Sustainable Congestion-Busting Alternatives to a new M4 Motorway in South East Wales

South East Wales is home to some of the most populated areas of Wales, including the capital Cardiff and the city of Newport. It has long suffered from an acute congestion problem on the M4 motorway.

The independent South East Wales Transport Commission was set up in 2019 by Wales' First Minister, Mark Drakeford, following his decision to not proceed with a new relief road on the M4 motorway. We were tasked with finding alternative ways to tackle the congestion problem on the M4. The broad remit given to us by Welsh Government reflects Wales' sustainability legislation, the Well-being of Future Generations Act 2015.

M4 congestion is essentially a symptom of a broader problem: people do not have good transport alternatives to the motorway. At the outset of our work, it became clear that existing rail and bus services that currently operate across the region do not cater for the types of journeys people want and need to make. Bus, rail and active travel are also insufficiently integrated – the result is that most journeys are quicker, easier and cheaper using the private car on the M4.

Our recommendations are structured around a 'Network of Alternatives': a new, integrated regional public transport network to give people genuine alternatives to the way they currently travel, allowing them to be able to travel without a car. This provides benefits for those currently using the M4, as well as the nearly 30% of households in South East Wales who do not own a car.

At the heart of our public transport network is the concept of the rail 'backbone'. This is important because the majority of current M4 journeys are longer than 20 miles, involving travel within a relatively concentrated west to east corridor between Cardiff, Newport and Bristol. For distances of this length, rail is the most appropriate mode for swiftly getting a large number of people to their destination.

Our rail backbone requires investment in the region's strategic rail infrastructure, the South Wales Main Line (SWML). By enable upgrading and reconfiguring the existing four electrified rail lines, we can nearly double the capacity of the infrastructure at peak times. This would allow the introduction of new, local commuter rail services which would be able to run separately from the inter-city services. Access to the rail network would be transformed by increasing the number of stations between Cardiff and the River Severn from three to nine. The new network we propose would see over 90% of people living in Cardiff and Newport being within one mile of a rail station or rapid bus corridor. The proportion of Newport's residents living within one mile of a rail station would double.

In addition to the backbone, the new network provides new rapid bus and commuter cycle corridors across Cardiff and Newport and establishes a 'hub and spoke' of bus and cycle corridors within Newport city. These support journeys in their own right, as well as connecting people to the rail line.

To fully transform the region's economic, environmental and health profile, we have gone further than just recommending infrastructure and services, by proposing policies that will encourage the necessary behavioural change and lock in the benefits.

To ensure successful integration and coordination, we recommend a formal partnership of Welsh Government, Transport for Wales and Local Authorities in South East Wales to govern transport design and operation. Welsh Government should also legislate for a broader range of bus regulation powers as soon as possible in the next Senedd term. We believe that to progress our proposals it will cost in the region of £600m to £800m over the next 10 years, with rail infrastructure being the most expensive element. Given responsibility for Welsh rail infrastructure, including the SWML, currently lies with the UK Government, governments in both Westminster and Cardiff will need to work together to prioritise the investment and delivery of the rail backbone given its keystone role in our plan.

We advise that land use planning should ensure new developments are built around the public transport network rather than the motorway and encourage Welsh Government to continue to call in planning applications which are inconsistent with sustainability. We also recommend that once the network is implemented and with affordable public transport fares in place, a Workplace Travel Parking Levy should be considered alongside significantly ramped up workplace travel planning and the creation of flexible office hubs in major towns, cities and urban centres to support remote working.

Shifting journeys from the M4 to a new joined-up public transport and active travel network can deliver many benefits beyond congestion alleviation – fairer and easier access to transport, improved air quality, reduced carbon emissions, and better public health are all clear opportunities.

These are an ambitious set of recommendations. We believe there is a strong case for investment. While demand for public transport has been understandably suppressed by this pandemic, our analysis suggests population growth will see demand for travel rise over the long term. The key is to use this time to prepare our recommended transport improvements so that we can capture this demand sustainably.

Lord Burns is Chair of the South East Wales Transport Commission.  He is a former Chief Economic Advisor to the Treasury and Head of the Government Economic Service. In 1991 he became Permanent Secretary to the Treasury, a post he held until 1998, when he was appointed a life peer.

This blog was published as part of the Decarbonising Transport series with Greener Transport Solutions