Ditchfield Bridge

Just another low level bridge that you’d hardly notice. The interesting aspect of this bridge is that it was designed so that it could be constructed within the 20 metre wide road reserve whilst maintaining two-way traffic through the site. Normally a side track is constructed, and though quite straightforward on this site, the track would encroach beyond the road reserve and hence require a full Environmental Impact Statement to be prepared, at great expense and months of delay.

Waldren Bridges proposed a design using their Bridgette System for 3 x 8 metre spans (north/south), each span comprising five 2.5 metre wide deck units. The bridge was constructed in two stages. Stage one was the construction of the eastern side (3 deck units per span), which allowed just enough room to the west for a two-way side track within the road reserve.

Completion of Stage 1 resulted in a bridge with a deck width of 7.5 metres, just enough for two traffic lanes. Two-way traffic was then routed onto the new deck and Stage 2 began. With 2 decks per span another 5 metres was added, making the total deck width 12.5 metres.

The entire superstructure comprised precast concrete, which enabled speedy erection. The only other occasions that traffic was restricted was while concrete was pouring for the footings.