bluuebunny/crossref_metadata_2025 huggingface dataset:
Water-Quality Effects of Tire Shreds Placed Above the Water Table: Five-Year Field Study
Authors: Humphrey Dana N. , Katz Lynn E.
Published: April 2007

A field trial was constructed beneath a secondary state highway in North Yarmouth, Maine, to investigate the water-quality effects of tire shred fills placed above the groundwater table. Samples were collected in three 3-m2 geomembrane-lined basins located beneath the shoulder of the road. Two of the basins are overlaid by 0.61 m of tire shreds with a 75-mm maximum size topped by 0.72 to 1.37 m of granular soil. The third basin serves as a control and is overlaid by only 0.72 m of granular soil. Quarterly samples for inorganic constituents were taken from January 1994 through June 1999. In addition, samples were taken for volatile and semivolatile organic compounds on three dates. Filtered and unfiltered samples were analyzed for the following substances, which have a primary drinking water standard: barium, cadmium, chromium, lead, and selenium. There was no evidence that the presence of tire shreds altered the concentrations of these substances from their naturally occurring background levels. In addition, there was no evidence that tire shreds increased the levels of aluminum, zinc, chloride, and sulfate, which have secondary (aesthetic) drinking water standards. In a few samples, iron levels exceed their secondary standard. Manganese levels consistently exceeded their secondary standard; however, this is an aesthetic-based standard. Three sets of samples were tested for organics. Negligible levels of organics were found.
Utilization of Construction and Demolition Debris Under Traffic-Type Loading in Base and Subbase Applications
Authors: Bennert Thomas , Papp Walter J. , Maher Ali , Gucunski Nenad
Published: April 2007

As construction and remediation take place throughout New Jersey, the amount of construction and demolition debris increases, while the availability of landfill space decreases. A viable solution for disposing of these materials is to incorporate them into base and subbase applications. An extensive laboratory program was conducted on two types of construction and demolition debris: recycled concrete aggregate (RCA) and recycled asphalt pavement aggregate (RAP). These two materials were compared with dense-graded aggregate base coarse (DGABC), which currently is being used in roadway base applications in New Jersey. Both RCA and RAP were mixed at various percentages with the DGABC to evaluate whether an optimum mix blend could be formulated. The materials were evaluated under a traffic-type loading scheme that included resilient modulus and permanent deformation via cyclic triaxial testing. Laboratory tests indicated that the RAP, RCA, and DGABC blended materials all obtained higher resilient modulus values than the currently used DGABC. The permanent deformation results indicated that the RCA mixed samples obtained the lowest amount of permanent deformation when the material was cyclically loaded to 100,000 cycles. In contrast, the permanent deformation testing on RAP mixed samples resulted in the highest amount of permanent deformation at the same number of cycles. Existing models currently used for quarried base and subbase materials were used to predict the permanent deformation in the recycled materials. Laboratory test results indicated that these models could be used for predicting permanent deformation in unbound recycled materials.
Evaluation of Excess Foundry System Sands for Use as Subbase Material
Authors: Kleven Jay R. , Edil Tuncer B. , Benson Craig H.
Published: April 2007

Earthwork associated with highway construction provides an opportunity for high-volume reuse of excess system sands (ESS) discarded by the foundry industry. California bearing ratio (CBR), unconfined compressive strength, and resilient modulus tests were conducted on 13 ESS, one base sand, and two reference materials. Tests were conducted on specimens prepared dry of optimum, wet of optimum, and at optimum water content with standard and modified Proctor compaction effort. Results of these tests were used to identify characteristic engineering properties of ESS, appropriate compaction conditions for ESS when used as subbase, and empirical equations that can be used to predict the engineering properties of ESS based on index properties. Results of the tests indicate that ESS classify as SP, SM, or SP-SM (A-2-4 or A-3 in AASHTO) and should be compacted dry or at optimum water content and, if possible, with higher compactive effort. The CBR of the ESS ranged from 4 to 40 and averaged 20 when compacted with standard effort at optimum water content. Swell during the soaking portion of the CBR tests was small for all ESS. ESS compacted at optimum water content with standard effort had unconfined compressive strengths ranging from 71 to 190 kPa. Resilient moduli of the ESS were similar to that of a reference subbase material but smaller than a reference base material. A power function model in terms of bulk stress described resilient moduli of the ESS well.
Engineering Properties of Loess-Fly Ash Mixtures for Roadbase Construction
Authors: Zia Nayyar , Fox Patrick J.
Published: April 2007

Southwest Indiana has large deposits of wind-blown loess. Similar deposits are found in other states, including Illinois, Kentucky, Iowa, Minnesota, Missouri, and Nebraska. These soils consist of uniform silt with a plasticity index ranging from 0 to 10. This material is suitable for road construction if it is compacted dry of optimum. However, the material is difficult to work after it becomes wet, which commonly results in construction delays. Indiana also has large stockpiles of Class C fly ash from coal-burning power plants. The ash has cementitious properties after hydration (because of the high calcium content) and can be mixed with native soil to produce a weakly cemented soil. Significant interest exists at the Indiana Department of Transportation about the possibility of using Class C fly ash to improve the engineering properties of Indiana loess soils. The results of a laboratory testing program on the properties of loess–fly ash mixtures are presented. Various percentages of fly ash were mixed with loess soil and specimens were permitted to cure for 3 h to 28 days. Pure loess also was tested for comparison. Changes in Atterberg limits, moisture-density relationships, swell potential, and unconfined compression strength are presented. Based on this testing program, a simple method was developed to determine the optimum fly ash content for construction of a workable loess roadbed to avoid delays in construction due to wet conditions. The data presented will be useful for evaluating the stabilization of loess soils with Class C fly ash in Indiana and other states with significant loess soil deposits.
Influence of Soil Suction and Environmental Factors on Drying Characteristics of Granular Subgrade Soils
Authors: Ping W. Virgil , Ling Ching-Chin , Ho Robert K. H.
Published: April 2007

According to contractors in Florida, construction problems have emerged because pavement soils hold excessive water and are difficult to dry and compact. Recent research on the effects of soil suction and environmental conditions on drying rate characteristics of six types of troublesome granular soils is presented. Two types of tests were conducted for the study: soil suction tests using the thermocouple psy-chrometer method and drying rate tests using an environmental chamber. The experimental results showed that both the soil suction and relative humidity had direct effects on the soil-drying rate. The drying rate decreased with an increase in soil suction for each soil type and also decreased with an increase in the percentage of fines. The influence of relative humidity on the soil-drying rate was much more significant than the effect of the temperature. The rate of water evaporation was extremely low for the soils with a higher percentage of fines when the relative humidity was high. The A-2-4 soils with greater than 20 percent of fines may have such a low drying rate in an environment with high relative humidity that they are difficult to handle during construction.
Safety Models for Rural Freeway Work Zones
Authors: Venugopal Shyam , Tarko Andrzej
Published: April 2007

Construction and maintenance work zones have traditionally been hazardous locations within the highway environment. Studies show that the accident rates during road construction are generally higher than during periods of regular traffic operations. The increase in the number of crashes may be attributed to ( a) general disruption to the flowing traffic due to sudden discontinuities caused by closed lanes, ( b) improper lane merging maneuvers, ( c) the presence of heavy construction equipment within the work area, ( d) inappropriate use of traffic control devices, and ( e) poor traffic management. Research was conducted to develop regression models predicting the expected number of crashes at work zones on rural, two-lane freeway segments. Crashes on approaches to work zones and those inside the work zones were analyzed separately. For developing these models, an extensive database was obtained, including freeway data, crash data, and work zone characteristics. Negative binomial models were developed with average daily traffic, the length of the work zones, and the duration of the work projects as exposure-to-risk variables. The cost of the various work projects was found to be a good substitute for some of the exposure-to-risk variables. The investigated variables included the number of on and off ramps, both on approaches and inside the work zones; the type of work; and the intensity of the road work involved. The models may be used to evaluate beforehand the expected number of crashes on the work zone, given the work zone characteristics.
Evaluation of Orange Removable Rumble Strips for Highway Work Zones
Authors: Meyer Eric
Published: April 2007

Rumble strips can be effective in alerting drivers to road conditions that merit special attention. The Kansas Department of Transportation (KDOT) requires the deployment of rumble strips on state routes during maintenance work that necessitates the closure of a lane on a two-lane highway. In such a case, a temporary signal is placed at each end of the work zone, and rumble strips are used to alert drivers that they may need to stop. Currently, cold-mix asphalt is used to create the rumble strips. A new product, orange removable rumble strips, promises to reduce significantly the effort required to apply and to remove rumble strips, while improving safety by increased conspicuity. These removable rumble strips were evaluated at a bridge repair site in rural Kansas. Vehicle speeds were recorded with only the standard asphalt rumble strips in place; then the removable rumble strips were installed and more speed data were collected. Installation and removal times also were compared. Strips were easily applied and easily removed. The audible and tactile effects of the strips were weak due to their 3.2-mm (1/8-in.) thickness in comparison with the 12.7 to 19 mm (1/2 to 3/4 in.) thickness of standard asphalt rumble strips. However, the orange removable rumble strips were found to have a significant effect on vehicle speeds, attributable to their high visibility. KDOT plans to conduct another evaluation using a version of the same device that is 20 percent thicker.
Estimating Subgrade Stiffness and Bedrock Depth: Combined Falling Weight Deflectometer and Simplified Spectral Analysis of Surface Waves Measurements
Authors: Aouad Marwan F. , Stokoe Kenneth H. , Joh Sung-Ho
Published: April 2007

The spectral analysis of surface waves (SASW) method is an in situ seismic technique that is used for evaluation of the stiffnesses of pavement systems at low strain levels. The stiffness of the surface layer can be determined by direct measurements in the field. Stiffnesses of the layers beneath the surface layer require forward modeling of SASW field data in order for the pavement profile to be obtained. The forward modeling process can be time consuming, especially if a three-dimensional model is used. A simplified procedure is proposed for determining an average value of the subgrade stiffness without performing forward modeling. Additionally, the simplified procedure can be used for determining the depth of shallow bedrock beneath pavement sites. The recommended procedure is based on SASW tests performed at 24 flexible pavement sections in the state of Texas. Parametric studies were also conducted with idealized rigid and flexible pavement profiles for the purpose of verifying the accuracy of the procedure and evaluating its limitations. An important point is that SASW measurements associated with the simplified procedure can be performed in conjunction with falling weight deflectometer (FWD) measurements using the drop weight as a source. The drop-weight source generates the frequency range required for SASW receiver spacings of 3, 6, and 9 m, which are recommended in the simplified procedure. The subgrade stiffness and depth to bedrock (if it exists) determined by the simplified procedure can be used as input parameters for enhancement of the backcalculation procedure associated with FWD measurements.
Dynamic Interpretation of Falling Weight Deflectometer Test Results: Spectral Element Method
Authors: AI-Khoury Rafid , Scarpas Athanassios , Kasbergen Cor , Blaauwendraad Johan
Published: April 2007

The use of spectral analysis as a means of analyzing the dynamic impact of falling weight deflectometer (FWD) load pulses on pavements is covered. The spectral element technique is utilized. Only forward analyses of pavement dynamics are presented, with the emphasis on the suitability of the method for solving inverse problems. LAMDA (layered media dynamic analysis), a newly developed spectral element program, is utilized for the simulation of the interaction between the FWD load pulse and the pavement structure. In LAMDA, the formulation of the wave propagation, reflection, and refraction in a layer is done in a closed form. The assembling of the elements (in the multilayer system) is carried out in a manner similar to that in the finite element method. Consequently, the size of the mesh of a pavement structure is as large as the number of the layers involved. This reduces the computational requirements substantially and hence enables utilization of LAMDA in iterative algorithms for backcalculation purposes.
Backcalculation of Thermally Deformed Concrete Pavements
Authors: Shoukry Samir N.
Published: April 2007

Nonlinear explicit three-dimensional finite element (3-D FE) modeling is used to investigate the performance of the falling weight deflectometer (FWD) test in the evaluation of layer moduli of jointed plain concrete pavements (JPCP) subjected to nonlinear thermal gradient through the slab thickness. Concrete slab separation from the base, in-plane friction at the concrete-base interface, the gravitational forces, and the interface characteristics between dowel bars and surrounding concrete are all represented in the 3-D FE model. Experimental verification of the model is obtained through comparison of the 3-D FE generated response to ( a) the FWD measured deflection basin and ( b) the measured response of an instrumented rigid pavement section located in Ohio to a loaded truck moving at 21.8 m/s (48 mph). Several cases of linear and nonlinear thermal gradients are applied to the model, and deflection basins are obtained. Two backcalculation programs, MODULUS 5.0 and EVERCALC 4.0, are used for prediction of the layer moduli in each case, and the values are compared. The results indicate that thermal curling of the slab due to negative thermal gradient has little effect on the accuracy of backcalculated moduli. Warping of the slab due to positive thermal gradient greatly influences the measured FWD deflection basin and leads to significant errors in the backcalculated moduli. These errors may be minimized if the time an FWD test is conducted falls between the late afternoon and midmorning (from 5:30 p.m. to 9:30 a.m. during summer in West Virginia).
Crash- and Injury-Outcome Multipliers
Authors: Kim Karl
Published: April 2007

In 1992 the University of Hawaii was one of six institutions to receive a Crash Outcome Data Evaluation System grant from the U.S. Department of Transportation, NHTSA. As part of the Hawaii CODES Project, police crash data, emergency medical services (EMS) data, and hospital data were linked using a probabilistic linkage software known as Automatch. An advantage of linked data is the ability to determine injury outcomes for various types of crashes. A simple technique—crash and injury outcome multipliers for examining the relative safety of various types of crashes—is presented. Using the crash as the unit of analysis, a measure is derived that indicates the number of fatalities, incapacitating injuries, nonserious injuries, EMS transports, and hospitalizations produced over a period of time by those particular crash types. In addition to comparing vehicle-to-vehicle crashes, various crash types such as head-on, rollover, sideswipe, broadside, and fixed-object collisions are also examined. The relative crash and injury outcomes for speed-related crashes, alcohol-related collisions, or any number of other types of safety concerns can also be tabulated. The simple technique is illustrated using both conventional police crash data on injuries and a linked file containing EMS and hospital records. In addition to demonstrating the technique, some potential uses are described.
Prediction of Risk of Wet-Pavement Accidents: Fuzzy Logic Model
Authors: Xiao Jie , Kulakowski Bohdan T. , EI-Gindy Moustafa
Published: April 2007

Researchers developed a fuzzy-logic model for predicting the risk of accidents that occur on wet pavements. Preventing wet-pavement accidents has been an extremely difficult and elusive task because they are stochastic events whose occurrence is related to a variety of factors, including vehicle, roadway, human, and environmental characteristics. Conventionally, researchers use linear or nonlinear regression models and probabilistic models to predict wet-pavement accidents. However, these models often are limited in their capability to fully explain the process when the underlying physical system possesses a degree of non-linearity. Therefore, the potential of applying fuzzy logic in this area might be promising. Two fuzzy-logic models were developed and evaluated using accident data and the corresponding traffic data collected from 123 sections of highway in Pennsylvania from 1984 to 1986. The models use skid number, posted speed, average daily traffic, percentage of wet time, and driving difficulty as input variables and the number of wet-pavement accidents as the output variable. The first model is based on Mamdani’s fuzzy-inference method, and the second is a Sugeno-type fuzzy-logic model using the fuzzy-clustering method. The two fuzzy-logic models show superiority over the probabilistic model and the nonlinear regression model. Results indicate that, in addition to predicting the risk of wet-pavement accidents, the fuzzy-logic model can be applied conveniently to determine specific corrective actions that should be undertaken to improve safety.
Analysis of Accident-Reduction Factors on California State Highways
Authors: Hanley Kevin E. , Gibby A. Reed , Ferrara Thomas C.
Published: April 2007

Accident reduction factors (ARFs) are mechanisms that the California Department of Transportation employs in calculating Traffic Safety Index values, which are used to prioritize safety-improvement projects on California state highways. Many factors that affect motorist safety have changed over the nearly 30 years in which ARFs have been used in the Traffic Safety Index Program. It is therefore appropriate to review and update, as needed, these accident-reduction factors. The research focused on four accident-reduction factors that are currently in use (rumble-strip installation, shoulder widening, superelevation correction, and curve correction). An accident-reduction factor was developed for a fifth treatment category (wet-pavement treatments). Data were gathered for all projects proposed for funding in the state of California’s Safety Improvement Program from 1985 through 1995. Projects completed from 1988 through 1992 were considered for inclusion in a before-and-after study that employed empirical Bayesian statistical analysis. A Bayesian statistical software package, BEATS (Bayesian Estimation of Accidents in Transportation Studies), was used in the analysis. The study reviewed scope of work for each of the projects of interest that were completed from 1988 to 1992. Thirty projects—the most frequently occurring individual treatments and treatment combinations—were categorized by treatment type and analyzed. Accident-reduction factors of sufficient statistically significant strength were found for wet-pavement treatments, rumble-strip installations, and shoulder-widening projects. Data for shoulder widening, superelevation correction, and curve correction projects also are presented, but small sample size hampered statistical significance for these projects. Results of the study revealed the importance of improving curve radius during superelevation correction and lane- and/or shoulder-widening treatments.
Estimating Traffic Accident Rates While Accounting for Traffic-Volume Estimation Error: A Gibbs Sampling Approach
Authors: Davis Gary A.
Published: April 2007

Traffic-accident rates that are estimated for individual roadway sites are often used to identify potentially hazardous locations. Occasionally they are used to test whether an accident countermeasure is associated with a statistically significant change in accident rate. In assessing the uncertainty attached to estimated accident rates, it is often implicitly assumed that the total traffic at a site is known with certainty, when in actuality the total traffic almost always must be estimated from a short sample of traffic counts. This introduces estimation error, which, if ignored, can lead one to overstate the accuracy of an accident-rate estimate. An explanation is provided about how Bayes estimates of accident rates, which explicitly account for total traffic estimation error, can be computed readily using a (relatively) new estimation method called “Gibbs sampling.” A model of how traffic-count samples are related to total traffic is incorporated from earlier work done by the author and his students. In tests conducted using accident counts and traffic data from 17 automatic traffic-recorder sites in Minnesota, it was found that, when using a 2-day traffic-count sample, the traditional method for estimating accidents rates understated the likely error of these estimates by 12 to 40 percent, depending on the site.
Examination of Methods That Adjust Observed Traffic Volumes on a Network
Authors: Kikuchi Shinya , Miljkovic Dragana , van Zuylen Henk J.
Published: April 2007

As the models of transportation planning and engineering become more and more sophisticated, the quality of data that is used as input to the models is of critical importance to the integrity of the analysis. Several methods that adjust the field-traffic-volume data so that they become consistent and useful information for the subsequent analysis steps are examined. Consistency as satisfaction of flow conservation and other relationships underlying the network flow in question are defined. Six methods, including the manual method, are presented, and the logic and computational process are explained for each method. Except for the manual method, the methods are grouped into two general categories and discussed—one considers inconsistency in the data as a result of the statistical error and uses the classical-regression approach, and the other considers the observed value as the approximate value and uses the fuzzy-set theory. These methods are compared for their performance using an example problem. Transportation analysts’ alternative methods for volume adjustment are provided, and the analysts’ theoretical and practical implications are explained.
Day-to-Day Travel-Time Trends and Travel-Time Prediction from Loop-Detector Data
Authors: Kwon Jaimyoung , Coifman Benjamin , Bickel Peter
Published: April 2007

An approach is presented for estimating future travel times on a freeway using flow and occupancy data from single-loop detectors and historical travel-time information. Linear regression, with the stepwise-variable-selection method and more advanced tree-based methods, is used. The analysis considers forecasts ranging from a few minutes into the future up to an hour ahead. Leave-a-day-out cross-validation was used to evaluate the prediction errors without underestimation. The current traffic state proved to be a good predictor for the near future, up to 20 min, whereas historical data are more informative for longer-range predictions. Tree-based methods and linear regression both performed satisfactorily, showing slightly different qualitative behaviors for each condition examined in this analysis. Unlike preceding works that rely on simulation, real traffic data were used. Although the current implementation uses measured travel times from probe vehicles, the ultimate goal is an autonomous system that relies strictly on detector data. In the course of presenting the prediction system, the manner in which travel times change from day to day was examined, and several metrics to quantify these changes were developed. The metrics can be used as input for travel-time prediction, but they also should be beneficial for other applications, such as calibrating traffic models and planning models.
Identifying Decision Structures Underlying Activity Patterns: An Exploration of Data Mining Algorithms
Authors: Wets Geert , Vanhoof Koen , Arentze Theo , Timmermans Harry
Published: April 2007

The utility-maximizing framework—in particular, the logit model—is the dominantly used framework in transportation demand modeling. Computational process modeling has been introduced as an alternative approach to deal with the complexity of activity-based models of travel demand. Current rule-based systems, however, lack a methodology to derive rules from data. The relevance and performance of data-mining algorithms that potentially can provide the required methodology are explored. In particular, the C4 algorithm is applied to derive a decision tree for transport mode choice in the context of activity scheduling from a large activity diary data set. The algorithm is compared with both an alternative method of inducing decision trees (CHAID) and a logit model on the basis of goodness-of-fit on the same data set. The ratio of correctly predicted cases of a holdout sample is almost identical for the three methods. This suggests that for data sets of comparable complexity, the accuracy of predictions does not provide grounds for either rejecting or choosing the C4 method. However, the method may have advantages related to robustness. Future research is required to determine the ability of decision tree-based models in predicting behavioral change.
Stochastic Frontier Models of Prism Vertices
Authors: Kitamura Ryuichi , Yamamoto Toshiyuki , Kishizawa Keiko , Pendyala Ram M.
Published: April 2007

A methodology to estimate the location and size of space-time prisms that govern individuals’ activity and travel is presented. Because the vertices of a prism are unobservable, stochastic frontier models are formulated to locate prism vertices along the time axis using observable trip starting or ending times as the dependent variable and commute characteristics, personal and household attributes, and area characteristics as explanatory variables. Models are estimated successfully with coherent behavioral indications. A mean difference of 1.46 h is found between the observed trip ending time and the expected location of the terminal vertex for workers’ evening prisms. The estimation results aid in enhancing the understanding of prism constraints by identifying the determinants of prism vertex locations.
Dynamic Analysis of Traveler Attitudes and Perceptions Using Panel Data
Authors: Sunkanapalli Sridhar , Pendyala Ram M. , Kuppam Arun R.
Published: April 2007

A dynamic analysis of travelers’ attitudes, preferences, and values was carried out using three waves of the Puget Sound Transportation Panel survey to investigate dynamics in traveler attitudes and perceptions. An in-depth descriptive analysis was performed to examine the variations in attitudinal ratings over time. A traditional one-way analysis of variance (ANOVA) method was used to explore for similarities and differences in traveler attitudinal ratings across different waves of the panel survey. A similar analysis was performed on the stayer sample (i.e., the respondents who participated in all three waves of the panel used in this study). The ANOVA results show significant differences in mean attitudinal ratings across the three waves of the panel survey. The differences in traveler attitudes and perceptions among stayers, dropouts (respondents who leave the panel survey), and refreshments (respondents who are newly recruited as the panel survey proceeds) were also captured. Finally, differences in traveler attitudes and preferences across different modal market segments were examined. The results indicate the need for greater consideration of attitudinal dynamics in transportation planning and policy analysis.
Car Ownership in Great Britain: Panel Data Analysis
Authors: Hanly Mark , Dargay Joyce M.
Published: April 2007

The analysis of the factors determining changes in travel behavior on the individual (or individual household) level requires information on the behavior of individuals over time. Such “transport” panel surveys are rarely available, particularly for a sufficiently long time period to examine such changes more than cursorily. For the United Kingdom, none exists for other than limited regions. However, the ongoing British Household Panel Survey (BHPS), begun in 1991, provides some information related to transport—specifically, household car ownership—as well as information on the economic and sociodemographic characteristics of the households surveyed. BHPS data for 1993 to 1966 are used to analyze car ownership and the factors determining car ownership decisions on an individual household level. As far as is known, this has not yet been done in any systematic manner. The relationship between car ownership, income, and sociodemographic factors such as household composition, residential location, and population density (persons per hectare in the local authority district in which the household resides) is investigated. Both descriptive statistical measures and formal modeling approaches, based on dynamic discrete choice models and panel data econometric techniques, are used.
Truck Trip Generation Models for Seaports with Container and Trailer Operation
Authors: Al-Deek Haitham M. , Johnson Gene , Mohamed Ayman , El-Maghraby Ashraf
Published: April 2007

Freight movement throughout the United States continues to evolve as a significant challenge to the transportation industry. Seaport operations dominated by container and trailer movements will require operational and infrastructure changes to maintain the growth of international cargo operations. Transportation planning models can be used to determine the needs of port and street network modifications. Described is the research and initial development process of models for predicting the levels of cargo truck traffic moving inbound and outbound at the Port of Miami. The models were restricted to container and trailer truck configurations that transport virtually all of the Port of Miami’s freight. Consequently, this associated truck traffic moves through the nearby street network within downtown Miami. The purpose of the trip generation models is to predict volumes of large inbound and outbound trucks for specified time frames. The concern is to know how many large cargo vehicles are traveling on the only road leading to the port. Primary factors affecting truck volume were found to be the amount and direction of cargo vessel freight and the particular weekday of operation. Time series models for predicting seasonal variations in freight movements were developed as part of the study. These models are useful for long-term forecasts of the input variables used in the trip generation models. Truck trip generation models will provide transportation planners and public agencies with valuable information when making transportation management decisions and infrastructure modifications. This information also is necessary for prioritizing funds for roadway upgrade projects.
Assessment of Market Demand for Cross-Harbor Rail Freight Service in the New York Metropolitan Region
Authors: Cutler Marc , Grenzeback Lance , Cheng Alice , Roberts Richard
Published: April 2007

An investment study sponsored by the New York City Economic Development Corporation with Intermodal Surface Transportation Efficiency Act of 1991 funds evaluated strategies for improving the movement of freight by rail to an 11-county subregion (including New York City) of the New York and northern New Jersey metropolitan area located east of the Hudson River. The major achievements of the process were the use of choice modeling techniques to understand the decision making of shippers and, in combination with other data sources, forecasting the demand for freight infrastructure investments. The methodologies described are applicable to the study of freight transportation investment strategies in many settings. The key finding of the analysis is that a rail freight tunnel would increase rail mode share relative to other alternatives and the so-called No Build case. The subregion east of the Hudson contains two-thirds of the region’s population, but it is at a significant disadvantage in the movement of freight relative to the subregion west of the Hudson. Rail accounts for only 2.8 percent of all the subregion’s shipments, compared to 15 percent within the subregion west of the Hudson. Two limited rail crossings of the Hudson River provide access to New York City and the rest of the east subregion. These conditions affect the level of truck traffic and air pollution within the subregion, the subregion’s overall economic competitiveness, and the viability of its port facilities. To address these concerns, four families of alternatives that could improve cross-harbor rail freight service were analyzed. Discussed is how the market demand for these alternatives was analyzed by linking six distinct methodologies and data sets: ( a) regional economic forecasts, ( b) commodity flow data, ( c) a modal diversion model, ( d) regional port forecasts, ( e) a regional travel demand forecasting model, and ( f) user benefit calculation models.
Use of Traveler Information in the Puget Sound Region: Preliminary Multivariate Analysis
Authors: Viswanathan Krishnan , Goulias Konstadinos G. , Jovanis Paul P.
Published: April 2007

Recent developments in information technologies, providing new ways to disseminate and use information, may help alleviate congestion, reduce user cost and time, and enhance safety. This influence of technology use, however, is mediated by telecommunication and information technology ownership and use. A multivariate probit model specification is used to determine how these parameters influence traveler decision making when one is confronted with information about traffic problems before making a trip to work or school, en route to or from work or school, and before making a trip from work or school. Addressed is the key relationship between telecommunication and information technology ownership and use with travel decisions when information about traffic problems is available. Data from the Puget Sound region for 1997 are used in the analysis. The results suggest technology ownership and use influence travel decision making in different ways for each stage of travel—before leaving home, en route, and returning home.
Estimation of Annual Average Daily Traffic on Low-Volume Roads: Factor Approach Versus Neural Networks
Authors: Sharma Satish C. , Lingras Pawan , Liu Guo X. , Xu Fei
Published: April 2007

Estimation of the annual average daily traffic (AADT) for low-volume roads is investigated. Artificial neural networks are compared with the traditional factor approach for estimating AADT from short-period traffic counts. Fifty-five automatic traffic recorder (ATR) sites located on low-volume rural roads in Alberta, Canada, are used as study samples. The results of this study indicate that, when a single 48-h count is used for AADT estimation, the factor approach can yield better results than the neural networks if the ATR sites are grouped appropriately and the sample sites are correctly assigned to various ATR groups. Unfortunately, the current recommended practice offers little guidance on how to achieve the assignment accuracy that may be necessary to obtain reliable AADT estimates from a single 48-h count. The neural network approach can be particularly suitable for estimating AADT from two 48-h counts taken at different times during the counting season. In fact, the 95th percentile error values of about 25 percent as obtained in this study for the neural network models compare favorably with the values reported in the literature for low-volume roads using the traditional factor approach. The advantage of the neural network approach is that classification of ATR sites and sample site assignments to ATR groups are not required. The analysis of various groups of low-volume roads presented also leads to a conclusion that, when defining low-volume roads from a traffic monitoring point of view, it is not likely to matter much whether the AADT on the facility is less than 500 vehicles, less than 750 vehicles, or less than 1,000 vehicles.
Using Brokers to Determine North American Free Trade Agreement Truck Origins and Destinations at Texas-Mexico Border
Authors: Harrison Robert
Published: April 2007

U.S.-Mexico trade continues to grow, much of it crossing into Texas, where bridges over the Rio Grande carry the vehicular and rail traffic. Currently, more than 70 percent of North American Free Trade Agreement U.S.-Mexico trade is by truck, and substantial delays and other social costs are a feature of border port-of-entry systems. New bridge locations are being proposed, and each site must be carefully evaluated to ensure that it is economically feasible. As part of this evaluation process, origin and destination surveys are used to determine bridge location and demand. Many of the truck trailers are moved by drayage companies or by drivers who have not brought the load from its origin or who will deliver it to the final destination. It is argued that surveys of these drivers are flawed and give limited data. A report is made on a method with which to interview and survey customs brokers to derive truck origin and destination data; this report was successfully employed at the Anzalduas International Bridge site near McAllen, Texas. Because many ports of entry in Texas are similar to McAllen, the survey method can be applied across the whole border.
Innovative Data Collection Techniques for Roadside Origin-Destination Surveys
Authors: Quiroga Cesar , Henk Russell , Jacobson Marc
Published: April 2007

Described are the results of a pilot application intended to automate the data collection and data reduction phases of roadside origin-destination (O-D) studies. Most techniques used to obtain O-D data are quite labor intensive, during both the data collection and the data reduction phase. Frequently, they result in extensive data quality checks and long turnaround periods between the data collection work and the submittal of the corresponding survey report. The application described automates the data collection and data reduction phases by using portable, handheld data collection devices. These devices can be connected to a desktop or laptop computer to transfer the O-D data to a depository database. Included are a brief background discussion, a description of the hardware and software used and the design and development of O-D applications, a description of two applications of the handheld data collection devices, and a list of lessons learned.
Maine’s Approach to Data Warehousing for State Departments of Transportation
Authors: O’Packi Paul , Dubois Rick , Armentrout Nancy , Bower Steve
Published: April 2007

Most transportation agencies are faced with changing needs, challenges, and limited resources. State departments of transportation need tools to address these issues. One such solution combines data warehouse and geographic information systems (GIS) technology to allow easy access to reliable information for systemwide query, analysis, and reporting. To meet these challenges, to be more responsive, and to provide staff and managers with a better platform with which to deliver integrated transportation information to both internal and external customers, the Maine Department of Transportation (MeDOT) has turned to integrating data warehousing and GIS technologies. A detailed overview of MeDOT’s Transportation Information for Decision Enhancement (TIDE), a robust GIS-linked data warehouse, is given. A range of inherent technical issues involved in a project of this nature is discussed. The role that TIDE has played in breaking down the functional boundaries that have existed on both informational and technical fronts and how this robust tool facilitates the growth of agency integration also are discussed.
Geographic Information System–Based Analysis of Right-of-Way Cost for Highway Optimization
Authors: Jha Manoj K. , Schonfeld Paul
Published: April 2007

At the planning stages of a highway project, various location alternatives must be explored, subject to a set of design constraints. A computerized tool with which to compare alignment alternatives would significantly reduce the time and resources spent as well as help find a minimum cost (or maximum net benefit) solution. Highway design optimization (HDO) is a computerized process that minimizes an objective function composed of significant highway costs, subject to a set of design constraints, including curvature, gradient, and sight distance. Several costs of alignments, such as right-of-way, earthwork, and environment costs, are sensitive to geography. A geographic information system (GIS) may be exploited to compute such costs for use in HDO models (HDOMs). Most known HDOMs focus only on refining the optimization approach and do not provide a comprehensive formulation for all costs sensitive to alignment. Provided is a comprehensive formulation for right-of-way cost computation. A GIS-based algorithm is developed to compute the right-of-way cost, which is integrated with an HDOM based on genetic algorithms. Two examples are used to demonstrate the effectiveness of the proposed approach.
Transitions from Guardrail to Bridge Rail That Meet Safety Performance Requirements
Authors: Eugene Buth C. , Menges Wanda L. , Mak King K. , Bligh Roger P.
Published: April 2007

Three guardrail-to-bridge rail transitions were developed and subjected to full-scale crash tests. The transitions were ( a) a nested W-beam with W-beam rub rail that transitioned from a W-beam guardrail to a vertical concrete parapet bridge rail, ( b) a nested thrie-beam that transitioned from a W-beam guardrail to a tubular steel bridge rail, and ( c) a tubular steel transition that transitioned from a weak-post box-beam guardrail to a tubular steel bridge rail. The nested W-beam and the tubular steel transitions were tested and met NCHRP Report 350 Test Level (TL)-3 requirements. The nested thrie-beam transition was tested and met TL-4 requirements.
Safety Effectiveness of Upgrading Guardrail Terminals to NCHRP Report 350 Standards
Authors: Ray Malcolm H.
Published: April 2007

Developing safe and effective guardrail terminals has been a high priority of roadside safety researchers for several decades. Numerous full-scale crash tests have been performed, and many types of new terminals have been developed. In recent years, the FHWA has formalized the evaluation and certification process for roadside safety hardware, meaning that all guardrail terminals used on the National Highway System must satisfy the full-scale crash test and evaluation requirements of NCHRP Report 350. Although the newer guardrail terminals undoubtedly have better full-scale crash test performance, the relevancy to reducing serious and fatal injuries in real-world guardrail terminal collisions is not quite as clear. The in-service performance of guardrail terminals was evaluated to determine if upgrading the terminals to NCHRP Report 350 standards would reduce serious and fatal injury accidents.
Incorporating Subgrade Lime Stabilization into Pavement Design
Authors: Qubain Bashar S. , Seksinsky Eric J. , Li Jianchao
Published: April 2007

The benefits of subgrade lime stabilization are incorporated, for the first time, into the design of a major interstate highway pavement in Pennsylvania. The project comprises widening and complete reconstruction of 21 km of the Pennsylvania Turnpike in Somerset County. Field explorations indicated that the subgrade is fairly homogeneous and consists primarily of medium to stiff clayey soils. To safeguard against potential softening due to rain, lime modification has been traditionally utilized as a construction expedience for highway projects with clayey subgrade. Such an approach, however, does not take advantage of the added strength of the lime-stabilized subgrade in pavement design. Lime improves the strength of clay by three mechanisms: hydration, flocculation, and cementation. The first and second mechanisms occur almost immediately upon introducing the lime, and they have been investigated in the study; the third is a prolonged effect. Laboratory tests were performed to accurately capture the immediate benefits of lime stabilization for design. Both treated and natural clayey samples were subjected to resilient modulus and California bearing ratio testing. To prevent cementation, the lime-treated specimens were not allowed to cure. Nevertheless, they showed significant increases in strength, which, when incorporated into design, reduced the pavement thickness and resulted in substantial savings.
Lime Requirement for Stabilization
Authors: Rogers Christopher D.F. , Glendinning Stephanie
Published: April 2007

Lime is used in construction as a rapid and economic method of improving the strength and stiffness characteristics of clay soils. For economical design, an engineer must know how much lime is required to initiate the required improvements. If lime stabilization is to be compared with alternative solutions in the early stages of a project, it must be possible to make this assessment rapidly and with the minimum expenditure on additional specialist testing. The ASTM Standard Test Method for Determining Stabilization Ability of Lime (MDSAL) aims to determine the quantity of lime required for stabilization using simple methodology to generate results quickly. Additional, much lengthier testing is recommended to verify the lime requirement if lime is considered feasible following MDSAL testing. Problems have been found in the execution of the test and interpretation of results, concluding in inconsistency in the lime quantities calculated. This inconsistency could lead to substantial differences in the estimated cost of the overall scheme and possibly to the unwarranted rejection of lime stabilization as a potential solution. The methodology of the MDSAL test through practical experimentation is reviewed and recommendations for its future use are made. The sensitivity of the test to changes in lime quality, volume of water added, and temperature of the soil-water-lime mixture is examined. It is shown that, although extremely sensitive to changes in these parameters, a revised interpretation of test data means that a reliable and consistent result can be achieved. The scientific basis for this revised interpretation is also demonstrated.