Direct answer: Road tar is the common name people give to black road-binding materials, although modern roads are usually made with asphalt mixtures bound by bitumen rather than true coal tar.
Coal tar and tar-derived binders were historically used in roads, especially before petroleum bitumen became dominant. The word tar survived in everyday speech, so people still say tarmac, tar, or tarred road even when the actual material is asphalt.
Road tar belongs to paving history, civil engineering terminology, and common speech. It matters because a driver, homeowner, or history reader may use “tar” to mean anything from sticky summer road residue to a full asphalt surface.
Bitumen is a petroleum-derived binder. Asphalt is usually a mixture of aggregate and binder. Coal tar is a coal-derived product with a different chemistry and hazard profile. Road tar is often a loose phrase that needs translation.
In short: Often used colloquially for asphalt road material. Historic roads sometimes used coal-tar binders. Modern road surfaces are commonly asphalt mixtures with bitumen. The phrase needs context before it can be precise.