The first steps towards building the Croxley Rail Link will be taken next month as site surveys get underway along the new route.

Hertfordshire County Council announced today work will begin in mid-August on topographical surveys to gather land information for the Metropolitan Line expansion.

Landowners affected by the project are due to be contacted by the council and the surveys are expected to go on until the end of October.

The work represents the first real progress towards building the rail link, which will see the Metropolitan Line routed through to Watford Junction station.

Funding has been promised for the £118 million scheme since 2011 but work was not able to commence until the Department of Transport signed Transport Works Act Order last week.

The act gives Hertfordshire County Council and London Underground the legal powers needed to build, operate and maintain the new rail link.

Terry Douris, the Hertfordshire County Council’s Conservative cabinet member for highways, said: "Now that we’ve had approval to construct the new rail link, we’re not going to waste any time getting the works underway.

"These surveys will help our engineers draw up detailed designs and make sure we’re in a position to start construction works in the spring."

The project will see the Metropolitan Line redirected from Croxley station, through to new ones in Ascot Road and Vicarage Road before linking with Watford High Street Station and terminating at Watford Junction.

Construction, which is expected to start next year, will include laying track and building a new viaduct over the A412 and Grand Union Canal.

Hertfordshire County Council said a more detailed works programme is currently being drawn up and will be published once detailed engineering designs are completed. The target date for trains to start running on the new link is 2016.

Last week it was also announced Watford Metropolitan Station would close to passengers as part of the rail link. Residents and local politicians had lobbied for some sort of service to be maintained from the station in Cassiobury Park Avenue.

The Mayor of London, Boris Johnson, made the final decision to turn it into a siding for trains.