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Sunday, 29 July 2012

Work Restarts, and This Time it's Tunnels ...

The following's a bit of an introduction to the present work. Since there's a lot going on, it's not easy to keep up with the work in progress (which is a good thing!). All the photos are clickable . . .

The New Bridges

Monksdale Road Bridge sections
Monksdale Road bridge delivery
They're not tunnels, but there's nothing wrong with bridges of course. Bridges are good. We're lucky the route's gaining bridges - and unexpected bridges at that, because we never expected that the two new bridges would find funding so quickly. Sustrans gets the credit for that. April saw the first of the bridges open at Monksdale Road.

Dartmouth Avenue bridge site
Dartmouth Avenue: bridge site.
Work to put Dartmouth Avenue's bridge in place is now well under way. The first task is moving what's rumoured to be Shepton Mallet's gas main. It's a job that's closed both Dartmouth Avenue and Linear Park at that point for the time being. This second bridge site is more constricted - unlike at Monksdale Road, it does not have a parcel of land alongside it available for use as a work compound. The contractors need some of the road space from which to work - even when they're not in the process of digging a trench clean across it.

In digging said trench, Hydrock encountered a very large slab of concrete - and now we really are now the 'Three tunnels campaign': Hydrock lowered the trench and tunnelled gently beneath the obstruction. The gas main will now be at some depth ...

The next task will be to build the two approach embankments and the concrete plinths on which the bridge will sit. 25% longer than its sister at Monksdale Road, the bridge will be delivered in two sections - this time of 18 and 22 metres in length.

The bridge sections will be brought in via Millmead Road. We're surprised that it will get round the junctions, but the suppliers, who are very experienced at this, have walked the route and they're happy with bringing the bridge in this way. For just a few days the delivery will result in extensive parking restrictions ...

The Tunnels

Lighting trials, Combe Down Tunnel
LED lighting trial at milepost 3
As good as it is to see the improvement to Linear Park made by the bridges, our title 'Two Tunnels campaign' suggested we'd missed the target somewhat ...

The section between Devonshire Tunnel's approach cutting and Tucking Mill Viaduct up until mid July, had seen a great deal of planning, but very little by way of physical work.

Long Arch bridge, Somerset and Dorset
Looking to Midford Station site
It's a curiosity, this stretch of the old line - it's now very obscure. Many long term residents know the route, having used its trains, but its existence is complete news to many, even if they're near neighbours to the route. Between Oldfield Park and Midford, the old line is a very low-key presence - though it crosses several of Bath's major roads, it runs deep beneath high ground,  remaining unseen. Even when not underground, the old route is hidden away in the depths of little-known Lyncombe Vale.

Bloomfield open space: access road for the work site

Bloomfield Road, Two Tunnels project
Worksite approach road on the left.
The original line was built 'By hand'. 3000 navvies toiled mainly with hand tools, excavating the tunnels and cuttings and using the spoil from those to raise its embankments. The work would have been largely self-contained - much material perhaps being transported in trucks carried on temporary rails, laid along the axis of the route.

The work to create the Two Tunnels route echoes this in some ways - the access route at Bloomfield Road being used to deliver the people, the materials, the plant that will construct the route through both tunnels.

Hence the early task for the contractors, Hydrock: organise a (temporary) surfaced route to Devonshire Tunnel through Bloomfield Road open space. The constricted Lyncombe Vale Road will not play a major part in providing access for the work. Wessex Water is kindly helping with access for work to Tucking Mill Viaduct, and also to nearby Combe Down Tunnel, both are close to its water treatment works there.

Devonshire Tunnel

This temporary road is now in place, and work has begun on Devonshire tunnel itself - including installation of the cabling for the lighting, any structural repairs, and a certain amount of cleaning. The tunnel will then be used as an access route to assist with construction of the remainder of the route.

The photo was taken with work underway in the tunnel itself, hence a certain amount of smokiness picked out by shafts of sunlight that find their way through the tree canopy there.

Combe Down Tunnel

The block wall at the north end has been removed and replaced with security fencing - this has been done to ventilate the tunnel, which is now a workplace along with the rest of the Lyncombe Vale length.

Masonry inside the portal that has not seen sun for some twenty years will be readied for its new purpose - though for the most part the structure is in good condition and needs only minor attention.

The photo shows the accumulated soot at what is the 'Uphill' end of the tunnel - for 90 years or so, loco exhaust would gently drift out of one end or the other, depending on the direction of the wind, but much of the sootier stuff on the walls wouldn't have stayed airborne for long - the wall's appearance speaks volumes for the conditions on the footplate for the loco crew, some of who referred to the entire four miles from Bath to Midford as 'Four miles of hell'.

Also in the photo is the strip of clean tunnel lining, running the length of the crown of the tunnel - the loco exhaust scouring the masonry - exhaust from machines such as Evening Star - which you can visit at the National Railway Museum at York, and looking at it, you'll probably wonder how such a machine ever fitted through the tunnels at all, and how people in Oldfield Park and Lyncombe Vale ever dried any washing.

Tucking Mill Viaduct 

Tucking mill viaduct, two tunnels route, under repair
Tucking Mill Viaduct: scaffolding.
With the line closed, this viaduct was very much at risk of demolition and was also quickly vandalised. (Curiously, one of the very individuals who vandalised the parapet sent us an anonymous message a couple of years ago saying how sorry he was for the behaviour of his younger self) 

One of the spurs to the Two Tunnels campaign is to ensure that the value of the structures along the route are recognised - giving them a long term future. That's why we're particularly pleased that July has seen the start of work to the viaduct. It now has  scaffolding to allow access for repointing, attention to its drainage, and work to the parapets.

Minor Structures

Moger's Viaduct
Mogers Viaduct awaits repair.
As well as two tunnels and a viaduct, the route has a number of bridges, all of which have seen little maintenance and one of which is missing completely. It's very fortunate that we have the survivors - in more exposed locations, they would probably have ended up in the way of some development or other and have been removed. Their forty year maintenance holiday is almost at an end: each has been surveyed for defects, the next few months will see some attention to all of them.

Missing Structures

Ketley's bridge site, Somerset and Dorset railway
Ketley's Bridge site
Ketley's bridge in Lyncombe Vale was iron: it was removed along with the track when the line was scrapped. This left such a pointless gap in what rapidly became a footpath that a very flimsy footbridge was added by persons unknown. The Two Tunnels route will see the abutments made good and a beam deck put in place once more, albeit probably not with quite the same strength as the original - see 'Evening Star' above.  Replacing the bridge will be an early task - its completion is needed as this will open up access for plant to work on the remainder of the route in Lyncombe Vale.

Concluding ...

Combe Down Tunnel north portal
Combe Down Tunnel: north portal.
In many ways it's an accident of history that led the railway company to build this most unlikely line - there would have been a lot to say for the route being taken to Bristol rather than to Bath across rather easier countryside. Build it they did, and between Midford and Bath there was very little of the resulting line that was not either above ground level or well beneath it.

Tucking Mill Viaduct under repair
Tucking Mill Viaduct
After it closed, the scale of the route's engineering meant that it would not have been easy to remove the remains from the landscape. Building the line, and demolishing it after it closed - both proved unaffordable.  However, its value as a walking route was all the more appreciated when the trains had stopped running - for many years the great tunnel beneath Combe Down was in very regular use as a footpath, more or less without incident. In many ways the Two Tunnels route will more or less simply recreate that resource.

Combe Down Tunnel
South of the tunnel
Combe Down Tunnel's cutting just before work started in mid-July, badly drained and slowly filling with detritus.

It's another of those places that could easily have been lost - the trackbed south of the cutting is somewhat covered by dumped material. In the late seventies, the cutting itself was blocked halfway along its length by a ramp of soil put there in connection with works to a pipeline. Surprisingly, the ramp that blocked the cutting was then removed, leaving no trace that it had been there, but it may have been this work that broke the drain leading along its right hand side - the water from the tunnel now runs down the middle of the trackbed before disappearing into the drainage system once more.

It's interesting to reflect that in a few month's time this will be an easy stroll or cycle - and even accessible to someone using a wheelchair.

In the short term, we appreciate the support that's been shown by organisations and individuals - even on occasion from people inconvenienced by the current work programme - this helps everyone, not least the contractors involved in building the route. If you'd like to track the project day-to-day, our Twitter feed provides more frequent updates.

You can help too - support the work of Sustrans, or give the local authority a hug for the part that Bath and North East Somerset Council is playing in bringing this route into being, especially as, being a local authority, no one ever hugs them - and also because they have the less glamorous task of providing a connection between the Two Tunnels route and the riverside path. - a riverside path that is suddenly much more useable, having had a haircut at last.