1844, and the Act included the road bridge. Definite plans The Newcastle and North Shields Railway had opened in 1839 from its own terminus at Carliol Square, on the north-east edge of Newcastle. As a purely local concern, the disconnection was not important, but interest gathered in a railway to central Scotland; the "Edinburgh Railway" foreseen by Grainger. A Scottish concern, the North British Railway, had got its Act of Parliament the previous year to build as far south as Berwick (later known as Berwick-upon-Tweed. Now Hudson was intent on capturing the line to Edinburgh for his empire, and he encouraged the development of railway plans to get there; the route such a line might take continued to generate considerable controversy. There was still ambiguity about Hudson's intentions for the bridge—an easier crossing point at Bill Quay, two miles downstream had been considered—and Newcastle Town Council sought undertakings from him. In addition, he promised a footway crossing; this was apparently not a sweetener to the Town Council, but a commercial decision, expected to bring in £250 a week. The footway crossing was later extended to include horse-drawn vehicles. Finally, the Newcastle and Berwick Railway was authorised by Act of Parliament of 31 July 1845. The line would cross the Greens' high level bridge, starting from the Gateshead Greenesfield station, and commitments made to the building of a bridge by the Newcastle and Darlington Junction Railway were transferred to the Newcastle and Berwick Railway. Design The bridge was to be designed by Robert Stephenson; T E Harrison did the detailed design work. The height of the railway, at about above high water, was determined by the level of the Brandling Junction line in Gateshead. A double-deck configuration was selected because of road levels on the approaches, and to avoid the excess width of foundations which a side-by-side arrangement would require. The deck width was determined by the useful roadway width plus the width of structural members, which gave the railway deck the width for three tracks. The foundations were to be difficult because of the poor ground conditions in the river, and this ruled out an all-masonry structure, so cast iron or wrought iron was inevitable for the superstructure. A tied arch (or bow-string) design was favoured because the outward thrust imposed by an arch is contained by the tie; no abutments capable of resisting the thrust could be provided here.