Broad-gauge

a broad-gauge railroad track

Source: wiktionary

Broad-gauge track consists of both bullhead and flat-bottom rails, carried on a variety of sleepers—treated soft wood, hard wood, steel trough—and cast-iron pots and plates.

Source: wiktionary

An offensive against Germany would require large forces and offered no certain prospect of success. An attack on Austria promised great victories, the destruction of the whole Austrian army and of the Austro-Hungarian state itself, the reordering of half of Europe—and meanwhile Russia would need only small forces to defend herself against the Germans, inflicting on them the disadvantages of poor roads and Russian broad-gauge lines.

Source: wiktionary

In the Gladstone photo, the sitters look too small for their conveyances, and this is because they were sitting in extra-wide - that is, broad-gauge - wagons of the Great Western, which would run along the Met on broad-gauge tracks (7 foot 2 inches between the rails), together with trains using standard-gauge tracks of 4 foot 8½. In the Met's own language, the line ran on 'the mixed-gauge principle', which makes the arrangement sound almost sensible. That broad gauge did not last long, and all Underground trains today run on the standard gauge.

Source: wiktionary