Transport Research Laboratory (TRL) engineers have carried out smoke tests in the Ramsgate Harbour Approach Tunnel in south-east England.
The TRL team worked with the contractor, a Taylor Woodrow/ Perforex joint venture, to run a programme of fan control sequences, using ‘atomised’ vegetable oil discharged into the exhaust of space heaters to simulate the heat of a fire. The programme tested fans and their controls for various fire locations.
Babtie is the project engineer on behalf of client Kent County Council, Halcrow is the civil designer, with MEA carrying out m&e design.
The Ramsgate tunnel has four high-volume, low-speed, low-noise Howden SX axial extractor fans of a design new to tunnel installations, plus 18 Howden jet fans mounted in pairs along the crown of the 790m-long bi-directional road tunnel.
Extractor fan blades are made of fire-resistant, glass-fibre-reinforced polyester. This allows the whole fan to be specified for one hour’s operation at 600oC. Tunnel fires can generate 1,000oc temperatures, but no means of handling the emissions of such fires have yet been devised.
The extractor fans can only remove a small amount of smoke, but this is intended to leave a gap for fresher air closer to the road.
The tunnel will ease the passage of heavy freight trucks to continental ferries, eliminating a steep down-grade and hair-pin bend. Proximity to a residential area added to environmental considerations in the design. These include the use of the low-noise Howden extractor fans in a low-profile shaft housing.
The 25-month contract is set to be completed to the fixed budget of £26.1M ($38.33M).
