Arrangement of tracks at a major junction where one or more running lines were carried over others by means of an embankment and overbridge rather than crossing on the level, thus avoiding conflicting movements. The first flyover built to replace a flat junction was at Weaver Junction, brought into use in November 1881; it carried the new up Liverpool main line via Runcorn, after the building of Runcorn bridge, over the up and down main lines. Other important flyovers were at Vauxhall (Birmingham), Rugby Clifton Road and Liverpool Edge Hill. Lack of space prevented the construction of flyovers at other busy locations where they would have been beneficial. A few more flyovers were in fact constructed in later (BR) years, including Rugby North (No.7 box) and Bletchley, thelatterbeing something of a white elephant.