Overpass in the context of "Viaduct"

A level crossing is an intersection where a railway line crosses a road, path, or (in rare situations) airport runway, at the same level, as opposed to the railway line or the road etc. crossing over or under using an overpass or tunnel. The term also applies when a light rail line with separate right-of-way or reserved track crosses a road in the same fashion. Other names include railway level crossing, railway crossing (chiefly international), grade crossing or railroad crossing (chiefly American), road through railroad, criss-cross, train crossing, and RXR (abbreviated).

There are more than 100,000 level crossings in Europe and more than 200,000 in North America.

In civil engineering (and more specifically, highway or railway engineering), grade separation is a method of aligning a junction of two or more surface transport axes at different heights (grades) so that they will not disrupt the traffic flow on other transit routes when they cross each other. The composition of such transport axes does not have to be uniform; it can consist of a mixture of roads, footpaths, railways, canals, or airport runways. Bridges (or overpasses, also called flyovers), tunnels (or underpasses), or a combination of both can be built at a junction to achieve the needed grade separation.

In North America, a grade-separated junction may be referred to as a grade separation or as an interchange – in contrast with an intersection, at-grade, a diamond crossing or a level crossing, which are not grade-separated.

A cross-platform interchange is a type of interchange between different lines at a metro (or other railway) station. The term originates with the London Underground; such layouts exist in other networks but are not commonly so named. In the United States and Canada, it is often referred to as a cross-platform transfer.

This configuration occurs at a station with island platforms, with a single platform in between the tracks allocated to two directions of travel, or two side platforms between the tracks, connected by level corridors. The benefit of this design is that passengers do not need to use stairs to another platform level for transfer. A cross-platform interchange arrangement may be costly to build due to the complexity of rail alignment, especially if the railway designers also arrange the track with flyovers (which is typically done to increase efficiency).

A box girder bridge, or box section bridge, is a bridge in which the main beams comprise girders in the shape of a hollow box. The box girder normally comprises prestressed concrete, structural steel, or a composite of steel and reinforced concrete. The box is typically rectangular or trapezoidal in cross-section. Box girder bridges are commonly used for highway flyovers and for modern elevated structures of light rail transport. Although the box girder bridge is normally a form of beam bridge, box girders may also be used on cable-stayed and other bridges.

Queensway, in Birmingham, England, most often refers to the Queensway Tunnel, a 1,798 feet (548 m) long road tunnel in the centre of the city. The tunnel forms part of the designated A38, which locally is a major carriageway that cuts through Birmingham city centre. "Queensway" as a suffix is also the name of several other roads and circuses in the city (such as Smallbrook Queensway); all these roads including the tunnel collectively made up what was once called the Inner Ring Road, an orbital dual carriageway which has now been dismantled.

The old Inner Ring Road, which was also referred to as the "Queensway" and designated as the A4400 road, was completed and opened in 1971. Described as an "urban motorway" (although it was not officially designated as a motorway), it featured largely grade separated junctions and most of them allowed vehicles staying on the road to pass over or under those using the junction. Pedestrians were kept physically separate from vehicular traffic and used subways to cross the ring road. Although seen as revolutionary when first opened, the 'Concrete Collar', as it became known, was viewed by council planners as an impenetrable barrier for the expansion of the city centre. By the 1990s, changes were made to the road as the council sought to improve pedestrian links, and vehicular movements were increasingly shifted out to the Middleway. The Inner Ring Road was effectively dismantled in the early 2000s, with many of its roads having been rebuilt and downgraded to surface-level streets, resulting in them resembling city streets far more. The Queensway Tunnel and St Chad's Tunnel, as well as the Lancaster Circus and Suffolk Street flyovers, are remaining relics of the ring road and make up most of the present A38 carriageway in this area.

A loading gauge is a diagram or physical structure that defines the maximum height and width of railway vehicles and their loads. The loading gauge is to ensure that rail vehicles can pass safely through tunnels and under bridges, and keep clear of platforms, trackside buildings and other structures. Classification systems vary between different countries, and loading gauges may vary across a network, even if the track gauge is uniform.

The term loading gauge can also be applied to the maximum size of road vehicles in relation to tunnels, overpasses and bridges, and doors into automobile repair shops, bus garages, filling stations, residential garages, multi-storey car parks and warehouses.