SAS® helps North Carolina lower cost of roads

Analyzing geographic data narrows road corridor choices, saves time and money

CARY, NC  (Nov. 17, 2011)  – Using SAS Analytics, North Carolina is building roads faster, for less, while minimizing environmental disruption. The NC Department of Transportation (NCDOT) is analyzing cutting-edge, geographic data to help narrow the choices of possible road corridors while reducing costly land surveys. The process can save $500,000 per project and shave 20 percent off the time needed to select and plan a road.

SAS provides the engine for this innovative and collaborative project between NCDOT and the North Carolina Division of Water Quality (NCDWQ), which won an Environmental Excellence Award from the Federal Highway Administration.

To protect water sources, planners assess a transportation project and propose ways to avoid, minimize and mitigate environmental impacts. Road builders typically verify geographical surveys by sending surveyors and water quality experts into the field to document streams and wetlands.

A large project – such as a bypass – can require substantial time and manpower to survey thousands of acres in order to identify environmental issues. 

“You might have hundreds of possible combinations for one road,’’ explains Morgan Weatherford, Environmental Program Consultant with NCDOT’s Natural Environmental Section. “It’s a major challenge to comply with federal and state environmental regulations in a manner that is beneficial for the environment and  taxpayers as well.”

In recent years, a new data source emerged with potential to eliminate some costly field work. Light detection and ranging (LIDAR), which uses laser pulses to record the distance between two points, is particularly good for charting land elevation – key to locating wetlands and streams. LIDAR data is used extensively to update flood maps and is considered more detailed than geological survey information.

LIDAR produces large volumes of data. One transportation project might involve upward of 30 million records with 30 different attributes per record. Before SAS' work with NCDOT, nobody had used LIDAR data to predict stream and wetland locations for construction planning purposes.

"The analyses help us narrow the corridor choices to a handful, so surveyors can focus on the most likely areas for construction," said Weatherford.

The NC Division of Water Quality (NCDWQ) built models to predict headwater streams and tested the accuracy with field surveys. 

“The models were 85 to 95 percent accurate, depending on the terrain,’’ said Periann Russell, Environmental Senior Specialist, NCDWQ.   

NCDOT also used LIDAR data for a much larger project that includes predicting stream and wetland locations for an entire county. The data will help transportation planners choose a corridor for a 20-mile bypass. It will also be used on several bridge modernization projects and be available to private developers for their proposed developments. 

"Every time we impact a wetland, we have to restore a wetland. If we impact a stream, we have to restore one. Good data not only protects the environment, it saves money.'' Weatherford said. 

"From saving time, money, manpower and environmental impact to analyzing novel data sources, these departments are finding innovative ways to save taxpayer dollars," said Paula Henderson, Vice President of the SAS State and Local Government Practice.

SAS is used in all 50 state governments to transform their operations to deliver the right services, at the right time, with the appropriate resources. SAS offers a wide array of data integration, business intelligence and analytics solutions, and collaborates with government to create innovative offerings tailored to specific departmental and agency goals.

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