Appendix D - traffic impact assessment

Table 3-2: Elm Street (Cooroy Connection Road) / Pearsons Road intersection SIDRA assessment outcomes, 2018 Base
Year and 2028 Design Year – priority control (give-way sign)


                                   Degree of         Level of           95th Percentile Queue     Delay
 Scenario                          Saturation        Service (LOS)      Length (m)                (s)

Base Development Year 2018
2018 AM Peak Hour – without             0.39                A                     11                      2
development traffic
2018 AM Peak Hour – with                0.40                A                     12                      3
development traffic
2018 PM Peak Hour – without             0.30                A                     18                      2
development traffic
2018 PM Peak Hour – with                0.34                A                     23                      3
development traffic
Design Horizon Year 2028
2028 AM Peak Hour – without             0.55                B                     29                      4
development traffic
2028 AM Peak Hour – with                0.56                B                     35                      5
development traffic
2028 PM Peak Hour – without             0.44                A                     47                      4
development traffic
2028 PM Peak Hour – with                0.50                B                     59                      5
development traffic
Note: the above values are the “worst” values resulting from the assessment

The key outcome from the assessment is that all movements and legs are forecast to operate at an acceptable Level of
Service (LOS) of either “A” or “B”. The worst 95th percentile queue length was 59m occurring at the through and right turn
movements from the south approach on Elm Street. All of the traffic operations output parameters are well within the
bounds of what are considered to be satisfactory operational conditions. For example, the worst degree of saturation is
0.56 in the future year 2028 morning peak hour, versus an upper limit Practical Degree of Saturation of 0.80. Refer to the
SIDRA output in Appendix C. Based on the SIDRA analysis and anticipated traffic volumes at the site, it is
recommended that the following intersection arrangements be adopted:

       At the south approach, consideration of a channelised right turn lane be provided. The SIDRA results in Table 3-
        2 show that the worst 95th percentile queue length is 59m, which suggests a storage length of 10 vehicle lengths
        (60m total) plus tapers is appropriate. SIDRA sensitivity testing was conducted in relation to the storage length
        for the channelised right turn from the southern approach of the intersection. The sensitivity testing took into
        account a higher proportion of the development traffic accessing the site at the Elm Street / Pearsons Road
        location. That is up to 75% of the ILU’s and 100% of the aged care facility development traffic. The results of the
        sensitivity testing indicated that the 95th percentile queue remained at 59m. Hence, consideration for the
        provision of a channelised right turn lane of design storage length equivalent to 10 vehicle lengths (60m) is
        recommended at this location.
       At the north approach, it is recommended for consideration that a short auxiliary left turn lane be installed, as per
        the future year TMR warrants for the left turn into Pearsons Road.
The detailed design of all intersection turn treatments are to be undertaken in accordance with the relevant design
standards and guidelines.




B14158ER01 | TRAFFIC IMPACT ASSESSMENT | PALM LAKES RESORTS                        COOROY RETIREMENT COMMUNITY | 14