Half Moon Lane Bridge (Gateshead)

Section of girder on display at the Discovery Museum, Newcastle

The lower portions of the wrought iron plates are badly corroded, and additional plates had at some point been welded over the corroded areas, attached to the original plates and to the top of the angle iron which connected the side and bottom plates

Note the cracks associated with the boss below the nut in the cast iron beam, and also porosity in the casting

This is a railway bridge crossing Half Moon Lane, on the approach to the High Level Bridge.

As built c.1848, it had an early and unusual form of box girder construction. Each box girder was made of riveted wrought iron plates. Sandwiched between these at the top was a cast iron beam, to which the plates were riveted. There were bosses at intervals along the cast iron beams to accommodate wrought iron hanger rods which supported cross beams carrying the deck. The nearby West Street Bridge was of similar construction, but of much greater span, with considerable skew.

In plan, the Half Moon Lane bridge was of 'truncated triangle' shape. The longer outer girder was of 75 ft span, while the shorter one was only 35 ft, and there was a 30 ft girder in between. In 1982 the longer girder was removed and replaced, but sections were saved, while the 35 ft span girder was left in situ, but carried no load.

A section of the removed girder is on display Discovery Museum, Newcastle, although it is wrongly identified as being from the High Level Bridge. The thinness of the plates is readily apparent. They would have been stiffened at intervals by T-section bars riveted at the junctions between plates.

See Also

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Sources of Information

• 'The influence of William Fairbairn on Robert Stephenson's bridge designs: four bridges in north-east England' by R. W. Rennison, Industrial Archaeology Review, Vol XX, 1998