How could Severn Beach Line capacity be improved?

Trains pass on double track near Clifton Down Station, Severn Beach Line

FoSBR have long championed the re-doubling of the Severn Beach Line, in whole or part, to support a higher frequency passenger service. Here we look at ways that Severn Beach Line capacity could be improved. 

The FoSBR Plan for Rail promotes a turn-up-and-go, 15-minute frequency, electrified rail service to most suburban stations. This includes the Severn Beach Line as far as St Andrews Road. In December 2021 the Severn Beach Line timetable was upgraded to half-hourly (to Avonmouth, hourly to Severn Beach). In December 2018 Filton Bank was re-quadrupled. These have been important stepping stones.

It is exciting to see that potential further service uplift and capacity improvement on the Severn Beach Line is attracting more widespread attention.

SevernNet recognise importance of Severn Beach Line

SevernNet represents businesses and the community across Portbury, Avonmouth and Severnside. The SevernNet Transport Charter of late 2021 emphasises the Severn Beach Line as a key element to enable the flow of employees into this employment area to serve shift patterns 7 days per week, 364 days per year.

Network Rail identify Severn Beach Line as needing service uplift

Network Rail recently issued the Greater Bristol Rail Network Strategic Study which seeks to answer the question “How can rail best support sustainable economic and housing growth in Greater Bristol?”

The top 5 priorities for the study were:

…and finally:

  • improved frequency of services for stations on Severn Beach Line

These strategic studies are wide-ranging. With regard to the Severn Beach Line, the study does not identify the infrastructure interventions necessary to improve capacity. Nor does it specify the aspiration for frequency of service. 

It does suggest new/extended Severn Beach branch passing loops and re-instated platforms. Network Rail are doing further analysis and stakeholder engagement to prioritise potential interventions across the region.

Where can trains currently pass on the Severn Beach Line?

The current timetable relies on southbound trains passing northbound trains at either Avonmouth or Clifton Down or on the four-tracked Filton Bank. Avonmouth and Clifton Down have double-tracked ‘loops’, and two platforms. The rest of the line between Narroways Junction and Severn Beach is single track.

The freight line to Filton which diverges at Hallen Marsh Junction is double-track but is only currently used by freight traffic. Reintroducing passenger trains on the Henbury Loop is also an ambition in our FoSBR Plan for Rail.

These limited passing opportunities restrict the number of trains that can run on the line, and can cause a domino effect at times of disruption, as punctual trains have to wait for late trains. 

Re-doubling through Redland?

FoSBR members have long suggested that continuing the double-tracking from Clifton through Redland station would allow more flexibility for timetabling. It would also allow a few extra minutes for trains to re-set at times of disruption, allowing southbound trains to wait at Redland for late-running northbound trains rather than waiting at Clifton Down.

This would also require re-instatement of a northbound platform at Redland, so that even this modest advantage involving extension of around 800m of double-track would cost millions of pounds.

Re-doubling from Montpelier to Narroways Junction?

WECA’s Strategic Rail Investment Plan of December 2020 suggested doubling the Severn Beach line between Montpelier and Filton as a long-term aspiration. This was later clarified to mean between Montpelier and Narroways Junction rather than the alternative interpretation of re-doubling all the way around from Montpelier to Filton via Avonmouth and the Henbury Loop.

The Strategic Rail Investment Plan also mentioned the possibility of a proposed new chord from north to east of Hallen Marsh Junction. This would allow Severn Beach trains to access the Henbury line from the north. It would also open up the possibility of a new Severn Beach to Yate service, serving the YTL arena and Bristol Parkway. 

Re-doubling north of Avonmouth?

A train-driving FoSBR member brought another opportunity to our attention. The track layout north of Avonmouth could be improved to both the advantage of the passenger and freight networks.

The Bulk Handling Terminal (BHT) coal conveyors and silo train loaders at St Andrews Road are currently being demolished. The removal of the silo loaders offers the opportunity to re-double the passenger line north of Avonmouth.

The track is double through Avonmouth station and Avonmouth Station level crossing. It reduces to single track for 300m through St Andrews Road level crossing.

After the level crossing, the single passenger line continues through St Andrews Road station and Hallen Marsh junction to form the single line to Severn Beach. Starting at the level crossing, the St Andrews Road hopper sidings fan out, and eventually continue as double tracks through Hallen Marsh to form the freight only Henbury Loop.

In this proposal, the passenger line would be re-doubled from along the 300m single track stretch through the St Andrews Road level crossing. The huge concrete stop block outside St Andrews Signal Box would be removed, allowing connection to the line known as the Loco Release Line. This line would be upgraded to passenger standard, and a new platform would be required at St Andrews Road to fully realise the benefits.

There would need to be a crossovers from the Severn Beach single line to the Loco Release Line and/or Henbury Loop line (note also the WECA suggestion above of a chord from the Severn Beach Line to the Henbury line). The new layout around St Andrews Road would in part re-create the track layout pre-1992 before the Bulk Handling Terminal was built.

Possible track interventions north of Avonmouth
Possible track interventions north of Avonmouth

These changes would allow extra capacity in this section, with a larger window for trains to cross. They would allow greater flexibility in timetabling for Severn Beach trains, and their intersection with trains routing via the Henbury Loop. 

The doubled track across the level crossing at St Andrews Road (access to the main port gate) could potentially reduce the amount of time that this crossing is closed to road traffic, in that northbound and southbound trains could be timetabled to pass at the same time.

More study needed

It is difficult to compare the relative benefits of these different interventions without the tools available to timetable planners, using the variables of costs, desired service frequency, passenger train destinations (both on the line and beyond Temple Meads) and freight train movements.

The Avonmouth suggestion is also likely only cost-effective if more trains continue to Severn Beach, and/or the Henbury Loop is re-opened to passengers, and/or the Bristol Port Company proceed with construction of their deep sea container terminal.   

The Bristol Port Company have planning permission to build a deep sea container terminal adjacent to Hallen Marsh on the Severn. It would service not only today’s largest container vessels but also future generations of ultra large container ships (carrying up to 14,000 containers) entering service, with three 400m berths dredged to a depth of 18m. If the Port decide to proceed, rail access to the proposed terminal would be via the line marked Royal Edward Yard on the track diagram, connecting at Holesmouth Junction.

Comments

One response to “How could Severn Beach Line capacity be improved?”

  1. Bernard Lane avatar
    Bernard Lane

    When Henbury loop is reopened in full, there will be a need for double track at more places than suggested.
    Redoubling CD to Montpelier tunnel, doubling at Avonmouth as described and a long loop at Sea Mills would be necessary. All stations have 2 platforms so bringing them into use might not be so expensive…

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