Design and Engineering
Construction began on the Matt Talbot Bridge in April 1976 to a design by LF Stephens from De Leuw, Chadwick and O’hEocha, Consulting Engineers Dublin with Mott Hay and Anderson, London, sub-consultants. The contractors were Ascon Ltd.
The purpose of the bridge was to create, in conjunction with the proposed Frank Sherwin Bridge, a gyratory movement on the north and south quays, reversing traffic flows on the quays and also to remove traffic eastwards from the city centre. Design conditions were imposed by the Port Authority in relation to clearance for river traffic and aesthetic restrictions due to its proximity to the Custom House completed by Gandon in 1791. To provide for navigational requirements a single-span solution and a three-span solution were examined. A three-span beam bridge was adopted with two north and south spans of 22m and a centre span of 34m.
It was built by founding the bridge piers on rock using interlocking steel sheet piling to form cofferdams and precast, prestressed beams with an in situ deck for the superstructure. The structure is founded on a very deep stratum of hard calp limestone. The main river piers take the form of slender reinforced concrete piers offering minimum obstruction to the flow of the river, which are carried down into the rock by spread footings. Some delay was incurred as a result of difficulties in sealing and drying out the cofferdams. At the south abutment it was necessary to stabilise and strengthen the existing river wall with reinforced concrete, overlay with a capping beam which carries the bridge bearing. The bridge bearing at the north abutment consists of a reinforced concrete pile cap carried by a system of reinforced concrete piles.
The superstructure consists of eleven precast beams which are I-shaped and of varying section, with thickening of the webs over the support. These beams are clad with precast concrete panels (Wicklow and Scottish granite dust, surface-treated by acid etching) to make the elevation visually satisfactory. This process was developed especially for use on this bridge. The beams also carry an in-situ reinforced concrete deck 180 mm thick. The prestressed concrete beams were post-tensioned in a two stage stressing operation, to provide for maximum structural economy.
The cantilever span beams were placed into position by a rolling operation. Each beam was first jacked onto purpose made steel swivel plates supported on industrial skates. It was then moved along the quay until reaching a steel gangway which spanned from the quay wall to the pier in the river. One end of the beam then travelled along the steel gangway until reaching the pier where it was lowered into position, one end resting on the river pier and the other on the quay abutment. The suspended span beams, over the middle of the river, were placed in their final position by first lifting them onto a barge at the quayside. Then the barge was towed into mid-river, between the piers. The beams were finally hoisted from the barge by cranes standing on the end of each of the already constructed bridge deck.
The bridge carries four lanes of traffic plus two footpaths. The construction time was 20 months, April 1976 to February 1978 with a final cost of £1.05 million.