Kevin Gilday, Group Product and Compliance Manager at SRL Traffic Systems, explains how a temporary traffic light solution kept traffic flowing on the M6 and A556 in Cheshire.
Kevin will be presenting at the JCT Traffic Signals Symposium at Nottingham Trent University on 15 and 16 September.
The challenge
Junction 19 on the M6 motorway is a busy intersection close to Knutsford, Cheshire. It links to the recently improved A556, which connects Northwich to Manchester.
Around 65,000 vehicles currently use the junction every day, however, with the £1 billion Airport City Manchester commercial development underway and more than 260,000 new homes set to be built in the region, traffic is predicted to rise dramatically.
In order to ease pressure on the junction, Highways England announced a £43 million improvement plan to build a new bridge through the existing roundabout and over the M6 to create a better flow between the motorway and the A556, whilst easing traffic congestion across the junction. A first for the UK, the new ‘through-about’ will increase the route’s capacity without having to widen the gyratory system.
With a long and complex construction schedule, it was essential to design and install a safe and robust temporary traffic light system to smooth traffic flow and minimise queues on the motorway exit slip roads during works.
The solution
The construction of the new bridge is being managed by AmeySRM – a joint venture between Amey and Sir Robert McAlpine. Having reviewed a number of mobile intelligent transport systems (ITS), AmeySRM chose Urban64® from SRL Traffic Systems.
AmeySRM made the decision not to adapt the junction’s original traffic light system into a ‘poles in barrels’ format in favour of using SRL’s Urban64® – the first, and only, standalone temporary traffic light solution to feature permanent technology. The Junction 19 scheme features 40 Urban64® signals, which are split between two master controllers that are wirelessly MOVA (Microprocessor Optimised Vehicle Actuation) linked. It is one of the UK’s most prominent projects to feature Urban64®.
SRL’s intelligent Urban64® solution utilises video detectors to provide virtual MOVA loops. Eliminating the need to physically install or maintain MOVA loops in the carriageway, these virtual loops can easily be adjusted to suit the temporary lanes.
The installation at Junction 19 is one of the first linked MOVA Urban64® systems to operate on such a significant junction in the Highways England network.
Ideal for busy motorway junctions and routes with varying traffic flows, MOVA technology continually monitors the number of vehicles approaching the signals and adjusts the green time required to effectively reduce congestion.
The scheme also integrates bespoke red/green man signalised pedestrian crossings, designed specifically to help construction workers reach the centre of the roundabout safely to carry out works.
A key factor in AmeySRM choosing SRL as a supplier was the fact that one of SRL’s 30 regional depots is based in Middlewich, just minutes from Junction 19. Being in such close proximity meant that the SRL team could be on site rapidly in the event of an emergency callout. The scheme was also installed with SRL’s 360 degree CCTV system to deliver remote monitoring via a 4G router, whilst providing AmeySRM with additional peace of mind.
Furthermore, as a local supplier, SRL is also helping AmeySRM to minimise the environmental impact of the project by reducing the number of miles that vehicles have to travel to deliver products and materials.
The benefits
The Urban64® system has been in place since September 2020 and it has been highly effective, both in enabling the efficient flow of traffic and helping to ensure the safety of pedestrians and roadworkers.
Using MOVA algorithms to detect trends and set responsive traffic light timings to minimise congestion, Urban64® is able to identify saturated and unsaturated conditions on each arm of the junction. This is a significant improvement on the previous system, which would not have been able to respond to fluctuating traffic levels. It has been particularly beneficial during the Covid-19 pandemic, when traffic flows have been constantly changing.
The system has given AmeySRM greater control and flexibility over traffic flows through the diversion, by allowing individual signals to be switched off to provide a continuous flow. This means that even when the M6 traffic is flowing over the roundabout diversion, the signals can be manually controlled if required.
Urban64® can also adjust to cope with any tailbacks that may arise, for instance allowing the team to control the signals and shut down the adjoining A556 to allow the M6 traffic to flow.
Unlike poles in barrels, which require digging to accommodate underground cabling, Urban64® has low voltage overhead cabling, which is faster and simpler to install. Avoiding the need for temporary road crossings while breaking ground, Urban64® can be easily moved to allow layouts to be adjusted as the project progresses.
If poles in barrels had been used, the site might have needed to revert to fixed time CLF control unless new above ground configurable detection systems and controller configurations were installed. The SRL system provides adaptive control which provides the flexibility in quieter conditions that fixed time control cannot achieve.
Furthermore, because the cabling is overhead, workers do not come into contact with potentially dangerous live cables in the ground during works.
Pat Cumming, senior project manager at AmeySRM, says: “This project is complex and it required a flexible and reliable temporary traffic management system to help us keep to our schedules and reduce congestion on the M6. I’ve been very impressed with the SRL Urban64® system – it has performed very well – better in many ways than permanent systems.
“SRL set the timings to suit the traffic flows and this has improved the flow through the junction. The system is clever and adapts to demand, but it also gives us the ability to manually control signals if we need to. Safety is naturally a major focus for us – our operatives feel confident that they can safely cross the roundabout and there have been no collisions because of the temporary lights. I would highly recommend SRL and would use them again in the future.”
(Pictures – SRL)
