Procurement is now underway for the Highways Agency’s first multi-site automatic ramp metering signal installation off the motorway network. David Crawford reports.
Introduction of ramp metering at six Tees Valley locations in the North East represent a major application of the Highways Agency’s policy of reducing journey times, improving travel planning and technology, and laying additional blacktop as a last resort.
Ramp metering is a way of restricting the flow of traffic onto busy dual carriageways through the use of traffic lights on slip roads. Sensors on the main carriageways bring the traffic lights into operation when traffic volumes reach predetermined levels. The idea is to ensure that busy roads are not brought to a standstill by steady streams of traffic joining from slip roads.
The work will be completed by March next year at five slip roads on the A19 between its junctions with the A689 and the A174 and on the A66 near Teesside Park.
The £4M project is designed to create sufficient additional vehicle capacity for just over 2,500 planned new homes by March 2016. These housing developments might otherwise have been delayed due to their potential impact on the road network.
The processing of a number of recent planning applications has been prolonged by potentially lengthy negotiations with the Highways Agency. The issue has been agreeing sets of improvements to the trunk road network.
Motorway installations show travel times past junctions falling by 9% and speeds downstream increasing by 7.5%.
But the Agency is now satisfied that motorway-style ramp metering will enable better use of existing capacity in the area. This, it believes, will avoid congestion caused by the influx of additional road users.
The scheme was born out of the Department for Transport’s Planning and the Strategic Road Network circular 2/2007, which sets out the requirement for the Agency to participate in all stages of the planning process.
It gives it powers of direction to local authority planners on measures which must be implemented to deal with resulting traffic pressures.
The ramp metering installations form an integral part of the £577M Tees Valley Area Action Plan (AAP), the first of its kind in the country. It covers the boroughs of Darlington, Hartlepool, Middlesbrough, Redcar & Cleveland and Stockton-on- Tees.
These boroughs are working together as Tees Valley Unlimited. The partnership is a response to the demand for economic regeneration in the region, which has also been designated a housing growth point by the Department for Communities and Local Government (DCLG).
One specific concern about future traffic congestion stemmed from widespread use of strategic routes as local roads. This was particularly evident on the A66 around Darlington and in the area of the A19/A66 interchange between Stockton and Middlesbrough.
These pressures have stemmed largely from the poor quality of public transport in the area, which has been producing an average annual 3% drop in bus use. In a parallel initiative, the £57.5M Tees Valley Bus Network Improvements Scheme aims to raise passenger use by 7% along the 20 busiest corridors by implementing route enhancements by 2016.
The Highways Agency has used its national criteria to check the suitability of each new ramp metering site, and then modelled it using standard micro-simulation techniques developed for its existing 90 locations.
Typical results from motorway installations show travel times past junctions falling by 9% and downstream speeds increasing by 7.5%, creating worthwhile additional capacity.
“We’ll play our full part to make UTMC a unified, open multimodal intelligent transport system framework”
The design work is the responsibility of Amey, the agency’s technology managing agent contractor, or TechMAC, for network area 14, which covers Teesside. The construction work is going out to competitive tender.
The new system will be ready to be activated as soon as traffic detectors on the main carriageway pick up the onset of flow breakdown, normally at peak travel times.
As a default, to avoid the risk of a queue on a slip road backing up onto the local road network, detectors on the ramps will monitor any traffic build-up there and override the metering signals for short periods as necessary.
The long-term intention is for the ramp metering system to link into a £2.5M Tees Valley-wide integrated urban traffic management and control (UTMC) system. This is due to be operational by 2014 and is being developed by Middlesbrough Council as the lead authority from the existing local urban traffic control (UTC) bodies.
Achieving the necessary connection, however, is a national issue as Highways Agency systems are not currently UTMC-compliant and not compatible with the local authorities’ system.
Highways Agency traffic technology division director Robert Castleman says this will be resolved. ” We are keen to play our full part to make UTMC a unified, open multi-modal intelligent transport system framework,” he says.
Next-stage proposals for 2014-2016 could see further implementation of motorwaytype technology on Tees Valley trunk roads. This would involve installing active traffic management in the form of variable speed limits and lane utilisation controls in each direction on the A19 between junctions with the A174 and A689.
The Tees Valley scheme arose from a successful bid by the sub-regional local authorities to DCLG for housing growth point funding to accelerate the development of available regeneration sites. The department also invited the successful authorities to bid for funding for transport projects designed to unlock their potential.
Tees Valley Unlimited identified the relevant strategic road interventions and the Highways Agency then carried out an impact assessment of the traffic that would be generated by their development. It came up with ramp metering as a solution for coping with the travel needs of the 2,500 proposed homes.