C. RAILWAY CONSTRUCTION (cont.)
St Pancras Passenger Station
St. Pancras passenger station of the Midland Railway is the most recently constructed metropolitan terminus. The approach to the land on which the station is built was crossed by the Regents Canal, and in order to secure good gradients and suitable levels for metropolitan suburban stations the main passenger line is carried over the canal; and, as a result, the level of St. Pancras station is from 12 to 17 feet higher than that of the adjoining roads. The St. Pancras branch, on the contrary, for effecting a junction with the Metropolitan Railway, leaving the main line some distance from the terminus, descends through a tunnel beneath the Regents Canal and the passenger station, as well as under a considerable length of the main line. The height of the rails above the ground-level admitted of the construction of a lower floor with direct access to the streets, built and arranged for Burton beer traffic. The floor of the station is supported on girders and columns extending from side to side and acting as a tie for the roof girders, which start from the ground-level and form the roof as a single arch. The ribs or girders forming the roof are laid to a clear span of 240 feet; the walls built between the ribs are 245 1/2 feet apart. The clear height of the ribs above the level of the platforms is 96 feet at the centre. The length of the station is 689 feet 4 inches. The lower floor contains 720 cast-iron columns set on brick piers, and 49 rows of principal girders across the station, with 15 rows longitudinally. Upon these intermediate girders are carried, and the whole is covered in with Mallets buckled plates. The cost of the ironwork of the floor was £57,000, being at the rate of £3, 0s. 6d. per square yard. The roof girders, twenty-five in number, are placed at intervals of 29 feet 4 inches, except at the outer end, when the last two girders are only 14 feet 8 inches apart. The cost of the roof, including covering, with two gables and screens, amounted to £69,365, being at the rate of £40, 18s. per square of 100 square feet or 10 feet square. If there had not been any floor-girders to act as roof-ties, the extra cost for ties at the level of the floor would have been about £1 per square.
Table XXVI. gives the spans and areas covered by the roofs of some of the principal London passenger termini: