34 Elm St - Traffic Assessment - Rev C

34 Elm St, Cooroy


For SISD calculations Austroads Guide to Road Design Part 4A Section 3.2.2 allows for a 3.0 second
observation time.

When calculating the sight distance requirements in accordance with AS2890.1, Figure 3.2
assumes a reaction time of 2.0 seconds for driveways to commercial properties.

Based on Austroads Guide to Road Design Part 3 Section 5.2.3 a coefficient of deceleration of 0.36
has been adopted and is considered to be appropriate for Elm St and Opal St.

It is estimated that on average the approaches to the access are approximately 2% longitudinal
downgrade to the east and the west.

The existing speed limit along Elm St is 60km/hr and the existing speed limit along Opal St is
50km/hr.

The design speed for vehicles coming from Elm St and turning left onto Opal St has been
calculated to be approximately 25km/hr based on a turning radius of 15m. The design speed for
vehicles turning right onto Opal St from Elm St has been assumed to be 20km/hr.

2.4      Minimum Sight Distance Calculations
Safe Intersection Sight Distance (SISD) and Safe Stopping Distance (SSD) have been calculated in
accordance with Austroads Guide to Road Design Part 4A Section 3.2.2 and AS2890.1. Table 2
provides a summary of these results.

Table 2 – Summary of sight distance requirements

                                                                  Required Sight Distance
                                      Design
                                                                     (Minimum) (m)              Sight Distance
                                      Speed
                                                   Estimate                                      as measured
                                    (Frontage    Longitudinal     Austroads       AS2890.1
       Approach Direction                                                                           on site
                                   Road Speed)    Grade (%)
                                                                MGSD     SISD     (Min SSD)
                                                                                                     (m)
                                       km/h
                                                                (m)       (m)

       Opal St Access - East            60
                                                      -2         83       125         65            180m
                                       (50)

      Opal St Access - West             25
                                                      -2         35       42          35            53m
                                       (60)




As demonstrated in Table 2, the sight distances from the proposed access to Opal St, comply with
Austroad’s Guide to Road Design, SISD and MGSD and with AS2890.1 minimum SSD requirements.

No modifications are proposed to improve the sight distance at the access to Opal St.



360 Civil Consulting - Traffic Assessment                                                     Page 7 of 13