Maximum Grades Grades of footpaths and drop kerbs are important as they affect the usability and safety of pedestrian facilities. Long sections of high grade footpath can be extremely difficult for mobility impaired users to negotiate. High grade kerb ramps can also cause safety issues for mobility impaired users. Users can become vulnerable to general traffic as they attempt leave the carriageway and proceed up steep ramps. It is noted that AS 1428.1 Design for Access and Mobility – 2009, specifies that any footpath should not exceed a gradient of 1:8 as wheelchairs may tip backwards. This is considered as an absolute maximum ramp gradient and should only be used in extenuating circumstances. Table 4-2 shows the maximum desirable grades for footpaths and kerb ramp treatments. Table 4-2 Maximum Grades Footpaths Recommended maximum grade (footpaths) Absolute maximum grade (kerb ramps)
Grade 1:20 (2.5% cross fall) 1:8
Source: AS1428.1 Design for Access and Mobility Part 1 2009 –General Requirements for Access-New Building Work
In hilly areas, these gradients are not always achievable and where possible, consideration to alternative routes should be made. Kerb Ramps The difference in the level between the footpath and the roadway is a common situation that poses difficulties for pedestrians, particularly with mobility and vision impairments. A drop kerb or kerb ramp provides a smooth change in the level between the footpath and the roadway (maximum grade of 1:8). The general dimensions of a drop kerb are illustrated in Figure 4-2. The Austroads Guide to Road Design Part 4 – Intersections and Crossings – General states that: ‘A minimum footway width of 1330 mm should be provided beyond the top of the ramp, to ensure that users of the footway along the street are not inconvenienced by the ramp.
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