PennTraff
Recent projects
PennTraff continues to undertake occasional projects in both the private and public sectors. 

Speed Surveys

I have recently undertaken some speed surveys on behalf of private residents wishing to create or improve their access usually onto a busy main road. This is relatively easy to do and I write a brief report or note making recommendations based on the observed speed profile at the site. These can then be forwarded by the client to the local Highway Authority.

Brockley Cross, Lewisham

This is a redesign of a reasonably successful double mini-roundabout. The present layout unusually has the yield lines too far forward encouraging or even forcing straight paths across the junction. My redesign sets the yield lines back, enlarges the two central islands and makes more sense of the central dividing island. The object of the study is to try to reduce the numbers of crashes occurring although the rate per 100M vehicles crossing is not that high. A better design with more deflection should improve safety. Local enhancement of the area is also proposed.


This is a very densely trafficked site! The traffic capacity is so good that exits are often observed to block.
The accident rate is not that high but any improvement should reduce the numbers.
It is unusual at any mini-roundabout to observe the three right turns occurring at the same time,
but this is happening at the far mini-roundabout.
A larger central island (proposed) enables this to take place more easily.

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Halfway Street/Willersley Avenue, Bexley

This hybrid roundabout was suggested as part of a Safer Routes to School scheme in Sidcup, Bexley, first implemented in the summer 2001. It would have removed virtually all the through traffic past the schools at their busy times allowing a relatively easy bypass. Congestion in Willersley Ave (opposite) which was a side-road prevented easy access to Halfway Street (left - right). The scheme was introduced only after all the alternative options were rejected. Hollies Avenue (towards the bottom) might have been closed to enable a 3-arm mini-roundabout to be installed but local residents objected strongly. Signals were tested and failed on capacity grounds. Initially the four-arm roundabout failed an ARCADY test; however the Sawers formula suggested that there would be no congestion on the basis of the figures analysed. Once approved by the council, it was necessary for a special authorisation as the central island was to be larger than the standard 4m. The scheme was implemented in June 2005 and has worked well with only very minor accidents attributable to the junction operation.

Innovative 7m diameter central island at crossroads mini-roundabout
See www.midi-roundabout.co.uk - image courtesy of Bexley Council
Note: The central island was intended to be more raised and have steeper edges;
The very smooth profile has led to much abuse with overrunning and possibly crashes...

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Yarnton Way, Bexley
Transport Road Safety Award 2005 nominee

This was the highway part of a major Safer Routes to School scheme constructed in 2004. Installing the four roundabouts along Yarnton Way was just one of the innovative safety features recommended.
It was proposed too that the carriageway should be reduced to a single lane in each direction and have cycle lanes added. This reduced overtaking and provided more space for traffic to wait in the now widened central reservation crossovers. An additional Toucan (cycle and pedestrian) crossing was installed; secure cycle racks were introduced at Bexley Business Academy, the focal point for pupils. 

New cycle routes to link up with residential areas to the north remain to be constructed. The scheme is located in a relatively poor area of North Bexley and received much support from an initially nervous local populace.

This scheme has been most successful. The latest is that the local people would like at least one further roundabout installed on Yarnton Way. The site may be viewed on PixPlot - opens in a new window...

Yarnton Way - the urban dual two-lane carriageway Single Lane dualling with four roundabouts

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External links to other sites:

Mini-roundabouts - Getting them right!
The MIDI-roundabout - minis with larger central islands than standard

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Penntraff - Nov 2016