bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Evaluation of a Pavement Imaging System
Authors: Mraz Alexander , Gunaratne Manjriker , Nazef Abdenour , Choubane Bouzid
Published: May 2018

The Florida Department of Transportation (FDOT) has acquired and validated a multifunctional survey vehicle for the collection of highway pavement–related data at normal operating speeds. With its ability to collect pavement, right-of-way, and side-view images together with position location, cross-slope, grade, curvature, rutting, and roughness data, this state-of-the-art vehicle enables the rapid and automated evaluation of roadway performance and identification of hazardous conditions. Manual surveys that involve a high degree of subjectivity, a low production rate, and exposure to hazardous conditions are still the most widely used means for evaluating pavement distress. The pavement evaluation subsystem of the FDOT survey vehicle represents an efficient, cost-effective, and safe alternative for the collection and evaluation of pavement distress data. In the research reported in this paper, the precision and accuracy of the pavement imaging subsystem was tested under different lighting conditions, speeds, pavement types, and with or without the special pavement lighting system. The evaluation of pavement image quality has been achieved with the signal-to-noise ratio. Moreover, the effect of the vehicle's speed and the geometrical distortion in the image caused by optical distortion and distance measurement sensor error were also investigated. The conclusions and the recommendations drawn from this study can be used to identify the limitations of automated surveys and to determine the optimum conditions for the most accurate distress evaluation.
Development and Validation of a Mechanistic Recursive-Incremental Deterioration Model for Cement-Stabilized Base Courses
Authors: Busch Christian , Thøgersen Finn , Henrichsen Anders
Published: May 2018

Contemporary pavement analysis and design is increasingly relying on recursive–incremental analysis in the prediction of pavement performance. This paper describes the development and calibration of a model for the prediction of deterioration of cement-stabilized base course layers. The model was developed on the basis of full-scale testing of six pavements with different aggregate compositions and strength characteristics. The model was then validated against measured performance on actual motorway sections, and it was found that it could be applied directly without any shift factor functions. The result is a central estimate recursive–incremental model suited for application in performance-simulation design systems and a generalized set of equations defining mechanistic–analytical design criteria.
Visual Rating and Strength Testing of 40-Year-Old Precast Prestressed Concrete Bridge Piling
Authors: Shdid Caesar Abi , Ansley Marcus H. , Hamilton H. R.
Published: May 2018

The rating of bridge piles is primarily visual and requires judgment to quantify damage levels and, ultimately, to estimate the pile's remaining structural capacity. A series of tests was run to evaluate the existing capacity of piles that have been in service in a harsh saltwater environment for more than 40 years. In 2004, the Bryant Patton Bridge over Apalachicola Bay in the Florida Panhandle was replaced with a new bridge. The original bridge, which was demolished as part of the construction project, was constructed in 1963. During demolition, 12 pre-stressed concrete piles with varying levels of corrosion damage were recovered. Two of the selected piles were equipped with cathodic protection at the time of their installation in 1994 as part of a repair project that involved most of the pilings supporting the bridge. Visual inspections were conducted by Florida Department of Transportation divers on the selected piles before they were removed. After recovery of the piles, they were cleaned and flexurally tested to failure in a four-point bending test. The results of the flexural tests are presented along with a visual rating of the piles from the divers’ inspection. Flexural capacities of the existing piles were compared with the calculated moment capacities and the undamaged flexural capacities (determined from testing). A few piles that showed little outward sign of damage had a severe reduction in the actual flexural capacity, indicating that assessments by visual inspection do not necessarily correlate well with the actual flexural capacity of piles.
Construction-Induced Stresses in H-Piles Supporting an Integral Abutment Bridge
Authors: Sandford Thomas C. , Davids William G. , Hartt Sarah L. , DeLano John G.
Published: May 2018

Although the advantages of integral abutment bridges are widely known, design practices and assumptions vary extensively, especially when bridges have skew. Some agencies explicitly calculate bending effects on piles, but many do not consider the dead load bending. Piles traditionally have been required to be deep enough in soil to achieve fixity. The monitoring of the performance of a skewed integral abutment bridge on shallow bedrock in Coplin Plantation, Maine, during construction is reported. The sequence and procedure of construction was analyzed to assess its effects on stresses in the pilings. Stresses from bending in the direction of the centerline were equal to or greater than stresses from axial loading of the piles. These stresses were related to rotation of the abutment caused by dead loads. Stresses from bending perpendicular to the roadway centerline were apparently related to the skew and were less than one-third of the bending parallel to the centerline. Axial loads and maximum stresses varied among piles, although skew effects and pile foundation fixity differences accounted for some, but not all, variability. Maximum stresses were less in the piles without fixity; this indicates that construction loadings support the feasibility of designing integral abutment piling without fixity.
Numerical Simulation of Dynamic Behavior of Geofoam Embankment
Authors: Kalinski M. E. , Pentapati D. P.
Published: May 2018

Geofoam is gaining in popularity as a lightweight alternative to soil for construction of embankments. However, its properties are significantly different from those of soil, and the dynamic behavior of the embankment is affected by the presence of geofoam. Two-dimensional numerical modeling of a simple embankment was performed to quantify the effect of geofoam on the dynamic behavior of the embankment. The dynamic responses of three embankments–-one constructed entirely of soil, one constructed entirely of geofoam, and one constructed of geofoam with a soil veneer–-were simulated. Regarding surface shaking, accelerations on the surface of the geofoam embankments were higher than those on the surface of the soil embankment. Regarding liquefaction, cyclic stress ratios of subgrade soils beneath the geofoam embankment were higher than those beneath the soil embankment, primarily because of the reduced effective stress caused by the use of geofoam instead of soil. Finally, factors of safety against interblock slippage calculated within a geofoam embankment indicate that earthquake-induced interblock sliding is more likely near the center and top of the embankment. These observations indicate that caution is warranted when geofoam is used in areas of high seismicity to anticipate properly the effect of geofoam on the behavior of the embankment and subgrade during strong ground motion shaking.
Deflection of Prototype Geosynthetic-Reinforced Working Platforms over Soft Subgrade
Authors: Kim Woon-Hyung , Edil Tuncer B. , Benson Craig H. , Tanyu Burak F.
Published: May 2018

Large-scale experiments were conducted on working platforms of crushed rock (breaker run stone or Grade 2 gravel) overlying a simulated soft subgrade to mimic conditions during highway construction where a working platform is used to limit total deflections because of construction traffic. Tests were conducted with and without geosynthetic reinforcement to evaluate how deflection of the working platform is affected by the presence of reinforcement, type of reinforcement, and thickness of the working platform. Four different geosynthetics were used: geogrid, woven geotextile, nonwoven geotextile, and drainage composite. Reinforced working platforms deformed at a slower rate, and, in most cases, deformation of geosynthetic-reinforced working platforms nearly ceased after approximately 200 loading cycles. Total deflections at 1,000 cycles were smaller by a factor of approximately two for reinforced working platforms relative to unreinforced working platforms, and smaller deflections were associated when less extensible geosynthetics were used for reinforcement. The thickness of a geosynthetic-reinforced working platform needed to meet a target deflection diminished approximately linearly with increasing logarithm of the interaction modulus, a measure of in situ extensibility measured in a pullout box. The reduction in working platform thickness attained with reinforcement was also larger when the target total deflection was smaller.
Cyclic Performance of Precast Concrete Segmental Bridge Columns
Authors: Ou Yu-Chen , Chiewanichakorn Methee , Ahn Il-Sang , Aref Amjad J. , Chen Stuart S. , Filiatrault Andre , Lee George C.
Published: May 2018

The cyclic performance of an unbonded precast concrete segmental bridge column system is examined in this paper. This system uses unbonded posttensioning to enhance the self-centering capability and mild steel reinforcement extended across the segment joints to enhance the energy dissipation capability. A simplified analytical method for the system under lateral load is established, and the simplified analytical results are compared with those obtained from the three-dimensional (3-D) finite element method (FEM). On the basis of the simplified analytical method, suggestions are made about both the height of the column to which the mild steel should be continued from the foundation and the limitation of the steel ratio to minimize residual displacement. With the steel ratio varied, the correlation between the energy dissipation capability and the self-centering capability of this system is investigated by means of the 3-D FEM. From simulation results, it was found that both the energy dissipation and the residual displacement increase as the steel ratio increases. It was also found that the system with a steel ratio suggested by the proposed equation resulted in a significant increase in energy dissipation compared with the one without mild steel across the joints, while the recommended system maintained a small residual displacement after loading reversals.
Parametric Study of Influence of Profile Geometry on Structural Performance of Buried Profile-Wall Pipe
Authors: Burgon Rex P. , Folkman Steven L. , Moser A. P.
Published: May 2018

A study at Utah State University examined the performance of buried high-density polyethylene profile-wall pipe to provide guidance for its proper design. One aspect of this effort was a parametric study of various pipe profiles through use of linear, three-dimensional finite element models. An experimental portion of this project showed that pipes that performed well in buried tests also performed well in parallel-plate tests. This paper summarizes the results of a parametric study of profile-wall pipes in parallel-plate tests. Among the several profile features examined were pipe profile height, profile curvature, wall angle, rib width, and wall thicknesses. In the completed parametric studies, a single dimension was varied while most of the remaining parameters were maintained at constant values. To simplify the analysis, this effort was limited to linear finite element models: the displacements are assumed to be small and the material linear elastic. The small displacement assumption was accurate for the estimation of stiffness at 5% deflection but may not represent buckling correctly. Linear static and linear buckling analysis results are presented. One of the most significant conclusions from this study was that the arch curvature or profile shape had a significant effect on the stability of profile-wall pipe. Plots showing the influence of parameters such as profile height, shape, and thickness on pipe stiffness and buckling are presented.
Cost-Effective, Structural Stay-in-Place Formwork System of Fiber-Reinforced Polymer for Accelerated and Durable Bridge Deck Construction
Authors: Ringelstetter Thomas E. , Bank Lawrence C. , Oliva Michael G. , Russell Jeffrey S. , Matta Fabio , Nanni Antonio
Published: May 2018

This paper describes research on the evolution of a cost-effective, structural stay-in-place (SIP) formwork bridge deck system with an integrated modular three-dimensional fiber-reinforced polymer (FRP) reinforcement cage. Recent research conducted at the University of Wisconsin is reviewed to show the evolution of the reinforcing system to include an integral FRP SIP form. The evolution occurred through laboratory testing, which was followed by the design and construction of two bridge structures owned by the State of Wisconsin. Each structure used different FRP reinforcement and formwork. These projects pointed out the need for a competitive SIP formwork to be used in conjunction with FRP reinforcement. Two specimens with different FRP reinforcement and SIP formwork arrangements were tested. Full-scale deck slab specimens were tested by applying a simulated wheel design load to investigate the static response, ultimate capacity, and failure mechanism. The most economical FRP reinforcing system has been implemented in a superstructure replacement project in Greene County, Missouri.
Exploratory Analysis of Children's Travel Patterns
Authors: McDonald Noreen C.
Published: May 2018

Recent concerns about obesity in children have focused attention on children's travel behavior; however, there has been little study of children's travel. Five questions should be asked to fill this knowledge gap: ( a) How much are children traveling? ( b) Why are children traveling? ( c) With whom are children traveling? ( d) How do the observed travel patterns vary with demographic characteristics such as age, race, sex, and income? and ( e) What are the barriers to the analysis of children's travel? Data from the 2001 National Household Travel Survey show that children's travel is similar to that of adults. For example, youth travel is dominated by the automobile, with nearly 75% of trips being made in a private vehicle. But in important ways children's travel is different. Because of their youth, children often travel with others. However, the burden of transporting children is not distributed equally between parents; young children are more than five times as likely to travel with their mothers as with their fathers. Age also greatly affects how much children travel. Finally, small changes in current travel surveys could make them much more useful for the analysis of children's travel.
Manifestations of Development Goals in Transit-Oriented Projects
Authors: Dunphy Robert T. , Porter Douglas R.
Published: May 2018

Transit-oriented development (TOD) has become popular across the nation not just as a partial solution for rampant highway traffic congestion but also as a way of life. The emphasis of TOD on creating a close-knit, pedestrian-friendly, distinctively designed form of urban and suburban development appears able to elicit support even where transit service is minimal or nonexistent. TOD is solidly ensconced as a significant component of smart growth, sustainable development, and new urbanism. Public officials often view the concept as a valuable building block for developing accessible and attractive communities, and transit agencies value its generation of increased ridership. The benefits of TOD for transit operators and broader transportation policies are fairly well established. Less well appreciated is that urban sites most suitable for TODs are transit friendly but often developer unfriendly, since they are often more expensive and more complicated to develop. In contrast, the suburban locations most desired by residents and businesses are developer friendly but transit unfriendly. For them to support transit requires special efforts to increase density, mixed uses, and pedestrian orientation, qualities uncommon and often resisted in the suburbs. A number of projects generally considered among planners and developers to be effective TODs were examined, and their strengths and weaknesses are reviewed from a transit perspective, on the basis of several specific principles. The TOD concept is demonstrated to be alive and well and evolving toward the described ideals.
Social Commitments and Activity-Travel Scheduling Decisions
Authors: Kemperman Astrid , Arentze Theo , Timmermans Harry
Published: May 2018

Social activities have received only scant attention in activity-based analysis. These activities commonly have been considered as one coherent group or have been combined with other discrete activities. Because more knowledge about social activities and commitments is needed, several descriptive and explanatory analyses are presented to examine the differences in the scheduling of various social activities. Results indicate that different kinds of social commitments and activities show distinct scheduling patterns.
Impact of E-Economy on Traffic and Traffic-Related Indicators in Urban Areas
Authors: De Jong Gerard , Algers Staffan , Papola Andrea , Burg Robert
Published: May 2018

As part of the Prediction of E-Economy Impacts on Transport (POET) project for the European Commission, the impact of the e-economy (including an increasing uptake of teleworking and teleshopping and better use of intelligent transport systems) on transport in a number of selected urban areas in Europe was modeled. The modeling for the urban areas used existing transport models (passengers and freight) for Paris; Stockholm, Sweden; Naples, Italy; Hamburg, Germany; and the Randstad, the Netherlands. Second, it used several scenarios on the degree to which information and communication technologies would be adopted for the year 2010. The third element in the modeling at the urban level was the use of so-called front-end models, estimated on new stated preference data. The outcomes in vehicle kilometers were also used to calculate the impact of the e-economy on energy use, emissions, and traffic accidents. Also, for some areas, impact on congestion and accessibility was calculated. For some of the areas and scenarios, considerable reductions in passenger kilometerage were found as a result of e-economy developments, but freight transport increased.
Noncoordinated Phases in Coordinated Traffic Signal System
Authors: de Castro-Neto Manoel Mendonca , Urbanik Thomas , Han Lee D.
Published: May 2018

Currently, there is no standard nomenclature to describe coordination modes. Different traffic signal controller manufacturers use various terms, and the terms are not always easily understood. Furthermore, there is no documented understanding of the effectiveness of alternative approaches. The purpose of this study is to investigate the main issues related to noncoordinated movements of coordinated semiactuated traffic signals. A set of consistent terms and definitions is proposed. Based on this terminology, three coordination modes are presented, and their performance is evaluated for three different volume-to-capacity (v:c) ratios by using hardware-in-the-loop simulation. With average vehicle delay as the measure of effectiveness, results suggest that for lower v:c ratios, the modes perform differently. This paper provides some guidance on the use of coordinated semiactuated traffic signal operation by making traffic engineers aware of how different coordination modes can affect intersection performance.
In-Service Evaluation of Detection–Control System for Isolated High-Speed Signalized Intersections
Authors: Zimmerman Karl , Bonneson James A.
Published: May 2018

An innovative detection–control system was developed for the Texas Department of Transportation to reduce both delay and crash frequency at rural intersections. This system was implemented at several intersections in Texas, and its safety and operational benefits were evaluated. This report documents findings and conclusions reached after a 3-year implementation project. The detection–control system was installed and evaluated at each of five intersections in Texas during the 3-year period. Evaluation of before-and-after data indicates that the new detection–control system was able to reduce approach delay by 14%, stop frequency by 9%, red light violations by 58%, heavy-vehicle red light violations by 80%, and severe crash frequency by 39%.
New Method to Design Traffic Control Programs
Authors: Muller Theo H. J. , de Leeuw Martijn
Published: May 2018

A control structure shows the sequence of realization of all green phases. Often, control structures designed for fixed-time control are based only on the order of the critical conflict group. When applied to vehicle-actuated control, structures based only on the critical conflict group regularly lead to inefficient control structures. Because of its flexibility, vehicle-actuated control requires a different approach for designing control structures. This paper presents a design method based on combining maximum conflict groups (mutual conflicting streams), resulting in all possible control schemes. Based on volume and saturation flow rate and assuming a uniform arrival process, each control scheme has a specific minimum cycle length. By ordering a control scheme according to its minimum cycle length and its flexibility to adjust green periods to varying traffic demand, the designer is supported in the process of choosing the most appropriate control scheme. This method was recently implemented in the Traffic Control Program Generator design support program and is used for training practitioners. If the minimum cycle length is less than the accepted maximum cycle, volumes can be increased proportionally to find maximum extension green times. In the near future, the Dutch province of South Holland intends to implement this method in a controller to generate online the most suitable control structure and control parameters.
Application of Microscopic Simulation Model Calibration and Validation Procedure
Authors: Park Byungkyu (Brian) , Won Jongsun , Yun Ilsoo
Published: May 2018

In the application of microscopic simulation models, the importance of model calibration and validation cannot be overemphasized. A recent study proposed a systematic approach for conducting a simulation model calibration and validation procedure on the basis of experimental design and optimization and applied it to an isolated intersection with a VISSIM simulation model. The present study further evaluates the previously developed simulation model calibration and validation procedure by applying it to an urban arterial network consisting of 12 coordinated actuated signalized intersections. Both VISSIM and CORSIM simulation models were used. Travel time was used for the calibration measure, and maximum queue length was used for the validation measure. Study results showed that calibrated and validated simulation models were able to represent field conditions adequately, whereas default parameter–based models could not. As such, the previously developed simulation model calibration and validation procedure was proved effective for an arterial network under both VISSIM and CORSIM simulation models.
Effects of Base Type on Modeling Long-Term Pavement Performance of Continuously Reinforced Concrete Sections
Authors: Johnston Daniel P. , Surdahl Roger W.
Published: May 2018

Newer continuously reinforced concrete (CRC) pavements in South Dakota have exhibited undesirable levels of transverse cracking. This poor performance was not expected under the current recommended design practices. Long-term pavement performance (LTPP) CRC pavement data, previously analyzed by others, also could not account for the cracking. To seek an explanation, the original LTPP CRC data was reanalyzed with a more thorough approach. With multiple regression techniques on selected LTPP CRC data sets of comparable accuracy, consequential conclusions can be drawn once the base types are separated into subsets in the database. A similar model was developed for newer CRC pavements in South Dakota, and they showed the same response variables as the LTPP subset for granular bases. Significant correlation was found between cracks and steel depth, cracks and steel size, and cracks and pavement thickness, such that recommendations are made for South Dakota to decrease the steel depth and decrease the steel size and percentage. The nominal top size of the coarse aggregate was also found to be a significant contributor to crack width, with a shift from 3/4 in. to 11/2 in. resulting in a reduction in crack width and a much slower development of cracking over time.
Implications of Risk Perception under Assumption of Rational Driver Behavior
Authors: Tarko Andrew P. , Figueroa Medina Alberto M.
Published: May 2018

This paper presents research on driver risk perception and its connection with driver selection of speed and with highway safety. The paper also supports the theory of rational behavior. The implications of driver risk perception on the speed–safety relationship and on use of speed as a surrogate measure of safety are discussed. The authors distinguish two distinct speed–safety relationships: one under fixed roadway conditions and the second under changing roadway conditions. The paper demonstrates that a population of drivers can perceive risk that is consistent with the actual risk of crash, and that assumption of rational behavior is useful in explaining why roads with higher speeds are perceived as, and tend to be, less risky. Road improvements are used by drivers mainly to improve mobility and, to a lesser extent, their road safety. Speed can be used as a surrogate measure of safety if the change in speed has been accomplished without changing the road geometry. Otherwise, the safety effect of the improvement is not clear and should be evaluated directly using crash-based statistics.
Modeling Pipeline Driving Behaviors
Authors: Zou Xi , Levinson David M.
Published: May 2018

Driving behaviors at intersections are complex. At intersections, drivers face more traffic events than elsewhere and are thus exposed to more potential errors with safety consequences. Drivers make real-time responses in a stochastic manner. This study used hidden Markov models (HMMs) to model the driving behavior of through-going vehicles on major roads at intersections. Observed vehicle movement data were used to estimate the model. A single HMM was used to cluster movements when vehicles were close to the intersection. The reestimated clustered HMMs could more accurately predict vehicle movements compared with traditional car-following models.
Rewards for Safe Driving Behavior
Authors: Mazureck Undine , van Hattem Jan
Published: May 2018

The most important objective of the Department of Transport (DOT) in the Netherlands is to make Dutch freeways safer and less congested. To achieve these objectives, standard practice has been to influence the behavior of road users through punitive measures. To investigate the feasibility of doing the opposite, namely, influencing behavior by offering rewards, and of its usefulness if it worked, the DOT launched the Belonitor trial. Each year, tailgating and speeding cause much irritation on roadways. Moreover, these violations often play a role in accidents and congestion. The Belonitor trial therefore focuses on two preferred modes of behavior: maintaining sufficient distance and maintaining the applicable maximum speed. The lease company LeasePlan Nederland N.V. (LPNL) fitted 62 lease cars with equipment that recorded whether drivers maintained sufficient distance from the car ahead and drove within the posted speed limit. The equipment included a display that continuously showed drivers their following distance and speed. LPNL rewarded lease-car drivers for good driving behavior over a 16-week period. The data obtained from surveys, interviews, and the in-car system indicate that feedback and rewards have a strong positive effect on safe driving behavior. The trial results also indicated differences in how drivers handle speed and following distance. In the Belonitor trial, DOT traffic safety objectives were successfully combined with profit goals of the lease company.
Learning to Drive the Transportation System
Authors: Paine Scott C. , Kramer Jeff , Beardall Hal , Perdomo Jessica
Published: May 2018

Members of a key set of players in the transportation planning process achieve positions of influence, not by virtue of training or experience in the field, but by virtue of popular election. These individuals often begin their service on metropolitan planning organization (MPO) governing boards with little or no background in transportation planning. What would it take to provide these “lay” governing board members with the knowledge they need to be effective decision makers in the transportation planning process? A study of MPO planning participants in Florida sought to answer this question. A combination of focus groups and survey research was used to develop a priority ranking of broad subject areas and a critical short list of key concepts for training MPO governing board members. While MPO structures and practices vary from state to state, MPO staff and other transportation professionals from across the country will find the research results described in this paper valuable when considering the probable training needs of their own MPO participants.
I-285 Matrix Variegator
Authors: Simons Chris
Published: May 2018

When trip tables from travel demand models are applied to simulation modeling, the demands are often unrealistically high. Unreasonable demands produce extreme congestion in simulation models, resulting in unusable results. This problem is often resolved by using travel demand model trip tables as seed matrices for matrix estimation procedures. Matrix estimation procedures leave simulation model developers with difficult decisions of how to factor estimated existing trip tables to produce future trip tables, which may also produce unreasonably high demands. Matrix capping reduces trip tables to ensure select links are not over capacity. And although matrix capping has been justified by assuming peak spreading occurs, historical efforts have not applied a systematic process for estimating peak spreading for all trip interchanges. A method is described to refine travel demand model trip tables for use in simulation modeling. Trip table refinement procedures are validated against observed traffic counts by using base year travel demand model trip tables as input. The validated procedures can then be applied to future year travel demand model trip tables to produce reasonable trip tables for simulation purposes. The selected method applies a unique temporal distribution to each origin–destination pair, when appropriate temporal distributions are based on the amount of congestion that is present between each pair. The experience of applying the procedures in the development of a large simulation model of Interstate 285, a major circumferential freeway around the city of Atlanta, Georgia, is summarized.
Centralized and Decentralized Multimodal Statewide Transportation Planning
Authors: Miller John S. , Evans Linda D.
Published: May 2018

Statewide multimodal transportation planning may be centralized through a single office or decentralized through separate modal agencies (e.g., aviation, transit, highway, port, rail, and toll agencies). To determine the value of each approach, representatives from 41 states were surveyed by questionnaire or telephone about the usefulness of centralized versus decentralized planning. Each approach offers benefits. Centralization provides consistency of modal plans, better modal coordination (including detection of modal conflicts earlier in the process), an ability to examine the entire transportation system holistically, collective attention brought to smaller modes that otherwise might be overlooked, economies of scale for service delivery and employee development, and a greater likelihood that long-range planning will be performed rather than eliminated by more immediate tasks. Decentralization, however, provides greater ease in obtaining modal support for a long-range plan (since the planners and implementers are in the same functional unit), greater ease of tapping mode-specific expertise, and an ability to focus on the most critical mode. External factors that may override the importance of either approach are mode-specific funding requirements, the increasing relevance of metropolitan planning organizations, and the fact that modal location in the same office is not synonymous with coordination. A subset of the free responses to the survey indicated that centralized multimodal planning can be beneficial but only if four constraints are met: modal staff work collaboratively, the centralized unit has funding or other authority, necessary mode-specific planning is not eliminated, and there is a clear linkage between this unit and the agencies that perform mode-specific planning such that the latter can implement the recommendations of the former.
Developing a Statewide Travel Demand Model from a Person-Based Time Series Household Survey
Authors: Thompson-Graves Scott , DuRoss Mike , Ratledge Edward C. , Racca David P.
Published: May 2018

Balancing the funding needs of data collection and model development is a recurring problem for state departments of transportation and metropolitan planning organizations throughout the country. To address this problem, the Delaware Department of Transportation (DelDOT) and the University of Delaware have developed an innovative and cost-effective person-based time series household survey that has been conducted annually since 1995. The survey diverges from traditional household travel diary surveys in that it is a telephone survey that collects detailed demographic information on all household members but collects trip information from only one randomly selected household member. While the survey costs between 20% and 50% less than a typical household travel diary survey and greatly reduces nonresponse bias, this survey poses two complications. The first is that household trip generation rates must be synthesized if trip productions are to be estimated on the basis of household cross-classification tables; the second is that the data must be normalized to represent a data set for a single year. A description is provided of the procedure by which this survey was used to perform a major update of DelDOT's statewide travel demand model in 2003. The survey was relied on to provide key information in the first three steps of the four-step travel demand modeling process. This survey method has the potential for widespread application, particularly for microsimulation models, which would not require the household synthesis step.
Forecasting Traffic Impacts on a Citywide Street Network in the Absence of a Travel Demand Model
Authors: Perone Steve , Carr Theresa , Upton Dorothy
Published: May 2018

A process is described for predicting traffic volumes along the transportation network of a small city in western Oregon, for which a travel demand model is not available. A cumulative analysis method which considered traffic generated by expected development as well as external traffic traveling through the study area, was used. A buildable lands inventory based on tax assessor records and a geographic information system (GIS) was updated and queried to identify vacant and underdeveloped parcels inside the city limits. The city's comprehensive plan was used to identify expected growth by land use category. GIS tools were used to allocate growth on the basis of the location and attractiveness of available land, its access to urban services, and current plan designations. Peak hour trip generation was calculated with the Institute of Transport Engineers's Trip Generation report. Trips were distributed to the network, following general principles of the gravity model and by using historical traffic counts as a guide. Through trips were identified by using a number of factors including road classification, existing traffic volumes, and historical growth rates. Trips were assigned and used to identify deficiencies on the future transportation network. This process is valuable to cities developing long-range transportation plans in the absence of a travel demand model. The tools needed for this analysis—comprehensive plan, tax assessor data, trip generation rates—are available to cities of all sizes. Innovations in the geospatial analysis arena facilitate this analysis without requiring large investments of time or money.
Service Times and Capacity at National Park Entrance Stations
Authors: Upchurch Jonathan
Published: May 2018

As many recreational tourists know, long queues of vehicles at park entrance stations during peak season are a problem for many national parks and monuments. In some instances, on holiday weekends the lines are known to extend 1 mi or more. Information is presented on the capacity of entrance stations as determined from data collected at Arches National Park in Utah, supplemented by data collected at Grand Canyon National Park. At Arches National Park the capacity of an entrance station lane is 112 vehicles per hour. This value can be used as a general guide by other parks. The service time per vehicle at a park entrance station will vary from park to park depending on ( a) the proportion of visitors who hold a previously purchased pass (short transaction time), ( b) the amount of printed information and safety advisories given to the visitor, ( c) the proximity of a visitor center at which the visitor can ask questions, and ( d) other factors. The capacity of an entrance station lane is important and useful information to the National Park Service for analyzing the number of needed lanes at an entrance station, the benefits of a lane dedicated to automated entry, and other possible solutions to the queuing problem. A number of national parks have implemented automated lanes at entrance stations. An overview of the operation of automated lanes also is provided.
Estimating Bicycle Usage on a National Cycle Network
Authors: Richardson A. J.
Published: May 2018

This paper describes the methodology and results from the 1999–2002 Veloland Schweiz surveys of the Swiss national cycle network, using an intercept survey technique, supplemented by cyclist counts and trackside interviews, to obtain information on the magnitude and characteristics of cyclist flows on the Veloland Schweiz national cycling routes. The project used a method of weighting and expanding the sample data obtained from the survey sites to obtain estimates of annual trips and kilometers traveled for catchment areas around each survey site and for the network as a whole. These expansion weights account for the response to the survey and to the spatial and temporal sampling involved in the survey. They also account for weather conditions on the days when the sample surveys were conducted compared with the average weather during the survey year. Finally, cycling-related expenditures associated with trips made on the national network are estimated. Although this method was developed in the context of a national network of cycle routes, it is considered to be applicable at other geographic scales including regional and citywide cycle networks.
Development of Bicycle and Pedestrian Detection and Classification Algorithm for Active-Infrared Overhead Vehicle Imaging Sensors
Authors: Noyce David A. , Gajendran Arunkumar , Dharmaraju Raghuram
Published: May 2018

Existing algorithms used with active-infrared overhead vehicle-imaging sensors consider vehicle size and speed attributes as basic parameters to detect and classify 11 categories of motorized vehicles. These algorithms could not detect and classify bicycles and pedestrians. This research focused on developing and evaluating algorithms for active-infrared overhead vehicle-imaging sensor technology to detect and classify non-motorized users. Development of the theory and algorithm used to automate the simultaneous detection and classification of bicycles and pedestrians along with the field investigations to evaluate its effectiveness are described. The new algorithm used the concept of message sequencing to incorporate existing active-infrared technology theory. Bicycles and pedestrians intersected the infrared scan patterns in different sequences that, along with the infrared images, provided unique detection and classification identification. The algorithm was integrated within the existing active-infrared technology, and a field evaluation was conducted on bicycle and pedestrian trails. The algorithm created an intelligent technology to detect and classify bicycles and pedestrians. Nearly 100% of bicycles and pedestrians were detected, and about 92% of them were successfully classified. Automated data collection technology can be useful in obtaining more comprehensive travel data and in forecasting demand for design and policy making related to nonmotorized transportation.
Transportation Finance, Congestion, and Equity
Authors: Lari Adeel , Iacono Michael
Published: May 2018

Traffic congestion continues to be a major concern for policy makers and transportation professionals in most large U.S. metropolitan regions. While demand for travel continues to increase, traditional sources of revenue used to finance transportation at the state and local levels are yielding fewer resources (or at least slowing in their rate of growth). As a result, transportation decision makers continue to seek new sources of revenue to finance expansive highway and transit plans. While much effort is expended in seeking adequate revenue sources, little effort is given to determining the equity effects of these new revenue sources, much less the policies they are designed to support. This paper investigates one particular aspect of equity, vertical equity, in relation to transportation finance and policy. Through the use of sets of data (travel demand, financial, and operational) from Minnesota and specifically from the Twin Cities region as illustrations, the authors argue that current policies toward transportation finance and congestion do little to further the interests of low-income individuals and may in fact benefit others at their expense. The authors conclude with some recommendations aimed at redistributing more equitably the burden of financing transportation programs among users and nonusers.
Comparison of Buyers of Hybrid and Conventional Internal Combustion Engine Automobiles
Authors: de Haan Peter , Peters Anja , Mueller Michel
Published: May 2018

Two factors are important for assessment of the fuel-saving potential of hybrid vehicles. First is the future market share, which depends on the present status of hybrid vehicles in the technology adoption life cycle. The latter can be assessed by examination of characteristics and preferences of hybrid vehicle buyers. Second is consumer behavior, with the key issue being whether the purchase of a new hybrid vehicle is related to above-trend increases in vehicle size or vehicle ownership. Two groups were surveyed: ( a) all buyers of the hybrid car Toyota Prius 2 in Switzerland in the first 9 months after the vehicle entered the market and ( b) a control group of buyers of conventional internal combustion engine Toyota Corolla and Avensis. Hybrid car buyers had a significantly higher household income and education level. They rated fuel consumption and technology higher at the expense of other criteria, such as brand preferences and design. It was concluded that hybrid vehicles were still mostly bought by consumers from the early adopter segment of the market and that hybrid technology had not yet entered the majority market. The survey found neither of the two so-called direct-rebound effects that could possibly occur when buying hybrid cars. The surveyed rate of vehicle purchases for which no previously owned vehicle had been replaced was 13.7% for Prius buyers. This rate was comparable to that for the control group and below the simulated 20% limit taken into account in a population with constant vehicle ownership. It was concluded that hybrid vehicle technology might allow for important fuel savings in the future, once it succeeds in entering the majority car market, as no counteracting rebound effects are to be expected.
Detailed Analysis of Urban Station Siting for California Hydrogen Highway Network
Authors: Nicholas Michael A. , Ogden Joan
Published: May 2018

Station availability is a major concern when the deployment of an alternative fuel such as hydrogen is considered. Too few stations will make the network inconvenient, while too many will make the refueling network cost prohibitive. As a follow-up analysis to two station siting analyses completed by the authors for the California Hydrogen Highway Network, this report takes a closer look at the regional differences between the four main metropolitan areas in California: Greater Los Angeles, the San Francisco Bay Area, the Sacramento metropolitan area, and the San Diego metropolitan area. The purpose of this analysis is twofold: to generate a general model to assess hydrogen needs in different regions, and to apply the model to compare its results with the California hydrogen highways report. In the analysis that follows, average driving time to the nearest station (convenience metric) is used to determine the number of stations necessary for each region. By using convenience to determine the share of stations, regions that are less dense will be served as well as those regions with high density. The results suggest that the percentage of stations needed to meet a convenience target differs among regions depending on density. For example, a 4-min average travel time in Sacramento requires 7.2% of stations, whereas it requires only 3.3% of stations in Los Angeles. The developed equation predicts station needs as a function of population density and a desired level of convenience; if the caveats explained in the paper are observed, the prediction equation can be applied to any region.
Systems Analysis of Hydrogen Transition with HyTrans
Authors: Leiby Paul N. , Greene David L. , Bowman David , Tworek Elzbieta
Published: May 2018

The U.S. government is carefully considering the merits and the long-term prospects of hydrogen-fueled vehicles. The National Academy of Sciences has called for the careful application of systems analysis tools to structure the complex assessment required. Others, raising cautionary notes, question whether a consistent and plausible transition to hydrogen light-duty vehicles can be identified and whether that transition would, on balance, be environmentally preferred. Modeling the market transition to hydrogen-powered vehicles is an inherently complex process encompassing hydrogen production, delivery and retailing, vehicle manufacturing, and vehicle choice and use. This paper describes the integration of key technological and market factors in a dynamic transition model, HyTrans. The usefulness of HyTrans and its predictions depends on three key factors: the validity of the economic theories that underpin the model, the authenticity with which the key processes are represented, and the accuracy of specific parameter values used in the process representations. The paper summarizes the theoretical basis of HyTrans and, with sensitivity analysis, highlights the implications of key parameter specifications.