A1307 Babraham Institute roundabout - some progress

On behalf of the parish council at Babraham I asked the road safety team at the County Council to assess the roundabout on the A1307 where it leads off to the Babraham Institute. It has a reputation for catching drivers unfamilair with its lay-out unawares, and there have been accidents there. The good news is that possible changes to the lane designation markings and signage have been drawn up. These will be going through the road safety audit very shortly. We will then need to get the county to cost them and schedule in to the work programme. 

In more detail:

A review of the police collision records for the junction shows that there have been slight injuries in 3 crashes over the last 5 years, and the route carries about 15,000 vehicles per day. Roundabouts in rural areas tend to have a reasonably good safety record and this is well below what is seen at other types of junction along the A1307. Babraham crossroads (west of Fourwentways) has seen 4 slight injuries and 3 serious, and for closer comparison The Gogs roundabout has seen 6 slight injury crashes and 2 serious.

 The road safety engineering team have carried out investigatory surveys including:

- a laser scanner survey of the levels/camber and

- a grip tester survey to check the surface texture.

The scanner survey shows that the Babraham roundabout has a fairly typical camber on the circulatory carriageway falling half towards the centre and half towards the outside of the circle. There is a slightly flat spot, but this does not seem to be so bad that it is holding water and creating an damp surface and therefore reduced grip.

The main issues reported with loss of control at the roundabout seem to be from the east to the west along the A1307 so this manoeuvre was looked at in particular detail. The roundabout is like many retrofitted roundabouts “offline” (ie not central to the main road but offset). This is common because the landowner and/or developer rarely owns land on both sides of a road. Tthere are 2 lanes marked at the giveway entry onto the roundabout. Two lane entries do tend to see higher numbers of injury collisions than single ones. Potential changes to the lane designation markings and signage have been drawn up. These will be going through the road safety audit very shortly but the highways team are waiting on griptester results to see if any retexturing or similar might be beneficial or not. The grip tester site work was completed some weeks ago, but there has been a glitch with the data so the team is still waiting to get useable data.