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By Frank Phillipson
Further to my previous article on improvements needed if there is an increased use of the access to Newlands Corner, additional investigation has been carried out.
Where the earlier sketch showed the location of the proposed new access to be, the sight line southwards is impeded by the gradient and crest of the hill.
To achieve adequate visibility in this direction that provides an acceptable stopping sight distance (SSD or ‘y’ distance) the proposed access needs to be moved further northwards and a maximum speed limit of 40mph imposed on all the approaches to Newlands Corner. This will then give an absolute minimum SSD of just over 90m (see diagram).
Imposing a 40mph speed limit would also be beneficial to pedestrians and horse riders.
With regard to the provision of the ghost island right-hand turn lane, according to Highways England’s Design Manual for Roads and Bridges (DMRB) the requirement to provide this is reached when the traffic flow on the minor road or access carries a two-way (in and out) annual average daily traffic (AADT) level of 500 vehicles.
Surrey County Council claims that its traffic survey (carried out in 2004 and 2007) gives a figure of 122,000 vehicles visiting Newlands Corner per year. If this is taken as being the total ‘In’ and ‘Out’ (i.e. two-way movements) the AADT for Newlands Corner is 334.
However, given that the proposed development would lead to increased in vehicle numbers and that the DMRB states that a right-hand turn lane should be provided if the following apply:
1. If there is a likelihood of right turning accidents.
2. If vehicles on the major road waiting to turn right inhibit the through flow and create a hazard.
3. If there is high seasonal variations, or short, intense peaks in the traffic flow.
The provision of a ghost island right-hand turn lane would therefore seem to be justified.
If Surrey County Council’s figure of 122,000 per year just represents the number vehicles visiting Newlands Corner then this figure needs to be multiplied by two to represent all the inward and outward movements by these vehicles. The annual two-way figure then becomes 244,000 vehicle movements which gives an annual average daily traffic (AADT) level of 668 vehicles. If that is the case it means that the existing access should already have a right-hand turning lane.