Summit Tunnel fire

On 20 December 1984 a dangerous goods train passing through the Summit Tunnel on the Greater Manchester/West Yorkshire border, caught fire on the rail line between Littleborough and Todmorden, England.

History

Main article: Summit Tunnel

The tunnel, which is 1.6 miles (2.6 km) in length, was built in the late 1830s. The construction shafts, at intervals of (approximately) 220 yards (200 m), were left open to help vent smoke and steam from the locomotives that passed through it.

Other Railway Accidents during December 1984

The incident was one of an unfortunate series of railway accidents during 1984, coming only days after the fatal collision between an express passenger train and a train of fuel oil tankers at Eccles, Greater Manchester on 4th December. One day earlier on 3rd December a train guard had been killed after a collision between a diesel multiple unit and parcels vans at Longsight also in Manchester. This third serious railway accident in the North West of England in less than 3 weeks, led the Littleborough and Saddleworth MP Geoffrey Dickens to call for an inquiry into railway safety, in particular with respect of the conveyance of dangerous chemicals such as those involved in the accidents at Eccles and Summit Tunnel.

Fire

The fire occurred at 5:50 a.m. on 20 December 1984 just after the 01.40 a.m. goods train from Haverton Hill to Glazebrook oil distribution terminal in Merseyside, carrying more than 1,000,000 litres (220,000 imp gal; 260,000 US gal) (835 tonnes or 822 long tons or 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 the damaged axle box.

The three train crew members 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 (at approximately ) and discharged their remaining loads as floods.

The fuel supply to the fire was so rich that 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. 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 cleanup 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 mid-afternoon 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 another 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.

Aftermath

Of the 1,100,000 litres (240,000 imp gal; 290,000 US gal) of petrol carried by the train, 275,000 litres (60,000 imp gal; 73,000 US gal) were rescued by the train crew when they drove the locomotive and the first three tankers to safety. A further 16,000 litres (3,500 imp gal; 4,200 US gal) of petrol were recovered after the fire was extinguished, and 900,000 litres (200,000 imp gal; 240,000 US gal) (670 tonnes or 660 long tons or 740 short tons) burnt. The rest of the petrol is presumed lost in the accident.

The damage done by the fire was minimal. Approximately half a mile of track had to be replaced, as did all the electrical services and signalling. The biggest surprise was how well the brick lining had stood up to the fire. Although some bricks in the tunnel and in the blast relief shafts had become so hot, they vitrified and ran like molten glass, most of the brickwork lining of the tunnel was scorched but still serviceable. One of the photographs taken in the aftermath shows a rail tanker directly beneath shaft 9: it is crowned with a mass of vitrified slag from bricks in the shaft that had melted and dripped down.

Once British Rail had replaced the track and electrical services, shored up the bases of vent shafts 8 and 9 and filled the two shafts with inert foam (all this took eight months), locals were allowed a once-in-a-lifetime opportunity to walk through it before train services resumed.

The Summit Tunnel fire is worthy of note for several reasons:

• The size of the fire: it is probably the biggest underground fire in transportation history, certainly bigger than the 1996 Channel Tunnel fire (a relatively meagre 350 megawatts) and probably bigger than the ill-defined Salang tunnel fire in Afghanistan.
• The luck of those who fought it: The BR train crew who returned to the site to rescue a locomotive and three tankers left the fire site shortly before one of the other petrol tankers filled the tunnel with flames. The firefighters in BA sets who were in the tunnel when filled with flames were saved because blast relief shafts 8 and 9 acted as flame vents (a function their designer never envisaged).
• The amount of damage to the primary structure of the tunnel was minimal, although some of the bricks melted.

At the Masons Arms public house in Todmorden, there is a small collection of photographs noting the fire, along with the statistics of the construction and a quotation by George Stephenson, the tunnel's builder, who said, "I stake my reputation and my head that the tunnel will never fail so as to injure any human life".

External links

• Summit Tunnel booklet, Rochdale Boroughwide Cultural Trust
• firewestyorkshire.com, Report and photos
• Granada TV newscast, Contemporary Newscast