VicRoads policy offers greater access certainty for quad axle combinations

Quad axle semi-traliers and longer B-doubles with quad axles offer significant productivity benefits over standard combinations, and are an economically attractive high-productivity vehicle. Under the PBS scheme, they can be demonstrated to offer better levels of safety than conventional heavy vehicles.

Recognising their potential, the industry has for many years sought access approval for these combinations. Despite their excellent performance, road managers have been somewhat hesitant in granting access, the primary concern being increased mass and potential bridge impacts.

This led to access uncertainty, which has severely limited industry uptake. As the first step in addressing this, VicRoads has released new policies that offer greater access certainty for quad axle semi-trailers up to 20 metres and 50.5 tonnes, and for quad-tri and quad-quad B-doubles up to 36.5 metres and 77.5 tonnes, on a limited network in Victoria.

The new policies include various template heavy vehicle configurations, as depicted below. Individual axle load limits are those applicable under current Higher Mass Limits (HML) and the National quad-axle policy. B-doubles can be up to 30 metres long for operation in metropolitan Melbourne, and up to 36.5 metres long for operation in regional Victoria. Overall height is restricted to 4.3 metres for all combinations.

Quad axle semi-trailer (up to 50.5 tonnes Gross Combination Mass)

Quad-tri B-double (up to 73.0 tonnes Gross Combination Mass)

Quad-quad B-double (up to 77.5 tonnes Gross Combination Mass)

The policies include an interactive map that depicts the access status of available roads. This is the most useful aspect, as it clearly depicts the permitted roads and mass limits. The provision of this advice effectively negates the riskiest and longest parts of the process for applicants, as they do not have to obtain separate bridge impacts or geometric route assessments.

Green roads are approved for the quad axle combinations at the full masses listed above. Orange roads are approved for access, but some mass restrictions apply. Red roads are also approved, but mass is limited to 68.5 tonnes. Purple roads are currently under assessment. Blue roads will be approved at full mass in the future, following infrastructure upgrades.

The reason for the mass restrictions is that VicRoads has assessed the capacity of bridges within the network and found that some cannot carry the full 27-tonne quad axle load. Those bridges are marked with a red or orange dot. An orange dot means that the quad axle mass is restricted to between 22.5 and 27 tonnes. A red dot means that the quad axle group mass is restricted to 22.5 tonnes.

In the interactive maps, clicking the dot provides information on the allowable gross mass for B-doubles for that specific bridge. For semi-trailers, the process of determining the allowable gross mass is to take the bridge’s quad-quad B-double mass limit, subtract 23.5 tonnes, and divide the result by 2. That gives the allowable load on the quad axle group of the semi-trailer. Then, add 6.5 and 17 tonnes to the result (to account for the steer and drive axle groups), to obtain the allowable semi-trailer gross mass.

For example, consider a bridge that has a quad-quad B-double gross mass limit of 76 tonnes. Subtracting 23.5 tonnes gives 52.5 tonnes. Dividing by 2 gives 26.25 tonnes. That is the allowable semi-trailer quad axle group load for that bridge. Adding 6.5 and 17 tonnes gives a quad axle semi-trailer gross mass of 49.75 tonnes.

Various operating conditions apply for combinations under the new policy, as follows:

Quad axle semi-trailers

• vehicles must satisfy the Performance Based Standards (PBS) that correspond to the desired level of access
• vehicles must be fitted with a GPS device that is accredited under the Intelligent Access Program (IAP)
• vehicles must be fitted with a certified On Board Mass (OBM) system that can be integrated with IAP, when such systems become available in the marketplace (this requirement is waived until that time)
• vehicles must be accredited under the Mass Management module of the National Heavy Vehicle Accreditation Scheme
• vehicles must be fitted with an ABS system that operates on all axles
• vehicles must be fitted with a certified Road-Friendly Suspension (RFS) system

B-doubles with quad axle groups

• vehicles must satisfy the Performance Based Standards (PBS) that correspond to the desired level of access
• vehicles must be fitted with a GPS device that is accredited under IAP
• vehicles must be fitted with a certified OBM system that can be integrated with IAP, when such systems become available in the marketplace (this requirement is waived until that time)
• vehicles must be accredited under the Mass Management module of the NHVAS
• vehicles must be fitted with an ABS system that operates on all axles
• vehicles must be fitted with a certified RFS system
• vehicles are restricted to a maximum speed of 90 km/h
• vehicles must display ‘long vehicle’ warning signs front and rear

Operators must also obtain a permit from the Over Dimension Load team under the Department of Economic Development, Jobs, Transport and Resources. Applications must indicate vehicle length, and expected times of day of the proposed trips.

Of course, the new policies do not guarantee access in all instances, as there may be ‘last-mile’ issues, depending on the nature of the operation, and the roads that are needed to access start and end points.

Nevertheless, if you have previously considered combinations with quad axle groups in Victoria, or wish to understand the potential productivity benefits, we recommend you contact us to discuss your options. We will explain the process from start to finish, and give you a realistic picture of the costs and timeframes.

As with any PBS vehicle, the first step is to discuss the vehicle concept and proposed operation with VicRoads, in order to obtain in-principle support. Advantia can complete that process, and if successful, complete the PBS application, and assist in addressing any last-mile queries that road owners may pose.

The full policy for quad-axle semi-trailers is available to view here.

The full policy for quad-axle B-doubles is available to view here.

The interactive map can be accessed here.

Please contact Advantia for more information.