ENGINEERS HAVE solved a maintenance access problem on the QEII Bridge over the Thames at Dartford by specifying a high-tech working enclosure under the deck.
The problem has emerged on the northern approach viaduct, as it crosses the route of the Channel Tunnel Rail Link (CTRL), now under construction.
When the CTRL is complete, trains will pass under the viaduct, creating a new hazard for maintenance teams.
The answer is the FaberMaunsell developed Caretaker soffit enclosure system, fabricated from pultruded glass fibre reinforced polymer components.
Contractor Bridge Technology International will install it later this summer on a single 50m span of the 20m wide viaduct.
The enclosure will be supported off the bottom flanges of the five steel beams which form part of the composite deck. It will allow maintenance work to take place beneath the viaduct while high speed trains run directly below.
FaberMaunsell bridges and special structures director Jolyon Gill said this week: 'This installation will be significantly tougher than normal to cope with the high aerodynamic suction loads from the high speed trains, ' 'It will also have enhanced insulation to prevent arcing from the railway's power lines below.'
Chosen colour is green, to match the green paintwork on the crossing's steelwork.