Fully automated queue management system, over 50km, to give buses priority but at minimal delay to other traffic.
The City of Edinburgh introduced a fully automated queue management system on the A90 approach, over 50km, to the city from the Forth Road Bridge, to give buses priority but at minimal delay to other traffic. Temporary signals are employed at two locations, activated by traffic density to stop all traffic, and buses are diverted to the head of the queue.

This is a route which is subject to significant congestion, particularly during the morning peak, approaching the city. The automatic system essentially manages developing queues by creating two reservoirs for general traffic and allowing buses to overtake the queues thus reducing bus journey times but with minimal delays to general traffic as a result.

Resources needed

£2million in 2000.
The cost of the A90 system was minimised, where possible, by using existing on and off slip roads to provide effective bus lanes, to allow the bus to reach the front of the queue.

Evidence of success

 Average 13 min saving for buses in peak time;
 Minimal to no delay for general traffic;
 Lower emissions from smoother traffic flow;
 Improved safety from lower speed limit and traffic control at slip roads;
 Encourages modal shift from car to bus.

Difficulties encountered

It can be difficult to convince stakeholders that the queue management system will work in the first instance. Technology should therefore be tested and easily obtained. It is also important to emphasise that the delay to all other vehicles caught in the reservoirs will be minimal.

Potential for learning or transfer

The A90 Queue Management System is a localised facility but is entirely transferrable for use in any heavily congested route, in any network, anywhere. Using the A90 as an example, buses are given a very visible advantage in terms of journey time to the city whilst delays to general traffic are slight.

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Main institution
Eastern Scotland, United Kingdom
Start Date
July 2000
End Date


Catriona Macdonald Please login to contact the author.

Good Practices being followed by

Andrea Vignoli

Italian National Association of Cities and Municipalities - Lazio