WTI Peer Reviewed Publications

When available, the abstracts appear below the publication information. Also if available, links are provided to the full text versions, although some must be purchased before viewing.

Title: PERFORMANCE INDICES TO IDENTIFY ATTRIBUTES OF HIGHWAY CROSSING STRUCTURES FACILITATING MOVEMENT OF LARGE ANIMALS
Author: Clevenger, A.P. and Waltho, N.
Series: Biological Conservation 121
Pages: pp 453-464
Date: 2005

Abstract: Studies assessing the efficacy of wildlife crossing structures often lead to spurious results because of their failure to address masking effects of confounding variables. Confounding variables include variation in human activity, density of crossing structures along the highway corridor, and equality of species’s perceived access to each crossing structure. We investigated these issues for wide-ranging large carnivores and their prey species in Banff National Park, Alberta, using data obtained from systematic, year-round monitoring of 13 newly constructed crossing structures for wildlife (underpasses and overpasses) for 34 months post-construction. We standardized the first confounding variable by selecting crossing structures remote from areas of human activity. The second confounding variable we standardized by developing probability models of crossing structure usage assuming habitat homogeneity. We standardized the third confounding variable by developing species-specific, perfomance indices of crossing structures (¼ observed through passage usage–expected through passage usage). We regressed the species performance indices against 13 crossing structure variables encompassing structural, landscape, and human activity. Our results suggest that, in the absence of substantial human activity, structural attributes best explained the performance indices for both large predator and prey species, while landscape and human-related factors were of secondary importance. Crossing structures that were high, wide and short in length strongly influenced passage by grizzly bears (Ursus arctos), wolves (Canis lupus), elk (Cervus elaphus), and deer (Odocoileus sp). More constricted crossing structures were favoured by black bears (Ursus americanus) and cougars (Puma concolor). Distance to cover was the most important crossing structure landscape attribute for cougars (negative correlation) and was a significant factor determining passage for grizzly bears, elk and deer (all positive correlations). Our findings (a)underscore the importance of integrating temporal and spatial variability when addressing the efficacy of crossing structures, and (b) demonstrate that species respond differently to crossing structure features. In light of these results, we suggest that to maximize connectivity across roads for multiple large mammal species, road construction schemes should include a diversity of crossing structures of mixed size classes. Mitigation planning in a multiple-species ecosystem is likely to be a challenging endeavour and long-term research will aid in the decision-making process.

The full text can be purchased from: www.sciencedirect.com

Title: IDENTIFYING OPPORTUNITIES FOR INTELLIGENT TRANSPORTATION SYSTEMS APPLICATIONS IN CALIFORNIA'S NATIONAL PARKS: PROJECT OVERVIEW AND SUMMARY OF RECOMMENDATIONS
Author: Strong, C., Eidswick, J. and Turner, S.
Series: Transportation Research Record 1895, Transportation Research Board, National Research Council
Pages: 170-181
Date: 2004

Abstract: A research project was conducted that sought to understand the transportation needs within California national parks by looking at two case study parks: Golden Gate National Recreation Area and Sequoia and Kings Canyon National Parks. After transportation needs for these parks were identified through outreach meetings and visitor surveys, potential intelligent transportation system (ITS) solutions or themes were recommended along with how to follow national guidelines for planning and implementing these themes and solutions. This study also includes solutions and themes that were not identified for the two case study parks but that show promise for other California parks. The goal of this project is to help managers of any park in California to identify and implement ITS solutions and themes that can address their park's specific transportation needs.

There is more information available at TRIS online http://trisonline.bts.gov/

Title: THE IMPACTS OF DITCH CUTTINGS ON WEED PRESSURE AND CROP YIELD IN MAIZE
Author: Huijser, M.P., Meerburg, B.G., and Holshof, G.
Series: Agriculture, Ecosystems and Environment 102
Pages: 197-2003
Date: 2004

Abstract: The Flevoland Polder in The Netherlands is characterized by large agricultural fields separated by ditches. The vegetation in the ditches is typically cut twice a year to ensure sufficient drainage. Removal of the cuttings, primarily reed (Phragmites australis), results in a substantial increase in biodiversity. In many cases, however, the cuttings are considered a waste product and the material is left on the spot. This paper focuses on a practical on-farm application for the cuttings that may stimulate farmers to remove the material from the ditches. Instead of treating the cuttings as a waste product they were used as green compost and plowed into a maize field after the harvest. This study investigates the effect of the cuttings on weed pressure and crop yield for two weed control systems, integrated and mechanical, for two years. The cuttings (15 and 30m3/ha) did not lead to a change in total weed cover in either weed control system. However, the cuttings did result in increased richness of weed species early in the first season. This effect disappeared after weed control. Taraxacum officinale, Solanum nigrum and Urtica dioica all increased when cuttings were applied, but their cover remained relatively low. The abundance of potential diaspores of P. australis did not result in its presence in the maize field. Despite a slight increase in weed pressure and possible immobilization of nitrogen due to decomposition of the cuttings, the cuttings did not affect maize yield.

The full text can be purchased from: www.sciencedirect.com

Title: CYCLIC TRIAXIAL TEST ON REINFORCED BASE COURSE MATERIAL
Author: Eiksund, G., Hoff, I. and Perkins, S.W.
Series: Proceedings of the Conference EuroGeo 2004
Pages: pp 619-624
Date: 2004

Abstract : Not available online

Title: TRANSPORTATION ENGINEERING IN COLD REGIONS: STATE OF THE PRACTICE REVIEW
Author: Mokwa, R.L.
Series: Proceedings of the 12th Annual Cold Regions Engineering Specialty Conference
Pages: pp 197-2003
Date: 2004

Abstract : Not available online.

Title: DEVELOPMENT OF DESIGN METHODS FOR GEOSYNTHETIC REINFORCED FLEXIBLE PAVEMENTS
Author: Perkins, S.W., Christopher, B.R., Cuelho, E.L., Eiksund, G.R., Hoff, I., Schwarts, C.W., Svano, G. and Watn, A.
Series: FHWA Report Reference Number DTFH61-01-XX00068
Pages: 0-263
Date: 2004

Abstract : Not available online.

Title: FINITE ELEMENT MODELING OF A GEOSYNTHETIC PULLOUT TEST
Author: Perkins, S.W. and Edens, M.Q.
Series: Journal of Geotechnical and Geological Engineering V.21 No. 4
Pages: 357-375
Date: 2003

Abstract: Advanced numerical modes used for the description of performance of geosynthetic reinforced soil structures in terms of displacements corresponding to working loads well below collapse levels has created the need for material models for the geosynthetic and geosynthetic-soil interaction accounting for stiffness, yielding and strength properties. A direction dependent isotropic hardening, elastic-plastic-creep model for the geosynthetic, an elastic-perfectly plastic direction and normal stress dependent geosynthetic-soil interaction model, and a bounding surface plasticity model for soil material have been used in a finite element model of a geosynthetic pullout test. Predictions from the model have been compared to a series of pullout tests where it is seen that the model provides reasonable predictions of load-displacement pullout behavior. Systematic removal of material model components has shown that geosynthetic creep properties have a noticeable but minor impact on load-dislacement predictions, while geosynthetic plasticity properties have a more significant role for load simulations where the material approaches rupture during pullout. Replacement of the bounding surface plasticity model for the soil material with a linear elastic model resulted in no significant differences in predictions.

Title: A DESIGN MODEL FOR GEOSYNTHETIC-REINFORCED PAVEMENTS
Author: Perkins, S.W. and Edens, M.Q..
Series: International Journal of Pavement Engineering V. 4 No. 1
Pages: 37-50
Date: 2003

Abstract: The first paper to this companion series of articles [Perkins, S.W and Edens, M.Q. (2003) "Finite elements and distress models for geosynthetic-reinforced pavements", International Journal of Pavement Engineering, 3(4), 239-250] described a finite element response model and empirical damage models that were combined to form a mechanistic-empirical (M-E) for geosynthetic-reinforced flexible pavement systems. The model provides predictions of an extension of service life or a reduction in unbound aggregate thickness for equivalent service life when the geosynthetic is placed at the bottom of the aggregate layer. In this paper, the model is used in a parametric study involving the analysis of over 465 cases to provide predictions of reinforcement benefit for a range of design parameters. The parameters varied are those that are believed to be most influential on reinforcement benefit and include thickness of the structural section, strength and/or stiffness of the subgrade, tensilemodulus in both principal directions of the geosynthetic and several other properties related to the type and structure of the geosynthetic. Regression equations are used to relate reinforcement benefit results from the parametric study to these pavement design parameters and form the basis of the design model presented in this paper. This model is calibrated against the results of large-scale reinforced pavement test sections. The design model allows for the design of geosynthetic-reinforced flexible pavements using generic input parameters for the pavement system.

Title: COLLECTING VEHICLE SPEED DATA BY USING TIME LAPSE VIDEO RECORDING EQUIPMENT
Author: Strong, C.; Lowry, S.; and McCarthy, P.
Series: Transportation Research Record 1855
Pages: 97-104
Date: 2003

There is more info available on TRIS online http://trisonline.bts.gov/

Title: A DESIGN MODEL FOR GEOSYNTHETIC-REINFORCED PAVEMENTS
Author: Perkins, S.W.; Edens, M.Q.
Series: International Journal of Pavement Engineering Volume 4 Issue 1
Pages: pp 37-50
Date: 2003

Abstract: The first paper to this companion series of articles [Perkins, S.W and Edens, M.Q. (2003) "Finite elements and distress models for geosynthetic-reinforced pavements", International Journal of Pavement Engineering, 3(4), 239-250] described a finite element response model and empirical damage models that were combined to form a mechanistic-empirical (M-E) for geosynthetic-reinforced flexible pavement systems. The model provides predictions of an extension of service life or a reduction in unbound aggregate thickness for equivalent service life when the geosynthetic is placed at the bottom of the aggregate layer. In this paper, the model is used in a parametric study involving the analysis of over 465 cases to provide predictions of reinforcement benefit for a range of design parameters. The parameters varied are those that are believed to be most influential on reinforcement benefit and include thickness of the structural section, strength and/or stiffness of the subgrade, tensilemodulus in both principal directions of the geosynthetic and several other properties related to the type and structure of the geosynthetic. Regression equations are used to relate reinforcement benefit results from the parametric study to these pavement design parameters and form the basis of the design model presented in this paper. This model is calibrated against the results of large-scale reinforced pavement test sections. The design model allows for the design of geosynthetic-reinforced flexible pavements using generic input parameters for the pavement system.

Notes: This paper appears in the International Journal of Pavement Engineering, Volume 4, Issue 1, August 2003. The full text can be purchased from: http://taylorandfrancis.metapress.com/openurl.asp?genre=article&issn=1029-8436&volume=4&issue=1&spage=37

Title: RELATIONSHIPS AMONG GRIZZLY BEARS, HIGHWAYS AND HABITAT IN THE BANFF-BOW VALLEY, ALBERTA, CANADA
Author: Chruszcz, B; Clevenger, A.P.; Gunson, K.E.; Gibeau, M.L.
Series: Canadian Journal of Zoology
Pages: pp 1378-139
Date: 2003

Abstract: Banff National Park and surrounding lands constitute one of the most developed landscapes in the world where grizzly bears (Ursus arctos) still survive. We examine the relationships among roads, grizzly bears, and their habitat in a protected area with low road density but dominated by a major transportation corridor and highway system. We examined grizzly bears' spatial response to roads, road-crossing behavior, crossing-location attributes, and habitat and temporal patterns of cross-road movements. Grizzly bears used areas close to roads more than expected, particularly roads with low traffic volume (low volume). Habituated bears were closer to roads than wary bears. Males were closer to low-volume roads than females but crossed roads less than females during the berry season. Bears were more likely to cross low-volume roads than high-volume roads and were more likely to cross at points with higher habitat rankings. In addition, bears were more likely to cross high-volume roads when movng from areas with low habitat values to areas with high habitat values. Efforts to prevent loss of habitat connectivity across highways should involve maintenance of high-quality grizzly bear habitat adjacent to roads and should address the effects of traffic volume on the road-crossing decisions of grizzly bears.

Notes: This paper appears in Canadian Journal of Zoology, Volume 81, Issue 8, August 2003. The full text can be downloaded from: http://pubs.nrc-cnrc.gc.ca/cgi-bin/rp/rp2_abst_e?cjz_z03-123_81_ns_nf_cjz8-03

Title: SPATIAL PATTERNS AND FACTORS INFLUENCING SMALL VERTEBRATE FAUNA ROAD-KILL AGGREGATIONS

Author: Clevenger, A.P.; Chruszcz, B.; Gunson, K.E.
Series: Biological Conservation
Pages: pp 15-26
Date: 2003

We examined the spatial patterns and factors influencing small terrestrial vertebrate road-kill aggregations in the Bow River Valley, Alberta, Canada. We surveyed roads varying in traffic volume, configuration and adjacent landscape attributes for road-kills between 1997 and 2000. The spatial pattern of road-kills was described using neighbor K statistics. We investigated the importance of road-kills at three taxonomic levels using logistic regression. Mammal and bird road-kill indices were consistently higher on a low volume parkway than on the high-speed, high volume Trans-Canada highway (TCH). Birds were more vulnerable to collisions than mammals on the TCH. Road-kill aggregations were nonrandomly distributed. Parkway road-kills were aggregated on small scales and characterized by low clustering intensities compared to the TCH. Road-kills were less likely to occur on raised sections of road. Road-kills tended to occur close to vegetative cover and far from wildlife passages or culverts. Our findings reeal how two distinct road types can have different effects in terms of vertebrate mortality and their spatial pattern. We recommend a series of mitigation measures for existing roads or future road planning projects.

Notes: This paper appears in the Biological Conservation Journal, Volume 109, Issue 1, January 2003. The full text can be downloaded from: http://www.elsevier.com/locate/biocon

Title: ROAD ECOLOGY: SCIENCE AND SOLUTIONS
Author: Forman, R.T.T., Sperling, D., Bissonette, J., Clevenger, A., Cutshall, C., Dale, V., Fahrig, L., France, R., Goldman, C., Heanue, K., Jones, J., Swanson, F., Turrentine, T. & Winter, T.
Series: Book, published by Island Press
Date: 2002

Abstract: A central goal of transportation is the delivery of safe and efficient services with minimal environmental impact. In practice, though, human mobility has flourished while nature has suffered. Awareness of the environmental impacts of roads is increasing, yet information remains scarce for those interested in studying, understanding, or minimizing the ecological effects of roads and vehicles.

Road Ecology addresses that shortcoming by elevating previously localized and fragmented knowledge into a broad and inclusive framework for understanding and developing solutions. The book brings together fourteen leading ecologists and transportation experts to articulate state-of-the-science road ecology principles, and presents specific examples that demonstrate the application of those principles. Diverse theories, concepts, and models in the new field of road ecology are integrated to establish a coherent framework for transportation policy, planning, and projects. Topics examined include: foundations of road ecology, roads, vehicles, and transportation planning, vegetation and roadsides, wildlife populations and mitigation, water, sediment, and chemical flows, aquatic ecosystems, wind, noise, and atmospheric effects, road networks and landscape fragmentation.

Road Ecology links ecological theories and concepts with transportation planning, engineering, and travel behavior. With more than 100 illustrations and examples from around the world, it is an indispensable and pioneering work for anyone involved with transportation, including practitioners and planners in state and province transportation departments, federal agencies, and nongovernmental organizations. The book also opens up an important new research frontier for ecologists.

Notes: This book was published by Island Press and can be purchased from: http://www.islandpress.org/books/Detail.html?cart=106493848441529&SKU=1-55963-932-6

Title: FINITE ELEMENT AND DISTRESS MODELS FOR GEOSYNTHETIC-REINFORCED PAVEMENTS
Author: Perkins, S.W.; Edens, M.Q.
Series: International Journal of Pavement Engineering
Pages: pp 239-250
Date: 2002

Abstract: A finite element (FE) response model has been developed to describe stress and strain response parameters for geosynthetic-reinforced flexible pavement systems where the geosynthetic is placed at the bottom of the unbound aggregate layer. The model contains membrane elements and an anisotropic linear-elastic material model for the geosynthetic inclusion. Elasto-plastic models are used for the asphalt concrete, base aggregate and subgrade layers. Principal response parameters extracted from the FE model include vertical strain in the top of the subgrade and bulk stress in the unbound base aggregate layer. These response parameters are used in empirical damage models for the prediction of long-term pavement performance and the definition of reinforcement benefit. Reinforcement benefit is defined in terms of an extension of service life of the pavement, a reduction in aggregate thickness for equivalent service life, or a combination of the two. The damage models are calibrated from reinforcedand unreinforced pavement test sections. The model is shown to provide general descriptions of reinforcement mechanisms that are consistent with those previously observed in instrumented pavement test sections. A companion paper (S.W., Perkins and M.Q., Edens (2003) A Design Model for Geosynthetic-Reinforced Pavements, International Journal of Pavement Engineering) describes the use of the response and damage models in a parametric study from which a design model for geosynthetic-reinforced pavements is developed.

Notes: This paper appears in the International Journal of Pavement Engineering, Volume 3, Number 4, 2002. The full text can be purchased from: http://taylorandfrancis.metapress.com/openurl.asp?genre=article&issn=1029-8436&volume=3&issue=4&spage=239

Title: STRATEGIES FOR UNGULATE-VEHICLE COLLISION MITIGATION
Author: Farrell, J.E.; Irby, L.R.; McGowen, P.T.
Series: Intermountain Journal of Sciences
Pages: pp 1-18
Date: 2002

Wildlife mortality caused by vehicles presents a serious conservation and economic problem, as collisions with large mammals are global, persuasive, and increasing. The combinations of increasing ungulate populations combined with increasing vehicle-miles traveled has heightened the significance of this problem. We reviewed the U.S. and, secondarily, European scientific literature pertinent to mitigating the effects of ungulate-vehicle collisions. This review presents an analysis of ungulate movement and behavior in relation to roads to further develop general conclusions about accurately locating high frequency collision areas. Some successes in reducing ungulate-vehicle collisions have been documented with fencing, modified fencing, and grade separation via crossing structures, although traditional solutions often are expensive, e.g., fencing, overpasses, have limited effectiveness, e.g., reflectors, static warning signs, or may further habitat fragmentation or create barriers to movement, e.g., ungulat-proof fencing, vegetation clear zones. We also present several case studies illustrating animal-detection driver-warning systems, technology based deployments, applied to the problem of ungulate-vehicle collisions. Although there is significant interest and potential in animal-detection driver-warning systems, many technical issues must be addressed before they are ready for general use. We emphasize the need for more sound statistical design in determining efficacy of treatments.

Notes: This paper appears in the Intermountain Journal of Sciences, Volume 8, Number 1, March 2002. The full text can be purchased from: http://www.montanatws.org/ijspages/toc/vol8num1.html

Title: CONSTITUTIVE MODELING OF GEOSYNTHETICS
Author: Perkins, S.W.
Series: Geotextiles and Geomembranes
Pages: pp 273-292
Date: 2000

Abstract: A constitutive model for geosynthetics is presented that incorporates components describing direction-dependent elastic, plastic and time-dependent creep properties. The model is compared to a series of uniaxial tension tests performed on a biaxial geogrid and a woven geotextile. Tension tests to which model predictions are compared include fast and slow monotonic tension, constant load creep tests and two series of cyclic tension. The model is shown to offer reasonable predictions of in-air tensile load–strain properties commonly associated with geosynthetic materials.

Notes: This paper appears in Geotextiles and Geomembranes, Volume 18, Issue 5, 2000.

Title: COST-EFFECTIVENESS OF CRACK SEALING MATERIALS AND TECHNIQUES FOR ASPHALT PAVEMENTS
Author: Johnson, DR; Freeman, RB; Stevenson, JR
Series: Transportation Research Record - Journal of the Transportation Research Board 1697
Pages: pp 31-40
Date: 2000

Abstract: Sealing or filling cracked asphalt pavements to prevent the intrusion of water into the pavement structure has long been an accepted practice of the Montana Department of Transportation. Attempts were made to establish the most economical and effective method of sealing pavement cracks for Montana and to better determine crack sealing's role within Montana's pavement management system (PvMS). Four experimental test sites were constructed within crack-sealing projects. The test sites included combinations of nine sealant materials and six sealing techniques. Monitoring of the test sites includes visual inspections (for all of the sites) and nondestructive structural readings and surface distress identification under Montana's PvMS (for one test location). One expectation of the inspections is an estimation of crack sealing's useful life. Information on project history and project methodology, including the methods used for evaluating the performance of sealed cracks, is presented. Interim onclusions are presented, most of which have been obtained from the two test sites that have been in service for 3 years. Similar performance has been observed for all materials with ASTM D5329 cone penetrations in excess of 90. In general, routing of transverse cracks improved the performance of the sealants. Routing did not appear necessary for centerline longitudinal cracks. Observations from the first year of service for the most recent installation are noted. Notably, router operators appear to prefer the shallow reservoir configuration over square reservoirs. The highest failure rates occur during the coldest period of the year, and much of this distress "heals" after exposure to the summer heat.

Notes: This paper appears in Transportation Research Record No. 1697, Maintenance and Management of Bridges and Pavements.

Abstract: As part of the COATS Program, a traveler-needs survey was conducted. This feature documents findings related to the first of the traveler-needs-survey objectives. Advanced Traveler Information Systems (ATIS)—consisting of data collection, data aggregation and processing, communications and traveler interface devices—have been touted to improve both the safety and efficiency of existing transportation systems. ATIS have been deployed extensively in urban areas but have experienced limited deployment in rural areas. Rural areas differ significantly in their travel characteristics and related challenges. For example, rural areas exhibit a propensity for non-recurrent congestion; single vehicle crashes; longer-distance recreational, farming and commercial trips; older, slow-moving vehicles; animals in the roadway and high travel speeds.1 ATIS deployed in rural areas must adequately address these unique travel characteristics and challenges to be successful. As part of the Northern alifornia/Southern Oregon Rural Intelligent Transportation Systems (ITS) Area-wide Travel and Safety Improvement Program (COATS), a traveler-needs survey was conducted. The anterior objective of the traveler-needs survey was to understand travel challenges (i.e., slow-moving vehicles, animals in the roadway) specific to Northern California and Southern Oregon as perceived by the rural traveler. Posterior objectives were to determine (1) what information the rural traveler needs and wants, (2) the medium through which information would be presented to the traveler and (3) where the traveler would want this information presented. This feature documents findings related to the first of the traveler-needs-survey objectives—understanding traveler perceptions related to Northern California/Southern Oregon corridor challenges. For findings related to subsequent traveler-needs-survey objectives, the reader is referred to the Northern California/Southern Oregon Rural Intelligent Transportation Systems (ITS) Areawide Travel and Safety Improvement Program Traveler Needs Survey, Volumes I and II.2. (http://www.coe.montana.edu/wti/wwwshare/coats/)

Notes: This paper appears in ITE Journal, Volume 70 Number 1, 2000.

Title: CAPTER 13: ADVANCED RURAL TRANSPORTATION SYSTEMS
Author: Albert, S.
Series: Intelligent Transportation Primer
Pages: pp 13-1 through 13-17
Date: 2000

Abstract: This is a single chapter in a book published by the partnership of Institute of Transportation Engineers, ITS America and the U.S. Department of Transportation. Chapter 13 discussed the following topics.· Vision for Rural ITS Applications· Critical Program Areas· Rural needs and issues· Examples of existing rural ITS programs· Regional planning activities·

Notes: This chapter appears in the Intelligent Transportation Primer, ISBN 0-935403-45-0. The Intelligent Transportation Primer can be purchased from the Institute of Transportation Engineers via their website: www.ite.org or by calling 202-289-0222.

Title: ARE INCIDENT MANAGEMENT PROGRAMS EFFECTIVE? FINDINGS FROM WASHINGTON STATE
Author: Carson, JL; Mannering, FL; Legg, B; Nee, J; Nam, D
Series: Transportation Research Record - Journal of the Transportation Research Board 1683
Pages: pp 8-13
Date: 1999

Abstract: The development of an incident response team (IRT) program has been touted to improve incident response and clearance times, as well as to improve interdisciplinary cooperation. To determine the effectiveness of its IRT program, the Washington State Department of Transportation ( WSDOT) commissioned a comprehensive study that considered both quantified and perceived benefits. The average duration of incidents to which the IRTs responded was reduced by 20.6 min from 1994 to 1995. The ability to statistically attribute this reduction in incident duration to the IRT was limited because only 2 years of data were available (i.e., reduction may be attributable to temporal variations in incident characteristics). Nonetheless, the implications of this reduction can be quantified. This reduction results in a monetary savings of $20,600 to $61,800 per incident and an annual savings of $3. 09 million to $9.27 million in King County. Comparing these monetary benefits to the IRT program costs in the Nrthwest Region results in a benefit-to-cost ratio of 4.3:1 to 12.9:1. Given these values, even minor reductions in incident duration attributable to IRTs can justify the program. Public support for WSDOT's incident response team program was high, with 62% of the respondents thinking it is a good idea. IRT program support from other response personnel was also high. WSDOT's IRT was viewed as an important service for improving scene accessibility and improving the safety of both the motoring public and the incident responders. Despite the positive feedback, inconsistency in operation among individual IRT members makes it difficult to draw conclusions as to the effectiveness of different operating styles, for other response personnel to work effectively with IRT members, and to build a positive consensus among the motoring public for continued program support.
Notes: This paper appears in Transportation Research Record No. 1683, Advanced Traffic Management Systems.

Title: SOIL-GEOSYNTHETIC INTERFACE STRENGTH AND STIFFNESS RELATIONSHIPS FROM PULLOUT TESTS
Author: Perkins, S.W. and Cuehlo, E.V.
Series: Geosynthetics International
Pages: pp 321-346
Date: 1999

Abstract: Pullout tests are commonly used to describe the ultimate shearing resistance developed along the interface between the confining soil and the geosynthetic as a function of normal stress confinement. Pullout tests can also be used to define the complete soil-geosynthetic interface relationship between shear stress and shear displacement interaction. Such a description of interface strength and stiffness characteristics is needed in analytical models used to predict a displacement response of geosynthetic-reinforced soil structures. Due to the extensibility of geosynthetics, data from pullout tests cannot be used directly to calculate strength and stiffness interface properties. The pullout test must be analyzed as a boundary-value problem with appropriate assumptions made regarding the constitutive relationship of the geosynthetic itself and for the interface interaction. An analytical method is presented that allows for the relationship between shear stress and shear displacement to be bak-calculated from pullout test data. This method is used to evaluate interface shear stiffness and shear strength for a geogrid and geotextile product for three normal stress confinement levels. The significance of material models used in the formulation is examined.

Notes: This paper appears in Geosynthetics International: Vol. 6, No. 5, 1999.

Title: MECHANICAL RESPONSE OF GEOSYNTHETIC-REINFORCED FLEXIBLE PAVEMENTS
Author: Perkins, S.W.
Series: Geosynthetics International
Pages: pp 347-382
Date: 1999

Abstract: Laboratory-based, large-scale experiments are reported on pavement test sections with aggregate base layers containing a layer of geosynthetic reinforcement. The tests involved comparative reinforced and unreinforced test sections with pavement layer materials and thicknesses commonly encountered in the field. Pavement load was provided by a nontranslating, cyclic load applied to a plate resting on the pavement surface. The test sections contained an extensive array of sensors to measure pavement load, surface deformation, stress in the base and subgrade layers, and strain in the asphalt concrete, base, subgrade, and geosynthetic layers. Test section variables include geosynthetic type, geosynthetic placement position within the base, and base layer thickness. The test results show a significant improvement in the permanent deformation behavior of the pavement system due to geosynthetic reinforcement for the variables examined. Stress and strain measurements illustrate reinforcement mechaisms pertinent to paved roadways, which include a reduction of radial strain developed in the bottom of the base, an improved vertical stress distribution on the top of the subgrade, and a reduction of shear deformation in the top of the subgrade. These mechanisms result in lower vertical strain in the base and subgrade layers. A comparison of benefits due to reinforcement and those realized by the addition of aggregate base shows that geosynthetic reinforcement and additional base aggregate provide similar structural enhancements to the pavement system.

Notes: This paper appears in Geosynthetics International: Vol. 6, No. 5, 1999.

Title: IMPROVING ROADWAYS: PERFORMANCE GRADED ASPHALT BINDERS
Author: Freeman, R.B., Johnson, D.R., Sauer, T.M
Series: Public Works Journal
Pages: p 24
Date: 1998

Abstract: How to select binders according to the new specifications

Notes: This technical paper appears in Public Works Journal: September 1998.

Title: MONTANA U.S. HIGHWAY 93: PUBLIC INVOLVEMENT THAT WORKS
Author: Staff Writer
Series: Public Works Journal
Pages: p 36
Date: 1996

Abstract: Environmentally sensitive highway expansion benefits from communication between government and concerned citizens.

Notes: This technical paper appears in Public Works Journal: December 1996.