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Monday, 10 January 2011

Linear Park Surfacing: start of physical work

Hydrock's digger awaits duty on the Two Tunnels route.
Two opportunities in one, a quick mid-day visit to the start of the surfacing works on Bath's emerging 'Two Tunnels' route with a chance to grab a bite to eat in the form of an 'Angelo' from Bear Flat's excellent 'Da Vinci' delicatessen.

Here, the digger that will be used to lay the surface for Linear Park waits at the top of the public open space on the Monday morning of the tenth of January.

It's a smaller digger than the two used by the contractors that made such a good job of excavating Devonshire Tunnel - Hope and Clay - but Hydrock, who will be working on this section of Linear Park, have a different task and won't need to move thousands of tonnes of spoil.

Hydrock are pleased to be involved in the construction of the flagship Two Tunnels route, particularly because they've worked on the route in the past - in the nineteen nineties the firm produced an engineering appraisal of Combe Down Tunnel in support of the previous campaign to build a 'Two Tunnels route'. They also have local connections, Hydrock were involved in the extensive stabilisation and infilling work carried out to an extensive range of unstable stone mines beneath Combe Down. (Thankfully, those mines had no impact on Combe Down Tunnel itself, the mines and the tunnel being separated by a great thickness of solid rock)

You'll see the digger has rubber tracks rather than steel ones - this has big advantages for this sort of work, the tracks exert much less pressure on the ground than steel tracks: this is more kind to anything underlying the route, and the machine can be driven on completed work with minimal impact.

Not representative of the whole stretch,
but some parts of Linear Park
are a bit of an ordeal ...
The physical work involves excavating to a depth of 10 to 100 millimetres and three metres wide, laying an impermeable membrane. On top of this goes a foundation, and then, in turn, a surface layer that will form the actual path. Certain sections will benefit from a drain too.

Before starting on the route itself, the first task for the contractors is to put down a haul road across the public open space, as was done for the excavation works to Devonshire Tunnel. This will allow materials to be brought to the route with minimal impact on the grassed park, allowing work to start on the route itself.


Rob said...

Excellent stuff.

There's actually a two tunnels group on flickr which I'd suggest that anyone getting any pictures of work in progress could post to....

Mark A said...

Rob, thanks for this, and yes, if supporters could post to the Flickr group then so much the better.

Anonymous said...

Interesting that the path will be laid to Devonshire tunnel but at some stage equipment will need to cross it to demolish and remove the existing wall. I would have thought going through the tunnel access would be easier from this end rather than the Lyncombe end.

Mark A said...

@Anonymous: indeed. I believe that work to the Lyncombe Vale section will be carried out from the Bath end of Devonshire Tunnel. Surfacing the section of route to Devonshire Tunnel will be carried out when it's no longer needed for access by plant.

(Why is 'Plant' called that, does anyone know?)

John Yeo said...

Mark, if it's any help, I don't know.