Strengthening two London Underground covered ways

Covered ways 12 and 58 are parallel covered ways carrying the District and Circle Lines of London Underground near the High Street Kensington Station. They were constructed in 1867 and support Kelso Place— a twin-ended cul-de-sac—and predominantly residential properties over the railway. The two covered ways are each approximately 110 m long, with interconnecting cross-passages. The roof comprises brick jack-arches spanning onto cast iron beams, 45 in each covered way. The cast iron beams were assessed for the building loads and highway loads, and found to be overstressed. Also, owing to the condition of the track, there had been a history of concerns by local residents relating to noise caused by the passage of trains through the covered ways. In order to improve the existing structure gauge clearances, the tracks were lowered. To minimise the overall construction depth and required track lowering, the new superstructure comprised ‘aerofoiľ-type semicircular steel beams erected within the jack-arches. Piled foundations were constructed in front of the existing piers and abutments to minimise any settlements that would have resulted following track lowering. New track supports were constructed over two sewer crossings in the covered ways. A new ballasted track bed was installed on a noise reduction mat.