Showing papers in "Transportation Research Record in 1998"
TL;DR: In this paper, the application of seasonal time series models to the single-interval traffic flow forecasting problem for urban freeways is addressed and the best-fit Winters exponential smoothing models are also developed for each site.
Abstract: The application of seasonal time series models to the single-interval traffic flow forecasting problem for urban freeways is addressed. Seasonal time series approaches have not been used in previous forecasting research. However, time series of traffic flow data are characterized by definite periodic cycles. Seasonal autoregressive integrated moving average (ARIMA) and Winters exponential smoothing models were developed and tested on data sets belonging to two sites: Telegraph Road and the Woodrow Wilson Bridge on the inner and outer loops of the Capital Beltway in northern Virginia. Data were 15-min flow rates and were the same as used in prior forecasting research by B. Smith. Direct comparisons with the Smith report findings were made and it was found that ARIMA (2, 0, 1)(0, 1, 1)96 and ARIMA (1, 0, 1)(0, 1, 1)96 were the best-fit models for the Telegraph Road and Wilson Bridge sites, respectively. Best-fit Winters exponential smoothing models were also developed for each site. The single-step forecast...
450 citations
TL;DR: A new and simple solution algorithm is proposed for all-to-one, all departure time intervals, shortest paths problems and it is proved, theoretically, that the new solution algorithm has an optimal run time complexity that equals the complexity of the problem.
Abstract: A solution is provided for what appears to be a 30-year-old problem dealing with the discovery of the most efficient algorithms possible to compute all-to-one shortest paths in discrete dynamic networks. This problem lies at the heart of efficient solution approaches to dynamic network models that arise in dynamic transportation systems, such as intelligent transportation systems (ITS) applications. The all-to-one dynamic shortest paths problem and the one-to-all fastest paths problems are studied. Early results are revisited and new properties are established. The complexity of these problems is established, and solution algorithms optimal for run time are developed. A new and simple solution algorithm is proposed for all-to-one, all departure time intervals, shortest paths problems. It is proved, theoretically, that the new solution algorithm has an optimal run time complexity that equals the complexity of the problem. Computer implementations and experimental evaluations of various solution algorithms ...
381 citations
TL;DR: In this paper, data collected from the states of Minnesota and Washington on rural two-lane highways are used to build accident models for segments and three-legged and four-legged intersections stop controlled on the minor legs.
Abstract: Data collected from the states of Minnesota and Washington on rural two-lane highways are used to build accident models for segments and three-legged and four-legged intersections stop-controlled on the minor legs The quantity, quality, and variety of data collected, together with the advanced techniques applied in the analysis, make this study of special interest Variables include traffic, horizontal and vertical alignments, lane and shoulder widths, roadside hazard rating, channelization, and number of driveways Models are of negative binomial and extended negative binomial form and yield R2 values from 042 to 073 and overdispersion parameters from 020 to 051 A segment model combining both states and including state as a variable, and intersection models derived from Minnesota data, are featured, along with summary statistics, goodness-of-fit measures, and cross-validation between the states Segment accidents depend significantly on most of the roadway variables collected, while intersection ac
339 citations
TL;DR: In this article, an ordered probit model was used to identify specific variables significantly influencing levels of injury in two-vehicle rear-end involvements on divided roadways and demonstrated the use of the ordered probability model in this complex highway safety problem.
Abstract: Collisions between heavy trucks and passenger cars are a major concern because of the severity of injuries. This research has two objectives. One is to examine the impact of various factors on injuries to passenger car occupants involved in such collisions. Due to the complex interaction of factors influencing injury levels in truck-car collisions, the ordered probit model is used to identify specific variables significantly influencing levels of injury in two-vehicle rear-end involvements on divided roadways. Another objective is to demonstrate the use of the ordered probit in this complex highway safety problem. A set of vehicle, occupant, roadway, and environmental factors expected to influence injury severity was developed. Given two-vehicle passenger car-truck rear-end collisions, the variables that increase passenger vehicle occupant injury severity include darkness; high speed differentials; high speed limits; grades, especially when they are wet; being in a car struck to the rear (as opposed to being in a car striking a truck to the rear); driving while drunk; and being female. The interaction effects of cars being struck to the rear with high speed differentials and car rollovers were significant. Variables decreasing severity include snowy or icy roads, congested roads, being in a station wagon struck to the rear (as opposed to a sedan), and using a child restraint. With injuries ordered in five classes from no injury to fatalities, the marginal effects of each factor on the likelihood of each injury class are reported.
308 citations
TL;DR: The research on which this paper is based was aimed at exploring in more detail the implications of metering traffic flow at levels below that at which a breakdown occurs, and it is shown that 1-min median lane flows that are 20 percent larger than queue discharge flows have only a 10 percent probability of breakdown.
Abstract: Of late, there has been a considerable volume of empirical research on freeway operations during periods of high flow. Part of the motivation for this realm of research is the attractive possibility of increasing flow and speed by preventing breakdown in congested operations. This possibility has been fueled by observations of a "capacity drop," wherein the discharge flow from the resulting queue is smaller than those observed before breakdown. The research on which this paper is based was aimed at exploring in more detail the implications of metering traffic flow at levels below that at which a breakdown occurs. From this perspective, the nature of precongestion flows is investigated empirically to determine the potential gains from such a policy. The most important contribution is an examination of the likelihood of success of such metering by establishing the probability of breakdown at various traffic flow levels. It is shown, for example, that 1-min median lane flows that are 20 percent larger than q...
273 citations
TL;DR: A new link-nested logit model of route choice that has a flexible correlation structure that allows for overcoming the route overlapping problem and a stochastic network loading procedure that obviates route enumeration is presented.
Abstract: A new link-nested logit model of route choice is presented. The model is derived as a particular case of the generalized-extreme-value class of discrete choice models. The model has a flexible correlation structure that allows for overcoming the route overlapping problem. The corresponding stochastic user equilibrium is formulated in two equivalent mathematical programming forms: as a particular case of the general Sheffi formulation and as a generalization of the logit-based Fisk formulation. A stochastic network loading procedure is proposed that obviates route enumeration. The proposed model is then compared with alternative assignment models by using numerical examples.
250 citations
TL;DR: In this article, the authors provided insights into plausible methodological frameworks specifically with respect to two key issues: mathematical formulation of the underlying process affecting median crossover accidents and the factors affecting the median crossover frequencies in Washington State.
Abstract: Insights into plausible methodological frameworks specifically with respect to two key issues—(1) mathematical formulation of the underlying process affecting median crossover accidents and (2) the factors affecting median crossover frequencies in Washington State—are provided in this study. Random effects negative binomial (RENB) and the cross-sectional negative binomial (NB) models are examined. The specification comparisons indicate benefits from using the RENB model only when spatial and temporal effects are totally unobserved. When spatial and temporal effects are explicitly included, the NB model is statistically adequate, while the RENB model appears to lose its distributional advantage. Such findings might be artifacts of the median crossover accident dataset used in this study. While the NB model appears to be the superior model in the present case of median crossover accidents, the marginally inferior performance of the RENB model warrants further examination through application to regular accid...
244 citations
TL;DR: An examination on how realtime information gathered as part of intelligent transportation systems can be used to predict link travel times for one through five time periods found that the modular ANN outperformed a conventional singular ANN.
Abstract: With the advent of route guidance systems (RGS), the prediction of short-term link travel times has become increasingly important. For RGS to be successful, the calculated routes should be based on not only historical and real-time link travel time information but also anticipatory link travel time information. An examination is conducted on how real-time information gathered as part of intelligent transportation systems can be used to predict link travel times for one through five time periods (of 5 minutes' duration). The methodology developed consists of two steps. First, the historical link travel times are classified based on an unsupervised clustering technique. Second, an individual or modular artificial neural network (ANN) is calibrated for each class, and each modular ANN is then used to predict link travel times. Actual link travel times from Houston, Texas, collected as part of the automatic vehicle identification system of the Houston Transtar system were used as a test bed. It was found that the modular ANN outperformed a conventional singular ANN. The results of the best modular ANN were compared with existing link travel time techniques, including a Kalman filtering model, an exponential smoothing model, a historical profile, and a real-time profile, and it was found that the modular ANN gave the best overall results.
238 citations
TL;DR: In this article, a particle hopping model for a single-directional pedestrian flow over a multilane walkway is presented, which offers the advantage of effectively capturing the behaviors of pedestrians at the micro-level while attaining realistic macro-level activity.
Abstract: In recent years cellular automata (CA) have been successfully applied to modeling traffic flow. Use of a CA for modeling pedestrian flows is examined here. A particle hopping model for a single-directional pedestrian flow over a multilane walkway is presented. This model offers the advantage of effectively capturing the behaviors of pedestrians at the micro-level while attaining realistic macro-level activity. The emergent group behavior is an outgrowth of the interaction of the rule set in simulation. The results indicate that a heuristically derived minimal rule set produces flow patterns that closely resemble the accepted fundamental diagrams. Important parameters for determining the shape of the fundamental diagrams are examined. Key rules used in a vehicular traffic CA are tested for their applicability to the pedestrian CA model.
233 citations
TL;DR: In this paper, a dual mechanism was proposed to explain the hyperbolic-like, time-versus-property plots characteristic of asphalt oxidative aging, and the oxidation kinetics provided further confirmation of the asphalt microstructural model.
Abstract: The kinetic data and chemistry of asphalt oxidative age hardening suggested a sequential, dual mechanism for asphalt oxidation. The dual mechanism rationalizes conflicts between earlier mechanistic investigations and explains the hyperbolic-like, time-versus-property plots characteristic of asphalt oxidative aging. The oxidation kinetics provide further confirmation of the asphalt microstructural model. It is proposed that the rapid initial oxidation rate of asphalt results from reaction of oxygen with limited amounts of highly reactive hydrocarbons. Final oxidation products of this initial reaction are sulfoxides and, most likely, ring aromatization. During this initial reaction, a slower oxidation reaction of asphalt benzylic carbons is initiated; final products are ketones and sulfoxides. The ratio of ketones to sulfoxides formed and the rate of age hardening were found to be dependent on temperature and oxygen pressure. Low-temperature oxidative aging, as occurs in pavements, was found significantly m...
192 citations
TL;DR: It seems that RBF and ESM can be a viable forecasting routine for advanced traffic management systems, although the performance of ESM is inferior to RBF, the former does not need a complicated training process or historic database, and vice versa.
Abstract: A radial basis function (RBF) neural network has recently been applied to time-series forecasting. The test results of an RBF neural network in forecasting short-term freeway traffic volumes are provided. Real observations of freeway traffic volumes from the San Antonio TransGuide System have been used in these experiments. For comparison of forecasting performances, Taylor series, exponential smoothing method (ESM), double exponential smoothing method, and backpropagation neural network were also designed and tested. The RBF neural network model provided the best performance and required less computational time than BPN. It seems that RBF and ESM can be a viable forecasting routine for advanced traffic management systems. There are some tradeoffs between RBF and ESM. Although the performance of ESM is inferior to RBF, the former does not need a complicated training process or historic database, and vice versa. However, even in the best performance case, 35 percent of the forecast traffic volumes showed 1...
TL;DR: In this paper, the authors present results of a life cycle inventory analysis of asphalt and steel-reinforced concrete based on publicly available data, and they find that asphalt appears to have higher energy input, lower ore and fertilizer input requirements, and lower toxic emissions, but it has higher associated hazardous waste generation and management than steel reinforced concrete.
Abstract: The public, industry, and governments have become increasingly interested in green design and sustainable development. Construction activities affect the environment significantly, so environmental issues should be considered seriously. Thousands of miles of roads are paved every year with asphalt and steel-reinforced concrete. What are the environmental effects of the two materials? If asphalt has been used overwhelmingly over concrete, is it a better choice for sustainable development? We present results of a life cycle inventory analysis of the two materials based on publicly available data. We find that for the initial construction of equivalent pavement designs, asphalt appears to have higher energy input, lower ore and fertilizer input requirements, and lower toxic emissions, but it has higher associated hazardous waste generation and management than steel-reinforced concrete. When accounting for the uncertainty in the data and when annualizing environmental effects based on assumed average service lives of the two pavement types, the resource input requirements and the environmental outputs are roughly comparable for the two materials. However, asphalt pavements have been recycled in larger quantities than concrete pavements, with consequent resource savings and avoided pollution, which suggests that asphalt may be a better choice from a sustainable development viewpoint. Of course, special functional requirements or economics may dictate the use of one material over the other in particular applications regardless of the overall environmental effects.
TL;DR: In this paper, the impacts of adverse weather and its interactions with driver and roadway characteristics on the occurrence and injury severity of selected crash types are analyzed, including single-vehicle, rear-end, and sidewipe.
Abstract: Adverse weather can reduce visibility and road surface friction and thus increase crash frequency and injury severity. However, drivers may compensate for higher crash risk by reducing speeds, maintaining safe spacing, and driving more carefully. The impacts of adverse weather and its interactions with driver and roadway characteristics on the occurrence and injury severity of selected crash types are analyzed. Single-vehicle, two-vehicle sideswipe, and two-vehicle rear-end collisions on limited-access roadways are considered. To analyze differential impacts of adverse weather on crash type, binary probit models are estimated for single-vehicle versus the two types of two-vehicle crashes, and for rear-ends versus sideswipes. To analyze injury severity, ordered probit models are estimated. The 1990-1995 Highway Safety Information System (HSIS) database for North Carolina was used for analysis. The results indicate that, for the selected crash types, drivers appear to compensate for increased injury risks i...
TL;DR: In this article, the authors developed a bicycle compatibility index that can be used by bicycle coordinators, transportation planners, traffic engineers, and others to evaluate the capability of specific roadways to accommodate both motorists and bicyclists.
Abstract: Presently, there is no methodology that is widely accepted by engineers, planners, or bicycle coordinators that will allow them to determine how compatible a roadway is for allowing efficient operation of both bicycles and motor vehicles. Determining how existing traffic operations and geometric conditions affect a bicyclist's decision to use or not use a specific roadway is the first step in determining the bicycle compatibility of the roadway. The Federal Highway Administration sponsored a study in which a methodology for deriving a bicycle compatibility index was developed. This tool can be used by bicycle coordinators, transportation planners, traffic engineers, and others to evaluate the capability of specific roadways to accommodate both motorists and bicyclists. It is intended to provide practitioners with the ability to assess the bicycle level of service present on existing facilities or on proposed facilities and can be used for operational, design, and planning analyses.
TL;DR: The network loading process of stochastic traffic assignment is investigated, and three logit-family models are investigated: the C-logit model, which was specifically defined for route choice; and two general discrete-choice models, the cross-nested logit models and the paired combinatorial logit model.
Abstract: The network loading process of stochastic traffic assignment is investigated. A central issue in the assignment problem is the behavioral assumption governing route choice, which concerns the definition of available routes and the choice model. These two problems are addressed and reviewed. Although the multinomial logit model can be implemented efficiently in stochastic network loading algorithms, the model suffers from theoretical drawbacks, some of them arising from the independence of irrelevant alternatives property. As a result, the stochastic loading on routes that share common links is overloaded at the overlapping parts of the routes. Other logit-family models recently have been proposed to overcome some of the theoretical problems while maintaining the convenient analytical structure. Three such models are investigated: the C-logit model, which was specifically defined for route choice; and two general discrete-choice models, the cross-nested logit model and the paired combinatorial logit model....
TL;DR: In this article, a review of literature and specifications, laboratory tests for characterizing aggregate toughness/abrasion resistance and durability/soundness were selected and evaluated, and those test methods that best correlate with field performance were determined.
Abstract: Numerous tests have been developed that empirically characterize aggregate without, necessarily, having a strong relationship to the performance of the final products incorporating these aggregates. This seems to be particularly true for aggregate toughness and abrasion resistance and durability and soundness. Toughness/abrasion resistance and durability/soundness tests for characterizing aggregate used in asphalt concrete were identified and evaluated, and those test methods that best correlate with field performance were determined. Based on a review of literature and specifications, laboratory tests for characterizing aggregate toughness/abrasion resistance and durability/soundness were selected. Sixteen aggregate sources with poor to good performance histories were identified for evaluation with the selected suite of tests. Performance histories of pavements containing these aggregates in asphalt concrete layers were established through personal contacts with state transportation agencies and performance evaluation questionnaires. Aggregate properties from laboratory tests were correlated with field performance. The micro-deval and magnesium sulfate soundness tests provide the best correlations with field performance of asphalt concrete and are recommended for characterizing aggregate toughness/abrasion resistance and durability/soundness.
TL;DR: In this article, the performance of asphalt paving mixtures in terms of permanent deformation, fatigue cracking, and moisture susceptibility was evaluated by six tests including Rigden voids, particle size analysis, and methylene blue test.
Abstract: Various studies have shown that the properties of mineral filler, especially the material passing through a 0.075-mm (No. 200) sieve (generally called P200 material), have a significant effect on the performance of asphalt paving mixtures in terms of permanent deformation, fatigue cracking, and moisture susceptibility. However, researchers have employed different characterization tests for evaluating the P200 materials. This study was undertaken to determine which P200 characterization tests are most related to the performance of asphalt paving mixtures. Six P200 materials representing a wide range of mineralogical composition and particle size were used. These P200 materials were characterized by six tests including Rigden voids, particle size analysis, and methylene blue test. Mixes were prepared with two fines to asphalt ratios (0.8 and 1.5) by weight. Mix validation tests included the Superpave shear test for evaluating permanent deformation and fatigue cracking, and the Hamburg wheel tracking test an...
TL;DR: In this article, a traffic prediction model that incorporates relevant demographic variables for county roads was developed for 40 out of 92 counties in Indiana using field traffic data collected from eight randomly selected counties.
Abstract: A traffic prediction model that incorporates relevant demographic variables for county roads was developed. Field traffic data were collected from 40 out of 92 counties in Indiana. The selection of a county was based on population, state highway mileage, per capita income, and the presence of interstate highways. Three to four automatic traffic counters were installed in each selected county. Most counters installed on the selected road sections were based on the standard 48-hour traffic counts. Then, the obtained average daily traffic was converted to annual average daily traffic by means of adjustment factors. Multiple regression analysis was conducted to develop the model. There were quantitative and qualitative predictor variables used in the model development. To validate the developed model, additional field traffic data were collected from eight randomly selected counties. The accuracy measures of the validation showed the high accuracy of the model. The statistical analyses also found that the ind...
TL;DR: In this article, a driving simulator study investigated the effect of automation of the driving task on performance under fatiguing driving conditions and found that performance recovery was better when drivers had full manual control of the vehicle.
Abstract: A driving simulator study investigated the effect of automation of the driving task on performance under fatiguing driving conditions. In the study, drivers performed both a manual drive, in which they had full control over the driving task, and an automated drive, in which the vehicle was controlled by an automated driving system. During both drives, three perturbing events occurred at early, intermediate, and late phases in the drives: in the automated drive, a failure in automation caused the vehicle to drift toward the edge of the road; in the manual drive, wind gusts resulted in the vehicle drifting in the same direction and magnitude as the "drifts" in the automated drive. Following automation failure, drivers were forced to control the vehicle manually until the system became operational again. Drivers' lateral control of the vehicle was assessed during three phases of manual control in both drives. The results indicate that performance recovery was better when drivers had full manual control of th...
TL;DR: In this article, the authors examined the impact of the light rail system (MAX) on single-family home values using distance to rail stations as a proxy for accessibility and distance to the line itself as a surrogate for nuisance effects.
Abstract: In theory, proximity to light rail transit (LRT) may have two different effects on residential property values. On the one hand, accessibility (proximity to LRT stations) may increase property values. On the other hand, nuisance effects (proximity to the LRT line and stations) may decrease property values. Existing empirical studies are inconclusive, and failure to separate the effects of accessibility from the nuisance effects may explain some of the ambiguity. An examination is presented of the impact of the light rail system (MAX) in Portland, Oregon, on single-family home values using distance to rail stations as a proxy for accessibility and distance to the line itself as a proxy for nuisance effects. Geographic information system techniques are employed to create spatial-related variables and merge data from various sources. The study results confirm the hypothesis that the light rail has both a positive effect (accessibility effect) and a negative effect (nuisance effect) on single-family home values. The positive effect dominates the negative effect, which implies a declining price gradient as one moves away from LRT stations for several hundred meters. Without controlling for the nuisance effect of the distance to the rail line, the estimated coefficients on distance from stations appear to be biased and would underestimate the accessibility effect. The finding of an independent nuisance effect suggests that previous hedonic models may have reached contradictory results because the nuisance effect differs with different types of rail or other local characteristics.
TL;DR: In this paper, the authors evaluated the effect of raising bicycle crossings by 4 to 12 cm and found that the paths with raised crossings attracted more than 50 percent more bicyclists and that the safety per bicyclist was improved by approximately 20 percent due to the increase in bicycle flow.
Abstract: Before-and-after study methodology was developed and applied to evaluating the effect on bicyclists' safety of raising urban bicycle crossings by 4 to 12 cm. In total, 44 junctions were reconstructed in this way in Gothenburg, Sweden. Four of these were studied in detail. Before the implementations, bicyclists were riding either in the roadway or on separate paths parallel to the roadway. The paths then ended with short ramps or curb cuts at each cross street, and bicyclists used nonelevated, marked bicycle crossings, similar to pedestrian crosswalks but delineated by white painted rectangles rather than zebra stripes. The results show that the paths with raised crossings attracted more than 50 percent more bicyclists and that the safety per bicyclist was improved by approximately 20 percent due to the increase in bicycle flow, and with an additional 10 to 50 percent due to the improved layout. However, the increased bicyclist volume means that the total number of bicycle accidents is expected to increase...
TL;DR: In this article, the authors present empirical findings on the relationship between urban form and work trip commuting efficiency, drawn from the analysis of 1986 work-trip commuting patterns in the greater Toronto area.
Abstract: Some empirical findings are presented on the relationship between urban form and work trip commuting efficiency, drawn from the analysis of 1986 work trip commuting patterns in the greater Toronto area. Work trip commuting efficiency is measured with respect to the average number of vehicle kilometers traveled (VKT) per worker in a given zone. Preliminary findings include VKT per worker increases as one moves away from both the central core of the city and from other high-density employment centers within the region; job-housing balance, per se, shows little impact on commuting VKT; and population density, in and of itself, does not explain variations on commuting VKT once other urban structure variables have been accounted for.
TL;DR: In this paper, the structural response of jointed plain concrete pavement slabs was evaluated using data obtained from instrumented slabs, which were part of newly constructed joints and overlay that was constructed on existing asphalt concrete pavement on 1-70 in Colorado.
Abstract: The structural response of jointed plain concrete pavement slabs was evaluated using data obtained from instrumented slabs. The instrumented slabs were a part of newly constructed jointed plain concrete overlay that was constructed on existing asphalt concrete pavement on 1-70 in Colorado, near the Kansas—Colorado border. The instrumentation consisted of dial gauges for measuring curling deflections at the slab corner and longitudinal edge and surface-mounted strain gauges for measuring load strains at the longitudinal edge at midslab. The through-thickness temperature profiles in the pavement slabs were also measured at 30-min intervals during the field test. Analysis of the field data showed that the instrumented slabs had a considerable amount of built-in upward curling and that concrete slabs on a stiff base can act completely independent of the base or monolithically with the base, depending on the loading condition. The built-in upward curling of the slabs has the same effect as negative temperature...
TL;DR: Several procedures for determining superior paths for the transport of hazardous materials in stochastic, time-varying networks are presented and the tradeoffs between the information obtained in the solution and computational efficiency are illustrated.
Abstract: The selection of routes in a network along which to transport hazardous materials is explored, taking into consideration several key factors pertaining to the length of time of the transport and the risk of population exposure in the event of an incident. That travel time and risk measures are not constant over time and at best can be known with uncertainty is explicitly recognized in the routing decisions. Existing approaches typically assume static conditions, possibly resulting in inefficient route selection and unnecessary risk exposure. Several procedures for determining superior paths for the transport of hazardous materials in stochastic, time-varying networks are presented. These procedures and their extensions are illustrated systematically for an example application using the Texas highway network. The application illustrates the tradeoffs between the information obtained in the solution and computational efficiency, and highlights the benefits of incorporating these procedures in a decision-sup...
TL;DR: A brief summary of recent research efforts to examine the problem of red- light running is provided, and the use of countermeasures, including red-light cameras, to reduce the problem is discussed.
Abstract: Deliberate running of red lights is a common and serious violation that contributes substantially to the more than 1 million motor vehicle collisions that occur at traffic signals each year. Urban-based highway safety research has examined various aspects of the red-light running problem, including the contribution of red-light violations to motor vehicle crashes, the frequency of red-light running, characteristics of red-light runners, and the influence of signal timing on red-light running behavior. A brief summary of recent research efforts to examine the problem of red-light running is provided, and the use of countermeasures, including red-light cameras, to reduce the problem is discussed.
TL;DR: In a survey conducted by the League of American Bicyclists in 1996, 20 percent of the members reported having had a serious crash (resulting in at least $50 of property damage or medical expense) in 1996 as mentioned in this paper.
Abstract: In December 1996, 20 percent (4, 712) of the League of American Bicyclists members were surveyed about their cycling experiences during calendar year 1996. The 33 questions included bicycle type and equipment, distribution of bicycle trips by purpose (e.g., work, on-road recreation), total distance cycled, commuting habits, accidents, and demographic data. The survey was designed to update one done by Kaplan in 1975. By the March 31, 1997, deadline over 2,400 (51 percent) had been returned. Of these, 19 percent were rejected due to incompleteness or inconsistent responses, leaving 1,956 valid surveys. The "average" respondent was a 48-year-old, married (66 percent) male (80 percent) professional (48 percent) who rode 4670 km in 1996. Just over 9 percent reported having had a serious crash (resulting in at least $50 of property damage or medical expense) in 1996. Based on the experience reported by these cyclists, the average cyclist in this group could be expected to ride for 11 years before having such a...
TL;DR: The dynamic traffic control problem and the dynamic traffic assignment problem are integrated as a noncooperative game between a traffic authority and highway users to find a mutually consistent dynamic system-optimal signal setting and dynamic users’optimal traffic flow.
Abstract: The dynamic traffic control problem and the dynamic traffic assignment problem are integrated as a noncooperative game between a traffic authority and highway users. The objective of the combined control-assignment problem is to find a mutually consistent dynamic system-optimal signal setting and dynamic user-optimal traffic flow. The combined control-assignment problem is first formulated as a one-level Cournot game: the traffic authority and the users choose their strategies simultaneously. The combined control-assignment problem is subsequently formulated as a bi-level Stackelberg game. The traffic authority is the leader; it determines the signal settings in anticipation of the users' reactions. The users are followers who choose their routes after the signal settings have been determined. Finally, the system-optimal control-assignment problem is formulated as a Monopoly game. The sole player—the traffic authority—determines both signal settings and traffic flows to achieve a dynamic system-optimal so...
TL;DR: In this paper, a case study on the effects of visibility and other environmental factors on driver speed was conducted as part of an intelligent transportation systems field operational test to reduce accidents caused by sudden changes in visibility levels.
Abstract: A case study on the effects of visibility and other environmental factors on driver speed was conducted as part of an intelligent transportation systems field operational test to reduce accidents caused by sudden changes in visibility levels. Baseline conditions established normal vehicle speeds for passenger cars and trucks. Reduced visibility and winds exceeding 40 km/h were found to be the primary factors affecting driver speed.
TL;DR: Comparison of the estimated headway distributions with real-life data shows that head way distributions can be realistically replicated with the Pearson-III-based mixed-vehicle-type GQM.
Abstract: Recently, a new statistical procedure was developed that enables fast, accurate, and robust estimation of composite headway distributions, such as Branston's generalized queueing model (GQM). Until now, the new procedure had only been applied to aggregate vehicular flow. In this paper, the estimation procedure is extended to headway observations segregated according to vehicle type and period of the day. Consequently, the parameters of a new mixed-vehicle-type headway distribution model based on Branston's headway model can be estimated. Distinction of vehicle type and sample periods provides additional insight into the plausibility of the headway distributions and parameter values, as well as into the car-following behavior of the distinct vehicle classes varying across the different periods. The estimation procedure was applied to traffic data collected on a two-lane rural road in the Netherlands. Comparison of the estimated headway distributions with real-life data shows that headway distributions can ...
TL;DR: The basic construction of the objective functions of the transit network design problem is described, and a new approach taking account of both passenger and operator interests is proposed.
Abstract: The basic construction of the objective functions of the transit network design problem is described, and a new approach taking account of both passenger and operator interests is proposed. The approach presented combines the philosophy of the mathematical programming approaches with decision-making techniques in order to allow the user to select from a number of alternatives. The nature of the overall formulation is nonlinear and mixed-integer programming.