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T.PDJM.V.2.3
(Al/2001)
3.3.5 Sight Distance
3.3.5.1 Table 3.3.5.1 shows the sight distances that must be provided on the approaches to and
through junctions, accesses, weaving sections and points of vehicular and pedestrian
conflict, and the aim should be to provide the desirable minimum distance, rather than the
absolute minimum distance.
Table 33.5.1
Sight distances
Design speed Desirable minimum Absolute minimum
(km/h) (m) (m)
120 295 215
100 215 160
85 160 120
80 145 110
70 120 90
60 90 70
50 70 50
3.3.5.2 The sight distances should be measured from a minimum drivers' eye height of between
1.05 m and 2.0 m to an object height of between 0.26 m and 2.0 m 5 both above the road
surface. Forward visibility should be provided in both the horizontal and vertical planes
between points in the centre of the lane nearest to the inside of the curve.
3.3.5.3 Because of the necessity of providing sight distances in accordance with Table 3.3.5.1 and
paragraph 3.3.5.1 it follows that junctions and accesses should not be located on sharp
curves, as this would result in extensive widening of verges, cuttings and bridge structures in
order to obtain the required visibility.
3.3.5.4 For locations, not mentioned in paragraph 3.3.5.1, that are away from the vicinity of a
junction or access or weaving section or place of vehicular or pedestrian conflict and where
on the inside of a curve an obstruction, such as cutting slope, retaining wall, noise barrier, or
bridge abutment, occurs, appropriate sight distances obtained in accordance with the
following, must be provided:
(i)
Low speed urban roads
Because there is little or no restriction on pedestrians and accesses along these roads
the sight distances in accordance with Table 3.3.5.1, measured in accordance with
paragraph 3.3.5.2 should be provided.
(ii)
Roads having design speeds of 80 km/h or greater and the radius of the bend is less
than R3
(a) For a 100 km/h design speed or greater a 4 m width must be maintained clear of
obstructions on the inside of the curve, the clearance being measured from the
edge of the running carriageway and may include any hard shoulder, marginal
strip or verge.