Surtees Bridge

The Surtees Bridge is a road bridge carrying the A66(T) road east west across the River Tees near Thornaby-on-Tees in the borough of Stockton-on-Tees in the north east of England. The bridge is situated one kilometre upriver from Stockton town centre, just upriver of Tees Bridge – a rail bridge carrying the Tees Valley Line. Built at a cost of £14. 3 million the bridge replaces an earlier Surtees Bridge that showed signs of distress resulting from excessive settlement. The Surtees Bridge and the A1 motorway bridge are the busiest over the River Tees with 55, 000 vehicles per day. The river level at this point is held at 2. 7 mOD by the Tees Barrage which makes the river here permanently navigable. The Surtees Bridge (1981)The original Surtees Bridge was a concrete and steel structure built by The Cementation Company with dual two lane carriageways, four intermediate piers, five spans and was 145 m long with 125 m between abutments. The bridge was opened in 1981 with a design life of 120 years. Geotechnical surveys prior to construction had indicated that the western approaches of the bridge would be liable to settlement and so they were built in early 1978 under a separate works contract and left to settle for 18–24 months before bridge construction started. Bridge construction took place from 1980 to 1982, during which time the eastern embankment was built, and the bridge was opened in 1981 but even then signs of distress were already showing. Later surveys showed the eastern abutment had rotated and moved by 100–150 mm and sunk 0. 7 m, and the bridge bearings had overrun by 100 mm. The bridge problems were caused by underestimations of the depth of the soft alluvial layers on the eastern bank, and secondly overestimation of the rate at which the ground would consolidate during construction which led to the assumption that the settlement of the eastern abutment would be largely over by the time the abutment was complete – instead significant settlement was to continue on after construction. Ground settlement is a problem in the area – the nearby 'Tees Bridge' rail bridge had speed restrictions imposed as it too showed signs of distress.

The Surtees Bridge is a road bridge carrying the A66(T) road east west across the River Tees near Thornaby-on-Tees in the borough of Stockton-on-Tees in the north east of England. The bridge is situated one kilometre upriver from Stockton town centre, just upriver of Tees Bridge – a rail bridge carrying the Tees Valley Line. Built at a cost of £14. 3 million the bridge replaces an earlier Surtees Bridge that showed signs of distress resulting from excessive settlement. The Surtees Bridge and the A1 motorway bridge are the busiest over the River Tees with 55, 000 vehicles per day. The river level at this point is held at 2. 7 mOD by the Tees Barrage which makes the river here permanently navigable. The Surtees Bridge (1981)The original Surtees Bridge was a concrete and steel structure built by The Cementation Company with dual two lane carriageways, four intermediate piers, five spans and was 145 m long with 125 m between abutments. The bridge was opened in 1981 with a design life of 120 years. Geotechnical surveys prior to construction had indicated that the western approaches of the bridge would be liable to settlement and so they were built in early 1978 under a separate works contract and left to settle for 18–24 months before bridge construction started. Bridge construction took place from 1980 to 1982, during which time the eastern embankment was built, and the bridge was opened in 1981 but even then signs of distress were already showing. Later surveys showed the eastern abutment had rotated and moved by 100–150 mm and sunk 0. 7 m, and the bridge bearings had overrun by 100 mm. The bridge problems were caused by underestimations of the depth of the soft alluvial layers on the eastern bank, and secondly overestimation of the rate at which the ground would consolidate during construction which led to the assumption that the settlement of the eastern abutment would be largely over by the time the abutment was complete – instead significant settlement was to continue on after construction. Ground settlement is a problem in the area – the nearby 'Tees Bridge' rail bridge had speed restrictions imposed as it too showed signs of distress.