One of the engineering wonders of the £5.2bn project CTRL was completed in 2003, the Thurrock Viaduct, the link between the Thames tunnel and Rainham Marshes. Thurrock Viaduct is one of the most spectacular achievements of the CTRL, a new viaduct crossing over the existing railway lines, over the Dartford Tunnel exit ramps and underneath the Queen Elizabeth the 2nd Bridge. This 1 km long viaduct was constructed over a year.