Traffic light sequence for the A720, Sherriff Hall Roundabout, Edinburgh: EIR release

Information requested

You asked "Please provide a traffic light sequence for the A720, Sherriff Hall Roundabout, Edinburgh."

Response

As the information you have requested is 'environmental information' for the purposes of the Environmental Information (Scotland) Regulations 2004 (EIRs), we are required to deal with your request under those Regulations. We are applying the exemption at section 39(2) of the Freedom of Information (Scotland) Act 2002 (FOISA), so that we do not also have to deal with your request under FOISA.

This exemption is subject to the 'public interest test'. Therefore, taking account of all the circumstances of this case, we have considered if the public interest in disclosing the information outweighs the public interest in applying the exemption. We have found that, on balance, the public interest lies in favour of upholding the exemption, because there is no public interest in dealing with the same request under two different regimes. This is essentially a technical point and has no material effect on the outcome of your request.

The signals run under MOVA (Microprocessor Optimised Vehicle Actuation) which is a method of controlling the traffic signals based on the presence of vehicles detected on the approach to a signalised junction, but this method controls one junction at a time rather than looking at traffic flow as a whole. The timing of the sequence can vary minute to minute depending on traffic.

Phases of the roundabout are:

Phase A: A68 Approach
Phase B: Circulatory
Phase C: A? Northbound
Phase D: Circulatory
Phase E: A720 Eastbound
Phase F: Circulatory
Phase G: A? Southbound
Phase H: Circulatory
Phase I: A6016 Approach
Phase J: Circulatory
Phase K: A720 Westbound
Phase L: Circulatory.

The above is written so that the phases that are in conflict with each other are grouped in pairs so phase A will conflict with phase B etc.

All circulatory signals have a leaving inter-green of not less than 5 seconds but should be 6 seconds on site.

All approach signals have a leaving inter-green of not less than 5 seconds. Both sets of inter-greens may be higher on street if they have been locally adjusted. (This is normal).

The phases described on the diagram you provided resulting in the collision point are Phase E: A720 eastbound and Phase F: Circulatory. These can't appear at green at the same time without switching the signals completely off on all approaches.

About FOI
The Scottish Government is committed to publishing all information released in response to Freedom of Information requests. View all FOI responses at http://www.gov.scot/foi-responses.