ATTCH 7 - IR Response - Engineering (Sheehy & Partners)

8531

Information Required

15. Modify the proposed vertical alignment of the proposed access to David Low Way,
to satisfy the grading requirements of AS/NZS 2890.1-2004, particularly in achieving
satisfactory grades across the verge and on the approaches to the existing
pedestrian / cycle path from both directions on the driveway (as vehicles using the
driveway will need to give way to pedestrians / cyclists on that path). The proposed
alterations to the existing vertical alignment of the existing path should also be
identified. :

Response:

The access grading is shown on Longitudinal Section 8531-R rev2. The grading requirements in
AS 2890.1:2004 are as follows:

“AS2890.1 2004

2.6.2 Gradients

The maximum gradient of domestic driveways shall be 1 in 4 (25%). The maximum

gradient of the associated access driveway across a property line or building alignment shall
be 1 in 20 (5%) and across a footpath as specified in Clause 3.3(d).

3.3 GRADIENTS OF ACCESS DRIVEWAYS

At entry and exit points, the access driveway should be graded to minimize problems
associated with crossing the footpath and entering the traffic in the frontage road.
Maximum gradients on and near access driveways, other than at domestic properties (see
Clause 2.6), shall be as follows:

(d) Across footpaths—where the driveway crosses a footpath, the driveway grade shall be 1 in
40 (2.5%) or less across the footpath over a lateral distance of at least 1.0 m.”

The proposed grading of the driveway does not exceed 25% with a maximum 20% adopted near
David Low Way to minimise the vertical realignment of the footpath and no greater than 16%
on the remaining access driveway. Across the footpath a gradient of 2.5% has been
incorporated to satisfy clause 3.3(d) of 2890.1:2004 with a 3% cross fall extended from the
existing David Low Way for the width of the left turn lane.

The existing shared footpath / cycleway generally follows the vertical alignment of the adjacent
David Low Way and has been realigned and regraded to suit the proposed access to the
development. Figure 1 below shows the proposed grading of the shared footpath / cycleway on
the approaches to the new access. The gradients on the approaches does not exceed 6.205%
(1:16). AS 1428.2:1992 suggests that rest points should be provided at 9m spacings for gradients
of 1:14 and 15m for gradients of 1:20 with values interpolated in between. As the proposed
gradient is 1:16 on the northern approach, the suggested spacing would be 10m. The proposed
regrading of the ramp on the north side of the access is 9m in length. It is therefore proposed
that the driveway access (2.5%) provides a suitable rest area within the 10m requirement and

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