Collapsible bollards among the recommendations for M4 bottleneck

26/02/2020 | RHODRI CLARK

Collapsible bollards at a motorway slip road and expanded traffic officer patrols are among the early recommendations of the South East Wales Transport Commission, whose remit is to suggest cheaper solutions to the notorious Newport M4 bottleneck.

Last June the Welsh Government cancelled the proposed £1.6bn M4 Relief Road, a southern bypass of Newport, because of cost and environmental issues.

It sugared the pill by announcing the formation of a commission of experts, chaired by Lord Burns, which would report within a year on a package of alternative measures. An interim report was promised by the end of 2019.

The commission got down to work in October. Its first progress update avoids recommending measures which could pre-judge or negatively affect its final recommendations, which are due around the end of 2020. Its analysis of the M4 congestion near the Brynglas tunnels has, however, enabled it to produce some early suggestions.

The nub of the problem is that the motorway narrows from three lanes to two in each direction at Newport. Widening is not feasible, particularly at the tunnels, but at peak times there are up to 1,500 more vehicles per hour than the maximum traffic volume for free-flow travel. Accidents cause severe congestion, not only on the M4 but also on local roads as through traffic seeks alternative routes through the city.

M4 Junction 25a seen from above the eastern portals of the Brynglas tunnels. Photo by the author

Abolition of tolls on the Severn Crossings in December 2018 has probably exacerbated the situation. Estate agents reported a surge of Bristol workers buying property in South Wales, where house prices are cheaper, on the assumption that commuting by car along the M4 would be cheap and easy.

The commission’s initial recommendations concern operation of the M4 rather than alternative transport modes – on which many of the final recommendations are likely to focus.

One initial recommendation relates to Junction 25a, near the eastern tunnel portals where three westbound lanes become two. The inside lane becomes the off slip towards the A4042, but many drivers wishing to continue through tunnel wait until almost the last moment to change lanes.

The commission recommends:

  • Altered lane markings to lengthen the slip road by around 300m, moving it further away from the tunnels;
  • Collapsible bollards which would divide the slip road from the through lanes, to direct drivers into the correct lane earlier and prevent late lane changes
  • Clear road numbers on the road surface.

‘Traffic data and modelling demonstrate this measure, when combined with an average speed control of 50mph, should greatly reduce the “ripple” effect of late lane changes, significantly improving flow into the Brynglas tunnels during peak periods,’ says the commission.

‘This should improve journey time reliability through narrowing the distribution of average speeds. Journey times along the road should therefore be more predictable as a result of the measures.’

The commission also identified differential speed limits on the M4 at Newport as a contributor to congestion. The central section has a permanent 50mph limit enforced by average speed cameras, to reduce air pollution. The sections to either side have variable speed limits, ranging between 30mph and 70mph according to conditions at the time.

The commission recommends enforced 50mph throughout, 24 hours a day. ‘A fixed speed limit should encourage vehicles to travel at a more consistent speed, making many journeys quicker and more reliable. A single speed limit should also reduce driver confusion and improve safety,’ it says.

‘Our analysis demonstrates 50mph to be the optimal speed in terms of journey time reliability and journey speeds, also taking account other important factors such as air quality, emissions and noise.’

However, it acknowledges that average speed cameras across the extended 50mph section may not be a fast-track measure, because of the technical and legal constraints to implementing the cameras.

The Welsh Government announced deployment of additional M4 traffic officers at Newport last summer, and the commission recommends expanding the patrols’ area to include the A48 Southern Distributor Road and the A4810 Queensway – principal diversionary routes for M4 traffic.

It suggests setting time targets for traffic officers to reach incidents, including a 10-minute response time during the peaks, backed up by monitoring and performance evaluation.

It also recommends a review to ensure response vehicles carry the best available tools, particularly for moving stranded vehicles onto the hard shoulder. ‘For example, the failure of an electronic handbrake can sometimes mean a car cannot be towed by traditional means. In these circumstances, “gojacks” trolleys could allow the vehicle to be removed safely,’ says the commission.

SEW Transport Commission members

Lord Burns (chair), crossbench peer and former HM Treasury permanent secretary

Peter Jones, professor of transport and sustainable development, University College London

Lynn Sloman, director, Transport for Quality of Life consultancy

Stephen Gifford, member of the National Infrastructure Commission for Wales

Elaine Seagriff, director of transport planning, Jacobs consultancy

James Davies, businessman and member of the Welsh Government’s economy and transport ministerial advisory board

Jen Heal, urban planner and co-chair of the Design Commission for Wales

Beverly Owen, strategic director for place, Newport City Council  

 

Highways InProfile

latest magazine issue
Highways jobs

Project Lead - Bridges and Structures WMF3037e

£45,718 to £46,731
We are currently seeking to recruit a Project Lead to join our Bridges and Structures team Kendal, Cumbria
Recruiter: Westmorland and Furness Council

Traffic Management Technician - WMF3040e

£27,711 - £28,624
Are you an organised and motivated individual who wants to make a difference to how our roads are managed? Cumbria / Various
Recruiter: Westmorland and Furness Council

Traffic Management Officer - WMF2114e

£37,035 - £37,938
Are you an experienced and motivated professional looking to take the next step in your traffic management career? Cumbria / Various
Recruiter: Westmorland and Furness Council

Senior Transport Planner

£47,532 - £50,574
Royal Greenwich is a borough synonymous with first class modern services Greenwich, London (Greater)
Recruiter: Royal Borough of Greenwich

Technician - Highway Inspector

Grade 8 £28,797 - £30,708 per annum (Pay Award Pending)
Within the Highways Maintenance Team we are looking for an enthusiastic, customer focused and experienced person to join the Service Derbyshire
Recruiter: Derbyshire County Council

Project Delivery Senior Team Leader

£74,480 - £85,964
Are you an experienced Chartered Civil Engineer (or equivalent professional qualification) Glasgow City
Recruiter: Transport Scotland

Assistant Traffic Management Technician - WMF2104e

£25,584 - £25,992
Westmorland and Furness Council is seeking an organised and enthusiastic individual to join our South Lakeland team Kendal, Cumbria
Recruiter: Westmorland and Furness Council

Bulky Operative

£25,584.00 - £27,269.00, Grade 5, 37 hours, Permanent.
An opportunity exists in the Council’s Street Scene Services for a Bulky Operative Wakefield, West Yorkshire
Recruiter: Wakefield Council

Project Delivery Team Leader

£57,710 - £71,842
Are you an experienced Chartered Civil Engineer (or equivalent professional qualification). Glasgow City
Recruiter: Transport Scotland

Traffic Management Officer - WMF2102e

£37,035 - £37,938
This is a key role supporting the delivery a wide range of traffic and road safety schemes. Kendal, Cumbria
Recruiter: Westmorland and Furness Council

Shared Service Manager (Waste) North Herts Council

£52000 - £61000 per annum
Shared Service Manager (Waste) North Herts CouncilNorth Herts CouncilPermanent, Full Time£52,866 - £61,866 per annum, plus car allowance (pay award pe England, Hertfordshire, Letchworth Garden City
Recruiter: Essex County Council

Traffic Management Officer - WMF2102e

£37,035 - £37,938
This is a key role supporting the delivery a wide range of traffic and road safety schemes. Kendal, Cumbria
Recruiter: Westmorland and Furness Council

Assistant Traffic Management Technician - WMF2104e

£25,584 - £25,992
This is a key support role, helping to deliver a wide range of traffic and road safety schemes across South Lakeland. Kendal, Cumbria
Recruiter: Westmorland and Furness Council

Flood Risk Engineering and Strategy Officer

£49,764 - £55,623
In line with our One Coventry Values, we want to ensure that our communities are represented across our workforce Coventry, West Midlands
Recruiter: Coventry City Council

Senior Integrated Transport Officer

£34,324 - £37,529
Are you an experienced transport planning professional ready to influence strategic policy and drive real change Matlock, Derbyshire
Recruiter: Derbyshire County Council

Roadworker Trainee LGV Driver (3 Posts)

Grade 6 £25,183 - £25,638 per annum (Pay award pending)
We’re looking for Roadworker/trainee LGV drivers to be part of our team undertaking major highway, bridge and related construction and reconstruction Derbyshire
Recruiter: Derbyshire County Council

Engineer

£44,430 - £51,663
This post is within the Highways Design and Delivery Team. London (Greater)
Recruiter: Tower Hamlets London Borough Council

Civil Enforcement Officer - WMF3013e

£27,711 -£28,624
Are you seeking an active and challenging role, part of a friendly and welcoming team? Cumbria / Various
Recruiter: Westmorland and Furness Council

UGO Bus Driver

Up to £25081.00 per annum
UGO Bus DriverPermanent, Part TimeUp to £25,081 per annum (full time equivalent)Location
Recruiter: Essex County Council

Head of Highways Operations

Salary
Somerset Council
Recruiter: Somerset Council
SUBSCRIBE NOW

Latest Video

Subscribe to Highways today to ensure you keep your finger on the pulse of everything happening in the UK road network throughout the year.

SUBSCRIBE NOW