Summit Tunnel Fire - The Fire

The Fire

The fire occurred at 5.50 a.m. on 20 December 1984 when a goods train carrying more than 1,000,000 litres (220,000 imp gal; 260,000 US gal) (835 tonnes / 822 long tons; 920 short tons) of four-star petrol in thirteen tankers entered the tunnel on the Yorkshire (north) side. One-third of the way through the tunnel, a defective axle bearing (journal bearing) derailed the fourth tanker, which promptly knocked those behind it off the track. Only the locomotive and the first three tankers remained on the rails. One of the derailed tankers fell on its side and began to leak petrol into the tunnel. Vapour from the leaking petrol was probably ignited by a hot axle box.

The three train crewmembers could see fire spreading through the ballast beneath the other track in the tunnel, so they left the train and ran the remaining mile to the south portal (where they knew there was a direct telephone connection to the signaller) to raise the alarm.

Crews from Greater Manchester Fire Brigade and West Yorkshire Fire Brigade quickly attended the scene. Co-ordination between the brigades appears to have worked well, perhaps because they had both participated in an emergency exercise in the tunnel a month before.

The train crew were persuaded to return to the train, where they uncoupled the three tankers still on the rails and used the locomotive to drive them out. Greater Manchester fire brigade then loaded firefighting equipment onto track trolleys and sent a crew with breathing apparatus (BA) in to begin their firefighting operation at the south end of the train. They also lowered hoselines down one of the ventilation shafts to provide a water supply. At the same time, crews from West Yorkshire fire brigade entered the tunnel and began fighting fires in the ballast at the north end of the train.

However, at 9.40 a.m., the pressure in one of the heated tankers rose high enough to open its pressure relief valves. The vented vapour caught fire and blew flames onto the tunnel wall. The wall deflected the flames both ways along the tunnel, the bricks in the tunnel wall began to spall and melt in the flames and the BA crews from both brigades decided to evacuate. They managed to leave just before the first explosion rocked the tunnel.

Left to itself, the fire burned as hot as it could. As the walls warmed up and the air temperature in the tunnel rose, all 10 tankers discharged petrol vapour from their pressure relief valves. Two tankers melted and discharged their remaining loads as floods.

The fuel supply to the fire was so rich, some of the combustibles were unable to find oxygen inside the tunnel with which to burn; they were instead ejected from vent shafts 8 and 9 as superheated, fuel-rich gases that burst into flame the moment they encountered oxygen in the air outside the tunnel. At the height of the fire, pillars of flame approximately 45 metres (148 ft) high rose from the shaft outlets on the hillside above.

The gases are estimated to have flowed up these shafts at 50 metres per second (110 mph). Air at this speed is capable of blowing around fairly heavy items: hot projectiles made from tunnel lining (rather like lava bombs from a volcano) were cast out over the hillside. These set much of the vegetation on fire and caused the closure of the A6033 road. In the clearup operation afterwards, small globules of metal were found on the ground surrounding shaft 9; these had been melted from the tanker walls, swept up with the exhaust gases, and dropped out onto the grass around the top of the shaft.

Unable to get close enough to safely fight the fire directly, the fire brigades forced foam into ventilation shafts far from the fire. This created blockages that starved the fire of oxygen. By midafternoon the next day, the inferno was no longer burning, though the fire was by no means knocked down. Petrol continued to leak from the derailed wagons through the tunnel drainage and ballast and the vapour sporadically reignited when it came into contact with the hot tunnel lining. It also became apparent that petrol vapour had leaked into the nearby River Roch, possibly creating explosive atmospheres in the nearby towns of Summit and Todmorden, which were partially evacuated in response.

The brigades continued to fight the fire for a further two days, until West Yorkshire fire brigade issued the stop message just after 6:30 p.m. on Christmas Eve. Fire crews remained at the site until 7 January 1985.