£88m scheme to reduce M4/M5 hold-ups reaches halfway

THE curse of the summertime traffic jams on motorways near Bristol could soon be over.

Each year the M4 and M5 get clogged with traffic as holidaymakers from the Midlands head towards the West Country for a summer break.

But an £88 million scheme to make traffic flow more easily through the Almondsbury Interchange is on target to be finished in March, 2014.

This means this summer should be the last when the motorways gets jammed with traffic and cause long tailbacks due to the sheer volume of vehicles.

Project leader Paul Unwin told The Post that he could not promise jams would be banished completely. But he said the “managed motorway” scheme should eliminate all jams except for those during the busiest peak periods.

He said the scheme was half-way completed with all of the 33 overhead steel gantries in place.

They were lifted into position by large cranes during a programme of night time motorway closures.

Motorways are normally closed at weekends when traffic volumes are at their lowest but due to the large number of holidaymakers who travel at weekends, the closures were organised during mid-week.

The next stage is to install more than 30 miles of fibre optic cables which will feed the sensors under the road, the speed cameras, monitors and visual displays.

Mr Unwin said one of the key advantages of the new scheme would be to “smooth out” traffic at busy times so it continues to flow, even if this might be at 30, 40, or 50mph.

He said it would also improve driver behaviour because there would be less incentive by impatient motorists to “lane hop” when traffic is reduced to a crawl.

The sheer volume of traffic can bring the motorways to a standstill.

If an impatient swaps lanes and several vehicles have to brake, then this can cause a tailback further down the road.

At peak times, tailbacks grow at a rate of a mile a minute.

Although the scheme is costing millions of pounds, it is expected to help the local economy in the long run. The savings come from less fuel being used, shorter journey times and a greater willingness by firms to re-locate where they know jams are less likely to occur.

How it works:

Sensors in the road will monitor traffic volume and congestion so the number of lanes available to motorists and speed restrictions can be managed.

At peak times, the hard shoulder will be opened up to create an extra lane.

Overhead gantries will indicate which lanes can be used and maximum speed limits which will vary according to road conditions.

Average speed cameras will be used to make sure drivers stick to the speed limits.

The scheme involves a five-mile stretch of the M4 between the M32 (Junction 19) and the Almondsbury Interchange (Junction 20) and a seven-mile stretch of the M5 between the interchange and Cribbs Causeway (Junction 17).

A control centre at Avonmouth, which already monitors motorways in the South West, will manage the scheme.

A similar system on the M42 near Birmingham has managed to keep traffic moving despite high volumes of traffic.

It has improved road safety by reducing the number of accidents, eased pollution and seen vehicles use less fuel.

A survey among road users showed that more than two-thirds (68 per cent) of drivers felt more informed about traffic conditions and nearly two-thirds (60 per cent) said they would welcome similar schemes in other parts of the country.

The gantries will mean that lanes can be closed down at very short notice to allow emergency vehicles to reach accidents quickly.

Some facts and figures:

The 12-mile stretch of “managed motorway” is used by 140,000 vehicles each day.

There will be 33 new overhead gantries and seven refurbished ones which will house 196 electronic signs and signals.

A total of 111 cctv cameras will keep an eye on the hard shoulders and seven emergency refuge areas for breakdowns.

The scheme uses more than 30 miles of fibre optic cabling and 299 sensors beneath the road surface to monitor traffic flow and speeds.