Fig. 153 gives the particulars of a plate-girder over-line bridge, carrying an important public road, 35 feet wide, over several main lines and sidings. The carriage-way is carried by two girders placed at 25-foot centres, and on the lower boom of these are riveted lattice-work cross-girders to receive the plate-iron longitudinal troughing and roadway. The footpath girders are set at a higher level, and the load placed on the lower flange. The curved side brackets merely act as bracing between the carriage-way girders and footpath girders. A cast-iron-plate parapet is bolted on to the top of each of the footpath girders, making a close screen, 6 feet high, above the footpath. Lattice-work cross-girders were adopted for the convenience of supporting small water mains and gas mains below the road-level. The roadway is formed of ordinary metalling, and the footpaths of asphalte pavement; the kerbing is of granite, and the side water-tables of crushed granite concrete. [Illustration: Fig. 149, 150, 151, 152] Fig. 154 is a cross-section of a small uncovered lattice-girder footbridge 41 feet span, and 5 feet wide, suitable for small roadside stations. The top and bottom flange consist each of two angle irons, those in the bottom flange being placed table side upwards, so as to bring the entire section of both angle irons fairly into play, and also to provide a better bearing for the channel-iron cross-girders which carry the planking of the footway. When planking is carried on the inside of light angle iron, as in Fig. 155, a severe strain is produced at the point A; this is entirely obviated by placing the bottom angle irons table side upwards, as in Fig. 156. Three of the channel-iron cross-girders are extended outwards, and to the ends of these are riveted tee-iron stiffeners to steady the main girders. In some cases stamped, or ribbed, wrought-iron plates are used for a footway, but, although more durable, they do not give such a secure or 149 agreeable foothold as timber. The ascent or descent of the bridge may consist either of steps and landings, or of ramps, according to circumstances or expediency. Sometimes these bridges are made with curved tops, terminating in steps when nearing the steps, or ramps. It is very questionable whether such an arrangement is a good one or a safe one. There is always a feeling of insecurity when walking over a sloping surface broken up by steps, and experience points out that it is better to continue the footway level right across to the place where the passenger must change his direction to go down the stairs or ramp.