Appendix E- Traffic Impact Assessment · MCU23/0135

                                                                                                                10 October 2023
                                                                                                    SLR Project No.: 620.V30926
Stockwell Development Group Pty Ltd                                                 SLR Ref No.: 620.30926-R01-v1.0 Noosa Civic
Noosa Civic Shopping Centre                                                                    Stage 2 Retail TIA 20231010.docx



9.0               Operational Assessment
9.1               Assessment Software
The study intersections were analysed for each of the scenarios using SIDRA Intersection 9.1
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 numerical outputs including Degree of Saturation (DOS), queues and
delays.

9.2               Performance Criteria
9.2.1             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 18 below.

Table 18 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 18 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.

9.2.2             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 19.

Table 19 Critical Delay Thresholds
LOS           Description                                                              Critical Delay (sec/vehicle) (1)
      A                               Good operation                                                         < 14 sec
      B                 Acceptable delays and spare capacity                                               15 - 28 sec
      C                                  Satisfactory                                                      29 - 42 sec
      D                                 Near capacity                                                      43 - 56 sec
      E              At capacity, requires other control mode                                              57 - 70 sec
 1.       For traffic signals, the average delay of all movements should be reported. For roundabouts and priority-control intersections, the
          highest average delay of the critical movement should be reported.




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