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Publication Number:  FHWA-HRT-08-004    Date:  Nov/Dec 2008
Publication Number: FHWA-HRT-08-004
Issue No: Vol. 72 No. 3
Date: Nov/Dec 2008


Deploying Technology in Challenging Terrain

by H. Gabriella Armstrong, Amit Armstrong, Gary L. Brown, and Roger W. Surdahl

Now 25 years old, the Federal Lands Highway Program is still making out-of-the-way places safely accessible.

The recently constructed east entrance road to Yellowstone National Park, WY, shown here, incorporates simulated stone-faced concrete retaining walls with guardrails. In rugged, environmentally sensitive areas such as this, FLH helps Federal land management agencies address engineering challenges on Federal lands.
The recently constructed east entrance road to Yellowstone National Park, WY, shown here, incorporates simulated stone-faced concrete retaining walls with guardrails. In rugged, environmentally sensitive areas such as this, FLH helps Federal land management agencies address engineering challenges on Federal lands.

Sinuous, exhilarating, emotive—the roads that provide access to the majestic peaks, magnificent vistas, and awe-inspiring terrain on the Nation's public lands are feats of engineering that safely guide visitors through what is known as some of the most spectacular scenery in the world. The topography of these rugged, remote, and environmentally sensitive areas poses engineering challenges for the Federal land management agencies (FLMAs) responsible for building and maintaining the roads and bridges that provide access to Federal and tribal lands.

The primary challenge of providing access to these lands is ensuring that roads, guardrails, and other infrastructure fit seamlessly with the natural environment while simultaneously meeting rigorous standards for safety and performance. For FLMAs, the goal is for visitors to experience safe and pleasant journeys when driving in national parks, forests, wildlife refuges, and Indian reservations. Over the past 25 years, FLMAs have relied on the Federal Lands Highway Program (FLHP) to construct these public roads, oftentimes deploying innovative technologies in the process.

The FLHP Approach

In 1982, the Surface Transportation Assistance Act created the FLHP to provide financial resources and technical assistance for a coordinated program of public roads that serve the transportation needs of Federal and Indian lands. The Federal Highway Administration's (FHWA) Office of Federal Lands Highway (FLH) is charged with overseeing the FLHP and providing stewardship and engineering services for planning, designing, constructing, and rehabilitating the highways and bridges on federally owned lands. The focus of the program is to define the challenges involved in its projects and then propose solutions using new, innovative, emerging, and underused technologies. (For more information on the history of the FLHP, see "Accessing America's Treasures" in the July/August 2008 issue of Public Roads, or visit www.fhwa.dot.gov/FLH.)

To streamline technology deployment for transportation projects on Federal lands, FHWA established the Coordinated Federal Lands Highway Technology Implementation Program (CTIP) in 1984 in cooperation with the National Park Service (NPS), U.S. Forest Service, and Bureau of Indian Affairs (BIA). In 1998 the program expanded by coordinating with the U.S. Fish and Wildlife Service (USFWS). Also in 1998, FHWA supplemented CTIP with the Technology Deployment Initiatives and Partnership Program (TDIPP), which was discontinued in 2005 with passage of the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU).

Through CTIP and other such initiatives and programs, FLH champions innovative technologies and approaches in numerous areas to design and build NPS roads and parkways, Forest Service roads, BIA reservation roads, and USFWS roads. Although the FLHP's focus is to deploy technology on low-volume, low-speed roads in difficult environments, many Federal lands are adjacent to urban or suburban areas that pose additional challenges, such as traffic congestion.

"Innovation is an important part of the Federal Lands Highway mission, and programs such as CTIP help us advance new products and tools for our partners," says FLH Associate Administrator John R. Baxter. "Any celebration of successes on U.S. highways in the last 25 years must include the innovations and solutions of CTIP."

CTIP innovations comprise four broad categories: safety enhancements, context sensitive solutions (CSS), acceleration of project de-livery and construction, and non-destructive evaluation (including field-based testing and evaluations). CTIP empowers FLH designers and engineers to use advanced technologies in current projects and plan for deploying emerging technologies in future projects. One avenue used by FLH to identify innovations is its partnership with the FHWA Turner-Fairbank Highway Research Center (TFHRC). (See "Innovations and Deployment: FLH and TFHRC" for more details.)

The following discussion of technology deployments on Federal lands over the last quarter century highlights the value the FLHP delivers to its partners and, ultimately, the motoring public.

Timeline of FLH Technology Deployment Program

1984: The Office of Federal Lands Highway (FLH) started its first technology deployment program, the Coordinated Federal Lands Highway Technology Implementation Program (CTIP), in cooperation with the National Park Service, U.S. Forest Service, and Bureau of Indian Affairs. Each partner agency contributed 0.5 percent of its highway funds for the program.

1985-1996: CTIP provided funding for the FLH technology deployment program. CTIP was implemented at the FLH headquarters level.

1998: The Technology Deployment Initiatives and Partnership Program (TDIPP) was established under the Transportation Equity Act for the 21st Century. Technology deployment positions were created at the three FLH divisions: the Western Federal Lands Highway Division in Vancouver, WA; Central Federal Lands Highway Division in Lakewood, CO; and Eastern Federal Lands Highway Division in Sterling, VA.

1998: The U.S. Fish and Wildlife Service joined CTIP. The CTIP council was established with membership from each partner agency. The council formalized the proposal review and funding process.

1997-2005: Technology deployment by all three divisions increased, helped by sufficient funding and involvement of partner agencies.

2005: TDIPP was discontinued under the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users.

2008: The FLH technology deployment program is cooperating successfully with partner agencies, State departments of transportation, local entities, and university transportation centers.

Safety Enhancements

"One of the primary objectives of FLH designers and engineers for each new construction or rehabilitation project is to include safety enhancements to bring the roadway to current safety standards," says Greg Schertz, FLH safety functional discipline leader. "However, meeting these safety requirements while also fulfilling the historic, cultural, aesthetic, and environmental requirements specific to the project poses a special challenge and requires innovative solutions. We have conceived, designed, and constructed aesthetically pleasing barriers and other safety devices to meet all these requirements for our partners."

Innovations and Deployment: FLH and TFHRC

The relationship between FLH and TFHRC is mutually beneficial. The TFHRC facility provides research services and a means to study the effects of innovations in the field, and FLH deploys innovations that solve problems on Federal lands. "Applying research developments and innovations in the real world in addition to the lab setting provides TFHRC with information, which contributes to development of better innovations and increased likelihood of technology and innovation deployment," says Michael Trentacoste, acting associate administrator of the FHWA Office of Research, Development, and Technology and acting director of TFHRC. FLH and TFHRC have collaborated on several innovations for deployment on Federal lands—a sampling follows.

  • The Pavement Surface Analysis Laboratory at TFHRC developed a series of noncontact devices to measure pavement surface texture, collectively known as the Road Surface Analyzer (ROSAN). ROSAN quickly became one of FLH's standard devices for measuring pavement smoothness, roughness, and texture. This innovation improves the safety and productivity of field staff because no traffic control is needed, and results are available almost in real time. Further, ROSAN increases objectivity, accuracy, repeatability, and speed of data processing by multiple orders of magnitude.
  • FLH volunteered to beta test TFHRC's Interactive Highway Safety Design Model (IHSDM), a computer-based system that enables roadway designers to assess the potential safety effects of alternative highway designs. IHSDM consists of several analytical modules: a crash prediction module, a design consistency module, a driver/vehicle module, an intersection diagnostic review module, a policy review module, and a traffic analysis module. "The benefits of using IHSDM for FLH are the same as for any organization," says Ray Krammes, technical director of the FHWA Office of Safety Research and Development. "The evaluation capabilities of IHSDM assist planners and designers to maximize the safety benefits of highway projects within the constraints of cost, environment, and other considerations. The benefit to us is that FLH will test the model and provide input and insights that will help us refine the product so we can provide the most useful software."
  • In another cooperative roadway safety project, TFHRC researchers analyzed existing bridge-related crash data to assist FLH in setting policy about the installation of bridge rails on low-volume Federal roads.
  • FLH and the FHWA Office of Research, Development, and Technology share a mutual interest in hydraulic analysis studies and software. For example, TFHRC and contractors enhanced the software program BRIdge Stream Tube model for Alluvial River Simulation (BRI-STARS), a generalized semi-two-dimensional water- and sediment-routing computer model that includes an integrated graphical interface. BRI-STARS can help solve complicated river engineering problems with limited data and resources and is particularly useful for evaluating sites where contraction scour and/or the effects of in-stream mining are concerns. The Western Federal Lands Highway Division has used the model in hydraulic analyses of several of its bridge locations.
  • When NPS experienced a problem with pavement rutting at the intersection of 15th Street and Constitution Avenue in Washington, DC, the agency contacted FLH for help. The standard asphalt mix for the District of Columbia was failing at the intersection, and the pavement was rutting prematurely. FLH in turn requested assistance from TFHRC, which evaluated the DC mix design using accelerated performance tests. Using the data from the evaluation, the District and FLH tried a modified asphalt mix for the first time.
  • Over the years, TFHRC has supported efforts to develop roadside hardware for FLH, including managing or conducting crash testing of proposed designs. Most recently, the Federal Outdoor Impact Laboratory at TFHRC conducted proof-of-concept testing for a new end treatment for steel-backed timber guardrail.
A recent collaboration involved steel-backed timber guardrail, shown here installed along a roadway in Yellowstone National Park in Wyoming.
TFHRC supports FLH in developing and crash-testing proposed designs for roadside hardware. A recent collaboration involved steel-backed timber guardrail, shown here (above) installed along a roadway in Yellowstone National Park in Wyoming. Below: A close up of the steel-backed timber guardrail.
Photo. This closeup photo shows steel-backed timber guardrail at Yellowstone National Park. The timber guardrail is attached to steel backing that is secured to log posts driven into the roadside.

Aesthetic Barriers for NPS. Due to safety concerns in the 1980s, FHWA mandated that roadside barrier systems must meet safety and crash test requirements. But the steel and concrete systems typically used by departments of transportation (DOTs) did not meet the cultural, historical preservation, and aesthetic requirements of the FLMAs. New barriers using stone and wood had failed crash tests conducted at the Texas Transportation Institute. The FLMAs tried a number of systems without identifying an acceptable design.

To solve the problem, FLH worked with the FLMAs to develop roadside barrier systems that would meet both aesthetic requirements and FHWA's safety requirements. FLH designed barriers using wood and stone but incorporated steel and concrete to enable the systems to pass the safety tests. Engineers designed timber and log barriers with steel backings placed behind the rails.

Construction crews in Glacier National Park, MT, built stone guardwalls with steel-reinforced concrete cores and stone facing. In Mount Rainier National Park, WA, FLH designed artificial stone guardwalls with steel-reinforced concrete cores and simulated stone facing. The FLH engineers raised barrier heights to match typical roadside barriers. The barrier system design also included bridge transitions and buried terminals used for anchoring the guardrails. The new barriers improved the safety and performance of roads on public lands and maintained the aesthetic standards the FLMAs desired.

Celebrating 25 years of the Federal Lands Highway Program - Accessing America's Treasures

CSS: Lying Lightly On the Land

Because FLHP projects are located in some of the most ecologically sensitive areas, program engineers learn to tread lightly on the land. The engineers strive not only to minimize construction footprints but also to blend projects with the natural environments. The construction approaches and resulting projects, while aesthetically pleasing and minimally intrusive, enhance safety and provide access.

FLH installed a crenulated stone-faced guardwall (shown here) with a concrete core at Logan Pass in Glacier National Park, MT.
FLH installed a crenulated stone-faced guardwall (shown here) with a concrete core at Logan Pass in Glacier National Park, MT.

FLH works with its partners in implementing CSS to ensure that roadway facilities balance local, regional, and national concerns with the scenic, aesthetic, historic, and natural environments, and that they add value to their communities. FLH now has expertise and a reputation for planning, designing, and constructing transportation facilities in some of the most environmentally, historically, culturally, and scenically sensitive areas of the country. FLH engineers and designers led development of a course titled Introduction to Context Sensitive Solutions (FHWA-NHI-142050), now offered by the National Highway Institute to Federal, State, and local transportation professionals.

Rustic Pavements. A "rustic pavement" is one that matches the historic character of a location while meeting current safety and traffic requirements. NPS asked FLH to design rustic pavements that would satisfy the criteria for long-term durability and aesthetics and could be placed using conventional hot mix asphalt paving techniques. NPS wanted a number of designs that could be used in different park environments in future years.

FLH utilized a transparent, amber-colored, synthetic binder that, when mixed with select aggregates, would achieve a rustic (that is, dirt- or gravel-colored) appearance. Engineers on the project used no pigments, so the aggregate's color and texture are visible. FLH investigated various aggregate sources, pavement types such as Superpave and stone matrix asphalt, and job mix formula combinations until it obtained the aesthetic and quality requirements. To assess the performance of the rustic pavement concept, researchers at TFHRC conducted a series of laboratory tests to study properties such as durability, weathering, moisture susceptibility, and resistance to rutting.

FLH first used this innovative pavement at Virginia's Richmond National Battlefield Park in 2003, and the next year placed it at the Pennsylvania Avenue pedestrian plaza in front of the White House in Washington, DC. (For more information, see "Rustic Pavements" in the September/October 2004 issue of Public Roads.)

Roadside Revegetation. In another CSS project, FLH worked with the FHWA Office of Planning, Environment, and Realty and the Forest Service to develop an integrated approach to use native plants for roadside revegetation. The approach provides a common framework for biologists and engineers to work together to minimize the disturbance within construction areas. The framework includes roadside revegetation within the timeline of roadway design and construction, making it an integral part of the project. WFLHD used this approach on a number of forest highway projects in eastern Oregon. (For more information, see "The Greening of Public Roadsides" in the November/December 2007 issue of Public Roads.)

A paver is placing this rustic pavement at Richmond National Battlefield Park in Virginia.
A paver is placing this rustic pavement at Richmond National Battlefield Park in Virginia.

Stabilized Grass Pulloffs. Grass shoulders are the standard design for NPS roads and parkways for aesthetics and to minimize the impact of roadway footprints on the environment. The Gatlinburg Spur Road of the Foothills Parkway in Great Smoky Mountains National Park, TN, is an atypical park road because of the large volume of high-speed traffic generated by the tourist towns at either end. The combination of high traffic volumes, high speeds, and changes in geometric configuration contributes to many crashes. The lack of paved shoulders creates additional safety hazards for park rangers and stranded motorists.

To enhance safety, FLH designed and constructed eight soil-stabilized pulloffs in areas prone to recurrent crashes, typically at the beginning or end of a horizontal curve or near roadside features that restrict the safety zone (that is, the shoulder and unpaved section). At all eight sites, workers placed woven geotextile fabric on the subgrade; used a combination of geocells, geoblocks, polyethylene ring and grid, and/or fiberglass grid for stabilization; and backfilled with an aggregate-topsoil mixture. FLH then seeded the pulloffs to form turf, helping them blend into the environment. The seeded pulloffs deter long-term parking as people are not used to parking on roadside vegetation.

Accelerating Project Delivery and Construction

Timely completion of projects is a priority for FLH. But any number of variables can hamper this goal: weather, changed site conditions, out-of-specification material or work, shutdowns, and contract disputes. For example, in September 2006 strong winds toppled a high-line crane at the Hoover Dam Bypass bridge project in Nevada, resulting in a 6-month delay. Other causes of construction delays are less spectacular but no less important: Variables might range from a snowstorm in June on an asphalt paving project to a rejected concrete drilled shaft for a bridge abutment. FLHP offers numerous solutions to address or circumvent these types of problems.

Design Visualization. FLH engineers used three-dimensional (3-D) design visualization technology to increase stakeholder interaction during planning, design, and construction of the Going-to-the-Sun Road project in Glacier National Park during 2006 and 2007. The technology helped accelerate project delivery by performing "what-if" analyses to assess stakeholder input in near real time. FLH now is using this approach for a number of phases of the Going-to-the-Sun Road project. This technology also will be used to simulate the new transit systems at Glacier National Park. (For more on design visualization, see "Virtual Highways—A Vision of the Future" in the May/June 2007 issue of Public Roads.)

Prefabricated Bridge Elements. Prefabricated bridge elements provide significant advantages in terms of construction time, safety, environmental impact, constructability, and cost. FLH uses prefabricated elements in many of its new and rehabilitation bridge projects.

In the early 1990s, FLH employed precast segmental bridge construction on the new Natchez Trace Parkway Bridge in Tennessee. The precast elements accelerated construction and enabled crews to do the fabrication offsite in a controlled environment. The practice also facilitated maintaining traffic on the State highway beneath the new bridge and otherwise reduced the construction footprint.

FLH placed rustic pavement in front of the White House on Pennsylvania Avenue, as shown here completed.
FLH placed rustic pavement in front of the White House on Pennsylvania Avenue, as shown here completed.

In 1998, FLH used precast bridge deck panels to rehabilitate three bridges on the George Washington Memorial Parkway in Virginia. The technique minimized disruption of weekday commuter traffic, and the bridge was closed for construction only during the weekend. During closures, the construction crew removed the old deck and railing, placed new panels, and installed longitudinal tendons to connect the panels so they would perform as a monolithic deck. Workers placed and post-tensioned a total of 142 panels in 10 weekends.

Workers install geoblocks for construction of a stabilized grass pulloff on Foothills Parkway in Great Smoky Mountains National Park, TN.
Workers install geoblocks for construction of a stabilized grass pulloff on Foothills Parkway in Great Smoky Mountains National Park, TN.

More recently, FLH employed prefabricated bridge elements for the substructure and superstructure of a small three-span bridge in the Parker River National Wildlife Refuge in Massachusetts. The construction project used prefabricated support piles for piers and abutments, pier caps, abutments and wingwalls (cast monolithically), and bridge beams. The prefabricated elements expedited work so the bridge could be constructed during the short time allowed. The prefabrication approach also reduced interruptions from adverse weather and enhanced quality control.

FRP Composite Bridges. FLH's partners—the Forest Service, NPS, and USFWS—support an extensive system of trails. These trails often cross streams and rivers and require lightweight, low-maintenance, easily constructed bridges. To fulfill these needs, FLH engineers developed a lightweight bridge using fiber-reinforced polymer (FRP) composites that can be transported to remote locations and erected without construction equipment.

The engineers used Falls Creek Trail in Gifford Pinchot National Forest, WA, as a case study for an FRP bridge. In 1998, they designed and constructed a 14-meter (46-foot) pedestrian bridge using a Pratt truss. Both top chords of the truss also worked as pedestrian handrails. Because the FRP composite sections are much stronger along their longitudinal axes than their transverse axes, they are ideally suited for narrow, long-span bridges. Also, they are easier to assemble because they are readily available in structural shapes. Based on the performance of this pedestrian bridge, FLH will deploy more FRP composite bridges on other trails in the future.

GRS Bridge Foundation. Low-lying wetlands with deep deposits of soft soil and frequent flooding, typical of many wildlife refuges, pose challenges for designing bridge foundations. In 2005, FLH bridge engineers used geosynthetic-reinforced soil (GRS) technology to construct cost-effective shallow foundations for three single-span bridges in the Upper Ouachita National Wildlife Refuge in Louisiana. Staff from the TFHRC geotechnical laboratory worked with FLH to design and monitor the three bridges.

GRS technology consists of alternating layers of geosynthetic fabrics and compacted granular soil that form an internally reinforced structure. At the wildlife refuge, FLH built a reinforced soil foundation in combination with a spread footing for load distribution. The approach reduced the applied bearing pressure on the subgrade soils, essentially "floating" the structure over soft and wet soil deposits. This treatment also reduced settlement while making it more uniform. The GRS technology significantly decreased construction time, used locally available material, and minimized impacts on wetlands. For more information, see the report Design and Construction Guide-lines for Geosynthetic-Reinforced Soil Bridge Abutments with a Flexible Facing at http://onlinepubs.trb.org/Onlinepubs/nchrp/nchrp_rpt_556.pdf.

Quantifying Construction Delays Due to Weather. Engineers can reduce weather delays by applying statistical techniques to assess the type and severity of rainfalls and other events expected over the course of a construction job. The planners then can modify the project construction schedule so that weather-dependent activities are scheduled properly to avoid delays.

This stabilized grass pulloff on Tennessee's Foothills Parkway blends into the surrounding environment.
This stabilized grass pulloff on Tennessee's Foothills Parkway blends into the surrounding environment.

FLH's weather prediction methods use information from one or more of the National Weather Service stations or other stations kept by NPS or USFS near a construction project to predict potential delays within set statistical limits. Weather prediction using location-specific data is more representative than weather charts developed from local or regional historical conditions.

The weather prediction methods included in the FHWA publication Quantifying Construction Delays Due to Weather (FHWA-CFL/TD-08-003) are based on historical weather data. The report includes weather-impact case studies for three recent FLH construction projects on five public lands: Humboldt-Toiyabe and Eldorado National Forests, CA; Six Rivers and Shasta-Trinity National Forests, CA; and Brazoria National Wildlife Refuge, TX.

Transportation designers created this rendering using 3-D interactive modeling to assess the location of a transit station and new comfort station at Logan Pass in Glacier National Park, MT.
Transportation designers created this rendering using 3-D interactive modeling to assess the location of a transit station and new comfort station at Logan Pass in Glacier National Park, MT.

Characterizing Defects in Drilled Shaft Foundations. Engineers increasingly are using drilled shaft foundations for bridge piers and abutments. The structural stability of the foundation depends on minimizing construction defects, such as voids, honeycombs, segregation, and soil contamination, during concrete placement in drilled shafts.

FLH engineers are using Crosshole Sonic Logging (CSL) to assess the integrity of concrete in drilled shafts. They analyze the defects and compare the shafts with lab samples of similar design mixes. The CSL results, provided in 3-D color-coded graphs, enable the engineers to make informed decisions about repairing or replacing shafts before disrupting construction schedules.

The FHWA technical report Drilled Shaft Foundation Defects: Identification, Imaging, and Characterization (FHWA-CFL/TD-05-007) offers methods to identify the nature, severity, and location of measured defects. The report analyzes actual field results for concrete drilled shafts on FLH projects in Hagerman National Wildlife Refuge, TX; Petrified Forest National Park, AZ; and Fishlake National Forest, UT.

MSE Wall System Design Guide-lines. Many FLH projects use mechanically stabilized earth (MSE) walls for road widening and new road construction. Typical MSE wall construction in steep terrain requires a level working space, or flat bench. The width of the bench should be at least 70 percent of the wall height; however, this is not always practical and can be expensive, especially in rugged areas.

In one innovative application, FLH used shoring methods to stabilize the back slope while building an MSE wall in front. Shored Mechanically Stabilized Earth (SMSE) Wall System Design Guidelines (FHWA-CFL/TD-06-001) documents these methods and illustrates how MSE walls can be constructed on a bench width that is only 30 percent of the wall height. In challenging environments, shoring significantly reduces excavation, providing cost savings and accelerated construction. In 2008, FLH used this shoring process to build an MSE wall in Yosemite National Park, CA, that saved more than $200,000 when compared to historical costs for conventional MSE walls.

Peering Into the Unknown: Nondestructive Evaluation

Road design and construction require significant engineering judgment. Construction plans reflect the best available knowledge of a project site, often derived from surveying, geologic mapping, hydraulic analysis, and geotechnical investigation. Engineers and designers typically need to perform such investigations without the benefit of in-person visual observations. Instead, they rely on innovative tools and techniques to "see" behind the rock, under the road, in the culvert, and deep into the water.

FLHP engineers use nondestructive evaluation methods to provide insight into what previously might only be assumed. Engineers now can investigate under water using a small submarine with an onboard video camera, look into confined spaces and pipes using a self-propelled crawler and camera, and determine the thermal signature of pavements and structures using an infrared digital camera. In addition, they can use electromagnetic induction, geophysical surveys, and step-frequency radar to look under pavement or underground.

Precasting this segmental arch bridge helped speed construction of the Natchez Trace Parkway in Tennessee.
Precasting this segmental arch bridge helped speed construction of the Natchez Trace Parkway in Tennessee.

Bridge Inspection. Safe, economical bridge inspection is an ongoing challenge for FLH and its partners. Engineers use several nondestructive techniques to evaluate a bridge's condition.

To determine the extent of concrete delamination, FLH, in cooperation with TFHRC, used an infrared camera to create thermal images of high-profile bridges along the George Washington Memorial Parkway and Baltimore-Washington Parkway in 2007. FLH performed ultrasonic testing on a large, steel cantilever bridge in Rocky Mountain National Park, CO, in 2000 to test for any flaws in the critical pin and hanger assemblies. FLH used eddy current technology developed by TFHRC to test fatigue-prone connection details of a high steel bridge on the George Washington Memorial Parkway in 2004. FLH also performed load tests using wire-deflectometer technology on bridges at Delaware Water Gap National Recreation Area, PA, in 2006 and 2007, and at Natchez Trace Parkway, AL, in 2005. All these approaches evaluated structural components of the bridges so engineers could determine safe loading capacities accurately.

Clay Seam Mapping. During geotechnical investigations of a project, engineers take samples approximately every 152 meters (500 feet). Engineers usually assume that the soil properties measured at these discrete locations are representative of the surrounding area; however, field sampling techniques are not perfect and do not provide a complete picture of a site. During construction, engineers can encounter deep and extensive pockets of clay not identified in sampling. Subexcavating and replacing these pockets (or seams) of clay (also called clay lenses) increases project costs and can delay the schedule.

A new process using electromagnetic induction (EMI) developed by FLH provides continuous mapping of subgrade material up to 3.7 meters (12.0 feet) deep and clearly identifies clay lenses. These clay pockets may originate from lesser quality construction methods, or be undisturbed layers that the original road was built upon. The EMI equipment and antennas are portable and easily towed behind an all-terrain vehicle while soil conductivity data is collected. Plan and profile sheets can illustrate these results as color-coded plots where areas of high conductance indicate clay-rich areas.

Engineers then can use the information to design more effective sampling plans for geotechnical investigations. Clay seam mapping also provides the planners with an estimate of the volume of material that needs to be subexcavated and replaced. The mapping provides information that can be used during both project design and construction.

Clay Seam Mapping With Electro-magnetic Induction (FHWA-CFLTD 05-010) details FLH's new method. The report includes results for FLH projects in the Jicarilla Apache Reservation, NM, and on the Natchez Trace Parkway.

Prefabricated decking enabled repair work on the George Washington Memorial Parkway to be completed on the weekends, when traffic was relatively light.
Prefabricated decking enabled repair work on the George Washington Memorial Parkway to be completed on the weekends, when traffic was relatively light.

Application of Geophysical Methods. FHWA published Application of Geophysical Methods to Highway Related Problems (FHWA-IF-04-021)to present the technological concepts and practical applications of geophysics and geotechnology to road design and construction. The report identifies the geophysical tools available to engineers and provides detailed solutions for specific geotechnical problems.

FLH used the methods described in the publication on various projects, including a seismic reflection survey using 3-D tomography on the Zion-Mt. Carmel Tunnel in Zion National Park, UT, in 2002, and 3-D tomography imaging to study compaction grouting in Rocky Mountain National Park in 2004. FLH recently used the step-frequency ground penetrating radar developed by TFHRC to survey the Cumberland Gap Tunnel on the Kentucky-Tennessee border.

Current and Future Projects

"From the beginning, the [FLHP] technology deployment has been driven by users—planners, designers, and engineers—and is now integrated into every aspect of road design and construction," says Keith Wong, FLH project manager. "I have been involved with the program since 1997—I have witnessed the growth of the program and have also seen the immense benefit in delivery of our projects."

This bridge foundation in Louisiana's Upper Ouachita National Wildlife Refuge employs GRS technology, a solution for soft and frequently wet soils.
This bridge foundation in Louisiana's Upper Ouachita National Wildlife Refuge employs GRS technology, a solution for soft and frequently wet soils.

However, some challenges remain. The speed of technological innovation is ever increasing and, as a steward of public funds, FLH needs to find the safest and most cost-effective solution for every project. In recent years, FLHP's task has been to concentrate resources on a small number of technical areas. The program now has a long-term roadmap for deploying new and innovative technologies. Current FLH projects include use of high-performance materials, implementation of management systems, and data visualization and analysis.

"Our partners have a wealth of information that cannot be harnessed unless the data are analyzed to provide meaningful answers," says James Amenta, FLH asset management coordinator. "The FLH Asset Management Strategic Implementation Plan helps our partners develop strategic roadmaps to organize and analyze their data. We are helping them optimize the operation, preservation, maintenance, monitoring, and timely replacement of highway assets through cost-effective management, programming, and resource allocation decisions using the asset management tools." 

FLH collects data for the Road Inventory Program (RIP) and Bridge Inspection Program (BIP) for FLMA partners, who then use the data to plan highway transportation projects. FLMAs now are using the data to develop management systems for pavements, bridges, safety, and congestion.

"A transportation-related geographic information system [GIS] is used to bring together all the data from the FLMA management systems—RIP, BIP, pavement, congestion, and safety [data]—and the FLMA internal maintenance systems and put them into a system that is easy to use and is related to actual geographic locations," says Dan Van Gilder, GIS specialist for FLH. The transportation GIS provides improved communications between stakeholders and better decisionmaking.

"One of the components of a transportation-related GIS is that it facilitates the viewing of data and information," Van Gilder says. "By linking the transportation data geographically, the collected data are related to the roadway both horizontally and vertically. Interrelationships of pavement character, horizontal alignment, vertical alignment, location of roadway features, bridge condition, traffic use, and safety can then be explored and queried."

In 2005, FLH and NPS agreed to develop an inventory program for retaining walls, similar in scope to the ongoing RIP and BIP inventories, according to Matt DeMarco, geotechnical engineer for FLH. "The program mission is to define and quantify wall assets associated with park roadways in terms of their location, geometry, construction attributes, condition, failure consequence, cultural concerns, apparent design criteria, and cost of structure maintenance, repair, or replacement," says DeMarco.

The wall inventory program provides asset and wall information to RIP to update equipment assets associated with the parent roadway asset. It also provides bridge and traffic barrier data. "Similar to RIP, it is the intent of the retaining wall inventory program to periodically reassess retaining wall resources at parks to ensure timely, accurate information is available to support NPS asset management initiatives," says DeMarco.

Satisfied Stakeholders

FLHP remains instrumental in delivering projects by working with other agencies and FHWA offices to find engineering solutions to the challenges posed by nature. Innovative use of technology, after successful testing and deployment for the first time, quickly becomes standard practice. The cooperative nature of the FLHP ensures that it delivers mutual benefits to all participating agencies.

"When the engineers and biologists got together in CTIP, we all learned to expand our respective professional cultures and linguistic understandings," says Sean Furniss, national coordinator for USFWS's Refuge Roads Program and a CTIP council member. "Working with the Forest Service's San Dimas Technology and Development Center and FLH has provided us numerous opportunities to combine highway engineering and road maintenance with biological and environmental concerns. I think we have all learned a great deal from each other in this program and added a certain amount of richness to our experiences."

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Shown here is a 3-D image of a drilled shaft with zones of 10 percent velocity reduction in the top and 20 percent velocity reduction near the middle as measured by CSL. A relative velocity scale, a picture of the CSL testing, and a closeup image of the lower defect are also shown.

Alan Yamada is a CTIP council member and engineering program leader at the San Dimas center. "The value derived from multiagency cooperation is multiplied both in terms of sharing the information and cost," he says. "Cooperation creates a win-win situation for all agencies. The Forest Service benefited tremendously, through participation in CTIP, by developing FishXing [a software program to design passages for aquatic organisms through roadway culverts] and a series of publications on road maintenance issues. These products, along with other CTIP publications, help Forest Service engineers design, build, and maintain better roads while protecting the surrounding environment."

Setting the Sights


Creating the best transportation system in balance with the values of Federal and tribal lands.


To continually improve transportation access to and through Federal and tribal lands through stewardship of FLH programs by providing balanced, safe, and innovative roadways that blend into or enhance the existing environment, and by providing technical services to the transportation community.

Although FLHP's success is reflected in the safe and accessible transportation system on federally owned lands, the reasons for that success are purposely disguised under the roads, morphed into the surrounding environments, or tucked behind the safety barriers. Only a trained or inquisitive eye might detect the innovative technologies at play on and around these roads—a perfect blending of technology and innovation with the surrounding environment.

H. Gabriella Armstrong is an information technology consultant and freelance writer. She received a bachelor's degree in comparative literature, with a minor in Spanish, from the University of Colorado at Boulder.

Amit Armstrong manages the technology deployment program at WFLHD. He coordinates deployment of new, innovative, emerging, and underused technologies for design and construction of roads on Federal lands. He has more than 15 years of experience in numerical simulation and visualization of natural systems. He received a doctorate in civil engineering from Texas Tech University.

Gary L. Brown is the technology engineer at EFLHD. He is responsible for coordinating deployment of new, innovative, emerging, and underused technologies for design and construction of roads on Federal lands. He is a 33-year veteran of FHWA. He holds a bachelor's degree in civil engineering from The Pennsylvania State University.

Roger W. Surdahl joined FHWA in 1987 with a master's degree in civil engineering from Montana State University. As the technology delivery engineer for CFLHD, he has a wide range of technical experience in highway materials, contract administration, and innovative solutions to transportation problems.

For more information, contact H. Gabriella Armstrong at 503-504-0340 or support@yourtechvalet.com, Amit Armstrong at 360-619-7668 or amit.armstrong@fhwa.dot.gov, Gary Brown at 703-404-6284 or gary.brown@fhwa.dot.gov, or Roger Surdahl at 720-963-3768 or roger.surdahl@fhwa.dot.gov.



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