A boom in U.S. energy development is challenging transportation agencies to alleviate the strain related to increased truck traffic on aging infrastructure.

For the first time in 40 years, the United States has achieved relative energy independence. Emerging and evolving energy development in the United States has become a bright spot in the national economy and has created opportunities for both skilled and unskilled labor.

While energy independence is good news, the expansion of these industries has implications for transportation infrastructure. For example, geographic shifts in oil and gas extraction have led to greatly expanded transport of oil by truck and rail. In many cases, expansion involves movement of heavy equipment and other supplies to rural locations and puts pressure on a functional class of roads and bridges that were not constructed to handle the heavy loads associated with expansion and increased traffic.

The U.S. Energy Information Administration reports that the variety and magnitude of energy development is either expanding or holding steady--a trend that is likely to continue. Transportation agencies are rising to the challenge to address the increased demand on the highway infrastructure and damage resulting from traffic related to energy development. Agencies that are responsible for transportation infrastructure are requiring surety instruments (a promise by one party to assume responsibility for the debt obligation of a borrower if that borrower defaults), permits, bonds, and excess maintenance agreements from energy companies. Some transportation agencies and infrastructure owners also are strengthening roads and bridges to carry the increased loads. In many areas, agencies also are addressing potential safety concerns from increased truck traffic. For the most current information and trends in energy development, visit the Web site of the Energy Information Administration at www.eia.gov.

The Effects on Roads and Bridges

Published by the National Cooperative Highway Research Program, Synthesis 469: Impacts of Energy Developments on U.S. Roads and Bridges documents the impacts of the energy sector on the transportation system and state-of-the-practice strategies to minimize damage. The report aims to help Federal, State, tribal, and local transportation managers better understand and communicate the negative impacts of energy development on roads and bridges, while also selecting appropriate strategies to manage them.

In addition to examining road damage from energy development, Synthesis 469 reports on the economic costs associated with supporting energy development. The report provides energy companies with the tools to assess the costs and help pay for infrastructure damage. The synthesis also looks at current design standards and engineering methods to address the increased frequency and weights of heavy truck traffic, practices used to address the safety implications of increased vehicle volumes, and examples of agency and industry collaboration to address roadway issues.

In addition, the synthesis discusses the efforts of departments of transportation in 40 States plus the District of Columbia, and related local public agencies to mitigate the effects of energy development, and provides examples of alternative options to manage those impacts more effectively. It also reviews engineering practices, funding approaches, and contractual mechanisms for dealing with the effects of energy development.

Roadway Deterioration

The most visible effect is the deterioration of paved and unpaved roads. When surveyed for Synthesis 469 in early 2014, 27 State DOTs indicated that they observed an increase in the amount of truck traffic volumes and heavy loads in recent years.

“Increased traffic volumes, particularly heavy trucks, have accelerated the deterioration of State highways in the oil-impacted areas,” says Ron Henke, P.E., deputy director of engineering at the North Dakota DOT. “Roadways in the western part of the State were originally built to handle agriculture traffic, small grains and ranching, and were not built to carry the heavy loads associated with oil development.” As a result, Henke says, “Design life on some roads in western North Dakota has been reached in a shorter amount of time [than estimated in the original design].”

He continues, “For example, U.S. Highway 2, which is a major corridor in western North Dakota, reached [the end of] its design life in 8 years rather than the [projected 20- to 30-year design life].”

State DOTs reported that secondary roadways are the most affected by truck traffic. In fact, 10 States noted a significant level of impact on local roads, while 7 States reported a significant level also for minor arterials or collectors and distributors. More than half of the respondent DOTs rated the impact on minor arterials and local roads at a moderate level. Interstates or freeways were the least affected.

According to Brian Roberts, executive director of the National Association of County Engineers, “The negative impact and accelerated deterioration on local roads in rural areas is significant, requiring increased levels of repair and maintenance and severely impacting the budgets of local jurisdictions.”

The damage attributable to heavy vehicles is difficult to quantify in rural areas, but some State DOTs, such as those in Arkansas, New Jersey, North Dakota, and Texas, are investigating ways to do this. The most common measure used to quantify damage is remaining service life for pavements and structural analysis for bridges. Synthesis 469 showed that the reduction in service life for pavements was up to 30 percent in some cases.

Damage to Bridges

Local bridges are also vulnerable to damage from increased truck traffic and heavy loads. Some overheight trucks have struck bridges, requiring closures and expensive repairs. Other safety concerns relate to the thousands of bridges that do not have adequate width to accommodate drilling rigs and other oversized loads, along with the necessary structural capacity to handle increased volumes of heavy trucks.

Recently, national media reports have covered the need for repairing thousands of bridges, even without the addition of energy-related truck traffic. In 2013, an Associated Press analysis of 607,380 bridges in the National Bridge Inventory showed that 65,605 were classified as “structurally deficient.”

The Texas DOT reports increased volumes of heavy trucks (typically 40–60 tons, 36–54 metric tons), particularly on narrow bridges, and truck mirrors striking as they pass each other. Other narrow roadways have experienced an increase in crashes, run-off-road incidents, and fatalities.

The Yoakum region of Texas (not far from San Antonio), a mostly rural area with significant energy development and nearly 4,000 bridges, has had multiple bridge collapses and crashes related to the width and height of bridges. Narrow, one-lane bridges require drivers to wait until a truck or other vehicle has crossed completely in order to advance. Communities in the region have complained about trucks on the bridges, and in response, TxDOT has increased signage that warns drivers about narrow bridges.

Funding Repairs And Improvements

Synthesis 469 shows the costs to DOTs to provide energy development companies with adequately performing roadway and bridge infrastructure. The synthesis also shows significant costs to energy developers from user delays that result from work zones necessitated by repairs to infrastructure and longer haul times because of detours. Duke University found that to support shale energy development, in a number of States, roadway costs have increased faster than the revenues from energy development.

Compensation paid from energy developers to States or local agencies includes fees for development impacts based on the magnitude of the developments or user fees based on measured damage to specific roads. Some States also set up donation agreements with energy developers; use energy-related permit fees; apply severance, property, production, or sales taxes; use lease revenues; and implement maintenance agreements.

State DOTs also are repairing damage with a combination of State and local funding. When surveyed, only six DOTs reported that they have established agreements with energy companies to pay for repairs.

Safety Concerns

The Upper Great Plains Transportation Institute reports that western North Dakota was continuing to experience an economic boom because of energy industry expansion in 2013. The institute also found that unanticipated traffic safety issues are occurring on roads originally designed for local access and agricultural purposes, because they are carrying high truck volumes to serve the expanding oil sector. In fact, the number of crashes in approximately half of the counties (in a 17-county area affiliated with oil production) is above the State average for crash risk, considering all crash types on rural roads.

The study team for Synthesis 469 identified North Dakota and Texas, as well as Colorado, Iowa, and Pennsylvania, for more detailed interviews based on their geographic distribution, level of growth in energy development, types of energy product transported, level of observed infrastructure and safety impacts, and methods used for quantifying the economic effects of energy development.

Based on these detailed interviews, as well as the surveys and literature reviews, the synthesis highlights effects on road systems observed by agencies and how they are addressing them. It presents effective practices such as techniques for meeting design challenges, tools to assess costs, use of contractual agreements, and methods to mitigate negative impacts on safety.

Strategies for Pavements

The most common method for assessing the effect on paved roads is by determining the remaining service life of the pavement. Road owners can compare the remaining service life to the predicted service life under typical conditions. Data inputs for computing a pavement’s remaining service life include portable and virtual weigh-in-motion devices for identifying traffic volumes and load levels, falling weight deflectometer and ground-penetrating radar for determining the structural capacity of pavement layers, and the automated road analyzer for collecting geographically related information on pavement condition.

Roadway repair methods include stabilization of unpaved roads, use of full-depth reclamation of existing pavements, addition of paved shoulders, and strengthening of gravel or dirt roads with geosynthetics. What follows are two examples of how State agencies are addressing the effects on paved roads.

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In 2010, North Dakota State University reported that load limits are necessary during spring thaws when the modulus of some soils increases the relative damage from heavy truckloads by up to 400 percent. Spring load restrictions typically lasted 6 to 8 weeks, depending on the soil conditions. To help predict when truck restrictions should be enforced, the North Dakota DOT has developed a predictive model for use in the western part of the State. The model could be adaptable for use by other States and Canadian provinces. In addition, according to North Dakota DOT’s Henke, “North Dakota DOT has worked with local officials in some communities to build truck bypasses or truck reliever routes around the cities to help alleviate truck traffic through the communities.”

In Texas, an ongoing study by the Texas A&M Transportation Institute (TTI) is evaluating practices used by DOT maintenance personnel, both routine maintenance activities such as patching and non--routine reconstruction tasks such as strengthening roadways, chip seals, and new base layer materials. The study also focuses on pavement design--including the cross-sectional width, layer thickness, and shoulder materials and widths--for affected farm-to-market roads.

During the study, TTI is testing whether expanding the width would benefit these roadways because their current narrow footprints are unable to handle the size and loadings of the trucks. Texas intends to widen horizontal curves and enhance vertical curve drainage to accommodate larger trucks more safely. The researchers are using a decision tree to tie together pavement performance and life-cycle costs in order to monitor repairs and rehabilitation strategies.

“Four workshops and a series of energy sector technical reports and briefs were generated from the research collaboration between TxDOT and TTI,” says Jon Epps, executive associate director of TTI. “These workshops and supporting documents will help ensure that the current state-of-the-practice guidelines are being utilized to repair damaged roadways. For instance, the technical briefs provide information on pavement analyses, which will [enable] district engineers to determine recommended roadway shoulder widths, as well as shoulder/edge repair techniques.”

Strategies for Bridges

A standard practice in most States is that if a bridge is unable to withstand the legal load limit, then the State DOT posts weight limits. If equipment going to or coming from the oil fields is overweight, the energy company can request a permit to run oversize or overweight loads on the roads. However, even with a permit, oversize or overweight trucks may not cross a posted bridge.

The issue of overheight trucks has been particularly prevalent in Texas. In 2014, Texas experienced 23 bridge hits statewide. TxDOT launched a publicity campaign to remind drivers about overpass height restrictions. The campaign included distributing pamphlets at truck stops, broadcasting by radio, and printing billboards in both English and Spanish. Other strategies that TxDOT uses include signing all bridges with heights under 18 feet (5.5 meters), as well as accelerating construction projects to raise the elevations within 6 to 12 months to accommodate energy activities.

In Pennsylvania, energy companies have used temporary “jumper” bridges to bypass the permitting process for oversize (excluding overheight, if height restrictions exist) and overweight loads, and to manage heavy truck traffic. The practice involves constructing temporary, modular superstructures over existing bridge decks to carry the heavy loads. The jumper bridges then are dismantled when the energy companies no longer need them. Energy companies used this practice to support drilling activities in Lycoming County, PA. A later inspection by the county found that the roadways underneath the jumper bridge were relatively undamaged because the temporary structures carried the loads.

Costs and Funding

To assess costs and pay for damages, States use a number of strategies. Among the most common are (1)identifying accurate truck volumes and their associated payloads; (2)using a variety of taxes, fees, adequate public facility ordinances, and other reimbursement mechanisms; and (3) applying the truck traffic percentage or the vehicle-miles traveled as a factor for use in a cost formula. Many States cited an increase in applications for oversize and overweight vehicle permits, along with more frequent requirements for roadway or bridge maintenance, as the basis for developing a cost formula.

State DOTs are repairing roads and bridges with a combination of State and local funding. Several DOTs--Arkansas, Iowa, Pennsylvania, Utah, and West Virginia--share a percentage of costs between their agencies and the energy companies, and have found this strategy to be effective. The DOT in Iowa indicated that energy development companies cover 100 percent of the costs for roadway and bridge repairs. In Pennsylvania, energy companies pay 100 percent of the repair costs in many cases, and the DOT and energy companies share costs in other cases. Both Arkansas and Utah DOTs cost-share at 75percent to the agency and 25 percent to the energy company. West Virginia DOT reports a cost-sharing split at 25 percent by the agency and 75percent by the energy company.

The Minnesota DOT uses an Excel^®-based cost calculator that enables users to estimate potential damage to pavements on local roads during the heavy construction traffic associated with wind turbine developments. The calculator is available for download at www.dot.state.mn.us/research/documents/trafficgenerator.xls. Users also can estimate costs to repair or reconstruct affected roadways.

The United States Forest Service’s model for funding requires energy developers to purchase road use permits. This process regulates access to forest roads by the developers, provides flexibility to modify permits for specific situations, and requires energy companies to improve and maintain the condition of existing forest roads to standard before and during use for energy development activities.

Financing Legislation

The Pennsylvania Department of Transportation (PennDOT) and local agencies in Pennsylvania frequently communicate and partner with energy development companies to minimize the amount of roadway damage caused by heavy trucks. PennDOT posts weight restrictions and uses agreements with energy development companies for roadway maintenance. The companies are required to submit an annual roadway maintenance plan. The plan must detail how the companies will repair damages when they occur and who they will contact to evaluate and complete the work.

In addition, Pennsylvania Act 89 legislation requires user fees to establish a funding source for transportation needs and assists in addressing the backlog of roads and bridges that need repairs. As part of the comprehensive Pennsylvania Act 13 legislation passed in 2012, an impact fee on energy companies was levied based on the level of drilling activity. The Pennsylvania Utility Commission collects fees, which it then distributes to municipalities and Commonwealth of Pennsylvania programs. For example, Lycoming County and its 52 local municipalities collectively received approximately $25 million from Pennsylvania Act 13 funds.

Pennsylvania is the only State that reported having such legislation in place during the Synthesis 469 survey. However, other States reported having similar legislation in the works.

The Path Forward

A clearer path forward is taking shape to balance the competing outcomes of energy development. However, agencies must recognize that energy extraction and production technologies are continually evolving and, as a result, some practices may not continue to be effective. To ensure the most effective practices, agencies should conduct periodic joint reviews with energy companies. Agencies also should consult periodically with freight planning offices in metropolitan and regional planning organizations. Monitoring the larger freight-planning picture will help agencies to recognize current or projected shifts in the transport of energy by rail, pipelines, or motor carriers.

Future data collection should consider the existence of adequate staff resources, efficient methods for comprehensive analyses of crash data, and use of available electronic databases. Agencies should review the contribution levels of energy companies, in terms of their size, to fund repairs and uphold maintenance agreements. Although many large companies contribute a share of the funding commensurate to the repairs required for roads and bridges, the industry does not yet know whether the same level is possible with smaller independent energy companies.

Additional areas of consideration may include the integration of transportation planning techniques with energy industry mapping of future development, the collection of safety and crash statistics on affected rural roads, improved methods for pavement and geometric design of affected rural roads, and engineering-based methods for detour routing during periods of high-activity energy development.

Synthesis 469 concludes with an analysis of research needs, such as quantitative information on the specific economic, safety, and social impacts of energy development activities on secondary roads. A clear need exists for research on predicting reductions to the service life of roads and bridges. In addition, a need exists to better quantify the extent of damage induced on more heavily traveled roadways such as freeways, interstates, and major arterials, particularly in areas near port facilities or where modal shifts are occurring. Synthesis 469 also recommends researching performance metrics to monitor quantitatively the effectiveness of practices addressing the various issues related to energy development in a given State or region.

Lastly, to gain a more complete picture of energy development and the impacts on State and local roadway infrastructure, State DOTs should consider input from other State agencies that manage activities such as economic development, public safety, and motor vehicle registration.

Leslie Myers McCarthy, Ph.D., P.E., is an associate professor in the department of civil and environmental engineering at Villanova University. Previously, she worked at the Federal Highway Administration in the Office of Pavement Technology (now the Office of Asset Management, Pavement, and Construction) and as team leader of operations in the FHWA Florida Division. She is a licensed professional engineer in New Jersey and Pennsylvania.

Seri Park, Ph.D., P.T.P., is an assistant professor in the civil and environmental engineering department at Villanova University. She conducts research on traffic control and operations, highway safety, traffic impact analysis, and intelligent transportation systems. Prior to her current position, she worked at Tetra Tech and taught at the University of California, Irvine. She is a certified professional transportation planner.

Anthony R. Giancola, P.E., is a transportation and local government consultant. He served as the executive director of the National Association of County Engineers from 1993 to 2011, as well as serving in the Civil Engineer Corps of the U.S. Navy for 20 years. Previous local government assignments include public works director for the city of Takoma Park, MD, and chief engineer of the division of public works in Frederick County, MD. Giancola is a licensed professional engineer in the District of Columbia.

For more information, see http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_syn_469.pdf or contact Leslie McCarthy at 610–813–2083 or leslie.mccarthy@villanova.edu.