This chart shows how the reliability of services on the Severn Beach Line has changed over the last few years:

Updated SBL graph to April 2020

Late” = services 5 or more minutes late on arrival at Severn Beach Line destination northbound, or Bristol Temple Meads southbound
Cancellations & turnbacks” = includes services cancelled throughout, services turned back prior to (or started after) scheduled stations and services that skipped scheduled stops
On Time” = services run to time or less than 5 minutes late

This data has been collected variously from realtimetrains, raildar and recenttraintimes, none of which guarantee 100% accuracy. (TM/CJD)

Number of services run per month depends on month length, weekdays in a month, extra summer Sunday services and scheduled timetable changes for engineering.

Noteworthy causes of service disruption/improvement have been:
July 2017 – issues with introduction of Turbo 166s
March 2018 – SBL problems due to snow
April 2018 – Network Rail (NR) complete Bristol Area Signal Renewal & Enhancement with some disruption to SBL services
Spring/Summer 2018 – GWR introduce measures to improve Turbo 166 performance on SBL, e.g. intermediate door controls
July 2018 – Network Rail complete BASRE/ARS tweaks to improve SBL regulation
Summer 2018 – several weekends of engineering bustitution
Autumn 2018 – Filton Bank blockade 27th October to 18th November plus weekends of 13th/14th Oct, 24th/25th Nov, 1st/2nd Dec
December 2018 – services are routed via four-tracks on Filton Bank
December 2019 – increase in IET London service frequency

March 2020 – at least 118 of these 134 cancellations were “planned cancellations” for GWR interim emergency Covid-19 timetable during week 23-27th March

April 2020 – official Covid-19 timetable introduced Monday 30th March – service reduced to 26pd Sunday, 32pd Saturdays, 26pd weekdays (28pd weekdays from 13th April)