Combe Down Tunnel
Combe Down Tunnel
![The approach cutting to the southern portal has retaining arches to hold back the weak Midford Sands.](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image1-100.jpg)
![The tunnel's southern section boasts near-vertical side walls and an arch soffit springing off high haunches.](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image2-100.jpg)
![Holes have been cut to allow water to drain from behind the lining. This has resulted in mineral deposits adorning the brickwork.](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image3-100.jpg)
![Profile changes come thick and fast, including an out-of-place sandstone arch - presumably, a hurried repair.](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image4-99.jpg)
![Four pieces of bullhead rail sit against the east wall. Did they formerly act as mileposts?](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image5-99.jpg)
![Around 300 yards from the south portal, a cabin provided teatime refuge for the tunnel's platelayers.](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image6-98.jpg)
![No doubt, anyone sitting inside would have been choked by smoke when a northbound train passed, labouring up the gradient.](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image7-96.jpg)
![The central section is mostly unlined but some of the refuges are still neatly fashioned in brick.](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image8-86.jpg)
![Water-borne minerals have 'glued' the remaining ballast together. Collars of brickwork serve as evidence of regular repair works.](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image9-73.jpg)
![One of the many junctions between Bath stone and the tunnel's lining.](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image10-58.jpg)
![A drain ran along the east wall, next to a cable trough.](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image11-43.jpg)
![A bizarre two-stage refuge for little and large platelayers!](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image12-31.jpg)
![Near the northern end, an abrupt change in section - presumably the result of an overbreak - sees the roof rise by several feet.](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image13-25.jpg)
![The green glow of daylight beckons explorers to the Bath exit.](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image14-18.jpg)
![The northern portal is masonry with a brick parapet wall.](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image15-9.jpg)
![Scurrying south, 75073 enjoys the sunshine once again.](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image16-6.jpg)
![The line curves south, past a pair of p-way cabins, to enter the inconspicuous northern entrance.](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image17-6.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image1-100.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image2-100.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image3-100.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image4-99.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image5-99.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image6-98.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image7-96.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image8-86.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image9-73.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image10-58.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image11-43.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image12-31.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image13-25.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image14-18.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image15-9.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image16-6.jpg)
![](http://www.forgottenrelics.org/wp-content/uploads/2023/03/image17-6.jpg)
The Somerset & Dorset’s extension into Bath involved serious engineering and first took the strain of commercial traffic on 20th July 1874.
On its southern approach to the city, the route burrowed 300 feet beneath Combe Down, a hill largely formed of oolite. Towards its southern end, the tunnel – the UK’s longest without intermediate ventilation – breaks through into the Midford Sands whilst, above it, a layer of Fuller’s Earth acts as a waterproofing course.
For much of its length, the predominantly dry tunnel rises on a 1 in 100 gradient before leveling out around 400 yards from the northern portal. It is brick-lined at both ends with near-vertical side walls and an arch soffit springing off high haunches. The left-hand curvature of 68 chains radius at the southern end is surpassed by a tighter curve of 29 chains radius as trains regain daylight on their approach to Bath.
Changes in profile are frequent – the product of significant and recurring repair programmes. For 10 yards close to the north portal, a significant change in section sees the roof raised abruptly by several feet, presumably the result of a huge overbreak during construction. The straight central section was completely unlined in 1874 but subsequent repairs involved the installation of many engineering brick rings.
Refuges are located frequently in both walls, many hewn from the bare rock. A platelayers’ cabin offered sanctuary towards the southern end.
The last train passed through the tunnel on 7th March 1966. Ownership was later transferred to Wessex Water but the tunnel is now in the hands of sustainable transport charity Sustrans which opened it to the public in April 2013 as part of the Two Tunnels Greenway project. This involved remedial works to the structure as well as the installation of lighting and a tarmac surface. ‘Living’ artworks, located in many of the refuges, add to the tunnel’s soundscape.