A straight-line diagram (abbreviated SLD) is a diagram of a road where the road is shown as a straight line. Such diagrams are usually produced by a highway department, and display features along the road, including bridges and intersecting roads. Rows below the diagram show data about the road, usually including speed limit, number of lanes, bridge numbers, and historical data, among other data. Subway lines also frequently employ straight-line diagrams.
- see also: [halo, comparison lens, inlay]