Air Balloon roundabout.

2.5 A number of small scale improvements have recently been implemented along the route and these are described in the sections below. Although these schemes have provided short-term improvements all parties acknowledge that a long-term solution is required.

Cowley Roundabout

2.6 At Cowley Roundabout the dual carriageway terminates and the road becomes a single carriageway for the next 6km. This creates a traffic bottleneck resulting in severe peak hours congestion with traffic queues extending several kilometres to the south-east. There are approximately 28,000 vehicles daily using this section of the road, with approximately 12% being HGVs.

Nettleton Bottom

2.7 Nettleton is in a pronounced and localised dip in the trunk road, where forward visibility is not as good as it should be for this standard of road.

2.8 Vehicles tend to develop high downhill speeds, well in excess of the 40 mph speed limit, in an effort to build up speeds before the uphill section. The steep gradients entering the dip (approximately 10%) make vehicle control under braking more difficult.

2.9 The access to the Golden Heart Public House is located at the lowest point of the dip making right turns into and out of the car park a hazardous manoeuvre.

2.10 The high traffic volumes and speeds along this section create a high degree of severance and accessibility problems.

2.11 Recent safety improvements at Nettleton Bottom have been completed which include localised widening of the existing carriageway, a right turn lane into the Golden Heart Public House car park, traffic calming measures and the implementation of a 40 mph speed limit.

Stockwell Junction

2.12 Vehicles turning into and out of this junction can hold up through traffic on the A417. The volumes of traffic using this junction are low but there was a serious personal injury accident at this location in 1999.

A417/B4070 Birdlip Junction

2.13 Birdlip Junction is a major/minor junction where the B4070 terminates with the A417. The A417 is single lane dualled through the junction with a central island and a dedicated right turn lane. The majority of the accidents at the junction involve right-turning traffic out of the B4070 and a fatal personal injury accident occurred in August 2000.

2.14 Right-turning traffic from the A417 has difficulty crossing the northbound carriageway due to high traffic volumes and high vehicle speeds. There is also potential for vehicles waiting to turn right to queue back onto the running carriageway of the A417, obstructing through traffic.

2.15 There is also a problem with traffic turning right out of the B4070 local road from Birdlip Village. Visibility is restricted by the existing vertical alignment and by queuing right turning traffic. Drivers turning right out of the junction also misjudge speeds of vehicles coming up Birdlip Hill.

2.16 In order to improve the operation of the junction, the layout has recently been improved. A longer right turn lane on the A417, reflective marker posts, differential surfacing and improved road markings have been installed.

Shab Hill Lane

2.17 Vehicles turning into and out of Shab Hill Lane can hold up trunk road traffic. The turning vehicles are vulnerable to tail end shunts since they have to contend with high vehicle flows and high vehicle speeds.

Air Balloon Roundabout

2.18 Congestion often occurs at the junction during peak hours, with southbound traffic queues regularly extending for several hundred metres down Crickley Hill.

2.19 Vehicles have difficulty turning into the Air Balloon Public House and Crickley Hill private residence because of the fast moving trunk road traffic.

2.20 The horizontal alignment of the existing roundabout produces tight vehicle turning movements, particularly for vehicles travelling along the A417 from Cirencester and heading towards Gloucester. The turning circle for large vehicles can result in conflict with other vehicles approaching the roundabout from the Gloucester direction in the outside lane.

2.21 Vehicles continuing along the A417 heading to Cirencester have to undertake an approximate 300 degree turning manoeuvre to travel from Crickley Hill towards the Birdlip Bypass.

2.22 Recent improvements at the junction have extended the climbing lane and provided two right turn lanes on Birdlip bypass. The roundabout has also been widened which has increased the existing capacity and helped increase traffic flow. Accident figures show that there are no serious personal injury accidents at the junction with congestion being the major concern.

Grove Farm and Cold Slad Accesses

2.23 Both the Grove Farm and Cold Slad junctions have dangerous direct accesses onto the A417. Work is currently being undertaken to investigate whether it might be possible to carry out safety improvements at both junctions.

2.24 Contributing factors that make these junctions dangerous include high traffic volumes, high vehicle speeds (some exceeding the 60 mph speed limit) and the steep gradient of Crickley Hill (approximately 10%). Cold Slad also sits on the inside of the bend and has restricted visibility.

2.25 Right turning traffic from Gloucester into Grove Farm access wait in the fast outside lane to turn across the downhill lane. These turning vehicles risk shunts from behind and driver stress is increased whilst waiting for a gap in the high speed downhill traffic.

2.26 Articulated heavy goods vehicles from Air Balloon sometimes move over the central white line, into the line of onward uphill traffic, in order to negotiate the tight left turn into Grove Farm. A number of impatient drivers travelling downhill have also been reported to move into the uphill lane when overtaking vehicles slowing down to turn left into Grove Farm. Vehicles waiting to turn right into Cold Slad obstruct all downhill traffic causing congestion and the risk of shunt type accidents. Right turning vehicles out of both Cold Slad and Grove Farm have to cross lanes of fast moving traffic.

2.27 The historical accident record does not indicate a major problem but increased flows and evidence of many reports of near misses have given rise to the perception of the junction being dangerous. The high speeds especially of HGVs on the downhill (10%) approach to the access causes particular stress for drivers making left turns into Grove Farm access.

Crickley Hill

2.28 Crickley Hill has two lanes up (one being a climbing lane) and one lane down. The maximum gradient of the road is approximately 10% and there is no central reservation or safety barrier. The road layout is well below the acceptable standard for this type of road and the traffic volumes (nearly 31,000 vehicles per day and 14% HGV) are high.

2.29 Slow moving vehicles regularly restrict uphill and downhill traffic. This leads to driver frustration, with some drivers making the dangerous manoeuvre of overtaking slow moving vehicles by the crossing the solid white central lines.

2.30 Due to the steep gradient, vehicle brake failure is one of the main causes of accidents. HGV drivers travelling up Crickley Hill have also been seen to struggle to maintain control their vehicles.

2.31 Broken down vehicles are another consequence of the steep gradient. These cause severe congestion and pose a significant safety hazard.