bluuebunny/crossref_metadata_2025 huggingface dataset:
Identifying Friction Variations with the Standard Smooth Tire for Network Pavement Inventory Friction Testing
Authors: Li Shuo , Zhu Karen , Noureldin Samy , Harris Dwayne
Published: May 2018

Because of the evident advantages associated with the smooth tire for the measurement of pavement friction, many highway agencies have become interested in the smooth tire. Pavement friction is the result of tire–pavement interaction. Because of the differences between ribbed and smooth tires, experiences with the ribbed tire may not apply to the smooth tire. Therefore, it is of great importance to evaluate those issues associated with the use of the smooth tire in network pavement inventory friction testing, such as variations in the friction testing system, seasonal friction variations, spatial friction variations, and temporal friction variations. The Indiana Department of Transportation (InDOT) has been using the smooth tire in the network pavement inventory friction test program since 1996. Large amounts of friction data have been obtained in the InDOT friction test track and network pavements. This paper presents the variations in the friction measurements obtained with the smooth tire because of testing system errors and seasonal and temperature effects. The paper also presents the spatial and temporal variations in the friction measurements. It was thought that the results provided in this paper would be useful for highway agencies for determination of test cycle, test spacing, and friction corrections for their network pavement inventory friction testing programs.
Modeling Hydroplaning and Effects of Pavement Microtexture
Authors: Ong G. P. , Fwa T. F. , Guo J.
Published: May 2018

Hydroplaning on wet pavement occurs when a vehicle reaches a critical speed and causes a loss of contact between its tires and the pavement surface. This paper presents the development of a three-dimensional finite volume model that simulates the hydroplaning phenomenon. The theoretical considerations of the flow simulation model are described. The simulation results are in good agreement with the experimental results in the literature and with those obtained by the well-known hydroplaning equation of the National Aeronautics and Space Administration (NASA). The tire pressure–hydroplaning speed relationship predicted by the model is found to match well the one obtained with the NASA hydroplaning equation. Analyses of the results of the present study indicate that pavement microtexture in the 0.2- to 0.5-mm range can delay hydroplaning (i.e., raise the speed at which hydroplaning occurs). The paper also shows that the NASA hydroplaning equation provides a conservative estimate of the hydroplaning speed. The analyses in the present study indicate that when the microtexture of the pavement is considered, the hydroplaning speed predicted by the proposed model deviates from the speed predicted by the smooth surface relationship represented by the NASA hydroplaning equation. The discrepancies in hydroplaning speed are about 1% for a 0.1-mm microtexture depth and 22% for a 0.5-mm microtexture depth. The validity of the proposed model was verified by a check of the computed friction coefficient against the experimental results reported in the literature for pavement surfaces with known microtexture depths.
Who Gains?
Authors: Fosgerau Mogens , Kristensen Niels Buus
Published: May 2018

A public decision by several countries on whether to cofinance an international infrastructure project is the subject of a cost–benefit analysis (CBA). The CBA elements are broken out and analyzed for each country. The issue of freight user benefits is discussed, and results are derived from a partial equilibrium model and point toward practical applicability. A recent analysis of the Fehmarn Belt Bridge, which will connect Denmark and Germany in a link in the Trans-European Network for Transport, is used for illustrative purposes.
Multicriteria Approach to the Evaluation of Intermodal Freight Villages
Authors: Kapros Seraphim , Panou Konstantinos , Tsamboulas Dimitrios A.
Published: May 2018

An integrated methodological process was developed to evaluate the expected effect of freight villages. Because the criteria differ as do their measurement units, multicriteria analysis is proposed. The process required an in-depth analysis of the decision-making process for creating a freight village, the operations and the actors involved, and the most recent best practices. The methodology identifies a set of decision criteria, including environmental quality; contributions to local, regional, and national economies; attractiveness for private financing; contribution to land use changes; and complementarity with other policy plans. In addition, the methodology defines the most appropriate corresponding indicators. The identification of stakeholder categories and decision criteria provides added value to the proposed methodological process. The importance of European transport policies on freight villages and terminals development could mean that the process would be the main contributor in developing a pan-European decision tool to assess such investments, especially if private and public funds were involved. The pilot application is an evaluation of investment in a freight village development in northern Greece. The location was selected because it is at the crossroads of important road and rail axes of trans-European transport networks and the interest expressed by the European Commission and Greek private investors.
Estimating the Impact of Seasonal Truck Shortages on the Movement of Time-Sensitive, Perishable Products
Authors: Jessup Eric , Herrington Ryan
Published: May 2018

This research focuses on the frequent and persistent problem of truck shortages for time-sensitive, perishable produce shipment out of the Pacific Northwest. Washington State is the number one apple-producing state in the United States, accounting for more than 2.7 million tons of apples per year valued in excess of $1 billion. However, without timely and accessible transportation to move the product from production to the consumer's table, the value to apple producers and the state's economy diminishes rapidly. This research aims to identify and quantify the change in total transportation cost that occurs as a result of seasonal truck shortages and associated rate increases and to provide an avenue for evaluating changes in specific destination markets, modal changes, and market competitiveness. A cost-minimizing optimization model is used to represent apple shipments from 29 producing supply points to 16 domestic markets and three international export markets over four seasons for two modes (truck and rail). Total transportation costs increase nearly $12 million as a result of truck shortages, from $245.6 million without shortages to $257.5 million under the current seasonal situation. Overall (across all seasons), the export markets of Nogales, Arizona; McAllen, Texas; and the Port of Seattle, Washington, are most affected by the truck shortages, followed by domestic markets near Seattle and San Francisco, California. The large markets of New York City, New York, and Los Angeles, California also experience relatively large increases in transportation cost per ton mile.
Impacts of Auction Settings on the Performance of Truckload Transportation Marketplaces
Authors: Figliozzi Miguel Andres , Mahmassani Hani S. , Jaillet Patrick
Published: May 2018

The performance of different sequential auction settings for the procurement of truckload services is compared. In this environment, demands arrive randomly over time and are described by pickup and delivery locations and hard time windows. When loads arrive, carriers compete for their transport. Different auction and information disclosure settings are studied. Learning methodologies are discussed and analyzed. Simulation results are presented.
Evaluation of Two Modeling Methods for Generating Heavy-Truck Trips at an Intermodal Facility by Using Vessel Freight Data
Authors: Sarvareddy Pradeep , Al-Deek Haitham , Klodzinski Jack , Anagnostopoulos Georgios
Published: May 2018

A methodology for building a truck trip generation model by use of artificial neural networks from vessel freight data has been developed and successfully applied to five Florida seaports. The backpropagation neural network (BPNN) algorithm was used in the design. Although the methodology was sound, a new model had to be developed for each of these intermodal facilities. Lead and lag variables were necessary input variables for most models to account for commodities stored on port property before export or pickup after import. Other modeling techniques were researched, and a fully recurrent neural network (FRNN) trained by the real-time recurrent learning algorithm was selected to develop a model for Port Canaveral and compare with a BPNN model. FRNN is dynamic in nature and was found to relate to the storage time of the commodities to truck trip generation. A developed Port Canaveral BPNN model was successfully validated at the 95% confidence level with collected field data. It was applied to conduct a short-term forecast of the port's truck traffic for 5 years. The average annual growth of trucks based on the estimated freight activity under the BPNN model was 5.07%. The Port Canaveral FRNN model adequately estimated the current conditions but failed to forecast truck growth. The FRNN model required more data for forecasting than backpropagation. However, when more consecutive data are available for training, FRNN may produce more accurate results.
Development of a Test Method to Measure the Quality of Milling Operations in Asphalt Pavements
Authors: Gallivan Victor L. , Gundersen Joseph F.
Published: May 2018

Cold milling operations have been used for more than two decades in Indiana, but little attention was given to the quality of the operations. Several alternatives for evaluating surface macrotexture were considered as a quality measure. ASTM E965-96 was selected as the best procedure on which to base evaluation of milled surfaces. The Indiana Department of Transportation developed Test Method ITM 812-03T to make the ASTM procedures workable for milled surfaces. The initial quality of hot-mix asphalt (HMA) construction directly affects the long-term performance and the service life of a transportation facility. It is directly dependent on the quality of the aggregates and binders and the production and laydown operations. Construction concerns include surface preparation, which is the removal of distressed materials to develop a stable working platform on which HMA materials can be placed. Indiana HMA contractors were experiencing numerous problems in meeting volumetric and density quality requirements on highway construction projects. A significant number of HMA mixtures were either being accepted with partial payment or replaced before being accepted. Investigation of the problem included observing the contractor's certified HMA plant production operations, mixture components (i.e., aggregates, binders, etc.), mixture transportation, laydown and compaction, and mixture sampling procedures. It was discovered that more problems occurred when cold milling of the existing surface was included in the project. A solution to these issues resulted in the development of improved milling design and construction requirements, which include quality measurement techniques for the milling operations.
Safety of U-Turns at Unsignalized Median Openings
Authors: Levinson Herbert S. , Potts Ingrid B. , Harwood Douglas W. , Gluck Jerome , Torbic Darren J.
Published: May 2018

Many state and local transportation agencies install nontraversable medians on multilane highways to improve safety and travel times and to manage local access better. While nontraversable medians restrict direct left-turn access to and from adjacent developments, traffic destined for these locations must use alternate routes, some of which may involve making U-turns at nearby median openings–-a movement often referred to as an indirect left turn. Until recently, the safety effects of increased U-turn volumes have been largely unknown. NCHRP Project 17–21, Safety of U-Turns at Unsignalized Median Openings, documented the safety performance and operational effects of U-turns at median openings. This paper presents the key findings from that research. It presents a summary of key literature and current highway agency practice related to median openings, a detailed classification scheme for median openings, and a summary of the results of comprehensive field studies. The research results indicate that access management strategies that increase U-turn volumes at unsignalized median openings can be used safely and effectively. Analysis of accident data found that accidents related to U-turn and left-turn maneuvers at unsignalized median openings occur infrequently. In urban arterial corridors, unsignalized median openings experienced an average of 0.41 U-turn-plus-left-turn accidents per median opening per year. In rural arterial corridors, unsignalized median openings experienced an average of 0.20 U-turn-plus-left-turn accidents per median opening per year. On the basis of these limited accident frequencies, there is no indication that U-turns at unsignalized median openings are a major safety concern.
Automation Adoption and Adaptation
Authors: Bolic Tatjana , Hansen Mark
Published: May 2018

The objective of this paper is to present the findings and a set of hypotheses that emerged in the initial steps of an assessment study of air traffic controllers’ adoption and adaptation of new technologies, with the user request evaluation tool (URET) as a case study. The hypotheses are the basis for further study on this topic. The importance of this investigation is to provide a better understanding of changes brought about by the use of decision support tools by sector controller teams. The main purpose of URET is to support sector team strategic planning and allow controllers to concentrate on more user-beneficial control actions. Actual improvements depend on the way controllers use the automation tools in their work. Three aspects were noted about URET usage: ( a) different sector teams use it in different ways, ( b) in many instances URET usage differs from what was intended, and ( c) usage varies across centers. Subject matter experts were interviewed to explore how controllers have adopted and adapted URET across the mentioned variations. The goal of this research is to draw lessons from the experience with URET that can inform technology deployments in the future.
Estimating Intersection Control Delay Using Large Data Sets of Travel Time from a Global Positioning System
Authors: Hoeschen Brian , Bullock Darcy , Schlappi Mark
Published: May 2018

Historically, stopped delay was used to characterize the operation of intersection movements because it was relatively easy to measure. During the past decade, the traffic engineering community has moved away from using stopped delay and now uses control delay. That measurement is more precise but quite difficult to extract from large data sets if strict definitions are used to derive the data. This paper evaluates two procedures for estimating control delay. The first is based on a historical approximation that control delay is 30% larger than stopped delay. The second is new and based on segment delay. The procedures are applied to a diverse data set collected in Phoenix, Arizona, and compared with control delay calculated by using the formal definition. The new approximation was observed to be better than the historical stopped delay procedure; it provided an accurate prediction of control delay. Because it is an approximation, this methodology would be most appropriately applied to large data sets collected from travel time studies for ranking and prioritizing intersections for further analysis.
Exploiting Correlations between Link Flows to Improve Estimation of Average Annual Daily Traffic on Coverage Count Segments
Authors: Goel Prem K. , McCord Mark R. , Park Changyi
Published: May 2018

A method is developed for exploiting correlations among segment flows that result from common origin–destination (O-D) path flows when average annual daily traffic (AADT) is being estimated on highway segments sampled with coverage counts. The method, which can be used with only two daily traffic volumes on the coverage count segment, is based on generalized least squares estimation of AADT, rather than on ordinary least squares estimation, which is traditionally used. The focus is on the correlation between the volumes on a single coverage count segment and a single segment equipped with a continuous automatic traffic recorder (ATR). The performance of this correlation-based method is compared with that of the traditional method through use of thousands of simulated O-D flow replications that are assigned on a small network to determine segment flows. The correlation-based method markedly outperforms the traditional method when the volume on the coverage count segment is highly correlated with that on the ATR segment. When the correlation between the volumes on the coverage count and ATR segments is low, the performance of the two methods is similar. It is expected that future developments for exploiting correlations between volumes on coverage count segments and multiple ATR segments will improve performance further.
Improved Dual-Loop Detection System for Collecting Real-Time Truck Data
Authors: Zhang Xiaoping , Nihan Nancy L. , Wang Yinhai
Published: May 2018

The Washington State Department of Transportation (WSDOT) has a loop detection system on its Greater Seattle freeway network to provide real-time traffic data. The dual-loop detectors installed in the system are used to measure vehicle lengths and then classify each detected vehicle into one of four categories according to its length. The dual loop's capability of measuring vehicle length makes the loop detection system a potential real-time truck data source for freight movement studies because truck volume estimates by basic length category can be developed from the vehicle length measurements produced by the dual-loop detectors. However, a previous study found that the dual-loop detectors were consistently underreporting truck volumes, whereas the single-loop detectors were consistently overcounting vehicle volumes. As an extension of the previous study, the research project described here investigated possible causes of loop errors under nonforced-flow traffic conditions. A new dual-loop algorithm that can address these error causes and therefore tolerate erroneous loop actuation signals was developed to improve the performance of the WSDOT loop detection system. A quick remedy method was also recommended to address the dual-loop undercount problem without replacing any part of the existing system hardware or software. In addition, a laptop-based detector event data collection system (DEDAC) that can collect loop detector event data without interrupting a loop detection system's normal operation was developed in this research. The DEDAC system enables various kinds of transportation research and applications that could not otherwise be possible.
Traffic Measurement and Vehicle Classification with Single Magnetic Sensor
Authors: Cheung Sing Yiu , Coleri Sinem , Dundar Baris , Ganesh Sumitra , Tan Chin-Woo , Varaiya Pravin
Published: May 2018

Wireless magnetic sensor networks offer an attractive, low-cost alternative to inductive loops for traffic measurement in freeways and at intersections. In addition to providing vehicle count, occupancy, and speed, these sensors yield information (such as non-axle-based vehicle classification) that cannot be obtained from standard loop data. Because such networks can be deployed quickly, they can be used (and reused) for temporary traffic measurement. This paper reports the detection capabilities of magnetic sensors on the basis of two field experiments. The first experiment collected a 2-h trace of measurements on Hearst Avenue in Berkeley, California. The vehicle detection rate was better than 99% (100% for vehicles other than motorcycles), and estimates of average vehicle length and speed appear to have been better than 90%. The measurements also yield intervehicle spacing or headways, revealing interesting phenomena such as platoon formation downstream of a traffic signal. Results of the second experiment are preliminary. Sensor data from 37 passing vehicles at the same site are processed and classified into six types. Sixty percent of the vehicles are classified correctly when length is not used as a feature. The classification algorithm can be implemented in real time by the sensor node itself, in contrast to other methods based on high-scan-rate inductive loop signals, which require extensive off-line computation. It is believed that if length were used as a feature, 80% to 90% of vehicles would be correctly classified.
Probabilistic Vehicle Identification Techniques for Semiautomated Transportation Security
Authors: Medeme Narasimha Rao , Sun Carlos C.
Published: May 2018

Intelligent transportation systems can play a significant role in transportation security in addition to their traditional roles in transportation operations and management. A multidetector semiautomated vehicle surveillance framework is presented. The objective of the framework is to assist in the search for a vehicle of interest involved with security threats such as terrorism, abduction, or crime. When a vehicle of interest is wanted, this framework can be applied to reduce surveillance data sets and thus reduce time and labor. This system estimates the a posteriori probabilities that indicate the closeness of the match between a vehicle of interest and any vehicle in the search space. This paper explores the use of multidetector fusion of video and inductive loop data by means of a linear fusion model. This system classifies vehicle pairs into possible correct match or incorrect match classes and transforms the problem into the probabilistic domain by using Bayesian neural networks and probabilistic neural networks (PNNs). The use of Bayesian and PNN classifiers assumes equal losses. With Bayesian estimation and generalized regression neural networks, the a posteriori probability is used as a threshold representing unequal losses. A comparison between the traditional Bayesian approaches and the equivalent neural network methods is presented. The use of different feature combinations, methods to balance training data sets, forward sequential search, and combined and uncombined feature approaches is also investigated. Field arterial data from southern California show that, by retaining only 29% of the search space, the framework produces 92% accuracy, which is a promising result.
Simplifying Delineator Applications for Horizontal Curves
Authors: Chrysler Susan T. , Carlson Paul J. , Williams Alicia A.
Published: May 2018

The human factors study being reported measured drivers’ estimates of horizontal curvature as a function of the size and spacing characteristics of post-mounted delineators. The study also assessed drivers’ understanding of delineator color applications. The main objective of this study was to provide support for simplifying delineator applications of FHWA's Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD), particularly the need to distinguish between single and double delineators and the need to have variable approach and departure horizontal curve delineator spacing. A closed-course nighttime study was conducted with 24 drivers aged 22 to 72 in a passenger sedan with low-beam headlights. Drivers rated their estimates of curvature for large- and small-radii curves from three stationary viewing distances. In addition, participants completed a test of their memory for the proper placement of yellow and white reflectors using photographs of roadways. Results from the visibility study show that drivers cannot distinguish between single and double delineators and they cannot distinguish between variable spacing and fixed spacing on approaches to horizontal curves. The results from the photograph test show that drivers do not understand the difference in placement for yellow and white delineators. As a result, the recommendations include the elimination of the single versus double delineator distinction in MUTCD and the use of a fixed spacing pattern for delineators on the approach to and departure from horizontal curves.
Standard and Nonstandard Roadway Lighting Compared with Darkness at Rural Intersections
Authors: Bruneau Jean-François , Morin Denis
Published: May 2018

This report evaluates the safety aspects of roadway lighting at rural and near-urban three-way and four-way junctions by comparing unlit intersections with those lit with two different types of lighting: ( a) standard intersection lighting provided by the Ministère des Transports du Québec, Canada, and ( b) nonstandard lighting provided by the local municipalities. A night–day accident rate ratio was used to estimate the accident rate reduction for three categories of severity: fatal and personal injury accidents, property damage only accidents, and all accidents. Sites were selected with two sampling modes. The objective mode selected sites according to the accident thresholds, and the arbitrary mode systematically selected all sites with standard lighting. The night–day accident rate ratio was measured for 376 sites by dividing the annual average number of accidents (6,546) with an annual average traffic flow (760 billion vehicles), calculated for both night and day. The accident rate reduction, expressed as a percentage, was tested for validity with the Student's t-test at the 5% p-level. The results were split into 49 categories with 20 variables to ensure that no significant variation existed in the accident rate reduction related to a specific roadway condition or environment. Rural lighting of an intersection significantly reduced the night accident rate by 29% for nonstandard lighting and by 39% for standard lighting, in comparison with darkness. When the two sampling modes were compared, standard lighting reduced the night accident rate of nonstandard lighting by 29%, significant at the 5% p-level, when only objective data in the sampling were used.
Implementing the Mechanistic–Empirical Design Guide Procedure for a Hot-Mix Asphalt–Rehabilitated Pavement in Indiana
Authors: Galal Khaled A. , Chehab Ghassan R.
Published: May 2018

One of the Indiana Department of Transportation's (INDOT's) strategic goals is to improve its pavement design procedures. This goal can be accomplished by fully implementing the 2002 mechanistic–empirical (M-E) pavement design guide (M-E PDG) once it is approved by AASHTO. The release of the M-E PDG software has provided a unique opportunity for INDOT engineers to evaluate, calibrate, and validate the new M-E design process. A continuously reinforced concrete pavement on I-65 was rubblized and overlaid with a 13–in.-thick hot-mix asphalt overlay in 1994. The availability of the structural design, material properties, and climatic and traffic conditions, in addition to the availability of performance data, provided a unique opportunity for comparing the predicted performance of this section using the M-E procedure with the in situ performance; calibration efforts were conducted subsequently. The 1993 design of this pavement section was compared with the 2002 M-E design, and performance was predicted with the same design inputs. In addition, design levels and inputs were varied to achieve the following: ( a) assess the functionality of the M-E PDG software and the feasibility of applying M-E design concepts for structural pavement design of Indiana roadways, ( b) determine the sensitivity of the design parameters and the input levels most critical to the M-E PDG predicted distresses and their impact on the implementation strategy that would be recommended to INDOT, and ( c) evaluate the rubblization technique that was implemented on the I-65 pavement section.
Testing Mixed Logit and Probit Models by Simulation
Authors: Munizaga Marcela A. , Alvarez-Daziano Ricardo
Published: May 2018

Discrete choice models with error structures that are not independent and identically distributed have received enormous attention in the recent literature. A detailed synthetic study tests this type of model in a controlled case. With mixed logit and probit models as the study objects, calibration was implemented with the use of software available on the Internet. The controlled situation was built as a simulation laboratory, which generated databases with known parameters. The effects of various elements were analyzed: number of repetitions of the simulation, number of observations in the database, and how the use of Halton sequences improves the mixed logit calibration. The scale effects on the different models are also discussed. The results obtained in this specific context lead to some recommendations for future users of these powerful modeling tools. In particular, flexible structures require large sample sizes to calibrate the elements of the covariance matrix.
Efficiently Estimating Nested Logit Models with Choice-Based Samples
Authors: Koppelman Frank S. , Garrow Laurie A.
Published: May 2018

Choice-based samples oversample infrequently chosen alternatives to obtain an effective representation of the behavior of people who select these alternatives. However, the use of choice-based samples requires recognition of the sampling process in formulating the estimation procedure. In general, this procedure can be accomplished by applying weights to the observed choices in the estimation process. Unfortunately, the use of such weighted estimation procedures for choice models does not yield efficient estimators. However, for the special case of the multinomial logit model with a full set of alternative-specific constants, the standard maximum likelihood estimator–-which is efficient–-can be used with adjustment of the alternative-specific constants. The same maximum likelihood estimator can also be used with adjustment to estimate nested logit models with choice-based samples. The proof of this property is qualitatively described, and examples demonstrate how to apply the adjustment procedure.
Use of Video Intervention to Increase Elders’ Awareness of Low-Cost Vehicle Modifications that Enhance Driving Safety and Comfort
Authors: Silverstein Nina M. , Gottlieb Alison S. , Van Ranst Elizabeth
Published: May 2018

Use of vehicle modifications might enable older drivers to stay on the road safely and provide a more gradual pathway between driving and driving cessation. Although adaptive features for automobiles have long been known by the disabilities community, they have not been well known by professionals in the network of aging programs and services or by elders themselves. This study examined the use of a video intervention to increase elders’ awareness of low-tech vehicle features. It was hypothesized that participants would have an increased awareness after viewing a video and would take steps toward using the features. The 23–min video was shown to 157 drivers age 70+ at seven Councils on Aging and senior centers in Massachusetts. The median age was 79, and 11% were age 85 and older. The participants completed pre- and postvideo questionnaires, and 127 of the participants (81%) were surveyed by phone approximately 2 months later. Familiarity significantly increased for 10 of 13 demonstrated features. On average, participants had taken two of five follow-up steps: 85% had read handouts, 63% had discussed features with family or friends, 20% had looked for features in stores or on the Internet, 9% had tried features, and only 2% had contacted a professional. Eleven percent of the telephone interviewees had purchased features. The video served the intended purpose of increasing awareness of vehicle modifications. Although some change was noted, 2 months may not have been sufficient time to observe change for the majority of the participants. Moreover, it is not known to what extent the participants may draw on this knowledge in the future, if and when they perceive a more direct need.
Programming Safety Improvements on Pavement Resurfacing, Restoration, and Rehabilitation Projects
Authors: Grile Cameron , Hunter-Zaworski Katharine M. , Monsere Christopher M.
Published: May 2018

As part of the project planning process, highway agencies must allocate limited funding to a substantial list of projects that exceeds available resources. For preservation projects, a key component of this decision is to determine which projects receive safety improvements and which are “pave only.” Traditionally, this decision has been made project by project, with the possible result of a selection that does not maximize safety benefits. This paper takes a case study approach and applies a new tool developed in NCHRP Report 486, the Resurfacing Safety Resource Allocation Program (RSRAP), to a subset of the Oregon Department of Transportation's (DOT's) highway network. The RSRAP tool maximizes safety improvements for a given set of projects and budget. Thirty-three projects scheduled to receive a new road surface were selected and analyzed with RSRAP. These projects were subdivided into smaller sites to meet the assumptions of RSRAP. Road geometry, traffic volumes, and crash history for each site were collected and input into the program. The type and cost of the safety improvements output by RSRAP were compared with those selected by Oregon DOT. This research determined that RSRAP, which selected more projects for safety improvements than did Oregon DOT, is a tool that could be used by the department to select various safety improvements on pavement preservation projects. It was also determined that the budget used by Oregon DOT was large enough that all cost-effective improvements could be made.
Modeling Traffic Volatility Dynamics in an Urban Network
Authors: Kamarianakis Yiannis , Kanas Angelos , Prastacos Poulicos
Published: May 2018

This article discusses the application of generalized autoregressive conditional heteroscedasticity (GARCH) time series models for representing the dynamics of traffic flow volatility. The methods encountered in the literature focus on the levels of traffic flows and assume that variance is constant through time. The approach adopted in this paper concentrates primarily on the autoregressive properties of traffic variability, with the aim to provide better confidence intervals for traffic flow forecasts. The model-building procedure is illustrated with 7.5-min average traffic flow data for a set of 11 loop detectors located at major arterials that direct to the center of the city of Athens, Greece. A sensitivity analysis for coefficient estimates is undertaken with respect to both time and space.
Trial-and-Error Procedure for Implementing a Road-Pricing Scheme
Authors: Meng Qiang , Xu Wei , Yang Hai
Published: May 2018

This paper deals with a road-pricing scheme that aims at alleviating congestion phenomena or air and noise pollution in some areas of a transportation network in such a way that the volumes of traffic flow on entry links to these areas do not exceed their respective predetermined thresholds by levying appropriate tolls at these links. This paper begins to show that the road-pricing scheme is equivalent to a problem that determines optimal Lagrangian multipliers for a user equilibrium traffic assignment problem with link capacity constraints. It then proceeds to devise a novel trial-and-error procedure requiring observed traffic flows at the entry links only, to identify a solution for the road-pricing scheme when link travel time functions, origin–destination demand functions, and users’ value of travel time are unknown. The procedure is as follows. A trial on a set of given tolls is conducted, and then the resultant link flows are observed. According to these observed traffic flows, a new set of tolls for the next trial is adjusted by executing a simple projection operation. The trial-and-error procedure is, in fact, a variation of a gradient projection method for dual formulation of the traffic assignment problem, and its convergence can be guaranteed under mild conditions. Accordingly, a conjecture for the convergence of trial-and-error implementation of the congestion pricing proposed by economists is rigorously proved. Furthermore, the iterative procedure presented in this paper in practice can facilitate the estimation of such tolls by land transport authorities.
Dynamic Vehicle Routing Problem with Multiple Objectives
Authors: Tang Hao , Hu Mingwei
Published: May 2018

This paper addresses a dynamic vehicle routing problem related to courier mail services with explicit consideration of multiple objectives. This problem is modeled as a dynamic traveling repairman problem with time windows, and with three objectives considered: maximization of the number of serviced customers, minimization of customer waiting, and minimization of total travel time. A solution (simulation) framework, extending techniques developed for single-objective dynamic routing problems in the literature, is proposed to tackle this multiobjective problem. An efficient chained local search heuristic is embedded in this solution framework to solve the underlying static problem, the traveling salesman problem with time windows. Comprehensive simulation experiments conducted on data sets derived from benchmark problems show that the proposed algorithmic approach is able to provide high-quality solutions with limited computing effort. These experiments also indicate that the multiobjective model proposed in this study can offer much more attractive solutions to decision makers than single-objective models.
Dynamic Prediction Method with Schedule Recovery Impact for Bus Arrival Time
Authors: Chen Mei , Liu Xiaobo , Xia Jingxin
Published: May 2018

This study develops a dynamic bus arrival time prediction model using the data collected by the automatic vehicle location and automatic passenger counter systems. It is based on the Kalman filter algorithm with a two-dimensional state variable in which the prediction error in the most recent observation is used to optimize the arrival time estimate for each downstream stop. The impact of schedule recovery is considered as a control factor in the model to reflect the driver's schedule recovery behavior. The algorithm performs well when tested with a set of automatic vehicle location–automatic passenger counter data collected from a real-world bus route. The algorithm does not require intensive computation or an excessive data preprocessing effort. It is a promising approach for real-time bus arrival time prediction in practice.
Communication Strategies for State Transportation Research Programs
Authors: Knott Diana , Martinelli David
Published: May 2018

Transportation research is often open ended and difficult to measure in that its beneficiaries may not know how they have been served by research activities and results. This research project sought to ( a) obtain feedback from Ohio Department of Transportation (Ohio DOT) constituents; ( b) develop a strategic communication plan that supports Ohio DOT's overall mission and goals, keeping in mind research office resources; and ( c) develop a communication template that other departments of transportation could model or use. To accomplish those objectives, existing knowledge, attitudes, and behaviors concerning Ohio DOT's research office were obtained through a number of surveys. Those surveyed included the Ohio general public, internal DOT constituents (technical liaisons, administrators and directors, district deputy directors, district research contacts, and FHWA regional center directors), and external DOT constituents (consultants, contractors, transportation committee legislators, and college civil engineering department heads). In addition, a nationwide survey of department of transportation research office directors was conducted to determine the constituents with whom these offices communicate and the means by which they do so. Common areas of interest among constituents were identified; from those, key research-office message points were proposed, as were constituents’ preferred methods of receiving research office information. The study also found that most research office directors believed that they communicated well internally but did not communicate effectively to external audiences. Part of this problem could lie in their failing to utilize communication office personnel, who have the expertise and contacts to spread the word about transportation research.
Transportation Megaprojects, Globalization, and Place-Making in Hong Kong and South China
Authors: Dimitriou Harry T. , Trueb Oliver
Published: May 2018

This paper draws on an argument presented at the 2005 TRB Annual Meeting by one of its authors claiming that traditional methods of evaluating transportation megaprojects (TMPs) are outdated in the new globalized world. Although planners understand the importance of conventional techniques of forecasting, appraisal, cost funding, and so forth to ensure that a project attains desired levels of operational efficiency, they are less familiar with the impact such projects have on places and communities in the name of enhancing competitiveness. In the context of Hong Kong and South China, this paper examines whether TMP experts are in the process of duplicating past errors of urban transport planners, but on a massively larger scale, by introducing new TMPs in a manner that restructures whole regions to meet the “operations efficiency” of networks above all else and, in so doing, benefits global (corporate) interests more than local, even though their patrons often have local and national governments meeting the lion's share of financial, social, and environmental costs (as well as risks).
Urban Campers as a New Population for Community Impact Assessment
Authors: Potier-Brown Laurie , Pipkin Gwen
Published: May 2018

All states and cities and most towns have urban camper communities. “Urban camper” is a working term for homeless people who live in urban or suburban areas. The term helps differentiate campers with stable, minimally developed night locations from those homeless who have nowhere consistent to go. Camper populations vary from one to several hundred. They live in tents or shanties without services or utilities. Many residents work, access shopping and services, and send their children to school. Their camp communities are their homes. Public safety and social service agencies know these people, but they are invisible to the average citizen. Many urban campers are U.S. citizens, but the mainstream community has traditionally overlooked their legal and personal rights. Acknowledging their rights may cause legal problems for local governments. Land development and land use changes can force campers out of campsite locations. Sometimes they find out about changes the morning bulldozers arrive. A widening of U.S. Highway 301 in Sarasota, Florida, would have displaced hundreds of urban campers who lived in wooded patches along the roadway. The Florida Department of Transportation asked a community impact assessment (CIA) team to identify the problem's scope and to ensure that this displacement would proceed better than past displacements. The CIA team surveyed area social service agencies (SSAs) that are used regularly by many urban campers. Because traditional CIA meetings were not feasible or welcome, SSA staff became the conduit for communication with informal camp leadership. The CIA team kept SSAs updated. Before construction started the majority of urban campers had melted away.
Fare Pricing Elasticity, Subsidies, and Demand for Vanpool Services
Authors: Concas Sisinnio , Winters Philip L. , Wambalaba Francis W.
Published: May 2018

Practitioners of transportation demand management consider pricing a crucial determinant of vanpool market demand. Publicly sponsored programs stress the significance of fare pricing and subsidies as key tools for increasing ridership. This paper considers the use of discrete choice modeling techniques to investigate the effects of fares and fare subsidies on the demand for vanpool services. With the use of employer and employee data from the 1999 survey of the commute trip reduction program of the Puget Sound region (Washington), a conditional discrete choice model is built to analyze the choice of vanpool services, with competing means of transportation as a function of various socioeconomic characteristics. The predicted value of the direct elasticity is -0.73; a 10% increase in vanpool price is associated with a 7.3% decrease in its demand and vanpool demand is relatively inelastic with respect to fare changes. For trips shorter than 30 mi, the individual elasticities are equivalent to the aggregate estimate. As the distance from home to work increases beyond 60 mi, individuals are less responsive to price changes. Subsidies have a relevant impact in increasing ridesharing, controlling for firm size and industry sector. Whenever employees are offered a subsidy, the predicted probability of choosing vanpool more than doubles. These results show that factors other than fare pricing, such as employee profile, industry sector, firm size, parking policies, and travel patterns, must be taken into account when policies or designing fare schedules geared at stimulating ridership are implemented.
Probe-Based Traffic Monitoring Systems with Wireless Location Technology
Authors: Fontaine Michael D. , Smith Brian L.
Published: May 2018

As agencies place more emphasis on monitoring and managing the roadway network, the concept of traffic monitoring systems based on wireless location technology (WLT) is generating increasing interest. WLT-based monitoring anonymously samples the location of probes or drivers by using wireless devices, such as cellular phones. By using a series of these probe vehicle locations, WLT-based monitoring systems could generate true point-to-point speed estimates with a minimal infrastructure investment. Unfortunately, early deployments of these systems have not been entirely successful in generating the quality of information needed by transportation agencies and the public. When transportation agencies are approached by vendors of WLT-based monitoring systems, they have little information to determine whether the system is likely to be effective. The relationship between the design of a WLT-based monitoring system and the accuracy of speed estimates that it generates is explored. A simulation-based approach was used to define general guidelines for different aspects of system design and roadway network characteristics. The type of map matching used, the frequency between position estimates, the error of position estimates, and roadway network geometry were shown to have a significant impact on generating accurate speed estimates from a WLT-based monitoring system.
Integration of Diamond Interchange and Ramp Metering Operations
Authors: Tian Zong , Messer Carroll , Balke Kevin , Urbanik Thomas
Published: May 2018

The aim of this research was to develop operational strategies for integrating the operations between diamond interchange traffic signals and ramp metering signals. Integrated operational strategies were developed on the basis of the two commonly used diamond interchange phasing schemes: the basic three-phase scheme and the Texas Transportation Institute four-phase scheme. The key elements of the integration system and its operations include a proposed enhanced detection system and an operational algorithm. Through implementation of special signal timings at the diamond interchange, the traffic flows feeding the ramp meters can be effectively controlled and thus minimize ramp queues and the resulting need to flush the queues, which would possibly lead to freeway breakdown. The operational strategies were evaluated with VISSIM microscopic simulation under three general traffic demand scenarios–-low, medium, and high–-as characterized by the volume-to-capacity ratios at the metered ramps. The results of the evaluation indicated that the integrated operations were most effective under a medium traffic demand scenario in preventing or delaying the onset of ramp metering queue flush, thereby reducing freeway breakdown and system delays.