Referenced Document - MCU12/0216

Quarry Rehabilitation
Lake Macdonald Drive, Lake Macdonald

© 2012 - TTM Consulting (SC) Pty Ltd                                         Reference No: 12SCT0037


7.2.1      Sight Distance Review
The Austroads document, Guide to Road Design - Part 4A: Unsignalised and Signalised
Intersections, provides details on intersection visibility guidance.
The guidance indentifies that a typical drivers eye height is 1.15m for a passenger vehicle,
however, this guidance also provides details on a typical truck drivers eye height being 2.4m. Due
to the design vehicle predominantly being a truck, this height has been used in assessing the
available intersection/access sight distance.
This additional height (2.4m) provides additional visibility for truck drivers over the crest to the
north of the site access, as shown in Figure 7.3. The available northern sight distance between the
drivers height at the site access (2.4m) and drivers height on Lake MacDonald Drive (1.15m) is
approximately 85m, which is further limited due to vertical downgrade alignment on Lake
MacDonald Drive.
In a review of the Austroads documentation: Guide to Road Design - Part 4A: Unsignalised and
Signalised Intersections an Approach Sight Distance (ASD) of 114m is recommended for an
80km/h speed environment.
However, if the through speed is reduced to 60km/h an ASD of 73m would be required, which can
be achieved on the basis of northwards truck driver visibility.
The sight distance to the north of the access is adequate with visibility greater than 200m.


7.2.2      Warrants for Turn Treatments Review
A review of warrants for turn treatments in Austroads Part 4A identifies that with the anticipated
traffic volumes, basic right (BAR) and basic left (BAL) turn treatments are required at each access
location.
Given the duration of haulage activities taking place and low existing background traffic volumes,
it is recommended that adequate signage be provided in lieu of the turn treatments noted above,
with any signage in accordance with the Manual of Uniform Traffic Control Devices (MUTCD).




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