Box Tunnel is a railway tunnel between Bath and Chippenham, dug through Box Hill and is one of the most significant structures on the Great Western Main Line. The tunnel is 1.83 miles in length, straight, and descends a 1 in 100 gradient from the east. It was originally built for the Great Western Railway under the direction of the GWR's engineer Isambard Kingdom Brunel.
This report is simply about a small secondary portal that exists at the Eastern Portal, and is not me entering the main Box Tunnel - being a live high speed rail line that would have been very silly and fatal. This secondary portal dates from at least 1886 and served Tunnel Quarry and later the WW2 era Central Ammunition Depot.
History
Construction of Box Tunnel began in December 1838, divided into six isolated sections. Access to each was via a 25 foot diameter ventilation shaft, which ranged in depth from 70 feet on the eastern end to 300 feet towards the western end. All men, construction equipment, materials and 247000 cubic yards of extract had to go in and come out via steam powered winches. The only lighting was via candlelight, which were consumed at the rate of one tonne per week, which was equaled by the weekly consumption of explosives. At the height of activity about 4000 men were employed, and perhaps a hundred lost their lives. Effective completion of the tunnel was in April 1841. When the two ends of the tunnel were joined underground, there was found to be less than 2 inches of error in their alignment.
The famous Corsham quarries, which produced Bath limestone, were in the hillside above the tunnel. By 1886 the East Portal of Box Tunnel was subsequently altered by the construction of a separate portal into Randell & Sanders' Tunnel Quarry (which lay north of the tunnel) through its own tunnel mouth a few yards forward of Brunel's portal. The siding extended over half a mile into the hillside to a loading platform.
Victorian Era Photo of the East Portal
In 1936 Tunnel Quarry was acquired by the War Office as one of the four sub-depots of the Corsham Central Ammunition Depot, a vast underground munitions storage facility in the Corsham quarries. The Royal Engineers undertook the conversion works, which probably included the brick alterations to the East Portal. Most of the ammunition during the war arrived and left by the former quarry siding, whose portal appears to have been remodeled in reinforced concrete.
WW2 era photo of the East Portal
Map of CAD - Tunnel Quarry Section. Red arrow shows the Box Tunnel East Portal
CAD closed at the end of WW2 hostilities, although was kept in an operational condition until the 1950s. The sidings were then cleared and not used again until the mid-1980s when a museum opened for a short period on the site. Today the former mine/CAD is used for secure commercial document storage.
Trip Report
This trip gave me my first ever Urban Explore trouser-ripping experience. Thank God the car wasn't too far away. I guess there will be more of those to come. Anyways onto the photos:
First view of the siding looking in
Leads to bricked doorway after about 50 metres. Only dynamite will allow access to Tunnel Quarry beyond and guess what I had forgot to pack.
And looking out
A WW2 era office lies to the side of the tunnel
Old light switch
Light fittings
Electrical thingys
This is a stalagmite rising from the floor
Thanks for looking, now I need to go and online shop for some Kevlar strength trousers. I'm sitting here on the sofa with no trousers on and it's alarming the wife a bit.
This report is simply about a small secondary portal that exists at the Eastern Portal, and is not me entering the main Box Tunnel - being a live high speed rail line that would have been very silly and fatal. This secondary portal dates from at least 1886 and served Tunnel Quarry and later the WW2 era Central Ammunition Depot.
History
Construction of Box Tunnel began in December 1838, divided into six isolated sections. Access to each was via a 25 foot diameter ventilation shaft, which ranged in depth from 70 feet on the eastern end to 300 feet towards the western end. All men, construction equipment, materials and 247000 cubic yards of extract had to go in and come out via steam powered winches. The only lighting was via candlelight, which were consumed at the rate of one tonne per week, which was equaled by the weekly consumption of explosives. At the height of activity about 4000 men were employed, and perhaps a hundred lost their lives. Effective completion of the tunnel was in April 1841. When the two ends of the tunnel were joined underground, there was found to be less than 2 inches of error in their alignment.
The famous Corsham quarries, which produced Bath limestone, were in the hillside above the tunnel. By 1886 the East Portal of Box Tunnel was subsequently altered by the construction of a separate portal into Randell & Sanders' Tunnel Quarry (which lay north of the tunnel) through its own tunnel mouth a few yards forward of Brunel's portal. The siding extended over half a mile into the hillside to a loading platform.
Victorian Era Photo of the East Portal
In 1936 Tunnel Quarry was acquired by the War Office as one of the four sub-depots of the Corsham Central Ammunition Depot, a vast underground munitions storage facility in the Corsham quarries. The Royal Engineers undertook the conversion works, which probably included the brick alterations to the East Portal. Most of the ammunition during the war arrived and left by the former quarry siding, whose portal appears to have been remodeled in reinforced concrete.
WW2 era photo of the East Portal
Map of CAD - Tunnel Quarry Section. Red arrow shows the Box Tunnel East Portal
CAD closed at the end of WW2 hostilities, although was kept in an operational condition until the 1950s. The sidings were then cleared and not used again until the mid-1980s when a museum opened for a short period on the site. Today the former mine/CAD is used for secure commercial document storage.
Trip Report
This trip gave me my first ever Urban Explore trouser-ripping experience. Thank God the car wasn't too far away. I guess there will be more of those to come. Anyways onto the photos:
First view of the siding looking in
Leads to bricked doorway after about 50 metres. Only dynamite will allow access to Tunnel Quarry beyond and guess what I had forgot to pack.
And looking out
A WW2 era office lies to the side of the tunnel
Old light switch
Light fittings
Electrical thingys
This is a stalagmite rising from the floor
Thanks for looking, now I need to go and online shop for some Kevlar strength trousers. I'm sitting here on the sofa with no trousers on and it's alarming the wife a bit.
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But but me is nice really... ask err err my mother
