Page:UK Traffic Signs Manual - Chapter 5 Road Markings. 2003 (Sixth Impression 2009).pdf/41

 To avoid frequent changes of pattern on long hills, or for safety reasons, the designer may on occasion use a downhill continuous line even when the visibility criteria for a broken line in Step 2 are satisfied, although the use of a prohibitory line on long straight sections should be avoided if possible.

The marking at the commencement of the climbing lane is designed to encourage uphill drivers to keep to the near side lane unless overtaking. In order to avoid a potential conflict at this point between uphill and downhill overtaking traffic, a length of double continuous line should be provided for a length equal to W in table 5-2 for the speed of the uphill traffic. This ensures that any downhill overtaking vehicle will be returned to the near side lane before coming into conflict with an uphill vehicle beginning an overtaking manoeuvre at the start of the climbing lane (see figure 5-6). In addition, the double white line may be extended to divide opposing traffic over the taper in order to prevent overtaking by downhill traffic. However, if visibility over this length is good, then observance may be poor and a warning line might be more effective.

This procedure will still allow downhill overtaking on long straight, or nearly straight, hills. It will restrict it elsewhere, particularly in those cases where visibility is poor for an uphill inside lane vehicle trying to pull out from behind a large vehicle.

The alignment at the end of a climbing lane should place the onus on the overtaking driver to rejoin the inside lane. Care should be taken to ensure that the return to a single lane does not occur where junctions or sharp curves may cause problems. See figure 5-6 for the layout of markings at the top and bottom of a climbing lane. Signs to diagram 517 should also be used (see Chapter 4, para 4.3).



Where there are climbing lanes on both sides of a sag curve, a conventional two-lane road layout may be used to link them, provided this is at least 500 m in length between tapers. For shorter lengths, the intervening carriageway should be maintained at 10 m wide and the climbing lanes extended 39