Att 2 - Traffic Plan

34 Elm St, Cooroy


The available sight distance can also be restricted by the driver’s ability to turn to see an on-
coming vehicle. In Austroads Part 4A, Section 3.2.3, this restriction is referred to as the sighting or
observation angle. The observation angle for right turn manoeuvres is limited to 110 degrees.
The angle from the exit only access to a southbound vehicle on Elm St is 102 degrees and hence is
complaint with the requirements of Austroads.

2.2     Sight Distances Requirements – General Information
This sight distance assessment includes the Safe Intersection Sight Distance (SISD) and the
Minimum Gap Sight Distance (MGSD) in accordance with Austroads, and the minimum Stopping
Sight Distance (SSD) as described in AS2890.1.

2.3     Design Parameters
Based on Austroads Guide to Road Design Part 3 Section 5.2.2 a reaction time of 2.0 seconds has
been adopted and is considered to be a reasonable reaction time for the Opal St environment.

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 accesses is 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.




360 Civil Consulting - Traffic Assessment                                            Page 7 of 22