Bridge Building at Cothill NNR


Our task was Bridge & Boardwalk construction at Cothill NNR on Sunday 11th May. We picked a good day for it. The sun was out & Cothill Fen was glistening with spring growth. When we arrived, we did a quick recky of the area where we were working & a young stag jump over a fence in front of us!

Cothill NNR is known for its fens and their rich invertebrate life.

Cothill NNR is known for its fens and their rich invertebrate life.

The 1st of the 3 tasks was nailing down decking to a boardwalk that has already been constructed. The decking’s larch wood However, the stringers, (rails), are made of composite plastic, making drilling & nailing a bit more laborious.

Boardwalk frame running into the woodland.

Boardwalk frame running into the woodland.

We had a generator with us to help with the drilling so progressed well through the day.

We had a generator with us to help with the drilling so progressed well through the day.

2nd of the 3 tasks was building a pedestrian bridge over a small stream. The area is boggy making foundations a little tricky. Oak sleepers were used for the foundations which were embedded into the ground either side of the stream. Three oak stringers then spanned the river. Planks of larch are then used for the decking.

A lot of directing while one's doing the work.

A lot of directing while one’s doing the work.

We got the bridge bridge pretty much finished. A bit of decking left to do. You can see a hole in each stringer. This is where they’ve been countersunk for the coach screws that fix them to the sleeper.

Volunteers admiring their work!

Volunteers admiring their work!

3rd of the 3 tasks was building a bridge over the same stream into a fen. This will be used by ponies which will graze the fen once everything’s constructed. Again the area is extremely boggy. No one fully fell over but there were a few close calls.

First job was clearing the area for the bridge.

First job was clearing the area for the bridge.

The bridge design follows that of the pedestrian bridge, i.e. 2 oak sleepers with 3 oak stringers. As the area is boggier & a greater distance is being spanned, supporting posts have been added as piers for the bridge.

Supports were completed. Stringers need to be attached.

Supports were completed. Stringers have yet to be attached.

 

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