Significant Cost Savings Forecasted From Accurately Modeling Underground Utilities

According to national statistics, in the United States an underground utility line is hit on average every 60 seconds. The total cost to the national economy is estimated to be in the billions of dollars per year. In most municipalities in North America underground utility lines have been put in the ground not according to plan, but wherever has been the easiest and cheapest way to build them. Compounding the problem, 2D as-builts of underground infrastructure are notoriously unreliable. The result is that in most municipalities the location of underground utilities is very poorly known.

Almost all construction projects for buildings or infrastructure contain a design constraint – existing utilities strung overhead on visible structures or hidden underground. For example in the transportation sector, historically the most convenient strategy for the designer was to ignore utilities during design and then relocate them if they conflict with the highway design. Utilities are routinely relocated, often at great expense and often unnecessarily. The other extreme is to design the highway to avoid utilities, but that requires reliable information about where the utilities are located, which is rarely available. Between the two alternatives of relocating utilities and designing the highway to avoid utilities whose location is poorly known designers try to find a workable compromise that meets the highway construction scope and mission, while minimizing impacts to utility facilities. If successful, this can result in substantial savings in utility relocation costs and impacts, as well as overall savings to the project budget and timeline.

A recent survey found that state Departments of Transportation (DOTs) would like to get utilities involved as early as possible primarily to determine what utility infrastructure is there and where it is located. The study found that there is a general consensus on how to make better decisions regarding relocation versus design-to accommodate. The most important is accurate and comprehensive utility location data. When comprehensive and accurate utility location data is available, better decisions can be made, and the risk of unforeseen problems with utility conflicts during the construction phase are reduced.

It has been difficult to quantify the cost and benefit of improving the location and other information about underground utilities, but in the last few years research has begun to put a dollar figure on the benefits of accurate location data for underground utilities.

According to a USDOT sponsored survey conducted by Purdue University in 1999, a total of US$4.62 in avoided costs accrued for every US$1.00 spent. In addition the researchers made the case that the qualitative savings (for example, avoided impacts on nearby homes and businesses) which were not directly measurable were significant and arguably many times more valuable than the quantifiable savings.

In 2004 in Canada, the Ontario Sewer and Watermain Contractors Association commissioned the University of Toronto to investigate several large infrastructure projects in Ontario. This study determined that the average rate of return for each dollar spent improved visibility of underground utilities on those projects that could be quantified was $3.41.

In 2007, the Pennsylvania DOT commissioned Pennsylvania State University to study the savings on ten randomly selected Penn DOT projects. The study found a return on investment of US$21.00 saved for every US$1.00 spent on improving the quality level of subsurface utility information.

In 2010 a 12-month study conducted by researchers at the University of Toronto took an in-depth look at 9 large municipal and highway reconstruction projects that developed an enhanced depiction of buried utilities. Based on this analysis, a cost model was proposed that takes into account both tangible and intangible benefits. All projects showed a positive return-on-investment (ROI) that ranged from $2.05 to $6.59 for every dollar spent on improving underground utility location data.

Motivated by these studies indicating a very significant financial benefit from improving the accuracy and reliability of information about location of underground utilities, municipalities and DOTs are beginning to look at ways of addressing the problem. Federal Highway Authority (FHWA) initiatives such as Map-21 and Every Day Counts are also motivating organizations to adopt new technologies such as 3D model-based design that will provide a foundation for realizing these benefits.

One example is the City of Las Vegas which is putting in place policies and technologies to develop an accurate 3D model of all of its above ground and below ground utility infrastructure. The major benefits that Las Vegas expects to see are:

1. Increased safety and lower costs because of the reduced risk of unexpectedly hitting underground utilities especially hazardous ones like gas mains during construction

2. Automated clash detection to identify potential problems during the design phase of construction projects

3. Reduced operating costs resulting from fewer truck rolls for cable/pipe locate operations.

Overall the City has concluded that the 3D model approach provides more information per dollar invested, in other words more capabilities at lower cost.

Images Courtesy of VTN Consulting