Moving forward for safer bitumen

Vicroad is planning to move its road sealing fleet to being fully forward moving in an effort to increase worker safety, reduce site costs and produce better road surfaces for Victoria.

VicRoads has recently announced plans to move towards using non-reversing aggregate spreaders for sprayed sealing operations.

Deputy Chief Executive of VicRoads, Peter Todd, said the change to a forward moving road sealing fleet will have several benefits for both road crews and road users, and have positive impacts on future road sealing projects.

“Forward moving aggregate spreaders deliver significant safety benefits as they allow operators a better view of potential hazards,” Mr Todd said.

“Forward moving aggregate spreaders also produce a higher quality surface, lead to potential savings on materials and require less sweeping of excess aggregate particles from the road surface.”

The risks of reversing trucks

Sprayed bitumen seals have been the primary road surfacing treatment used in Victoria for more than 80 years.

While there have been significant improvements in the size and productivity of equipment, the basic process has remained, for the most part, unchanged.

A bitumen sprayer applies bitumen to the road surface and aggregate spreading trucks reversing down the road behind the sprayer tip aggregate particles onto the freshly laid bitumen.

The trucks are required to reverse to avoid driving onto the exposed bitumen and many spread the aggregate through elevated tipper bodies.

When both the bitumen and aggregate have been placed, surface rollers then reorientate the aggregate particles to provide a robust seal.

While they are being constructed, sprayed seal sites are an inherently dangerous place to be with a combination of hot bitumen (up to 190°C) being sprayed under pressure and with loose aggregate chips being applied to the road surface – all under live traffic conditions.

In addition to the risks observed with the combination of reversing trucks and people on the ground, there are also other risks associated with conventional aggregate trucks including the potential to hit overhead services such as power lines and overhanging trees; roll over incidents that are often a result of hoist or hinge bolt failures on the tipper body; and other mechanical failures.

The complexity of alternative aggregate spreaders, combined with their cost, has seen the implementation of new technology stall in favour of persisting with the simple reversing trucks.

The time for change

Significant investment will be required from the industry to convert current fleets to forward moving vehicles, and VicRoads has implemented a five year transition period (1 July 2017 – 30 June 2022) to phase in the new spreaders.

VicRoads plan on introducing synchronised bitumen spraying and aggregate spreading machines that combine the application of the bitumen and aggregates as part of one operation.

Synchronised sprayers have been available for many years mainly from Europe and America, and in more recent times from China.

Forward moving aggregate spreaders have recently been developed in France, with two manufacturers currently trialling prototype units, and a handful of other companies, including some based in Australia, are also developing their own versions of this equipment.

There may be issues with the French units complying with Australian regulations but locally designed units should be produced to conform.

During the transition period, there is an additional payment of $0.50/m2 for works completed utilising forward moving spreading techniques.

This payment is intended to help alleviate the anticipated costs of the initial purchase and ongoing costs of operating these alternative plant items.

There is also an incentive payment to reward early adopters of forward moving spreading techniques, which recognises the potentially higher costs and risks for those contractors who purchase new plant items immediately and the disadvantage they face while trying to compete at the tender box with other companies that have not invested in the new equipment and technologies.

The transition commenced on 1 July this year, however, because the sprayed sealing season does not commence until October each year there have not been any projects completed using the forward moving technology as yet.

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