Attachment 4- Traffic Impact Assessment

                                                                                  21 November 2023
                                                                         SLR Project No.: 620.V30926
Stockwell Development Group Pty Ltd                       SLR Ref No.: 620.V30926-R01 VMU TIA v1.0
Noosa Village Mixed Use Development                                                   20231121.docx



9.2        Assessment Software
The study intersections were analysed for each of the aforementioned scenarios using SIDRA
Intersection 9 software (SIDRA). SIDRA is an industry recognised analysis tool used to
estimate the capacity and operational performance of intersections based on a variety of input
parameters including geometrical data and traffic volumes. SIDRA provides an estimate of an
intersection’s operation by reporting a number of numerical outputs including Degree of
Saturation (DOS), queues and delays.

9.3        Performance Criteria
9.3.1      Intersection Performance Thresholds
DOS thresholds, as defined in Guidelines for Assessment of Road Impacts of Development
(GARID) 2006, have been used to understand the operational performance of an intersection.
Whilst it is noted that these thresholds are no longer adopted by the GTIA, these parameters
are still considered to be relevant and appropriate for assessing the capacity and performance
of an intersection, particularly when assessing its operational performance under existing
conditions. The DOS thresholds, as defined by the GARID, are presented in Table 27 below.

Table 27 DTMR GARID Intersection Performance Thresholds
               Intersection Type                                 DOS Threshold
             Signalised intersections                       Less than or equal to 0.90
                  Roundabouts                               Less than or equal to 0.85
         Priority controlled intersections                  Less than or equal to 0.80

DOS values exceeding the thresholds presented in Table 27 indicate that the intersection is
nearing its practical capacity, and therefore, road users are likely to experience rapidly
increasing delays and queuing. Mitigation works may be required to maintain satisfactory
operation at such a point.

9.3.2      Critical Delay
The RMS (now TfNSW) Guide to Traffic Generating Developments (2002) recommends that
the average delay statistic for the critical movement provides a better indication of intersection
performance and safety for roundabouts and priority-controlled intersections than DOS. A
summary of the delay thresholds recommended by TfNSW is provided in Table 28




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