class 315s to inner suburban routes). Class 170 DMUs operate from Stansted Airport north through Cambridge to Birmingham on CrossCountry services. In 2020, new Class 745s were introduced on Stansted Express services, cascading the Class 379s to other WAML services. It is expected that both these and the delayed Class 720s will replace both class 317s & class 379s on the route by 2022. Future developments It seems likely that two tracks will be built alongside the line to Cheshunt as part of Crossrail 2. Intermediate stations from Tottenham Hale will transfer to Crossrail 2 releasing capacity on the mainline for additional trains. In August 2019, it was announced that funding had been approved for four-tracking and related platform construction work between Tottenham Hale and Meridian Water to enable up to 8 trains per hour to make local stops in this section at peak times. References Rail transport in Cambridgeshire Rail transport in Essex Rail transport in Hertfordshire Railway lines in London Railway lines in the East of England Standard gauge railways in England 5 ft gauge railways in the United Kingdom Rail transport in Cambridge