I have blogged numerous times about the challenge of accurately geolocating underground utilties. Most recently I blogged about the estimated ROI for investment in improving the geolocation and other information about underground utilities and the remarkable project of the City of Las Vegas to create a 3D model of its underground utilities.
How highway designers take utilities into account
In 2010 the National Cooperative Highway Research Program (NCHRP) published a report Utility Location and Highway Design: A synthesis of Highway Practice that summarizes research about how hghway designers incorporate the location of underground and above ground utilities into their designs. The Information was gathered through a literature review, survey, and interviews. The survey was sent to state Departments of Transportation (DOTs) representatives with utility responsibilities through the AASHTO Highway Subcommittee on Right-of-Way and Utilities. The survey was distributed to 50 state DOTs plus Puerto Rico, District of Columbia, and 9 Canadian provinces. 45 responses were received. The literatrure review identified the issues influencing the decision to keep utilities in place or to relocate them.
Historically, the transportation designer ignored utilities during design. If the utilities conflicted with the design they would be relocated. As a result utilities are routinely relocated, often at great expense and often unnecessarily. An alternative approach is to design the highway in a way that avoids the utiltiies so that the existing utilities remain in place. The challenge is that accurate data about the location of underground utilties is generally lacking. Between the extremes of relocating all the utilities and designing the highway to leave utilities in place is a workable compromise that meets the highway construction scope and mission, while minimizing impacts to utility facilities. With this optimal solution substantial savings in utility relocation costs and impacts, as well as overall savings to the project budget and schedule can be realized.
The survey results indicated that the state DOTs would like to get utilities involved as early as possible in the construction process. The most important reason is to determine as early as possible which utilities potentially will be affected and where they are located. The literature survey showed that there is a general consensus that accurate and comprehensive utility location data helps make better decisions and reduces the risk of unforeseen problems with utilities emerging during the construction phase.