Appendix H Traffic Impact Assessment · RAL25/0004

4.0 Impacts on the surrounding network


4.1 Dianella Ct / Lake MacDonald Dr intersection

In relation to the vehicular access opportunities for the site, it would not be appropriate to attempt to
achieve an independent site access onto Lake MacDonald Dr, because the combination of the existing
vertical and horizontal alignment of Lake MacDonald Dr west of the Dianella Ct intersection at the site
frontage is such that achievement of an isolated access location that achieves SISD requirements in a
position sufficiently clear of the Dianella Ct intersection is not possible.

The proposed upgrade to the Dianella Ct / Lake MacDonald Dr intersection and the access to the
development site off Dianella Ct, as shown on the Covey civil engineering plans at Appendix B, is
consistent with the arrangements shown in the concept plan at Appendix A and would operate in a safe
and efficient manner, satisfactorily ameliorating the impacts of the proposed development, subject to the
proposed raised central median in Lake MacDonald Dr east of the intersection as seen on the Covey
plans, being replaced with a painted median as shown on the concept plan at Appendix A. This is to
enable the small number of vehicles that currently turn right into Wilgee Ct from the east, to be able to
move into that painted median zone so that following westbound vehicles can then move safely past the
left-hand side of those vehicles turning right into Wilgee Ct.

With there being only about 300vph moving along Lake MacDonald Drive east of Elm Street, the
volumes of traffic using Dianella Ct and Wilgee Ct will not be sufficient to cause capacity concern, and
the proposed CHR(S) right turn lane treatment introduced to Lake MacDonald Dr at the intersection as
part of the intersection upgrade works, is all that is warranted by chart at Figure 3.25 of Austroads Guide
to Traffic Management Part 6.


4.2 Elm St / Lake MacDonald Dr intersection

To verify that the existing Elm St / Lake MacDonald Dr intersection has sufficient capacity to
accommodate traffic generated by the proposed development, assessment been undertaken using the
SIDRA software package, using default settings, under predicted year 2035 peak hour conditions with
the proposed development fully operational.

That assessment has assumed that the 2023 peak hour traffic flows indicated in Figure 2, would increase
at a rate of 1%pa compound across the 12-year period to 2035, and that site generated traffic flows in
Figure 6 would then be added. The resultant peak hour traffic flows are shown in Figure 7, and the
intersection configuration used in the analysis is shown in Figure 8.




Figure 7: Predicted year 2035 peak hour traffic flows with the proposed development




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