Tiger Spider was engaged by VicForests to conduct a heavy vehicle route assessment of Acheron Way and Warburton-Woods Point Road to determine the suitability of 23.0 metre B-double logging vehicles currently operating under permit. The routes have been separated into three sections:
- Acheron way from Marysville Road to Feiglins Road,
- Warburton-Woods Point Road from Cambarville Road to Nine Mile Road,
- Warburton-Woods Point Road from Nine Mile Road to the Loch Fyne Track
The objective of the route assessment was to determine the suitability of permitted 23.0 metre B-double logging trucks operating on Acheron way and Warburton-Woods Point Road. The key concerns identified in this assessment included the road width, road conditions, signage and posted speed limits. These concerns were particularly critical around blind and tight bends where vehicle interactions may occur.
The assessment includes:
- Preliminary analysis and consultation
- Route survey and assessment
- Field testing of permit B-Double stag trailer (≤ 23.0 m & ≤ 63.0 tonnes)
- Crash data analysis
- Report and recommendations
The main concern of this assessment is the width of the road along certain sections of the routes; in particular, where there is lane encroachment around blind corners and/or tight bends. Acheron way permits two-way traffic but only has sufficient space to accommodate a single heavy vehicle at any given point. If an interaction between a heavy vehicle and a passenger vehicle occurs, the passenger vehicle travelling in the opposing direction will need to pull off the carriage way to allow the heavy vehicle to pass; this may also be the case for two passenger vehicles.
The first section of Warburton-Woods Point Road can accommodate two lanes of traffic including two heavy vehicles at any given point along the route. Like Acheron Way, the second section of Warburton-Woods Point Road permits two-way traffic and in generally can only accommodate a single heavy vehicle. However, there were numerous overtaking opportunities along the route that would allow a passenger vehicle to safely pull off the carriageway.
A route assessment framework was developed for this assessment which was based on various route assessment guidelines, including: The Austroads Guide to Road Safety, National Transport Commission (NTC) Network Classification Guidelines for Performance Based Standard Vehicles and restricted access route assessment guidelines used in South Australia, Western Australia, Queensland and New South Wales.
The various guidelines all have a common risk based approach but consider some specific aspects to road safety that are particularly relevant for oversize restricted access vehicles, including:
- Safe speeds
- Road geometry – curvature, lane and shoulder width
- Overtaking provision
- Report and recommendations
- Sight distance
- Pavement and bridge capacity
Crash data provided by VicForests and obtained from the VicRoads open data system has also been analysed to determine whether there is any correlation between accidents and critical bends identified along the routes.
- It is recommended that 23 m B-doubles be permitted to operate on Acheron way in accordance with existing permit conditions.
- Pavement repairs are completed and certain shoulders are sealed and widened to reduce the likelihood of the rear B-double trailer off-tracking over the sealed pavement edge and causing accelerated pavement damage when rounding certain bends.
- Additional warning signs be included to alert drivers to critically narrow road sections where they may be required to pull over to allow a heavy vehicle to pass.
- VicRoads should consider reducing speed limits or providing speed advisory signs. An assessment of 600 different vehicle configurations was completed.
- All bends where encroachment was identified are cleaned and cleared of vegetation, dirt and debris. The route is re-assessed to confirm that there is sufficient road space for a B-double to ensure there is no encroachment into oncoming traffic.
- Additional warning signs be included to alert drivers to critically narrow road sections where they may be required to slow and/or pull over to allow a heavy vehicle to pass.
- There are regulator assessment and maintenance of the road to ensure that there is no build-up of vegetation, dirt and debris that would reduce the effective road space of the lane.
- All critically narrow sections of roads where there is insufficient site distance to warn a vehicle to pull over to allow the on-coming traffic to pass should be either widened to allow two lanes of heavy vehicle traffic.
- Additional controls (speed, traffic, radio) and warning signs and are put in place to sufficiently warn vehicles that they are entering a critical narrow section of road and may encounter a heavy vehicle.