PAVEMENT FAILURES

BRUCE McCLURE General Manager of the CMPA comments on the recent spate of road pavement failures around Victoria due to wet and cold weather conditions.

THROUGHOUT history mankind has used various techniques to improve the condition of the roads that were needed for people to move round, for commerce and unfortunately for military manoeuvres. The Romans were masters of road building and many examples of their abilities in this area are scattered around many countries. In fact many of the roads built by the Romans are still in use or are the foundation for generations of roads built upon them and updated ever since.

In the 21 century with all of our sophistification and technology it would seem that in Victoria we have lost some of the basic arts of road works and maintenance. Over the last few years especially as the drought affected years of the last decade fade into memory, we have gone through two rather wet years especially in the winter months. Driving around Victoria at present one would soon forget that once the roads throughout Victoria were the pride of the nation. Sadly this is not the case at present as a trip along many of our freeways, our highways and main roads shows examples of major pavement and roadside reserve failures.

For many people especially engineers with road construction experience to see state and local government attempting to construct substantial road works during the winter months over the last two years has been and still are a matter of grave concern. For many years it has been standard practice to reduce the amount of road works and major maintenance activities during the winter months to only essential activities especially those that affect the safety of the travelling public.

However, with the recent long drought in Victoria with weather especially wet conditions very limited, a pattern has arisen where contractors worked virtually all year on road and associated construction projects. Neither wet nor cold conditions impacted severely on their works. However the weather pattern has changed and we are now back to a more normal cycle of wet and dry months. It was standard practice when we expected a normal autumn, winter and spring rains to plan and execute the works to take into account the weather conditions.

This meant that there were months when we anticipated no construction activity (especially bituminous surfacing works) at all during these periods. It was the case that occasionally some major works had to be carried out for safety and/stability reasons but these were carefully planned and executed.

The State road authority VicRoads has detailed specifications that are used on the majority of road works in Victoria including those carried out by local government. These specifications are quite clear on pavement makeup, strength of materials to be used, the amount of water to be added to the products to get stability and in the case of bituminous surfacing works with both sprayed seals and asphalt, the surrounding air and road pavement temperatures at which the materials should be placed. Sadly we now see examples were these specifications are not be being adhered to.

In instances now where road construction is taking place in the winter months there are many examples of failures occurring in newly constructed works.

There are instances where the wet weather has left local council roads partially reconstructed for months as the contractors try to work around the rain. Not only is this bad practice but it is costing the community large sums of money due to rework, lost time and impacts on accessibility to areas.

On a number of state highways works also recently completed are showing major failures and are going to cost considerable sums of money to rectify.

With cost of living going up for all Victorians, to see our taxes our rates wasted because of poor planning, poor workmanship is simply not acceptable. It implies a loss of control of some aspects of works by VicRoads and problems with the current tendering process.

As a consequence of many pavement failures occurring one very bad aspect that is arising is that a number of suppliers of road making products are being blamed for supplying poor quality or out of specification materials to the road bed. No quarry can be blamed for the poor construction especially the actual timing of construction projects yet some are being blamed for issues that clearly relate to construction technique and the time of year and weather conditions prevailing.

It is very difficult to build good quality crushed rock pavements when it is wet, cold and raining. It is very difficult to bituminous seal or pave pavements when it is wet, cold and raining.

Once a pavement material has been supplied by a quarry (to the specification contracted to) and it is placed on the road or area to be paved, wet, cold and possible rain interludes dramatically impact on that material as it is placed and moved on site. In wet cold periods material over wet cannot be effectively dried out on the paved area and you will not get pavement stability. Moving the material around to try to dry it out will result in segregation, a possible loss of fines and a real chance of contamination. In these instances how is it the problem of the materials supplied by the quarry?

With many of the larger state government projects the construction time can be over several years. This obviously impacts on time frames especially during periods when weather conditions are not conducive for construction activities.

However, good project planners factor into their project timings period of limited construction due to weather conditions and contractors would be aware of these factors as well. Suspension of works due to weather conditions has always been part of the construction scene but it appears that this may not be a consideration for some projects and in reality some contractors are possibly being forced to complete works to comply with tender contract requirements. Consequently we end up with many contractors trying to construct and bituminous surface pavements in conditions that are totally unsuitable for these works.

There is a need for all authorities who are involved with the construction and bituminous surfacing of pavements whether roads, carparks, hardstand areas to reassess their planning and tender specification requirements to prevent what is happening across the state at present.

There is no excuse for poor planning and poor construction techniques and to blame the suppliers of products for failures when it is clearly one of poor workmanship at the worksite is simply not acceptable and will not be tolerated.

You must be logged in to post a comment Login