Recognising multiple objectives
The development of treatment regimes in Roadside Asset Management Plans must recognise the impacts on all roadside management objectives. Initiatives to address one management objective may have adverse impacts on other competing objectives. The case studies overleaf illustrate how the objectives might interact under different management scenarios.
Identifying the most appropriate treatments
It is important that treatments be assessed for their effectiveness in addressing the primary objective (in the short and long term), whilst balancing their ill affect on other roadside management objectives.
Where a proposed treatment has an unacceptable adverse impact on another objective, consideration should be given to alternative solutions or ways to minimise that impact on the other objective. For example:
- Can the affected asset be protected from the impact? e.g. wildlife underpass to avoid conflict with traffic.
- Can the impact be minimised by a selective treatment? e.g. removal of ground litter and shrubbery to reduce fire risk, rather than complete clearance.
- Can the asset be relocated to avoid the impact?
e.g. relocation of endangered flora/fauna species to an offset location.
- Can the (minimised) adverse impact be accepted, given the identified benefits of the proposed treatment?
Four principles for selecting roadside treatments are:
- Protect life and safety.
- Preserve high-value environmental and heritage assets.
- Select solutions which are cost-effective and sustainable, and are balanced with the achievement of other roadside objectives.
- Test the outcomes of the proposed solution against local and regional priorities expressed in the Roadside Asset Management Plan and/or by review with community and stakeholders.
Balancing potential impacts of roadside projects
The following case studies illustrate the ways that competing objectives need to be balanced in developing treatments for roadside areas.
Case study 1: Addressing a history of run-off-road crashes
VicRoads has identified a history of run-off-road crashes on a road length and found that the most cost-effective treatment is the installation of wire rope safety barrier. The primary objective is enhancing transport safety, efficiency and access and the treatment must be assessed against the other three objectives:
Protect environmental and cultural heritage values: Positive impact, as this option requires less vegetation removal than alternatives such as the removal of vegetation that poses a hazard.
Management of fire risk: Wire rope safety barrier reduces access to the roadside area, making grass cutting and timber and leaf debris removal more difficult. This can increase fire risk.
Preserve and enhance roadside amenity: Reduced access for maintenance as described above can lead to a negative impact on visual amenity.
In this case, assessing the impact of the wire rope safety barrier on other objectives highlights the need for access to the roadside behind the barrier. The negative impacts could be reduced by providing access points at appropriate locations.
Case Study 2: Fuel reduction burn
Once a high fire risk has been identified on a particular road length, it may be necessary to conduct a fuel reduction burn. The primary objective is management of fire risk and assessing its impact on the other objectives.
Enhancing transport safety, efficiency and access: There is the potential for road safety to be impacted during the burn as smoke can impair visibility on the road and the fire may encroach on the road.
Protect environmental and cultural heritage values: The burn would have a positive impact on this objective as biodiversity could be improved through seeds being released from native species and the reduction of weeds.
Preserve and enhance roadside amenity: Most likely to have minimal impact.
In this case, the negative impacts can be avoided by temporarily closing the road and arranging detour routes.
Case Study 3: Landscaping to enhance streetscape
VicRoads considers the aesthetic impacts of its projects and has included landscaping works in an urban road project. The primary objective is preserving and enhancing roadside amenity and its impacts on the other objectives are:
Enhancing transport safety, efficiency and access: Vegetation may become a hazard to traffic by encroaching onto the roadway, impairing visibility or becoming a significant hazard to vehicles that leave the road.
Management of fire risk: There will be negligible impact on fire risk, because fire is rarely carried in urban landscapes.
Protect environmental and cultural heritage values: Landscaping has a positive impact by improving the local environment and providing carbon offsets.
By selecting species carefully and considering the type and volume of traffic using the road, the risk to road safety can be minimised at the planning stage.