The New Zealand Railways Magazine, Volume 2, Issue 12 (April 1, 1928.)
Reinforced Concrete Overbridge
Reinforced Concrete Overbridge.
The overbridge at the south end of the yard carries a 46ft. roadway and two 10ft. footpaths, and has a total length of 190ft. There are five spans varying in length from 27ft. to 44ft. Cin.
Abutments and piers are of mass concrete construction, carried down about 15ft. through reclaimed ground to a foundation on a mudstone reef. The superstructure is of rolled steel joists encased in concrete and spaced at 5ft. 10 1/2in. centres. Skelton broad flange beams are used. The deck slab is 10in. deep, reinforced top and bottom with 1/2in. diameter rods, and covered by a 6in. wearing surface.
The parapet was built up of balusters, precast in short lengths, bedded in grooves left for that purpose in the plinth, and coped with a reinforced concrete railing spanning between massive posts erected at about 20ft intervals.
A plan illustration of the bridge is given in Fig. 2.
Concrete-encased joists have been used extensively in the work. This type of construction, although involving the use of a greater weight of steelwork than is required for rod-reinforcement, has proved to be cheaper because of saving effected in labour costs.