Biggleswade South Roundabout Email to CBC Highways, (not from me): I would like to express my concern about the road layout. This is particularly poor when heading/exiting north where the camber is flat or negative, the lanes are narrow and the curvature too tight. The visibility is poor due to the use of armco barriers in both north and south directions. The exit south is too tight and narrow and not helped by the slip lane joining far to close to the roundabout exit. I have used this road for nearly 20 years and am astounded at the poor and dangerous redesign of a previously safe roundabout. You have already had to alter the lane markings in the northerly direction because they were patently illogical. How much did that cost? I can only assume you used the same person to design this roundabout who created the markings on the Cardington Cross roundabout! Reply from The Senior Project Manager: Thank you for your communication. I am the Project Manager for the A1 Biggleswade Roundabout scheme acting on behalf of Central Bedfordshire Council (CBC) who have been constructing the scheme for the Highways Agency (HA), and respond to your complaint below. The design of this junction is for a four arm roundabout that is currently operating in a transitional phase, i.e. with the west arm closed. The roundabout has been elongated to allow for additional capacity into Stratton Business Park and to provide for public access to the eventual west arm when this land is developed by CBC. The oval shape may give rise to a perception of a tighter radius; however, the end radii of the ‘longabout’ are the same size as the former roundabout. Although I do not directly represent the Highways Agency (HA), the design and implementation of this project has been undertaken on their behalf by CBC in accordance with the HA’s express requirements, and has undergone their stringent design checking procedure. The scheme has also been subject to Road Safety Audits by independent auditors at design stage and pre and post completion. These audits did not cite the issue you raise as a road safety issue, the alignment of the northbound exit having been reviewed thoroughly (necessitated in order to remove a Departure from Standard) by the HA during the design phase. The designer confirms that the circulatory carriageway profile is designed to standard in terms of the gradient and camber where typically the surface falls towards the roundabout’s central island. There is a transition where the camber must be reversed to fall into the inside curve of the exit carriageway where speeds increase substantially beyond this point. The switches in camber are in the locations typical of a large roundabout. I was at the roundabout on Tuesday 14th October with representatives from the Contractor, the Designer and Highways Agency’s Framework Contractor (Amey) who look after the maintenance of the A1 trunk road. We drove round the scheme independently at normal speeds from all directions and did not find anything untoward regarding the radii, cambers or alignments, as also borne out by the pre and post construction independent Road Safety Audits. We also observed driver behaviour while we were there, especially those travelling from Biggleswade going north. On the whole most drivers displayed correct lane discipline and negotiated the roundabout effectively at seemingly normal speeds. The lane marking details on the northbound approach were originally installed to the current design standards which have been approved by the Highways Agency. However, after monitoring driver behaviour since completion and, further to several complaints from drivers related to the A1 northbound approach/circulatory manoeuvres and how the installed road markings are interpreted in order to negotiate the new junction in its ‘interim’ phase, i.e. no west arm, we have made the following changes recently. The direction arrow markings on the northbound approach were modified to show right turn arrows on the offside lane, and combined straight on/right turn arrows for the middle lane. The lane division markings were also changed to allow the offside lane to merge into two lanes (middle and offside) as you approach the roundabout while keeping the nearside lane traffic in its lane to continue on the A1. Also a sign to mirror the revised arrow markings has been installed in advance of the arrow markings in the nearside verge. The combined effect of the above allows drivers more time to get into the middle and offside lanes on the northbound approach in order to turn right onto the A6001 London Road to Biggleswade and Stratton Business Park, while also allowing traffic on the nearside and middle lanes to continue northwards on the A1. I sincerely hope that there are no serious accidents on the roundabout, but I am satisfied that the project team has done everything in its power to provide an appropriately designed roundabout. As explained, the Highways Agency are responsible for this road including the roundabout. If you have any further complaints then you should direct them through the HAIL system of the Highways Agency.
Posted on: Thu, 30 Oct 2014 17:54:58 +0000
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