This chapter covers a variety of techniques for communicating with drivers, to help them while they are driving through a road network. The three main types of conventional traffic signs are regulatory signs, which must be obeyed, warning signs alerting drivers to dangers ahead, and route information signs. Road signs are not yet standardised internationally. Principles for information signs include guidelines for lettering, layout, symbols, colour, and siting. Variable message signs (VMS) are used mainly to issue instructions, warn of dangers ahead, or advise about parking or routeing. The main functions of road markings are to guide vehicles into definite positions on the carriageway, and supplement the regulations and warnings of traffic signs and signals. Marking materials include thermoplastics, paints, tapes of embedded glass beads, and reflecting road studs. Guide posts can help drivers at night by outlining horizontal and vertical road alignments. In-vehicle information systems include autonomous units, which carry all their information with them, and communicating units, which receive current information by radio or other methods. Issues in providing in-vehicle information and guidance include: (1) benefits to the community; (2) criteria for route advice; and (3) information sources. For the covering abstract, see IRRD 892228.
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