Rob Grove advised delegates at the 7th National ASTT Conference in Sydney that if state road authorities are to have the confidence to implement more Trenchless Technology into their business activities, they need access to independent and reliable information about the available technology.
There is little internal knowledge of Trenchless Technology within road agencies in terms of understanding both the adequacy or suitability of various trenchless techniques and the risk of unsatisfactory performance said Mr Grove. In the past the approach has generally been to hold the contractor or private developer liable should there be a less than satisfactory impact on local or adjacent road infrastructure.
For Main Roads Western Australia, as steward of an $A18 billion road network asset, this approach is simply not good enough. Mr Grove is the Manager of Road & Traffic Engineering in Main Roads Western Australia, and is currently responsible for raising awareness of sustainability principles within his organisation.
Trenchless Technology online
Mr Grove believes that there is a real need for Main Roads staff to be able to access sufficient independent information to understand the trenchless technique being proposed by a contractor or developer, and the associated limitations or risks. In Western Australia he has been responsible for the development of an internet website to house Main Roads road design standards and guidelines, which are routinely accessed by consultants, contractors, local government and internal staff. “This increases the consistency of decision-making and enables subscribers to keep abreast of any changes,” he said.
In 2006, the ASTT identified the need to develop a framework to house Trenchless Technology standards and guidelines relevant to Australian and New Zealand conditions. Subsequently, Main Roads and the ASTT jointly engaged a consultant to carry out an overview of the available Trenchless Technology information world-wide and to consult with Australasian Trenchless Technology firms and local authorities. That review has led to the development of an internet framework to house key information for the benefit of clients, industry and contractors alike.
However, it will be some time before a complete service can be developed to fully populate that framework with desired information. In the meantime Mr Grove suggested that now would be a good time to reflect on the type of information that would assist a road agency to become more suitably informed. He said, “It would be of immense value to road agency staff, service authorities and contractors alike if there was access to basic information that explains the different trenchless construction method types and describes their potential uses and limitations.”
At present, information relating to Trenchless Technology is scattered over a number of publications and websites, but the age of the information, its accuracy and current relevance in Australian conditions are uncertain at best. Hence the need for a centralised data source, such as the one foreshadowed by ASTT. This data source, if it follows the lead of the Main Roads website, could be date-stamped, with the content reviewed and updated on a regular basis. “In Main Roads Western Australia our standards website is reviewed on a rolling five year frequency to ensure the currency of information,” Mr Grove said.
Trenchless Technology under the urban landscape
The road reservation contains a plethora of underground infrastructure – most of which is known; but some of which is unknown, incorrectly marked on plans or no longer in service. This is particularly the case at intersections where there are drainage and water supply pipes, traffic detectors and conduits containing power and communications. Interference with any of these services can have a very detrimental effect on local road operation, with potentially serious safety implications for road users.
The integrity of the relatively thin road pavement is also of major concern. In Perth, where there is generally an abundance of sandy soil, the pavement thickness is often less than 300 mm. In circumstances where the Trenchless Technology contractor is trying to minimise the depth of the operation there can be a very low margin for error before the conduit or tunnelling operation migrates into the susceptible pavement layer. Underground boring may lead to the pavement heaving, causing severe cracking of the thin layer of asphalt that provides waterproofing and a smooth running surface.
Accordingly, road agency staff are particularly interested to know the range of Trenchless Technology that is readily available in Australia and New Zealand, the limitations on each, what accuracy is attainable and what ground information is needed to assist in deciding to adopt a particular approach. It would be very helpful if there was a central place – such as the proposed internet website – to hold relevant information that would give confidence that the proposed technique is likely to be well suited to the local circumstances.
As the ASTT reflects on priorities to populate the proposed website to house Trenchless Technology standards and guidelines, consideration should be given to the development of a comprehensive summary of Australasian trenchless construction methods. These guidelines would be immensely useful to all road agencies, whether state or local government. Giving confidence to road authorities that they have access to reliable and independent information on a range of Trenchless technologies will greatly encourage wider and growing use of that technology.
Mr Grove concluded that the greatest need of road agencies is to be able to access in a timely manner, sufficient key data to confidently request, manage and monitor trenchless activities in their road reservations.
This is an edited version of Mr Grove’s presentation to the Trenchless Australasia Conference 2008.