Roundabout to Traffic Light conversion

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3 December, 2015 - 18:41
#1
Bracken Van Ryssen
Bracken Van Ryssen's picture
Roundabout to Traffic Light conversion

Hi all,
Solihull Council are consulting on proposed changes to a junction near the town center. The junction in question is being converted from a roundabout to a standard four-arm light controlled junction and is on a busy and well trafficed route between the town center and a large retail park. The road itself has 1.25 meter wide advisory cycle lanes and is a key cycle route for those brave enough to use it and has been targetted by the bicycle campaign as potential road for segregated cycle tracks to be added to. 

Image of the plans: http://content.govdelivery.com/attachments/UKSOLIHULL/2015/12/03/file_at...

More details: http://www.solihull.gov.uk/About-the-Council/Consultations/roadworkconsu...

Any thoughts for improvements?

Thanks in advance.
B

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Submitted by Bracken Van Ryssen on 3 December, 2015 - 18:41
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3 December, 2015 - 20:07
pete owens

Removing the dangerously narrow gutter cycle lanes would be a good idea. Combined with the wide centre hatching the road looks to be designed to engineer close passes.

The conversion to traffic lights looks like it would be an improvement on the existing roundabout. It would be better to have a single lane Dutch style roundabout - but that would be rejected out of hand since the aim of the scheme is to improve capacity - though I'm surprised the think the traffic lighs would have that effect. Putting ASLs on all the approach arms would help - as would tightening the corner radii.

A major failure looks like they are not even intending to include a pedestrian phase in the sequence.

Submitted by pete owens on 3 December, 2015 - 20:07
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3 December, 2015 - 20:32
(Reply to #2)
AndyR

Oddly enough I wonder if a single lane roundabout might be an improvement. At the moment in both directions on the mainline you've got two ahead lanes marked on the circulatory, requiring very sudden merging on the exits. This could be a real cause of delay. One lane on the approaches and circulatory, with a larger centre island giving a bit more separation between turning streams, could have a metering effect. I'd certainly like to see a microsim model of that option, rather than just rely on ARCADY with its entry width fetish (and also a video of how it works - or doesn't - currently).

Submitted by AndyR on 3 December, 2015 - 20:32
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3 December, 2015 - 20:38
AndyR

Oddly enough I wonder if a single lane roundabout might not be an improvement. At the moment in both directions on the mainline you've got two ahead lanes marked on the circulatory, requiring very sudden merging on the exits. This could be a real cause of delay. One lane on the approaches and circulatory, with a larger centre island giving a bit more separation between turning streams, could have a metering effect. I'd certainly like to see a microsim model of that option, rather than just rely on ARCADY with its entry width fetish (and also a video of how it works - or doesn't - currently).

 

ETA

In fact looking at Streetview it appears all the circulatory lanes, both north-south and east-west, have two ahead lanes marked out, which I'd say is...ambitious.

Submitted by AndyR on 3 December, 2015 - 20:38
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