Attachment 5 - Traffic Impact Assessment Final PTT · 132005.638.06

         Based on these assumptions, the 95th percentile design queues from the weighbridge have been
         calculated as follows:

         —        Tuesday: approximately 11 vehicles (~109m)
         —        Sunday: approximately 9 vehicles (~85m)

         2.6.2        Sensitivity Analysis
         It is expected that the site would experience fluctuations in demand. For example, peak arrival
         rates may increase during holidays, when people have time to bring waste to the dump, or after
         storm events. As such, a sensitivity analysis has been undertaken to determine the peak arrival
         rate that would result in unacceptable queue lengths from the weighbridge. Based on the
         assumptions above, if arrival rates exceed 100vph, the queue would extend onto the external
         road network (ie unacceptable queue length). This represents a relatively small (eg 3%) increase
         over the typical peak hour rates observed at the NRRC site access and highlights the sensitivity of
         the existing NRRC layout and operations to small changes in demand.

2.7      ACCESS OPERATIONS

         2.7.1        Intersection Assessment Parameters
         A series of SIDRA analyses were conducted to quantify the existing traffic operations at the
         Eumundi Noosa Road / Site Access priority-controlled intersection. The analyses were based on
         the traffic count data presented in Appendix B, with:

         —        Peak Flow Factors (PFF), as detailed in Table 2.4
         —        the observed proportion of heavy vehicles (%HV) for each movement
         —        SIDRA default values for other parameters

         The level of reduction with opposing flow rate factor is used to reflect the tendency of drivers to
         accept reduced gaps in circumstances where the opposing traffic volume is high. The adopted
         value of “low” is the lowest of three available values (excluding “none”). The application of this
         factor is consistent with guidance published in the SIDRA User Manual and is expected to
         accurately reflect the operation of the above intersections under existing, pre and post-
         development scenarios (refer to Appendix C for further information).

         The results are presented in terms of the degree of saturation (DOS), 95 th percentile vehicle
         queues, and critical movement at the intersection. The DOS for a movement is defined as the
         ratio of traffic demand to the capacity of the movement. The critical movement relates to the
         approach or movement with the highest DOS. Table 2.5 is an extract from the SIDRA manual
         and defines the operational rating and level of service for all intersection types.

         The Department of Transport and Main Roads’ (TMR) Guide to Traffic Impact Assessments (GTIA)
         states that the threshold for acceptable operations is LOS C/D, which translates to a maximum
         DOS of 80% for priority-controlled intersections.




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