Installation of new signalling systems has begun on London Underground by Thales.

When completed there will be a 33% capacity increase across four routes by 2022. It is replacing some signalling infrastructure that dates back to the 1930s according to Transport for London.

The work has begun between Edgware Road and Hammersmith. The four lines being modernised will be the Circle, District, Hammersmith & City and Metropolitan lines.

The system is similar to that already in place on the Jubilee and Northern lines. When fully installed, capacity will increase to 32 trains per hour at peak periods through London.

London Underground Managing Director Andrew Pollins said: “This is a major step in delivering this vital upgrade for millions of our customers. The signalling system on these lines is some of the oldest in use anywhere in the world, with parts of it dating back to the 1930s.”

Alistair McPhee, vice president of the Ground Transportation Systems business at Thales, said: “Getting installation underway takes us another step forward on our journey to provide the capacity on the network that London needs”.