Abstract:
The purpose of this research was to explore the relationship between roadway and roadside accidentrates for Washington State highways to improve the Washington State Department of Transportation's(WSDOT) process of modeling roadway and roadside accident rates and to arrive at possible improvements in the efficiency of WSDOT's safety project programming process.The project tested the use of the seemingly unrelated regression estimation (SURE) model to modelthe roadway and roadside simultaneously. The theoretical advantage of the SURE approach is that it does not impose any a priori assumptions on the explicit linkage between roadway and roadside accident rates, and there is no theoretical support for explicit linkage, either. The data used to derive this model were from a random sample of 500 one-mile sections from the Washington State highway system. Traffic dataincluded traffic volumes, truck compositions, AADT, traffic speeds, and other relevant information.Geometric data included lane, shoulder, median, curve, and intersection information. Historical weather data such as monthly precipitation and temperature were collected from the National Oceanic and Atmospheric Administration database.In comparing significant explanatory variables between the roadway accident rate and roadsideaccident rate models, very few variables were common. This confirms that it is preferable to specifyseparate functional forms for roadway and roadside accident rates. Empirical results indicated thatcorrelation between roadway and roadside accident rates was insignificant, indicating that efficiency gainsfrom the SURE model would be minimal. The important finding from a programming standpoint is thatjointly modeling the roadway and roadside simultaneously would not result in significant efficiencyimprovements in comparison to the current state-of-the-practice in Washington State.

Authors:
Chayanan,S., Nebergall,M., Shankar,V., Juvva,N., Ouyang,Y.

Keywords:
roadway, roadside, accident rates, safety programming, research, Washington, Washington state, highway, transportation, WSDOT, modeling, safety, regression, linkage, data, traffic, traffic data, volume, truck, speed, median, temperature, database, models

Download Report:

External Links: http://www.wsdot.wa.gov/research/reports/fullreports/562.1.pdf http://wsdot.wa.gov/Research/Reports/500/562.1.htm

Abstract:
Recently, WSDOT acquired a non-nuclear, non-destructive, density measuring device manufactured by TransTech called a Pavement Quality Indicator (PQI). TransTech's PQI measures pavement density indirectly by measuring its dielectric constant. A non-nuclear gauge is advantageous because it contains no radioactive source and is therefore not subject to radiological controls, and it can obtain readings in about 5 seconds versus to 4 minutes with a nuclear gauge. Currently, TransTech is collecting data from different agencies to determine the suitability for measuring asphalt pavement density. This brief study presents density measurements from PQI and compares them with nuclear density gauge and core density measurements from three WSDOT 1998 paving projects. This evaluation was a secondary study to 1998 study Asphalt Concrete Temperature in Washington State; therefore this study's experimental design was based entirely on the Temperature study requirements, which resulted in non-random samples and multiple populations within the same sample groups. Despite these problems, results indicate that, when averaged, PQI readings compare favorably with both nuclear measurements and core measurements.

Authors:
Muench,S. T., Mahoney,J. P., Cawley,B.

Keywords:
agencies, asphalt, asphalt concrete, asphalt pavement, concrete, control, core densities, data, density, design, evaluation, experimental, group, indicator, ITS, nuclear gauge, pavement, pavement quality, pavement quality indicator, population, project, quality, Study, temperature, Washington, Washington state, WSDOT

Abstract:
Funded by the 1987 Intermodal Surface Transportation Efficiency Act, the Strategic Highway Research Program (SHRP), was a five year, $150 million research program to improve the performance of the nation's roads by addressing four key areas: concrete and structures; highway safety and maintenance; asphalt; and long-term pavement performance. Nearly one-third of the $150 million was allocated for the study of asphalt, specifically to develop performance based specifications that would relate material properties of the binder and the mix to field performance. Superpave (Superior PERforming asphalt PAVEments) encompasses the products of the SHRP asphalt research program and consists of three interrelated elements: an asphalt binder specification with supporting tests; a mix design and analysis system with supporting tests; and performance prediction models. This report is a compilation and synthesis of Washington DOT's (WSDOT) experience with selected components and concepts of the SHRP/Superpave technology to include the following: performance graded (PG) binder usage and specification validation; gyratory mix design; the Superpave Shear Test (SST); and field performance of the Superpave mixes.Binders typically specified by WSDOT (AR400OW and PBAs -2, -5, -6. -6GR) were classified in terms of five Superpave performance grades: PG 58-22; 64-22; 64-28; 64-34; and 70-28. Although data from 171 weather stations suggest that as many as 6 low- and 5 high-temperature grades could be specified, binder availability and regional pavement distress were used to develop guidelines for statewide PG usage. Three binders were recommended for use in the western, northeastern and southeastern regions of the state as follows: PG 58-22; PG 58-34; and PG 64-28, respectively. Validation of the binder specification with respect to low temperature cracking was accomplished using binder and field performance data from 28 projects. The results were very encouraging: the original SHRP algorithm for binder selection correctly "predicted" field performance in 22 of 28 cases, whereas the LTPP algorithm for binder selection correctly "predicted" field performance in 26 of 28 cases.Additionally, a laboratory experiment using the Superpave Shear Test (SST) apparatus was undertaken to test the effectiveness of binder "bumping," i.e., increasing the high temperature grade because of exceptionally high traffic volume and/or slow or standing traffic. The data clearly indicate that the SST is an effective tool for discriminating between binders and that 'bumping" may be effective in reducing pavement rutting. Permanent shear strain for specimens made with a PB 70-xx binder was only 25 to 33% of the shear strain for specimens made with a PG 58-xx binder.As originally configured, the Superpave mix design matrix included seven traffic levels and four temperature regimes for 28 possible compaction levels. Recognizing that the 28 compaction levels made for a somewhat unwieldy system, WSDOT attempted to reduce the number of compaction levels by conducting a series of mix designs at each compaction level. The results of the limited experiment suggest that it might be possible to limit the number of compaction levels required for mix design. Research by Brown et. al. (NCHRP 99) tends to confirm this as they have suggested reducing the number of compaction levels and provided more definitive guidance with respect to each level.Since 1993 WSDOT has place 44 projects which include some component of the Superp ave technology. For 17 of these projects parallel Hveem and Superpave mix designs were conducted. In 13 of the 17 cases, the Superpave design asphalt content was equal to or greater than the Hveem design asphalt content, though the difference was usually no more than 0.2%. A fundamental difference between Hveem and Superpave mix design methods is the compaction device. Data from these field projects indicate that the current kneading and gyratory compaction protocols (at least for 109 gyrations) yield similar air void contents.As noted previously, Washington DOT has placed 44 projects which involve some component of the Superpave technology. For 18 of the projects a conventional Hveem mix design was conducted using a PG binder (Hveem-PG). The remaining 26 projects were truly Superpave, i.e., the materials selection and mix design were established in accordance with the Asphalt Institute's SP2, Superpave Level 1 Mix Design. According to WSDOT practice the following numerical indices trigger maintenance: Pavement Structural Condition (PSC) 10 mm; or International Roughness Index (IRI) > 500 cnVkm. Although relatively "young", the 44 projects are performing quite well. The average values of rutting, PSC, and IRI (4, 91, and 121, respectively) are all well below the "trigger" values. With respect to rutting and PSC, the performance of Hveem-PG and Superpave projects is virtually identical. However, the ride quality of the Superpave projects is a bit rougher than the Hveem-PG binder projects: IRI of 134 for the former and 103 for the latter. The higher values of IRI measured on the Superpave projects may be the result of the typically coarser aggregate gradation or differences in construction techniques.WSDOT's Superpave experience has not been without challenges. Still, its overall experience has been very encouraging. Experimentation with the revised compaction matrix, continued use of the SST, field validation of the "bumping" experiment, and long-term monitoring of field performance will provide the necessary data to allow WSDOTs critical assessment of Superpave's technical merit and economic viability.

Authors:
Leahy,R. B., Briggs,R. N.

Keywords:
SHRP, Superpave, asphalt, intermodal, transportation, transportation efficiency, highway, research, program, performance, concrete, structures, highway safety, safety, maintenance, pavement, specifications, specification, asphalt pavement, pavements, tests, design, analysis, prediction, models, Washington, WSDOT, data, temperature, cracking, LTPP, traffic, volume, compaction, materials, condition, international roughness index, roughness, index, ride quality, quality, aggregate, construction, ITS, monitoring

Download Report:

Abstract:
This report documents the moldeling strategy and associated verification which permits analysis of multiple PCC plain jointed slabs. Several subbase/soil layers below the slabs and separation of the slab and base layer are considered. Load effects include those associated with both multiple tire and linear temperature gradients. A technique for modeling aggregate interlock shear transfer across PCC pavement joints is developed and verified. The overall development is contained in the computer program EverFE. The computer program uses a graphical user interface which aids its use.

Authors:
Davids,W. G., Turkiyyah,G. M., Mahoney,J. P.

Keywords:
aggregate, aggregate interlock, analysis, base, computer, computer program, developed, development, EverFE, finite element, Finite elements, ITS, Joints, joints load transfer, modeling, pavement, pavements, PCC, permits, program, rigid pavement, temperature, tire

Download Report:

Abstract:
Temperature and wind are the major microclimate parameters that were considered the microzonation of Washington State. Thermal movements associated with bridges and wind pressure loadings for traffic signs, signals, and luminaires are major concerns in Washington. Air temperature data for 49 stations across the state were obtained and were converted to the corresponding composite bridge temperature values. Maps of maximum, minimum, and range of air and bridge temperatures were created to identify the temperature pattern of the state and also to develop an isothermal map of mean bridge temperature ranges. Wind microclimate study included an investigation into incorporating a three-second gust wind into the AASHTO standards for calculating wind pressure on structural supports of traffic signs, signals, and luminaires. The new value of Ch (boundary layer profile factor), the primary parameter that changes when using a 3-second gust, were obtained by comparing the velocity profiles for the hourly, fastest-mile, and 3-second gust wind speeds. Adjustment of the gust factor is also included.

Authors:
Kappayil,S., Reed,D.

Keywords:
temperature, wind loadings, bridge structural design, research

Download Report:

Abstract:
This final report demonstrates the feasibility of employing high molecular weight/high density polyethylene cylinders as the energy dissipating medium in highway safety appurtenances. It is shown that this polymer can dissipate large amounts of kinetic energy, undergo large deformations and strains without fracturing, and essentially restore itself to its original size, shape, and energy dissipation potential when the forcing function is removed.This research involves a quasi-static and impact loading experimentalinvestigation to determine the energy dissipation characteristics of HMW HDPEtubes as functions of temperature, radius to wall thickness ratio, strain,strain-rate, deformation, and repeated and cyclic loading. The results ofthis experimental program are analyzed to develop analytic energy dissipationexpressions which are then employed in the design of truck mountedattenuators (TMA), Finally, an expert system computer program, CADS, ismodified to use HMW HDPE tubes in the generalized design of crash cushions.The potential financial, legal, and safety payoffs for highway operationsassociated with developing highway safety devices which are essentiallymaintenance free are significant. Maintenance costs associated with therepair of impacted safety devices would be greatly reduced or eliminated.Tort liability exposure related to damaged or collapsed hardware would besignificantly decreased. Finally, the safety of the motoring public and themaintenance personnel involved in maintaining and repairing damaged hardwarewould be enhanced.

Authors:
Carney III,J. F.

Keywords:
computer, computer program, cost, costs, cyclic loading, density, design, development, Energy, experimental, expert system, exposure, highway, highway safety, impact, impact attenuation devices, ITS, maintenance, maintenance free, polyethylene, polymer, program, public, research, reusable, safety, self-restoration, strains, temperature, truck

Download Report:

Abstract:
This report describes the construction of an experimental section of asphalt concrete pavement overlay which contained the additive carbon black. A long term evaluation of the overlay seeks to determine if there is a significant difference in performance between it and an adjacent control section of pavement which contains no additive.Preliminary laboratory results indicate that the viscosity/temperature curve for the carbon black asphalt binder has been altered in a way that the temperature susceptibility of the pavement is decreased.

Authors:
Livingston,J.

Keywords:
additive, asphalt, asphalt concrete, Asphalt Concrete pavement, Carbon black, concrete, construction, control, evaluation, experimental, overlay, pavement, performance, susceptibility, temperature, terperature susceptibility

Download Report:

Abstract:
The cathodic protection system on the Yakima River Bridge on SR-24 near Yakima was evaluated for proper operation. Three out of six reference electrodes and rebar probes were found to be non-functioning. One temperature sensing thermistor was also found to be non-functional. All three deck zones were found to be receiving the proper cathodic protection current. Recommendations were made to continue the monitoring at regular intervals and maintain the present rectifier settings.

Authors:
Telford,E. R., ETCO Engineering Services,Inc

Keywords:
bridge, cathodic protection, Deck, monitoring, probe, protection, System, temperature

Download Report:

Abstract:
Hoarfrost formation in a maritime inversion climate has been studied via inferred snow/air interface temperatures, vertical temperature profiles of the interface, and application of dew point hygrometry. Two dominant growth situations have been discerned. The first involved highly saturated air near the interface and strong radiational cooling of the snow surface, producing a wide variety of crystal sizes (1-6mm). The second showed strong radiational cooling of the snow surface in an altered environment with secondary introduction of water vapour from the presence of supercooled clouds. The latter often showed accelerated growth, the formation of large dendritic crystals (8-15mm) in short time periods (less than four hours). Subsequent snowfalls of increasing water equivalent on surface hoar beds resulted in numerous direct action avalanches. Threshold crystal size for bed layer weakness varied widely (0.7-15mm) and was related to old snow surface roughness and new snow precipitation characteristics.

Authors:
Breyfogle,Steven R.

Keywords:
avalanche, environment, frost, hoarfrost, profile, roughness, snow, temperature

Download Report:

Abstract:
This summary report provides an overview of the performance of sulfur extended asphalt (SEA) paving mixtures at the WSU Test Track (Pullman, WA). A brief description of the mix designs, pavement structural design, test track loading apparatus and test pavement configurations is followed by a description of selected test track data (accelerations, temperatures and stain measurements). Finally, a description of the fatigue relationships developed from the WSU Test Track data is presented. Included are laboratory fatigue results.

Authors:
Mahoney,J. P.

Keywords:
911, asphalt, asphalt pavement, construction, data, design, developed, evaluation, Executive, Executive Summary, extended asphalt, fatigue, mixture, pavement, pavement evaluation, pavement performance, performance, sulfur, temperature, test track

Abstract:
The project identified various highway roadways subjected to load restrictions for cataloguing on a District-wide map. An investigation of freeze-thaw events and pavement deflections was conducted in addition to collection of weather data at selected sites. "Frost Tubes" were evaluated and found to be an effectivetool for measuring frost depths. Limited data was collected due to warm winters and short freeze-thaw cycles. It was concluded that load restrictions are not needed until the temperature changes to a warming period. Additional research is needed to determine when load restrictions should be removed.

Authors:
Whalen,K.

Keywords:
data, Freeze Thaw, freeze-thaw, frost, Frost Tubes, Frozen Pavement, highway, load restrictions, pavement, pavement deflection, project, research, roadway, temperature, winter

Download Report:

Abstract:
The pavement structure of SR 12 between Montesano and Elma, Washington was evaluated for the proposed heavy loads associated with construction of the Satsop power plant. Information used in evaluating SR-12 resulted from two sources which included field studies conducted by the Washington State Department of Transportation and development of various material strength parameters by the University of Washington. These data were used to model the pavement structure as a layered elastic system. By use of this analysis procedure, the stresses, strains, and deflections were estimated for the expected range of loading conditions. The results indicate that the most probable amount of damage (fatigue and rutting) expected for the non-cement treated base structural sections is less that one to two percent of available pavement life for the "expected" loading condition. An increase in either or both the trailer wheel load and pavement temperature will act to produce greater losses in pavement life. It is estimated that the tensile stresses in the cement treated base may exceed the tensile strength of this material.

Authors:
Mahoney,J. P., Tsunetta,Jerrold Y., Terrel,Ronald L.

Keywords:
analysis, base, condition, construction, damage, data, development, fatigue, highway, loads, materials, model, pavement, Pavement Evaluation, Materials Characterization, Layered Elastic System, Failure Criteria, Heavy Loads, pavement life, pavement temperature, strains, strength, stresses, System, temperature, transportation, Washington, Washington state, wheel load

Download Report:

Abstract:
A six year study of landscape plant establishment on roadsides as affected by a number of environmental conditions was initiated in April, 1970. The relationships between plant survival and soil texture, soil temperature, soil moisture, and exposure were evaluated. The affect of exposure on percent ground coverage of various grass species used in erosion control was also evaluated.

Authors:
Rosenthal,R. N.

Keywords:
condition, control, environmental, erosion, erosion control, exposure, highway, Landscape plant establishment, plant survival, roadside, soil, soil moisture, soil temperature, soil type, temperature

Download Report:

Abstract:
This report describes the results of a feasibility study comprising Phase I of a Central AvalancheHazard Forecasting Program for mountain passes in the State of Washington. The report describes existing weather and avalanche data sources, and suggests improvements and additions for improved input to and feedback from a centralized avalanche forecaster's office which will improve avalanche predictions for all passes within the State. WSDH and consultant efforts and results during FY 75 are described, and specific recommendations for PhaseII, implementation of avalanche hazard forecasting, are provided.

Authors:
Washington State Highway Commission Department of Highways

Keywords:
avalanche, avalanche hazard, weather, weather observations, wind, temperature, precipitation, data reporting, avalanche hazard forecasting, communications, data, data sources, forecasting, hazard, prediction, program, Washington

Download Report:

Abstract:
Tests were conducted on various pavements t o investigate the correlation between measurements obtained using the Impulse Index Computer and pavement condition as determined by other means. Benkelman Beam deflection measurements and Impulse Index measurements are compared along with Washington State Pavement Rating System results. Effect of temperature on the apparent Impulse Index is evaluated..

Authors:
Brands,F., Cook,C. J.

Keywords:
Benkleman beam, computer, condition, Deflection test, impulse index, impulse testing, index, pavement, pavement condition, pavement deflection, pavement evaluation, pavement maintenance, pavements, systems, temperature, tests, Washington, Washington state

Download Report:

Abstract:
There are indications that many trucks now have front axle loads approaching the maximum allowable for single axles which increases the potential for pavement damage. This report is intended to be a State-Of-The-Art approach to answer several pertinent questions from a theoretical study based on hypothetical pavements and loads, but based on reasonable material characteristics and pavement behavior from previous research. The results are a series of relationships based on pavement life which can be used to determine any number of "equivalencies." These equivalencies can be used to compare the destructive effects of various sizes of single and dual tires, axle loads , pavement thicknesses , speed and temperatures. The general nature of this report provides a wide range of conditions for comparison.on a relative basis.

Authors:
Terrel,R., Rimsritong,S.

Keywords:
asphalt pavement, axle, behavior, condition, damage, dual tires, equivalencies, loads, pavement, pavement damage, pavement life, pavements, research, single axle, speed, speed and temperature, state-of-the-art, temperature, tire, tire contact pressure, tires, truck, trucks, wheel load

Download Report:

Abstract:
A collection of reports about avalanche conditions and avalanche prevention measures on Washington mountain highways in general and to the North Cascade Highway in particular involving various aspects of creep deformation and glide of the snow cover as they affect avalanche defense structure design; reconnaissance of a proposed new highway route through the Cascade Mountains and a continuing study of the relationship between synoptic winter weather patterns and the formation and distribution of snow avalanches in the Cascades.The reports are entitled:1. Effect o f Glide and Creep on Rigid Obstacles by C.B. Brown and R.J. Evans.2. Creep and the Snow-Earth Interface Condition in the Seasonal AlpineSnow-Pack by D. M. McClung.3. In- Situ Investigations o f the Temperature Dependence o f the Creep ofLow Density Snow by D.M. McClung4. Naches Tunnel Avalanche Reconnaissance by E. R. LaChapelle.5. Investigation of Synoptic and Surface Weather Situations Leadinq toAvalanche Cycles in the Washinqton Cascades for the 1973-74 winter by M. B. Moore.

Authors:
Moore,M. B., McClung,D. L., LaChapplle,E. R., Brown,C., Evans,R. J., LaChapplle,E. R.

Keywords:
avalanche, Avalanche Forecasting, Avalanches, Cascade, condition, creep, density, design, glide, highway, Highways, North, North Cascade, seasonal, snow, Study, temperature, Washington, weather hazards, winter

Download Report:

Abstract:
This report presents results obtained from the analyses of data which were collected during the performance of Phase I and Phase of this project. The data were at the A. Riedesel Pavement Testing Facility which is operated by Washington State University and is located in Pullman, Washington. Regression analyses were formed in order to relate various factors to each other. The factors used in the analyses included stud type, stud protrusion, speed, air temperature, pavement temperature, environmental conditions, stud hardness and tread depth. The purpose was to evaluate the relative importance of these factors pavement wear. It was found that the type of overlay, the type of stud and the protrusion length were the most important factors affecting pavement wear under Test conditions. The other factors could not be sufficiently isolated to determine their relative importance. Average wear rates were calculated for the different types of pavements and by the different stud types. A formula was developed which can be used to calculate pavement life under certain conditions. The results obtained for Phase I and Phase were compared and the difference in these results is discussed. Some of the difference was due to the different between the two phases A comparison with other associated research was madeA striping paint study was made and the results are in this report.

Authors:
Sorensen,H.

Keywords:
condition, data, developed, environmental, facilities, overlay, pavement, Pavement Durability, life & performance, asphalt pavement, portland cement concretes, overlays, surface textures, studded tires, skid resistance, pavement life, pavement temperature, pavements, performance, project, regression, repair, research, speed, striping, striping paints, Studded, studded tire, Study, temperature, tire, Washington, Washington state

Download Report:

Abstract:
A four year study of landscape plant establishment as affected by a number of environmental conditions was initiated in April, 1970. The relationship between plant survival and soil texture, soil temperature and exposure were evaluated. The affect of exposure on percent ground coverage of various grass species used in erosion control was also evaluated.

Authors:
Rosenthal,Russell N.

Keywords:
condition, control, environmental, erosion, erosion control, exposure, highway, Landscape plant establishment, plant survival, soil, soil temperature, soil type, temperature

Abstract:
This report covers activities for the eighteen months ending September 1971 under a Washington State Highway Department Contract for Research Project No. Y1301 with the University of Washington. Snow and avalanche climate varies widely across the parts of the Cascade Mountains spanned by SR-20. Little information is presently available about temperatures and weather patterns over the passes, but a limited amount of snow depth data are available from snow courses. These snow data are presented and analyed.

Authors:
LaChapplle,E. R.

Keywords:
avalanche, Avalanches, data, highway, Highway SR 520, North Cascade, project, research, snow, temperature, Washington, Washington state

Download Report:

Abstract:
Three different kinds of base material of varying base thicknesses were tested at the Washington State University Test Track on Ring #3 during the fall of 1967 and the spring of 1968. Twelve 18-foot test sections consisting of 4.5, 7.0, 9.5 and 12 inches of untreated crushed rock surfacing top course base; 3.0, 5.0, and 7.0 and 9.0 inches of emulsion treated crushed surfacing top course base; and 0.0, 2.0, 3.5 and 5.0 inches of special non-fractured screened aggregate asphalt treated base, covered by a uniform 3.0-inch thick Class "B" asphalt concrete wearing course were tested during this period. This pavement structure was built on a clay-silt subgrade soil.Instrumentation consisted of moisture tensiometers, strain gages, pressure cells, LVDT gages and thermocouples for measuring moisture, strain, stress, dynamic deflections and temperatures. Benkleman beam readings were taken.The testing period revealed that the fall failure modes were different from the spring failures. The fall failure patter started from transverse cracks in the thin sections which developed into alligator cracking patterns. These cracks appeared after a period of cold weather and heavy rains followed by a warming period. It seems that thermal and mechanical loads were responsible for the fall failures on the thin sections. The spring failures were very rapid and sudden and were due to environmental factors which led to saturated subgrade, thus resulting in poor bearing capacity. Punching shear was the failure mode. The thickest sections survived without cracks but developed severe rutting. Examination revealed that these ruts extended into the subgrade and that fatigue cracking was developing on the bottom of the bases.Comparison of the results with those obtained from Ring# 2, which was similar in base materials and thickness, show that they were similar in many respects. This indicates that the test track is capable of replicating results and is a reliable research instrument.Equivalencies were developed for the different materials. On this basis the special aggregate asphalt treated base was superior to the emulsion treated and untreated crushed rock bases in that order. These results were comparable to those obtained from test Ring #2.Maximum values for static and dynamic deflections, strains and stresses for different times and temperatures were developed. The lateral position of the dual tires with respect to the gage severely affected the strain, stresses and deflection values. Temperature also caused variations in the measurements. Spring instrument readings for static and dynamic deflections, strain and stress show increased values by as much as 2 to 4 times of those obtained in the fall. Spring subgrade conditions probably are responsible for these differences.Ring #3 series operational time was twice that of Ring #2 and sustained four times the wheel load applications. Construction and testing environmental conditions were superior to those for Ring #2 and hence contributed to the longer test period. This points out that environmental factors are very important in pavement life.

Authors:
Krukar,M.

Keywords:
aggregate, Alligator Cracking, applications, asphalt, asphalt concrete, base, base materials, bearing capacity, Benkleman beam, concrete, condition, construction, cracking, dual tires, environmental, experimental, fatigue, fatigue cracking, loads, materials, pavement, pavement life, pressure, pressure cell, rain, research, research at the WSU, strains, stresses, subgrade, temperature, test track, tire, tires, volume, Volume No.4, Washington, Washington state, wheel load

Download Report:

Abstract:
Three different kinds of base material of varying base thicknesses were tested at the Washington State University Test Track on Ring #3 during the fall of 1967 and the spring of 1968. Twelve 18-foot test sections consisting of 4.5, 7.0, 9.5 and 12 inches of untreated crushed rock surfacing top course base; 3.0, 5.0, and 7.0 and 9.0 inches of emulsion treated crushed surfacing top course base; and 0.0, 2.0, 3.5 and 5.0 inches of special non-fractured screened aggregate asphalt treated base, covered by a uniform 3.0-inch thick Class "B" asphalt concrete wearing course were tested during this period. This pavement structure was built on a clay-silt subgrade soil.Instrumentation consisted of moisture tensiometers, strain gages, pressure cells, LVDT gages and thermocouples for measuring moisture, strain, stress, dynamic deflections and temperatures. Benkleman beam readings were taken.The testing period revealed that the fall failure modes were different from the spring failures. The fall failure patter started from transverse cracks in the thin sections which developed into alligator cracking patterns. These cracks appeared after a period of cold weather and heavy rains followed by a warming period. It seems that thermal and mechanical loads were responsible for the fall failures on the thin sections. The spring failures were very rapid and sudden and were due to environmental factors which led to saturated subgrade, thus resulting in poor bearing capacity. Punching shear was the failure mode. The thickest sections survived without cracks but developed severe rutting. Examination revealed that these ruts extended into the subgrade and that fatigue cracking was developing on the bottom of the bases.Comparison of the results with those obtained from Ring# 2, which was similar in base materials and thickness, show that they were similar in many respects. This indicates that the test track is capable of replicating results and is a reliable research instrument.Equivalencies were developed for the different materials. On this basis the special aggregate asphalt treated base was superior to the emulsion treated and untreated crushed rock bases in that order. These results were comparable to those obtained from test Ring #2.Maximum values for static and dynamic deflections, strains and stresses for different times and temperatures were developed. The lateral position of the dual tires with respect to the gage severely affected the strain, stresses and deflection values. Temperature also caused variations in the measurements. Spring instrument readings for static and dynamic deflections, strain and stress show increased values by as much as 2 to 4 times of those obtained in the fall. Spring subgrade conditions probably are responsible for these differences.Ring #3 series operational time was twice that of Ring #2 and sustained four times the wheel load applications. Construction and testing environmental conditions were superior to those for Ring #2 and hence contributed to the longer test period. This points out that environmental factors are very important in pavement life.

Authors:
Krukar,M., Cook,J. C.

Keywords:
aggregate, Alligator Cracking, applications, asphalt, asphalt concrete, base, base materials, bearing capacity, Benkleman beam, concrete, condition, construction, cracking, dual tires, environmental, equivalencies, experimental, fatigue, fatigue cracking, loads, materials, pavement, pavement life, pressure, pressure cell, rain, research, research at the WSU, soil, strains, stresses, subgrade, temperature, test track, tire, tires, volume, Washington, Washington state, wheel load

Download Report:

Abstract:
This report describes the results obtained from Experimental Ring No. 2, the first ring of a three-ring tests series on treated bases at the Washington State University Test Track. This experiment was concerned with studying the effects of controlled wheel load repetitions on untreated, emulsion, and specialaggregate asphalt - treated bases of four varying thicknesses. Construction, instrumentation, results , and conclusions are described and drawn. Benkelman beam, LVDT, strain gages, pressure cells and moisture tensiometers were used to measure deflections , strains , stresses and moisture. Maximum values are tabulated. Temperatures were also recorded. Testing can be divided into two time periods - fall of 1966 and spring of 1967. Values obtained from instruments show that different conditions existed during those testing periods, and that deflections , strains and stresses were two to four times higher in the spring than in the fall. Modes of failure were also different . Equivalencies between the different base materials were established. Other conclusions were drawn. Since this is a continuing experiment, it should be emphasized that results and conclusions are subject to change, depending upon data from the remaining experimental rings.

Authors:
Krukar,M., Cook,J. C.

Keywords:
asphalt, base, condition, construction, data, experimental, materials, pavement, pressure, research, strains, stresses, temperature, test track, tests, volume, Washington, Washington state

Download Report: