the placing of signs on the footway is permitted but in no circumstances must the width of the footway be reduced to less than 1 m, preferably not less than 1.5m.
D4.4.2 Speed limit repeater signs should be located immediately adjacent to traffic lanes where practicable. At sites where it is impractical to erect speed limit repeater signs immediately behind the coning within the works area, the signs shall be located on the near side verge or central reservation as appropriate. Care should be taken to ensure that these signs are not regularly obscured by site activities. If there is a risk of obscuration, consideration should be given to providing repeater signs larger than the dimensions given in Table 3.4 and to mounting them at a greater height than normal.
D4.4.3 Road works signs should be located so that if a vehicle leaves the carriageway the consequences are minimised. The use of the following procedures, which are also appropriate to temporary gantries and other temporary equipment, should be considered:
- the sign could be mounted behind a length of existing vehicle safety barrier,
- a new length of temporary safety barrier could be provided around the sign,
- the sign could be mounted further away from the carriageway, or
- passively safe posts and signs designed to minimise vehicle damage and injury to occupants could be used — scaffold poles must not be used.
D4.4.4 The recommended location, number and size of warning and other signs and cones are specified in Tables A1 to A1.3 of Appendix 1. It should be noted that these are minimum requirements for straight and level roads with verges. The presence of gradients, bends or side road junctions on the approaches to the site of any road works will call for adjustment of the siting distances.
D4.4.5 The absence of verges on which to display signs on roads with a permanent speed limit of 40 mph or less may require the use of the smallest size signs in order to minimise the encroachment upon the carriageway. On roads with a permanent speed limit of 50 or 60 mph, the appropriate size of sign should be used where this is practicable. On roads on which the national speed limit applies it is essential to use the appropriate size of sign. See Tables A1.1 and A1.2 of Appendix 1.
D4.4.6 If no verge exists, signs will probably need to be erected in a similar way to permanent signs. In this case, the posts may need to be "passively safe" depending upon their size and meet the requirements of BS EN 12767. The aim should always be to give drivers adequate advance warning, so that they can adjust the speed and position of their vehicles on the road in order to pass the obstruction in complete safety. If warning signs on the left-hand side of a single carriageway are likely to be obscured or overlooked then signs should be duplicated on the right-hand side of the carriageway. On dual carriageway roads and motorways, warning signs should be duplicated on the central reservation.
D4.4.7 Table A1.1 ([../A1|Appendix 1]]) specifies the size and minimum clear visibility distance to the first sign for different types of road. This table also gives the siting distances of the first signs in advance of the works in metres or miles. However, the distance to the road works given on the supplementary plate to the warning sign must be in imperial units to comply with the Regulations. Likewise speeds are given in miles per hour because they relate to speed limits.
D4.4.8 In this Chapter, siting distances are specified in metres and miles. However the Regulations require that all distances and speed limits are displayed in imperial units and accordingly these are shown as "yds" (yards), "miles" and "mph" (miles per hour). In siting signs it will not always be possible to adhere precisely to the required dimensions and variations in distance of up to 10% are generally permissible. The siting of certain signs shown on the plans have been rationalised within the permitted 10% variation, e.g. the 400 yards wicket signs being placed at 400m. Any further required adjustment in siting of these signs should take this into account in order that the placed signs remain within the permitted 10% tolerance. In practice this means that
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