Page:UK Traffic Signs Manual - Chapter 8 - Part 1 (Traffic Safety Measures and Signs for Road). Designs 2009.pdf/116



Wherever possible two-way traffic should be maintained using normal delineated traffic management arrangements. This system may be used provided that:


 * the carriageway unobstructed traffic width is as wide as is practicable, but no narrower than the minimum width given in Section D3.3 and Table 5.1 in Section D5.4, for the appropriate conditions.
 * the appropriate minimum safety clearances given in Section D3.2 are achieved.
 * there is always clear visibility of and through the site by the drivers of vehicles approaching from either direction.

Where the above criteria cannot be met, then consideration could be given to using a "give and take" system of shuttle working; see Section D56, or one of the positive traffic control systems should be adopted, see Sections D5.8 to D5.10.

These principles are illustrated in Plans SC1 and SC2. The relaxations referred to in this paragraph (D5.5.3) should not be applied when any of the following apply:
 * pedestrians are directed into the carriageway, or
 * when the speed limit is more than 30mph, or
 * the total two-way traffic flow exceeds 400 veh/hr, or
 * the total HGV flow (including buses) is more than 20 veh/hr.

Certain other signs, "road works" (7001) and "road narrows” (517), (see Part 2: Operations, Sections O3.19 and O5.9) may be omitted where either:
 * there is a works vehicle with a roof-mounted beacon in continuous use and drivers can see the beacon clearly from at least 50m in either direction (see Part2: Operations, Section O5.9), or
 * parked vehicles are present and are likely to be there for the duration of the works (see Part 2: Operations, Section O03.19).

The principles for the advance signing are:
 * two advance signs are normally required,
 * a "road works" sign (7001) on the near side only in both directions, a distance plate (572) is required for roads with a permanent speed limit of 50mph or more, and
 * a "road narrows” sign (517) on the near side only in both directions, on roads with a permanent speed limit of 50 mph or more a distance plate to diagram 572 is required.

On two-way single carriageway roads with three lanes, the sign to diagram 7206 is used in place of the "road narrows" sign (517) and full lanes must be closed and not closed partially as shown in Plans SC1 and SC2. 115