Brief Description Of Structure.docx

Brief Description of Structure The River Ash Culvert is a single 6.4m span simply supported culvert. The inlet of the culvert can be found between A308 London Road Eastbound Off-slip and A30 Staines Bypass Northbound On-slip; and the outlet can be found on the A308 Staines Bypass Westbound Off-slip. The exact path of the culvert is unclear; however, it is believed that the culvert runs underneath the Crooked Billet Roundabout. The culvert is approximately 265m long in total and has a clear span of 6.4m. The Culvert comprises of 4 distinct sections constructed at different times adjacent to one another to form the current structure. The sections are as follows: 1.

Billet Bridge: Before the construction of the Crooked Billet Roundabout the road crossing of the River Ash was located in the middle of the current roundabout. The structure consists of a reinforced concrete slab, simply supported on concrete abutments. The date of construction is unknown.

2.

Original Culvert (forming two sections): When the Crooked Billet Roundabout was constructed in 1960, Billet Bridge was extended both eastwards and westwards by a culvert, which is labelled “Original Culvert” in multiple reports. The deck consists of precast prestressed inverted T beams with in-situ concrete infill. The deck is simply supported on concrete side walls. Where changes in direction occur, the deck consists of an insitu reinforced concrete slab. The structure was constructed in 1960.

3.

Culvert Extension: After the construction of Crooked Billet Roundabout, the road layout was changed again and the culvert was extended further eastwards to its current layout. The structural form of the extension matches that of the Original Culvert. The date of construction is unknown.