10.7 Criteria for the provision of flashing amber lights are set out in table 10-1. These are based on the minimum desirable stopping sight distance specified in TD 9, in Volume 6 of the Design Manual for Roads and Bridges (see para 1.3). Lights are not recommended unless the driver’s field of clear visibility is less than the distance shown, or the traffic flow exceeds 10,000 vehicles per day on roads where the 85th percentile speed exceeds 30 mph.
| 85th percentile speed | Visibility distance |
|---|---|
| (mph) | (m) |
| Up to 30 | 70 |
| 31 to 40 | 110 |
| 41 to 50 | 150 |
| 51 to 60 | 200 |
| Over 60 | Not suitable |
10.8 Where conditions at a cattle crossing site meet these criteria and, on the same road within approximately half a mile there is another site which does not meet them, consideration should be given to the provision of flashing lamps at both sites.
10.9 The flashing lamp units should be erected on both approaches as close as practicable to the start and finish points of the cattle journey. The mid point between the flashing lamps must be between 2.4m and 4m above the adjacent carriageway. This allows a minimum headroom of 2.1 m to be maintained when the assembly is mounted over a footway.
OTHER ANIMAL SIGNS
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The above signs may be used with diagram 570. Diagram 550.7 may also be used with diagram 572 or 573
10.10 Signs to diagram 549 (sheep), 550 (wild horses) and 551 (wild animals) may be used wherever such animals are likely to be found in the road (see also para 10.3).
10.11 Diagram 550.1 warns of accompanied or ridden horses or ponies (as opposed to the wild or stray variety indicated by the sign to diagram 550) where numbers of horses are frequently walked or ridden along or crossed over the road. Warning of horses crossing the road ahead, e.g. where a bridleway crosses the road, can be given by adding the diagram 572 distance plate (or 573 if the crossing is in another road). Diagram 550.2 is used to warn of horse-drawn vehicles in the road ahead.
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