train's unusually long length. Rail replacement bus services are run under the headcode 0B00. In a similar manner, shipping services run on behalf of or in tandem with rail services are given headcode 0S00. Tyne & Wear Metro trains have three-digit numbers which are displayed in the driver's cab window. Those on the Sunderland line are generally in the range 101 – 112, and the set operates all day on the Newcastle Airport to South Hylton route with this number. When on Network Rail metals (i.e. south of Pelaw to South Hylton) the initial digit '1' is replaced by '2I' to give a four-digit TOPS Train Reporting Number, e.g. train 104 becomes 2I04, although the three-digit number in the cab remains unaltered. References External links RealTimeTrains - search headcodes and timetable data 2D53: Headcodes – a site with example photos. Rail transport in the United Kingdom Rail transport operations