Four studies have been published that state the trenchless construction cost comparison vs traditional trenching is massive and worth a look at.
It’s a no-brainer: America’s underground infrastructure needs work - lots of work. Pressing questions that municipalities and the private sector face include citizen reactions to disrupted business and activities. Elected officials will consider voter reactions to increases to cover the cost of the refit/rehab while city, county or state engineers will look for ways to minimize that cost. (Read on in "A Look at CIPP and Aging Drinking Water Infrastructure.")
A recent study shows that the trenchless construction cost comparison is lower than traditional open-cut methods in almost all categories. The ingrained habit may play a part as engineers look to the open cut-and-cover methods they’ve used for centuries, but advances in trenchless technology offer lower-cost, lower-impact solutions than conventional trench warfare on city streets.
So, how does trenchless technology financially stack up against conventional methods?
To Trench or not to Trench?
The traditional method of pipeline rehabilitation, replacement and new construction is the open-cut, also known as the open-cut-and-cover, method. Local government agencies, design and consulting engineers and municipalities appear to be beginning to recognize trenchless cost benefits over traditional open-cut methods.
While initial costs of open-cut construction might seem lower, comparing the two methodologies reveals that trenchless rehabilitation, or even new construction, is less invasive and less expensive than open trenching. A 2004 paper prepared for the American Society of Civil Engineers compared the cost-effectiveness of trenchless work in urban environments with that of the traditional open-cut method.
The study demonstrates engineering and capital costs as well as the social costs for both methods. Trenchless led the way in both savings and a lack of disruption to surface activities in most situations.
Counties, towns and cities in the U.S. confront the issue of underground utility replacement daily. (Read "Trenchless Installation of Utility Lines and Access Ports in Urban Areas.")
Trenchless technologies offer advantages that traditional methods don’t, including minimal disruption of activities in urban areas. One study cites the needs of “engineers and project owners” for “more data” on trenchless methods. (More in "Rehabilitating City Water Lines Using Trenchless Technology.")
Using a project in Troy, Michigan, which compared the costs of pipe bursting and open-cut pipe replacement, the authors concluded that pipe bursting and similar trenchless operations “could save municipalities millions of dollars in the renewal their of underground utility systems.” (Learn more in An Introduction to Pipe Bursting.")
Real-World Results of Trenchless Construction
The latest study of the metrics for trenchless versus traditional methods was prepared by David Boyce, CE, for the American Water Works Association, in 2015. This study, “Design Specifications and Selection Issues in The Application of Trenchless Technology for Water and Sewer Mains” compared replacement and rehabilitation of water and sewer lines in the Canadian province of Saskatchewan. (Read "Trenchless Sewer Repair and Cleaning 101.")
Pipe Size (mm)
Open Cut US$/Lm
Trenchless Cost Vs Open Cut Cost (%)
Cities and states have a massive task ahead of replacing aging infrastructure that includes the use of materials that were once considered fine but are now health risks, including lead pipes and asbestos piping. These issues can now be addressed in a more cost-effective manner.
Given the number and credibility of these and the many studies that compare trenchless and traditional underground construction methods, the advantages of trenchless construction are clear. The cost per foot of rehab or new construction, the social issues of surface activity disruption mean trenchless technology – which is still developing and adding tools to its inventory – has arisen as a solution of choice over traditional methods, for new underground utilities construction and rehabilitation.