Chilworth Roundabout

chilworth roundaboutA current talking point locally is the erection of a ‘sight screen’ at the top of The Avenue, which prevents the good driving practice of observing traffic already on the Chilworth Roundabout while slowing prior to joining it.  Anyone objecting to this receives the stereotyped letter below from Southampton council.  Please read on for a reaction, and for some other related points.


The accident statistics quoted in justification (see council’s letter below) are inaccurate and misleading as can be seen from this official resource.  The whole map may be found here.  This is a huge, distributed junction – in the part of the junction affected by the change there were about ten injuries in ten years rather than three, all slight.

The most dangerous things about the junction have now been fixed, and they would probably have made the junction safer even without the sight screen added.  They are the repainting of the worn out road-markings so that the lanes are now marked on the south-bound entry to the Avenue, and making the left lane of the westbound Bassett Green Road left turn only.  It’s a pound to a penny that a large proportion of the accidents that there have been on this junction will have resulted from northbound drivers not expecting vehicles in the left lane of Bassett Green Road to turn right towards the M3.

A number of people on the Science Park are agitating for a south-bound speed limit on the A33 to make joining from the direction of the Hilton hotel safer.  If you agree (or disagree) please comment below.

Here is a copy of the council’s letter:

“I am writing to thank you for your interest in the above scheme and to clarify some points that have been made. While some of the responses have been very positive, the majority have expressed some concerns which we would like to try and address.

The scheme, in conjunction with the sight barriers on the northbound approach to the roundabout, is designed to address a casualty issue at the location (ten injuries in the three year monitoring period) and is not intended to address other issues in the area which some correspondents have raised. There have been ten casualties at this junction in the three years 2008 – 2010, (the City Council monitors casualties over a period of time in order to ensure that there is an identifiable pattern and any measures taken will be as effective as possible). The average cost per injury to the local economy is £41,299.41; at a total scheme cost in the region of £23,500, each casualty saved returns a cost benefit (the first year rate of return is expected to be in the region of 321%). The City Council is in a position where failure to act would continue to put lives at risk, even though the changes may not receive the support of all users.

Some correspondents have queried the installation of the sight barriers. Analysis of incidents occurring at the location showed that a major element involved was drivers emerging from the top of The Avenue without giving due regard to the traffic already on the roundabout. The use of sight barriers is a proven method of slowing drivers before they reach the point of conflict, thus encouraging them to make a more thorough observation of the situation and has been shown to be a successful casualty-reducing method in other locations where this measure has been installed.

The main point of contention, however, has been that traffic queues have increased on Bassett Green Road and that pollution levels are likely to increase as a result. We would like to assure you that we are giving this issue serious consideration. We accept that the majority of traffic turns right from Bassett Green Road and, as a result of the level of complaints received, we are monitoring the length of queues via the traffic cameras and site visits; at the same time we will monitor issues such as difficulty exiting residential roads and the general behaviour pattern of drivers. At the same time as this, we are taking into account other issues which have affected the movement of traffic on the highway network. This monitoring is taking place with the understanding that the markings may need to be altered. Unfortunately, under the previous arrangement, drivers emerging north-bound from The Avenue appeared to be misjudging the path of travel of vehicles to their right, expecting traffic from the nearside lane of Bassett Green Road to turn left. While no-one should make assumptions as a road user, the reality is that mistakes are made and some of those resulted in injury.

Finally, one or two correspondents have mentioned the lack of consultation. It is part of the Local Authority’s statutory duty to address road traffic casualties by whatever means is appropriate; as such, consultation in its truest sense is not always appropriate, especially at a major commuter access point such as this, where it would simply not be possible to contact all users of the roundabout and might introduce lengthy delays to the implementation of a scheme designed to reduce the number of injuries.

I would like to reassure all correspondents that the scheme has been devised by qualified and experienced engineers following careful consideration of various options and taking all road users into account; the design has also passed an official safety audit. We will continue to monitor its effect and make any necessary alterations. We will also monitor the success of the scheme’s objective in reducing the number of casualties, although we will need to gather at least three years’ worth of data for confidence.

I apologise that this is a generic letter (it was felt that this would be the most efficient way to respond to similar issues raised by various correspondents), but hope that your individual concerns have been addressed; of course if you feel that they have not, please do not hesitate to contact me. I also hope you will see that we have worked hard to deal with the existing issue, although we are unable to mitigate all aspects of driver behaviour. In the meantime, if you have concerns about drivers who persist in risky behaviour, please do not hesitate to contact your local police and if you have any concerns about the condition of the roads in your area, please report them to the City Council’s Actionline (0800 5191919).”


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