View source for DSIR 12/181a

[[Category:Subseries DSIR 12]][[Category:Roundabouts]]
{{Header
| title     = Effect of installing signals at the Western Avenue/Greenford Road roundabout
| daterange = 1960
| nacatref  = 574828
| series    = DSIR
| subseries = 12
}}

==Context==
In the early 1960s roundabouts were something of a problem - clearly a promising idea in traffic control, and already found in great numbers around the country, but prone to locking up with the increasing post-war traffic levels. Experiments were carried out to find ways of making them more reliable under heavier traffic pressure.

The eventual solution, which was already being trialled at this time, was the now-familiar priority rule where entering traffic must give way to circulating traffic. This experiment carried out by the RRL came at the problem a different way, and was the earliest known instance of an existing roundabout being signalised.

The traffic signals were a fairly crude set-up, with traffic on the A40 Western Avenue being halted about fifty yards back from the Greenford Road roundabout. The experiment was closer to the modern idea of ramp metering than true signalisation, and its intention was to regulate the amount of A40 traffic that could reach the roundabout, preventing it from being overwhelmed.

The results of the experiment were not brilliant and the equipment was dismantled when the experiment ended.

==Contents of note==
* Photographs of the Greenford Road Roundabout signalisation scheme.

==Related files==
:'''[[DSIR 12/181b]]''' Effect of installing signals on approaches to roundabout at New York Road Circus, Leeds (1960)

==People with camera copies==
[[User:Chris5156|Chris Marshall]] has a partial copy, including all photographs.
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