|Traffic following the A624 from Chapel en le Frith towards Glossop must turn off right at this junction in order to stay on that route. The road continuing straight ahead is the B6062.|
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The acronym TOTSO is used on SABRE to refer to a junction at which the road continuing straight ahead does not bear the same number as the route we are currently following—we must therefore Turn Off To Stay On that same numbered route.
Reasons for their occurrence
TOTSOs occur for a number of reasons, but in most cases their origin can be traced to a change in the importance of one or more roads at the TOTSO. Examples can be found where:
- Road renumbering takes place to create a new route from existing roads. The A470 has numerous examples, such as its junction with the A438 east of Brecon.
- A new road is built, usually of a higher class than the original route, and the main line is diverted from the old route directly onto the new road. A good example of this is at the start of several motorways. For example, when the M2 was built in the 1960s, A2 traffic free-flowed directly onto the new motorway at the Park Pale Interchange, and the A2 turned off to head into Rochester. A more recent example is at M11 junction 8A, where the A120 free-flows into the new M11 link road, and the A120 itself turns off towards the original M11 junction 8.
- A Highway Authority chooses to change the priorities at a junction, either to improve traffic flow, or as a traffic-calming technique. These are most frequently found in urban areas.
Examples on motorways
TOTSOs are very numerous in Britain. There are even several TOTSOs between motorways:
- Belle Isle Interchange - M1 J43 (heading north: M1 turns off, M621 continues)
- Hook Moor Interchange - A1(M) J44 (heading south: A1(M) turns off, M1 continues)
- Coleshill Interchange - M6 J3A (heading north: M6 turns off, M6 Toll continues)
- M6 J11A (heading south: M6 turns off, M6 Toll continues)
- Pirnhall Interchange - M9 J9 (heading south: M9 turns off, M80 continues)
- Chevening Interchange - M25 J5 (heading anti-clockwise: M25 turns off, M26 continues)
- Chevening Interchange - M25 J5 (heading clockwise: M25 turns off, A21 continues)
- Umberslade Interchange - M42 J3A (heading northeast: M42 turns off, M40 continues)
- Coleshill Interchange - M42 J7B (heading southwest: M42 turns off, M6 Toll continues)
- Dunton Interchange - M42 J8A (heading northeast: M42 turns off, M6 Toll continues)
- M56 J3 (heading west: M56 turns off, route ahead soon becomes A5103)
- Simister Island - M60 J18 (heading clockwise: M60 turns off, M62 continues)
- Simister Island - M60 J18 (heading anti-clockwise: M60 turns off, M66 continues)
Northern Ireland has many TOTSOs, though not really on the motorway network. The Republic of Ireland has far fewer, having renumbered its roads in the 70s. There are a couple of motorway TOTSOs on the island, however:
- Greencastle Interchange - M2 (NI) J2 (heading north: M2 turns off, M5 continues)
- Turnapin Interchange - M50 (RoI) J3 (heading anti-clockwise: M50 turns off, M1 continues)
- Turnapin Interchange - M50 (RoI) J3 (heading clockwise: M50 turns off, spur to R139 continues)