Traffic Engineering Advice

increase this distance to approximately 19.5 meters (following the inside wheel line),
which decreases the vertical gradient slightly.

Duke Street is a hilly location and the steep frontage of the site makes it difficult to
limit the gradient of the driveway to less than 25%. The development is for domestic
use, and the length of the driveway is less than 20m long. In this situation AS2890.1
makes the following allowances;

          “It is recognized that limiting domestic driveway grades to 25% maximum
          may not be practical in some particularly hilly residential locations.".

It considered reasonable to apply a gradient of approximately 33% for this driveway.
This has been discussed with Council offices and is similar to the existing driveway
gradient on the site and adjacent properties.




                                    Figure 2: Driveway Layout

Clause 2.5.3(d) in AS2890.1 makes the following recommendations with respect to
changes in grade for ramps – to prevent vehicles scraping or bottoming.
       (i)     12.5% algebraically for summit grade changes; or
       (ii)    15 per cent algebraically for sag grade changes.

A review of the proposed driveway alignment and the requirements of AS2890 has
been undertaken to determine suitable grade transitions for the driveway. Table 1
provides a suitable long section that achieves these recommendations for the proposed
site. The long section includes a 2.5% crossfall across the 1.5m wide pathway
adjacent to the kerb. The driveway gradient for the remainder of the road verge
reflects the gradient of the existing verge and neighbouring properties. The long
section described in Table 1 is plotted in Figure 3.




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15681 Duke Street, Sunshine Beach                                                  Page 3 of 6