Battery-electric trains the preferred option to replace Class 165s and 166s on GWR cross-country route

Research into a strategy to decarbonise the North Downs Line has found that electrifying parts of the route would provide ‘poor’ value for money.

Network Rail and Great Western Railway are working on options to introduce battery-electric units to the 46-mile route between Reading and Redhill (of which 17 miles

is over third rail), and to replace 34-year-old Class 165/166 diesel multiple units (DMUs) that need to be retired from the route by 2035.

The joint report by NR and GWR has said that improving the rail offer could “encourage modal shift”.

The route currently has a half-hourly service from Reading- Gatwick Airport, but the Traction Decarbonisation Strategy has looked at other potential options, including a third train each hour to Gatwick as well as extending services to cities such as Oxford, Brighton or Portsmouth.

Out of those options, a more intense service, is the one most likely to encourage modal shift. However, this cannot be implemented at present due to the size of the fleet - GWR has seven ‘165/166’ units for the route, with around ten needed for a three- trains-per-hour service.

Class 769 tri-mode units were trialled on the route in 2021 and 2022, but these went back to Porterbrook when the Department for Transport abandoned plans for GWR to use them. GWR told RAIL the work done with ‘769s’ has not directly informed its DMU replacement project.

Any replacement units will appear as part of the operator’s ‘Churchward’ project. While battery-electric power is preferred, “DC-diesel also remains a proven solution”, the strategy reported.

GWR and Gatwick Airport are also aspiring to create an overnight service to Reading. The strategy document reported that 40% of flights take off outside current operating hours along the route.

Any overnight services are unlikely to start for another two to three years.