Westerleigh Junction – a major bottleneck

Westerleigh Junction is where the Cross Country route from York to Bristol Temple Meads meets the electrified South Wales Main Line from London Paddington to Swansea, near Yate. The junction is a major bottleneck because North-South trains have to cross over East-West trains and then share the two-track line between Westerleigh and Bristol Parkway.

This situation arose after the main line from Bristol to Gloucester (via Fishponds and Mangotsfield) was closed in 1970. This forced North-South trains to take a circuitous route via Filton Bank. Before this, these trains could pass under the South Wales main line without conflict.

Route of original Bristol-Gloucester line passes under South Wales main line near Westerleigh

The London to South Wales main line is very busy. This severely limits the number of trains that can turn at Westerleigh, restricting the number of trains that can travel on the Bristol – Gloucester – Birmingham corridor. It also restricts the number of train paths available for any future Thornbury passenger service. We last wrote about this junction in Newsletter 96 (January 2018).

It is a nationally strategic junction of intercity and freight routes. It is one of 38 priority projects selected by Western Gateway Sub-national Transport Body (STB) for inclusion in their regional Strategic Investment Plan (SIP). A Network Rail report in June 2022 looked at four options for changing the layout at Westerleigh.

Improving Westerleigh Junction

One of the options investigated by Network Rail (Option E3) was for a flyover to take trains travelling from Bristol towards Gloucester over the main line, joining up further to the west (technically called a ‘grade separated junction’). This would completely segregate the traffic on the main line from the Gloucester line. On the face of it this looks a very satisfactory answer to the junction problem. However Network Rail consider that building a flyover over the very busy main line would cause too much disruption to services and so would not be practical.

The report lists three other options that are worthy of further consideration:

Dive under

In this option (Option E7) the Gloucester lines are totally re-aligned from some distance before the existing junction. The new positions of these lines are shown in red. The line to Gloucester peels straight off from the line to London. The line to Bristol goes under the mainline (through a ‘dive under’ bridge) to re-join the mainline near Coalpit Heath. The green lines show the existing route of the Gloucester-Bristol track that lead to the existing Westerleigh Junction. This junction would be removed and replaced with plain line.

Network Rail believe this option is worth further exploration.

Sketch diagram of proposed Westerleigh Junction dive-under. This schematic diagram is based on the version in Network Rail’s report, which (rather unconventionally) has North at the bottom!

Other options

The other options being considered are:

Option E4: Triple tracking, keeping a similar operational model to the existing with higher speed crossings, and the junction transferred to Coalpit Heath. Natwork Rail recommend this option for progression.
Option E6: Quad-tracking at grade, with the junction transferred to the Coalpit Heath area. Network Rail believe this option is worth further exploration.

Network Rail will be doing much more work on these options – looking at the engineering, signalling, land acquisition and other operational constraints, as well as the beneficial effects on services. This will take some time and, then of course, there is the question of funding the selected scheme.

We fully support the remodelling of this problematic junction and will encourage local politicians and councils (particularly the West of England MCA) to get behind and promote such a scheme.

Posted

5 Dec 25

Capacity

Tony Lloyd

Tags:

Bristol to Gloucester, Thornbury Line

Comments

2 responses to “Westerleigh Junction – a major bottleneck”

David Naismith
5 Dec 25
How about a more strategic long-term option? Reinstating the line from Yate through Mangotsfield to Bristol along what is currently the Bristol to Bath railway path. Services from Bristol Temple Meads to Gloucester and Worcester could be routed this way, freeing up Westerleigh Junction for more east to west high-speed services whilst also freeing up Bristol Parkway for more local services – inc Henbury. This also creates capacity for future Thornbury services and improves connection throughout north Bristol towards multiple destinations. This would obviously be the most expensive option, but would be the one that connects the most people to the network and reduce congestion and air pollution.
Reply
Tim Weekes
5 Dec 25
From a rail perspective, reinstating the old ‘Midland’ line via Fishponds and Mangotsfield would have many benefits.
But it is now very well-established, both as a path (one of the busiest cycle routes in the Country) and as a string of local parks. Any plan to change its use would meet massive opposition.
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