Irthlingborough Viaduct

Irthlingborough Viaduct crosses the River Nene on the A6 to the east of Irthlingborough.

Opening

The 31 span concrete viaduct over the River Nene and railway was opened on 23 October 1936 by Leslie Hore-Belisha, Minister of Transport. It formed a southern extension of Irthlingborough Bypass (opened 1932) and bypassed the railway level crossing.

Construction

Length was 1,360 feet and width between parapets 40 feet. Height varied between 20 and 33 feet. The 31 spans were not of equal length, varying between about 33 feet and 44 feet and were carried on reinforced concrete trestles each containing 5 columns. Foundations were taken down to gravel level at between 6 and 13 feet depth. A 7.5 inch reinforced concrete slab spanned the beams and carried the concrete filling and 3.5 inches of tarmacadam for the road surface. The gradient of the bridge was 1 in 30. 20,000 cubic yards of filling were required for the approach embankments.

Light coloured local dry pit sand was used with Portland Cement and Triscosal as a surface finish on concrete. This gave a resemblance to a stone built structure. Over 600 tons of steel and 7,200 cubic yards of concrete was used in construction. Ten expansion joints were provided at roughly 150 feet intervals.

Architect was J.A. Gitch with Consulting engineer for the reinforced concrete work being Mr Vawdrey of the Indented Bar and Concrete Engineering Co. Ltd. of London. Bridge contractor was A.E. Farr of London with the rest of the scheme being completed by Council direct labour. Estimated cost was £55,750, of which 75% was paid by Ministry of Transport.