Complex flyover refurbishment in Southampton

An account is given of maintenance work carried out at the A35 Millbrook and Redbridge flyovers in Southampton where worn out bearings were replaced whilst keeping the road above open. The project involved the lowering of four abutment bearing shelves and the replacement of the four disc bearings at the seven concrete piers and abutments, each of which supports the bridge decks, as well as the installation and replacement of expansion joints and associated drainage work. Brief details are given of the techniques used to support the road deck, remove and replace concrete and bearingsand the monitoring system employed throughout the operation. The supportsystem utilised steel super props equipped with 520 tonne capacity short-stroke hydraulic jacks. Hydro-demolition techniques were used to remove concrete and bearings and to create voids for the new sockets. A continuous real-time monitoring system was designed by Testconsult to measure loadsand movement including rotational movement and displacement of the foundations.