Page:UK Traffic Signs Manual - Chapter 8 - Part 2- Traffic Safety Measures and Signs for Road Works and Temporary Situations) - Operations 2009.pdf/23

OPERATIONAL ISSUES but which is strong enough to withstand strong winds and the buffetting from passing vehicles, could suffice for this marking. The tape should break in tension cleanly without excessive stretching or elongation. See also paragraph O4.11.14.

Any lightweight barrier used should be installed at a constant height above the carriageway surface, be of conspicuous colour and be maintained in clean condition to ensure its visibility at all times. The boundaries of the safety zone or limit of the working space of the site should be sufficiently visible that workers do not stray into adjacent live traffic lanes. Supports should not be driven into the road surface, i.e. road pins are not permitted, but should be stable and able to withstand wind buffeting from passing vehicles.

Lightweight barrier systems used to delineate the inner edge of the safety zone should not be deployed in long interconnected lengths. Short adjacent lengths, no more than 50 m, should be used to minimise the hazards posed to workers if a section is struck by an errant vehicle and dragged into the works or highway.

For short-duration progressive works being carried out throughout the length of a closure, e.g. central reservation maintenance, a safety zone may be established by placing only traffic cones to delineate the inner boundary.

At works lasting less than one hour it may not be practicable to provide the type of inner delineation described above, but in such cases an attempt should be made to indicate the extent of the safety zone to help ensure it is not entered unwittingly. Where operatives are working on foot, this might be achieved by placing traffic cones or a light movable barrier or fence along the inner edge of the safety zone only at the point where work is in progress.

For works within the central reservation, safety zones (or safety lanes) should be provided on both sides of the works area. In certain circumstances (e.g. the absence of an intact vehicle safety restraint barrier system) this may involve closure of the off side lanes on both primary and secondary carriageways.

On motorways and dual carriageway roads a minimum clearance of 0.45 m should be provided between the carriageway in use and the nearest part of any temporary sign (excluding cones, cylinders, road markings and studs) or its supporting structure. If necessary, the signs placed on hard shoulders and central reservations may be angled within the limits shown in Figure 3.2 in order to achieve the minimum clearance. If this does not achieve sufficient clearance, the next smaller size of sign should be used and if necessary angled similarly to provide the specified clearance. Reflectorised signs are sensitive to changes in orientation. The contractor should ensure that the signs and material properties are suitable for the required orientation. In particular, signs manufactured from microprismatic materials should always be mounted vertically, not leaning backwards on A-frames. 21