The composite photo shown above is to give the reader some idea of the brickwork completed in the Widbrook tunnel. The positioning of the tunnel was chosen, and a small cofferdam was built from which the water was pumped or drained away. Still allowing the stream to flow around the sides. Any loose gravel and silt was removed until the firm bedrock of gravel was reached from which a foundation could be built.
The basic foundation was most likely made of concrete poured into sandbags and laid flat and tamped in the position. When the concrete was set, carpenters were called in to make a curved wooden framework the length of the tunnel. From there, bricklayers would lay the first course of bricks on top of the wooden frame, and when set, most likely a second layer was added to give strength. After which the wooden framework was removed. To this a concrete retaining wall was built to the ends of the tunnel; the Western retaining wall was the longest, due to the fact that part of the water splash was left intact for the cattle to cross from one part of a Common to the other. The Eastern side was much shorter, due to the fact that the water splash left was much narrower but still allowing cattle to cross the stream and will.
The lead up to the brickwork of the tunnel on either side was excavated and a large grade of agregate followed by a much finer grade towards the surface, before the final application of coal tar and chippings were applied and rolled into place. In 1935 or 1936 new approach leads to the tunnel were replaced by large core asphalt to strengthen the bridge and tunnel. This was the last time any serious work has been done.