Highway Slope Manual

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oadside slopes tend to have strong linear characteristics corresponding to the linear
character of highways themselves. In the roadside environment, hard, engineered lines that
look unnatural when seen in the wider landscape setting (e.g. those arising from the long and
linear features of a roadside slope) should be avoided. This should be done ideally by
rounding off the edges of the roadside slopes (Civil Engineering Department, 1991) and by
the use of curves instead of straight edges or planes for forming and blending roadside slopes
into their surroundings. An example of good practice is shown in Plate 6.6.
oadside slopes may also be distinguished from other types of slope by virtue of the
fact that they are often spatially constrained. This may mean that re-profiling of existing
roadside slopes is not always possible and the landscape works must fit the existing slope
form. Where a road verge or a footpath at the toe of a roadside slope is available, use of toe
planters should be explored to obscure the bottom few metres of the slope and contribute to
the greening of the roadside environment (Plate 6.7). Alternatively, planters on berms on the
slopes can help to break up the towering effect of a slope. eference should be made to
Works Branch (1992) for guidance on the allocation of space for urban street trees.
Because of their linear characteristics, roadside slopes are likely to appear monotonous
or boring. The principles of 'Pattern and Texture' and 'hythm and Complexity' identified
above should be applied to create variety and interest in long roadside slopes. Plate 6..
illustrates a good example of the creation of interest in an otherwise monotonous roadside wall.
Generally, roadside slopes have a high degree of visual exposure as they are not only
seen by those who live and work around them but also by potentially thousands of people who
travel on the roads each day. For this reason, it may be justifiable to expend a greater
proportion of the budget of roadside slopes on aesthetic design, than in the case of slopes in
other locations. Plate 6.8 shows a good example of the use of innovative landscape design in
a prominent urban location.
Plate 6. Toe Planters
Note: ven the smallest area can provide sufficient
space to establish trees of significant size.
Plate 6. Innoatie Landscape Treatment
Note: An example of a slope in a visually
prominent roadside location where additional
resources were made available to achieve an
innovative aesthetic design solution.