Cassiobridge was a proposed London Underground station in Watford, Hertfordshire, England. The station would have been part of the Croxley Rail Link project, a scheme to extend the Metropolitan line to Watford Junction railway station. It would have been served by Metropolitan line trains between Watford Junction and Central London via Baker Street. The railway line would run over Ascot Road via a viaduct and the platforms would have been situated on the east side of the road. Entrance to the station would have been from the west side of the road, with a ticket hall and other facilities at street level. Passengers would gain access to the platforms via stairs and lifts and a short footbridge over the road.The station is projected to offer interchange with local transport services, and operate as an unstaffed station, providing automatic ticketing facilities similar to a DLR station. There is potential for Park and Ride facilities to be provided, although planning documents indicate high levels of congestion on adjacent roads. Watford station would close to passenger services, so that all trains from Croxley would continue to Watford Junction.
The railway and station had been expected to come into service in 2020 but on 25 January 2017, the Watford Observer newspaper published an update on the Croxley Rail Link confirming that work had stopped as there was an ongoing funding issue.