D5SINGLE CARRIAGEWAY ROADS
D5.1GENERAL ISSUES
D5.1.1 This section sets out the principles for signing and guarding when carrying out works on all-purpose single carriageway roads.
D5.1.2 Whenever possible, any work involving a reduction in the number of traffic lanes, particularly on heavily-trafficked commuter routes, should be avoided between the hours of 07.00 and 10.00 and between 16.00 and 19.00. Local circumstances may permit or require a variation of these times. The Highway Authority should always be advised of any works to be undertaken on public roads so that any traffic measures deemed necessary can be co-ordinated.
D5.1.3 The reduced road width caused by works on a single carriageway road will result in lower capacity and this may introduce delay. The form of control and its operation should aim to reduce any traffic delay to a minimum, subject to acceptable safety standards.
D5.1.4 Two-way traffic should be maintained wherever possible, but where this is not possible single-file traffic (shuttle working) should be considered, see Section D33 for details of minimum lane widths.
D5.1.5 The period during which the traffic is subjected to one-way working should be kept to the absolute minimum. When possible, provision should be made for shared footways and/or exemption for cyclists during one-way working. At certain times, for example, outside normal working hours, it may be possible to reduce the extent to which the works occupy the carriageway and this should be done if, by doing so, it is possible to allow two-way working to resume during those times.
D5.1.6 On roads where flows are very high, overload of the controlled area is possible and exceptional delays may result. This can occur with two-way flows as low as 1300 vehicles per hour (for sites about 50m long) and with a one-way flow of 900 vehicles per hour (for longer sites with balanced flows) with signal control. If this is likely to occur, the designer will have to consider the implications and possible alternative options, for example, diversions or restrictions on the hours of working.
D5.1.7 Suitable diversions should be provided and adequately signed when a single carriageway road has to be completely closed. Any necessary statutory procedures should be followed in consultation with the relevant highway authorities. See Section D3.15 and Figure 3.3.
D5.2WORKS CARRIED OUT FROM A VEHICLE
D5.2.1 Work may be carried out on single carriageway roads using single vehicles standing or operating in the carriageway. Single vehicle works are dealt with in Part2: Operations, Section O8.
D5.3WORKS ON MINOR ROADS
D5.3.1 In the context of this section, a road is defined as a minor road if it does not carry a significant volume of through traffic or many large vehicles even during peak periods and if it fits either of the following descriptions:
- it is a single carriageway road in a residential or industrial district, or in a rural area. It may be an access road or possibly a local distributor, but it should not be a district distributor or a primary distributor, or
- it is either restricted to 30mph or less or its layout and general character is such that speeds greater than 30mph are unlikely.
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