Traffic Engineering Report dated 31 July 2014 W D Milligan

Manual, published by the Australian Roads Research Board (ARRB Group). Based on the
information provided in Chapter 4 of this manual, Top Forestry Road can in our opinion
reasonably be classified as a Class 4B Minor Road. According to the manual, a Class 4B Minor
Road generally has the following characteristics:
•           All weather two-lane road formed and gravelled or single-lane sealed road with gravel
            shoulders;
•           Carries an average of 50-150 vehicles per day;
•           Operating speed standard of 30-70km/h according to terrain; and
•           Minimum carriageway width is 5.5m.


Top Forestry Road generally meets the aforementioned parameters; however, as discussed in
Section 1.2, Section 2 (chainage 330m to 1,000m) of Top Forestry Road has a road width that
ranges from 5.2m to 5.4m. Even though 5.2m is considered theoretically an adequate road width
to accommodate two passing vehicles, the following mitigation measures are proposed to meet
the minimum ARRB width of 5.5m for a Class 4B Minor Road, whilst also improving the level of
comfort to local residents travelling along Top Forestry Road.
Adjacent to the subject site there are two of relatively tight horizontal curves. The horizontal
curve closest to the subject site (approx. chainage 1,300.00) has significant width around this
bend however the second bend situated at approximately chainage 1,100.00 would require
further works to adequately accommodate two vehicles (including an articulated vehicle) passing
each other on these bends. We have identified two options available for the resolution of this
horizontal curve.
Each recommendation has been identified in concept sketches included in Appendix D:
•           Relocate the existing Give Way sign at the Top Forestry Road / Old Ceylon Road to
            increase warning distance for drivers approaching the intersection;
•           From Chainages 450m to 800m, widen carriageway width to 5.5m, and reinstate the
            table drains;
•           Chainage 1,100m – Trim foliage to improve sight distance across the horizontal curve;
            and
•           From Chainages 1,050m to 1,286m - Improving drivability. There are two possible
            options:
            ­      Option 1 – localised widening to ensure a minimum carriageway width of 5.5m,
                   and widening the carriageway width to 7.5m around the curve at Ch.1,100m. The
                   widening has conceptually matched the existing embankment with the widening
                   being shown on the “uphill” side of the road to avoid widening on the downhill side



    Ref: B14101TR001_Final                       - 14 -   Proposed Poultry Farm – 136 Top Forestry Rd, Ridgewood