Our Association continues to raise concerns as to whether ratepayers’ money, along with the various public fund grants received from State and Federal governments, are being prudently invested.

Resealing the road again is not the solution. It is band-aid on a broken limb that needs urgent medical attention.

In the first instance OCC must identify what is the major contributing factor to the continuing problem. The sub-structure underneath the asphalt surface is undergoing a process which is referred to as ‘fowling’, or breaking up.

One ought to look no further than the way the road was originally constructed and the products used. What were the specifications and were they suitable for the purpose intended?

Were the specifications used designed for a country street, a sub-division or predominately for a major thoroughfare for heavy vehicles, in particular semi-trailers and prime movers?

Prior to the road being constructed, we understand that an OCC spokesperson announced on radio that OCC were going to place 150 millimetres of gravel underneath the bitumen surface. If this was the process that was initially used on land that is renowned for swamps and springs, it was obviously inadequate.

This type of preparation may have been suitable for a subdivision road, but not a major road or a quasi-highway.

The Northern Distributor Road appears to have been under-designed and constructed with apparent poor quality of materials being used in comparison to similar roads that are currently being constructed by the Roads and Maritime Services (RMS) at Kelso and Hartley.

ORRA has been advised that the damage caused to roads by semi-trailers compared to cars is in an approximate ratio of 1:1000. The damaged caused to road is due to a majority of semi-trailers having a maximum weight capacity of 38 to 42 tonnes, while a B-double truck can weigh up to 60 tonnes. Because of the ratio of trucks to cars that use the distributor the damage caused could be closer to a ratio of 1:1500.

Apart from the sub-standard structure used, another factor causing damage is that trucks have bigger load axles and the suspension can change rapidly. It is obvious trucks have axles following axles, which in turn places extreme stress on the asphalt.

By way of comparison, at Kelso the RMS are using 700mm of road base to the pavement with a stabiliser underneath. This consists of approximately 300mm of gravel, 220mm of concrete and then 175mm of asphalt.

A deflection test is then carried out to determine movement of the material base when a truck travels over it over a nine-metre distance. The waves in the pavement – caused by the truck tyres – give a reading as to the effect the vehicle is having on the pavement.

On the Kelso road, the RMS are required to obtain a reading of less than 1.6mm movement and this figure is based on an eight-tonne truck. 

The question has to be asked, how does the construction of our Northern Distributor Road compare to these specifications?

There are also some suggestions that the gravel used on the Northern Distributor Road may not have been of a suitable quality and as a result, this may have resulted in a poor quality road base.

A deflection test needs to be carried out on the Northern Distributor Road immediately to identify the full extent of the problem underneath the ground. A deflection test will also identify how much pavement needs to be applied onto of the road base to resolve the structural problems.

We have been told by the mayor and OCC public relations that the money spent by the RMS on the section of highway at Kelso would mean a properly built distributor would have cost $100 million.

As a matter of public interest, could OCC please provide the total amount of money that has been spent on the Northern Distributor Road.

As well intentioned as the OCC may have been at the time the road was designed and constructed, it is quite apparent the road isn’t up to standard and is a continual embarrassment to this city.

Where to from here and how much will it cost to fix the problem? Obviously if the levels of the road would allow, the most cost effective way of fixing the problem would be to try and stabilise the road and build new pavement on top.

However there are obvious major issues with curbing and roundabouts. Ideally, the road needs concrete and asphalt, which would be a 40- to 50-year solution.

The ORRA believe that an independent and extensive investigation needs to be undertaken immediately into the construction of the road and its ongoing maintenance.

The question then needs to be asked: does OCC have the required expertise to undertake the work themselves or do they need to acquire the services of an external consultant with relevant expertise in the field with geo-technical engineer designs?