2016-02-02 I&S Committee - Item 4 - Attachment 1 - Noosa Traffic Study

one or more of the approaches to the roundabout for virtually the entire peak period.

For roundabouts, when the DOS is below 0.75, delays and queuing are minimal. At DOS 0.85,
average delays would typically be about 15 seconds per vehicle, increasing to 20 seconds at
DOS 0.90, and greater than 30 seconds per vehicle for DOS 1.00. For example, the Moorindil
St / Poinciana Ave intersection operates over-capacity in the morning peak (DOS 1.10) with
long queues and delays on the Moorindil St approach at peak times. The Beckmans Rd /
Eumundi Noosa Rd intersection also operated over capacity (DOS greater than 1.0) during
peak periods when Walter Hay Drive was closed for reconstruction works in March 2015,
resulting in delays of over 10 minutes on the Beckmans Road approach.

For “give way” and “stop” controlled junctions, the industry standard DOS limit is 0.80, and for
signalised junctions it is 0.90. These have also been adopted in this study as being the trigger
points for upgrading of intersections.

It is noted that the Noosa Planning Scheme and current Noosa Priority Infrastructure Plan
identifies a desirable upper limit DOS of 0.70 for all intersections within Noosa. This was
selected about 20 years ago, with the aim of inherently making allowance for busier holiday
periods when applied to intersection analysis based on traffic counts in the non-holiday periods.
Now that there is more data available within Noosa in relation to the variation in traffic flows
during the holiday and non-holiday periods throughout various parts of the Council area, it is
appropriate in this study to make specific allowance in the traffic flows where appropriate for the
holiday periods, and then use the industry standard 0.85 DOS as the appropriate planning limit
for roundabouts.

Importantly, the upper limit DOS of 0.70 as outlined in the Noosa Planning Scheme and current
Noosa Priority Infrastructure Plan will be maintained for use by the development industry and in
the assessment of development applications as they will unlikely have access to the extensive
traffic data used in this study.




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