bluuebunny/crossref_metadata_2025 huggingface dataset:
Geographic Information System–Based Regional Transit Feasibility Analysis and Simulation Tool
Authors: Pendyala Ram M. , Ubaka Ike , Sivaneswaran Nadarajah
Published: April 2007

A regional transit feasibility analysis and simulation tool (called RTFAST) can be used to analyze and simulate regional transit system performance. The growth of urban areas coupled with changes in socioeconomic and demographic patterns has resulted in the need to provide for mobility and accessibility in regional and multijurisdictional contexts. In this context, the ability to analyze, simulate, identify, and plan regional transit systems to best serve personal travel patterns is necessary. RTFAST has been developed within a geographic information system–based environment and effectively interfaced with existing travel-demand modeling systems. The capabilities of the tool were demonstrated, and sample results were obtained from its application in Florida.
Integrated National Transit Database Analysis System
Authors: Gan Albert C. , Ubaka Ike , Zhao Fang
Published: April 2007

The Integrated National Transit Database Analysis System (INTDAS) is a user-friendly software designed to facilitate the retrieval and analysis of data from the National Transit Database (NTD). INTDAS is an integrated database system that ( a) combines individual NTD data files from multiple years into a single, standardized database and ( b) provides customized tools for easy data retrieval, visualization, analysis, and transfer. The system is useful for both the practitioners and researchers who use NTD data to improve transit performance and services. The INTDAS database combines the 1984 to 2000 NTD data for all transit systems reported to the NTD program. INTDAS is equipped with highly customized functions that allow the user to quickly retrieve data of multiple transit systems of multiple years for trend analyses, peer comparisons, and data inquiries. A customized query editor allows the user to identify transit systems that meet a certain profile. An automated Florida peer selection process is also implemented to allow the user to identify comparable transit systems in peer analyses. Retrieved data can be displayed in tables, forms, or charts. The user may also set up formulas to derive new variables from the original NTD variables. All output from INTDAS can be saved to files in various formats and automatically sent to a third party as an e-mail file attachment. Although the system was developed for Florida, its functions are applicable to general users.
CORBA-Based Distributed Geographic Information Systems for Transportation for Emergency Medical Services
Authors: Hu Ta-Yin
Published: April 2007

With the advancement of intelligent transportation systems, current and future emergency medical services systems are and will be characterized by real-time response, specialization, and decentralization. To provide a real-time response of medical services, several components are essential, such as dispatching, routing, emergency facilities, and patient’s medical history. A common object request broker architecture (CORBA)–based geographic information system for a transportation framework is proposed for the dispatching and assignment of medical vehicles for emergency services via wireless communication. The framework combines distributed object computing, geographic information systems for transportation, and transportation models in a single system, which provides flexibility and interoperability among existing medical service systems. The framework uses the concept of distributed systems and capabilities of CORBA to design objects and dynamically update medical facilities’ information to relay up-to-date information to ambulances. A real roadway network is used in the numerical experiments to illustrate dynamic aspects of the proposed system.
Motorway Flow Quality Impacts of Advanced Driver Assistance Systems
Authors: Hoogendoorn Serge P. , Minderhoud Michiel M.
Published: April 2007

An ex ante impact assessment of advanced driver assistance systems was conducted with focus on autonomous intelligent cruise control and intelligent speed adaptation. The effects of these systems on efficiency, reliability, driving comfort, and safety were addressed by microsimulation for different penetration levels and bottleneck layouts. The deployment of cruise control improves bottleneck capacity. The bottleneck reliability, however, deteriorates in most cases. No significant changes in traffic safety, expressed by the time drivers are exposed to small time-to-collision values, could be established. From the simulation experiments it appears that intelligent speed adaptation has no effect on capacity and provides no substantial contribution to bottleneck reliability. Contrary to expectations, no significant safety benefits could be established using the study’s assessment approach.
Freeway Guide Sign Design with Driving Simulator for Central Artery–Tunnel: Boston, Massachusetts
Authors: Upchurch Jonathan , Fisher Donald , Carpenter Rick A. , Dutta Arup
Published: April 2007

The Central Artery–Tunnel (Interstate 93) through downtown Boston, Massachusetts, is being reconstructed as a tunnel 2.4 km (1.5 mi) long. Within the tunnel several exits require guide signing for motorist safety and efficient traffic operation. Design and placement of this signing bring challenges due to the tunnel’s low ceiling height of 5.19 m (17 ft) and horizontal and vertical curvature that reduces the distance from which motorists can see the signs. Tunnel guide signs may also be blocked from view by large trucks, due to the lower than usual mounting height. Reconstruction of the Central Artery will improve traffic operations by reducing the number of exits and entrances on Interstate 93 from the current 27 exits and entrances (two-directional total) over 3 mi to 14. Yet, the tunnel will have 7 exits, 3 of them compressed into a southbound tunnel segment 1250 m (4,100 ft) long. These conditions may cause drivers—especially unfamiliar drivers—to have difficulty obtaining guidance information for their exit. This can lead to driver frustration and a reduction in safety caused by abrupt lane changing and other maneuvers. To address these problems with improved sign design and placement, a study using a driving simulator was undertaken. A computer-generated roadway through the tunnel was developed to replicate the tunnel geometry (including horizontal and vertical curvature and ceiling height) and sign placement. Test subjects drove through the simulated tunnel to evaluate the developed signing alternatives. The driving simulator was also assessed as a tool for improving freeway guide signing.
Evaluation of Clearview on Freeway Guide Signs with Microprismatic Sheeting
Authors: Carlson Paul J. , Brinkmeyer Greg
Published: April 2007

The legibility of the Clearview alphabet on freeway guide signs constructed with microprismatic retroreflective sheeting was studied. The Clearview legibility results were compared to the legibility of freeway guide signs constructed with the Series E (Modified) alphabet. A total of 60 subjects divided into three age groups participated in this nighttime study. The findings indicate that the Clearview alphabet provides statistically longer legibility distances than the Series E (Modified) alphabet. The largest 50th-percentile differences were 58 ft for shoulder-mounted signs and 54 ft for overhead signs. Depending on speed, these improvements can provide a driver with up to 0.7 s more time to read freeway guide signs. In terms of subject age, the largest benefits of Clearview were associated with older drivers.
Variations in Capacity and Delay Estimates from Microscopic Traffic Simulation Models
Authors: Tian Zong Z. , Urbanik Thomas , Engelbrecht Roelof , Balke Kevin
Published: April 2007

One of the issues involved in using microscopic simulation models is the variation in the simulation results. This study examined some of the more popular microscopic traffic simulation models, CORSIM, SimTraffic, and VISSIM, and investigated the variations in the performance measures generated by these models. The study focused on the capacity and delay estimates at a signalized intersection. The effects of link length, speed, and vehicle headway generation distribution were also investigated. With regard to variations in performance measures, the study found that CORSIM yields the lowest variations, whereas SimTraffic yields the highest. The highest variation in each simulation model normally occurs when the traffic demand approaches capacity. It was also found that delays are affected by the link length and speed in simulation models. Such an impact on delays is closely related to the range of speed variations. In general, shorter links and higher link speeds result in lower delays. There is no strong evidence that the headway distribution used to generate vehicles in the simulated network has any effect on capacity and delay estimates. Multiple simulation runs are necessary to achieve an accurate estimate on the true system performance measures. With a 10% error range in estimated delay, two to five runs may be enough for under-capacity conditions, but more than 40 multiple runs may be necessary to accurately estimate delay at, near, or over capacity.
Marginal Delay: New Measure for Quality of Service at Signalized Intersections
Authors: Rabbani Emilia Kohlman , Bullen Graham
Published: April 2007

Most existing analytical models determine signal settings at intersections by minimizing total delay. The main problem with these methods is that when green split is based on minimum total intersection delay, low-volume approaches are penalized. Although this may be appropriate, the extent of this penalty has never been theoretically resolved. A new concept and its methodology for determining traffic signal settings were proposed to provide a theoretical basis for this issue. This new concept, marginal delay, has its inception in marginal analysis and is defined as the increase in total delay resulting from a one-vehicle increase in the approach volume. Given the nature of the existing delay equations, marginal delay also represents the measure of the maximum individual vehicle delay for a given cycle. Three marginal delay equations were derived and analyzed over a range of 265 cases. Marginal delay analysis was applied to signal-setting calculations and compared with existing delay models. The work concluded that marginal delay is a significant variable in the calculation of signal settings, especially when large differences exist between the volumes of the different approaches. Furthermore, marginal delay used in conjunction with total delay can improve current signal-timing methods by quantifying the penalty applied to light-volume approaches and by providing a measure of variance between real-time flow and design flow.
Total Capacities at All-Way Stop-Controlled Intersections: Validation and Comparison of Highway Capacity Manual Procedure and Addition-Conflict-Flow Technique
Authors: Wu Ning
Published: April 2007

An iterative model for computing capacities at all-way stop-controlled (AWSC) intersections has been included in the new Highway Capacity Manual (HCM) 2000. The model is based on five saturation headway values, each reflecting a different level of conflict faced by the subject-approach driver. From this model the capacity and service time at any approach can be computed using iterative calculations. The model in the HCM is a so-called approach-based model, which only takes into account the conflicting cases among the approaches. The effect of turning streams or movements is not modeled in sufficient detail. In contrast, a theoretical, stream-based model for determination of capacities at AWSC intersections has been developed. This model is based on the addition-conflict-flow (ACF) method developed from graph theory and takes into account all the traffic streams at the intersection. This allows a systematic and realistic analysis of the traffic process at AWSC intersections. The computational procedure included in the model can be conducted without iterative calculation steps. The ACF and the HCM models for intersections with single-lane approaches were comprehensively validated, as well as a modified version of the HCM model that significantly enhances its features. The results of the validation indicate that the total capacity of an AWSC intersection with single-lane approaches based on the HCM model ranges between 1,450 and 1,550 passenger cars per hour (pc/h), whereas the total capacity based on the ACF model ranges between 1,600 and 2,000 pc/h. The modified HCM model yields total capacities ranging between 1,700 and 2,000 pc/h. The ACF model and the modified HCM model yield similar capacity results under normal traffic flow conditions.
Simulation of Freeway Weaving Areas
Authors: Skabardonis Alexander
Published: April 2007

The operation of freeway weaving sections is characterized by intense lane-changing maneuvers and complex vehicle interactions that often create bottlenecks along freeway facilities. The CORSIM microscopic simulation model was applied to simulate the operation of eight realworld weaving sites in California under a wide range of operating conditions. The results indicate that CORSIM with default parameter values underpredicts the speeds in the weaving section by about 19% on average. Numerous simulation runs were made with different values of the model parameters. The following parameters were found to significantly affect the CORSIM results: ( a) car-following sensitivity factor, ( b) lane-changing aggressiveness factor, and ( c) percentage of freeway through vehicles that yield to merging traffic. The calibrated CORSIM model reasonably replicated observed traffic operations at all test sites. The predicted average speeds were within ±5 mph for most test sites. Good agreement between measured and predicted values was obtained for all the combinations of design characteristics and demand patterns.
Field Evaluation of Highway Capacity Manual 2000 Analysis Procedures for Two-Lane Highways
Authors: Dixon Michael P. , Sarepali Satya Sai Kumar , Young Kevin Allen
Published: April 2007

Highway Capacity Manual (HCM) 2000 two-lane rural highway directional, two-way, and passing-lane analysis procedures based on field data and simulation were evaluated. Detailed field data were collected from two highway sections in northern Idaho, one with and one without passing lanes. The TWOPAS simulation model was used to provide additional insights. Particular attention was given to the differences in estimates for percent time spent following (PTSF) produced by the twoway and directional analysis procedures. It was found that the two-way analysis procedure was more accurate, although both procedures produced estimates that were too high. The passing-lane analysis procedure was also evaluated, and the HCM 2000 procedure was found to be conservative in its estimates of PTSF reductions due to a passing lane.
Comparison of Delays from Highway Capacity Software, Synchro, PASSER II and IV, and CORSIM for Urban Arterials
Authors: Benekohal Rahim F. , Elzohairy Yoassry M. , Saak Joshua E.
Published: April 2007

The delays for signalized intersections from the Highway Capacity Manual [using the Highway Capacity Software (HCS)], PASSER II-90, PASSER IV-96, Synchro, and CORSIM software were compared. An examination was made of how much delay reduction materialized when optimized signal settings were implemented. Synchro should not be compared with HCS unless certain precautions are taken to make the conditions analyzed in Synchro comparable with those analyzed in HCS. For both pretimed and actuated signals, if simultaneous phases exist in which one of them terminates ahead of the others, the results of HCS and Synchro are not comparable. For both pretimed and actuated signals, when the phases terminate simultaneously, whether the data are imported from Synchro or manually entered in HCS, the condition analyzed will not be comparable unless precautions are taken. Once these precautions were taken, control delays from Synchro and HCS were not significantly different for pretimed, uncoordinated signals. For actuated—uncoordinated and for actuated—coordinated controllers, the comparisons are not meaningful. Delays for optimized conditions for PASSER II and PASSER IV were not significantly different from the delays before optimization. However, for Synchro, the delays for optimized conditions were significantly lower than the delays before optimization. CORSIM was used to assess the impacts of the optimization. If optimized signal settings suggested by PASSER II, PASSER IV, or Synchro are implemented, the delays for the optimized condition would not be significantly lower than the delays before optimization.
Empirical Features of Congested Patterns at Highway Bottlenecks
Authors: Kerner Boris S.
Published: April 2007

An empirical study was undertaken of congested patterns at highway bottlenecks. On the basis of statistical data it was found that the spatialtemporal structure of congested patterns possesses some predictable features. From these features a classification of congested patterns was made. It was found that the most frequently observed congested pattern is the general pattern (GP). In GP synchronized flow occurs upstream of a bottleneck and wide moving jams spontaneously emerge in that synchronized flow. Capacity in free flow can be about twice as high as capacity in congested traffic upstream of the on-ramp if the GP has formed.
Reconstruction of False and Missing Data with First-Order Traffic Flow Model
Authors: Haj-Salem H. , Lebacque J. P.
Published: April 2007

In previous studies, two traffic data-cleaning algorithms were developed at the Institut National de Recherche sur les Transports on the basis of filtering techniques and statistical approaches. Because of their mathematical structure (linearity of the process), both algorithms present a high level of inaccuracy in the case of nonhomogeneous traffic conditions at the location of the measurement stations (for example, free flow upstream and congestion downstream, or vice versa). A new algorithm for solving the traffic data-cleaning problem on the basis of real-time application of a dynamic first-order modeling approach was devised to take into account the nonlinearity of the traffic phenomenon. The developed algorithm, named PROPAGE, was tested using real data measurements, including a wide spectrum of traffic conditions. Compared with results from previous algorithms, the results obtained were more accurate.
Hybrid Neuro-Fuzzy Application in Short-Term Freeway Traffic Volume Forecasting
Authors: Park Byungkyu “Brian”
Published: April 2007

A hybrid neuro-fuzzy application for short-term freeway traffic volume forecasting was developed. The hybrid model consists of two components: a fuzzy C-means (FCM) method, which classifies traffic flow patterns into a couple of clusters, and a radial-basis-function (RBF) neural network, which develops forecasting models associated with each cluster. The new hybrid model was compared with previously developed clustering-based RBF models. In addition, the dynamic linear model was studied for comparison. The study results showed that the clustering-based hybrid method did not produce time-lag phenomena, whereas the dynamic linear model and the RBF model without clustering revealed apparent time-lag phenomena. The forecasting performance for freeway traffic volumes from the San Antonio, Texas, TransGuide system shows that even though the hybrid of the FCM and RBF models appears to be promising, additional research efforts should be devoted to achieving more reliable traffic forecasting.
Kinematic Wave Traffic Flow Model for Mixed Traffic
Authors: Zhang H. M. , Jin W. L.
Published: April 2007

The Lighthill-Whitham-Richards kinematic wave traffic flow model was extended to describe traffic with different types of vehicles, in which all types of vehicles are completely mixed and travel at the same group velocity. A study of such a model with two vehicle classes (e.g., passenger cars and trucks) showed that when both classes of traffic have identical freeflow speeds, the model (a) satisfies the first-in-first-out rule, (b) is anisotropic, and (c) has the usual shock and expansion waves and a family of contact waves. Different compositions of vehicle classes in this model propagate along contact waves. Such models can be used to study traffic evolution on long crowded highways where low-performance vehicles entrap high-performance ones.
Application of Car-Following Systems to Queue Discharge Problem at Signalized Intersections
Authors: Cohen Stephen L.
Published: April 2007

The queue discharge problem at a signalized intersection was analyzed with application of the modified Pitt car-following system. The Pitt car-following system was implemented on an Excel spreadsheet in the form of a prototype simulation model. The situation consisted of a single intersection in which discharging vehicles were unconstrained by downstream conditions. It was asserted that the car-following parameters used in the queue discharge problem are significantly different from those used in the uninterrupted-flow problem and that this is consistent with the two-fluid model. A number of scenarios were executed for each situation, using the spreadsheet implementation to examine a number of issues, including the effect of the following: free-flow speed, car-following parameter variations, vehicle length, heterogeneous traffic streams, and lane changing. It was shown that all of these issues have significant effects on discharge headways and that the Pitt car-following system has a far wider range of applicability than the simple equal headway model. The intuitiveness of the findings and calibration and validation issues were also addressed.
Analytic, Microscopic Model of Traffic Flow and Travel Time
Authors: Leurent Fabien M.
Published: April 2007

A model of disaggregate interactions between individual vehicles was developed that makes explicit the vehicle classes, the class trip rates, and their kinematic parameters (free speed, acceleration rate, length, safety margin). Assuming exponential gaps between vehicles, analytic formulas were derived for the mean value and the variance of the path travel times within each class. The model was successively applied to one-lane roads; two-way, two-lane roads; one-way, two-lane roads; and two-way, three-lane roads.
Work- and Sleep-Related Predictors of Subjective On-Duty Alertness in Irregular Work Schedules
Authors: Pilcher June J. , Anderson Jennifer , Edwards Gina , Coplen Michael K.
Published: April 2007

Many transportation industries operate under conditions that require workers on a 24-h basis. Unfortunately, these working conditions often negatively affect the workers’ ability to obtain sufficient sleep and to maintain the necessary alertness while on the job. The work schedules of locomotive engineers provide one example of 24-h-based work. Most engineers, however, not only have to work at different times of the day and night, but also must work under an on-call system, which typically results in highly irregular work hours. The relationship between irregular work schedules as experienced by locomotive engineers and subjective alertness was examined by producing a predictive model of on-duty alertness using work- and sleep-related variables as predictors. One hundred twenty-four locomotive engineers completed a 14-day activity log on work time, time off work, sleep habits, and on-duty alertness. The results from the regression analyses indicated that the single best predictor of on-duty alertness was the time of day that alertness was recorded. This result indicated that the human endogenous rhythm to be alert during the day and sleepy at night was the major predictor of on-duty alertness even in the irregular schedules experienced by most locomotive engineers. Other work- and sleep-related variables such as time that the employee was notified when to report to work, work duration, and sleep duration were also significant predictors of on-duty alertness. Operationally, the current results suggest that nighttime workers will experience less alertness than daytime workers. Thus, specific countermeasures addressing alertness and fatigue during nighttime work should be developed, such as better predictability of work scheduling and on-duty napping.
Seeking a Reduction in Aggressive Driving Through Different Strategies
Authors: Raub Richard A. , Wark Richard I. , Lucke Roy E.
Published: April 2007

Reducing the likelihood of aggressive driving can provide a safer and less demanding travel environment for all road users. However, attempts to develop appropriate responses have been thwarted by a number of issues. Most prominent has been the need for an adequate and consistent definition. With a definition in place, measuring occurrences of aggressive driving, linking the behavior to crashes, and designing interventions are made easier. However, a better understanding of a definition is needed. Efforts undertaken to reach a consensus of what constitutes aggressive driving are discussed, and general responses that can be taken are indicated. Highway safety experts responded to a series of scenarios, identifying those they believed to be aggressive behavior. The findings from the survey show that most respondents agree that aggressive driving is behavior that is selfish or unsafe. It also directly affects other road users, or is directed against those users or traffic control devices. While traffic law violations can be part of the behavior, they are not necessarily a key indicator. Respondents then were asked to identify long-term corrective action. Education and engineering actions sometimes were more important than enforcement. This does not exclude enforcement and prompt punishment to stop acts in progress, but places them in a wider context of actions. A basis for designing countermeasures is provided. An important overall strategy is the need to have an interdisciplinary approach to aggressive driving that combines enforcement, engineering, and education to seek appropriate solutions.
Investigation of Behavioral Adaptation to Lane Departure Warnings
Authors: Rudin-Brown Christina M. , Noy Y. Ian
Published: April 2007

Behavioral adaptation describes the collection of behaviors that occur after a change in the road traffic system. Typically, those behaviors not intended by the initiators of the change having a negative impact on safety are of particular interest. Although behavioral adaptation is frequently cited as an explanatory variable for observed discrepancies between engineering estimates and actual outcomes of safety interventions, a thorough understanding of behavioral adaptation does not, at present, exist. Most theories posit that a driver’s goal to maintain an acceptable level of risk will determine if and when behavioral adaptation will occur; few models incorporate individual driver characteristics into their explanation of behavioral adaptation. Recently, a qualitative model of behavioral adaptation was proposed. The model predicts that the degree of behavioral adaptation to a novel road safety intervention depends on several psychological characteristics of the individual, including propensity to trust automation, “locus of control,” and inclination toward sensation-seeking. To test the predictions of this model, simulator and test-track studies were conducted to investigate the ability of lane departure warnings to induce behavioral adaptation in drivers performing a secondary number-entry task. While the presence of reliable warnings in both settings improved lane-keeping performance, drivers tended to report a high degree of trust in both accurate and inaccurate systems, despite the intentional infidelity of the latter. Externals and low sensation-seekers were more likely to report an increase in trust in the system, regardless of its accuracy. The collective results from both studies indicate that, because of the propensity of some people to trust unreliable or faulty devices, caution should be used in attempting to predict the aggregate safety benefits of these systems.
On-Road Versus Simulator Data in Driver Model Development Driver Performance Model Experience
Authors: Bittner Alvah C. , Simsek Ozgur , Levison William H. , Campbell John L.
Published: April 2007

Driver Performance Model (DPM) development has provided results reflecting on the debate between on-road and driving-simulator data in driving research. Developed for FHWA, DPM is a computational micro-process model of driver behavior that has been designed to simulate—in detail—the driver’s perceptual, cognitive, and control processes to generate steering, braking, and acceleration inputs to the vehicle. The requirement to develop driver data for prediction of absolute on-road performance—versus typical interest in ordinal findings to be later validated via on-road studies—led to the collection of comparable on-road and simulator data and their subsequent comparison. Comparisons of corresponding curve-entry speeds and speed profiles revealed a profound divergence between the on-road and simulator results ( t = 9.39, p < .005). Compared with simulator drivers, on-road drivers tended to have higher curve-entry speeds for the more difficult (sharper) curves and lower speeds for the less difficult curves. This trend, though reduced in magnitude, was apparent even after statistical adjustments for differences in respective tangent speeds ( t = 2.67, p < .01). These results are discussed in light of emerging on-road and simulator capabilities. The discussion and earlier results altogether supported two conclusions: ( a) debate concerning on-road versus simulator research studies is likely to continue with their rapidly emerging individual capabilities, and ( b) on-road research currently provides the best basis for driver model development where one-to-one real-world predictions are required (e.g., DPM).
Modeling the Dynamic Cut-In Situation
Authors: Sultan Beshr , Brackstone Mark , Waterson Ben , Boer Erwin R.
Published: April 2007

An instrumented vehicle study was performed on a motorway in the United Kingdom to examine the behavior of drivers faced with the cut-in of a vehicle lane-changing into the space between themselves and the preceding vehicle. Data concerning this activity are in short supply and may be used not only in formulating models of human response in driving but also in designing and optimizing driver assistance aids such as adaptive cruise control (ACC). The cut-in vehicle used was equipped with a rear-facing radar unit enabling it to monitor the degree and speed with which drivers attempted to restore their original headway. Cut-ins from both directions were examined—moving in from a slower lane (94 events) and from a faster lane (72 events). The criticality experienced by the follower vehicle ranged from moderately severe [time to collision (TTC) around 10 s and time gap around 0.35 s] to noncritical (lead car’s speed at cut-in greater than follower speed and time headway beyond steady-state values). Findings indicate that the “pullback” behavior, at least over the initial 5 to 10 s, can be described by a constant pullback speed (the rate of decrease of the initial speed), and causative models for this response have been derived using “instantaneous” variables (those that may be calculated on cut-in, such as relative speed and TTC) and longer-term “target” variables, such as desired headway, the former of which have been most effective in describing behavior. Finally, empirical responses have been compared with those that would be produced by ACC systems; it was found that a comparatively close match is produced for low values of relative speed.
Modification and Partial Validation of the Driver/Vehicle Module
Authors: Levison William H. , Bittner Alvah C. , Campbell John L. , Schreiner Chris
Published: April 2007

Four assumptions of the Driver/Vehicle Module of the Interactive Highway Safety Design Model were tested against data obtained in two on-road studies of driver behavior. Supported were assumptions that drivers track to the inside of horizontal curves and that a linear control model is adequate for describing steering behavior. Not supported were assumptions of consistent preferred lateral acceleration in horizontal curves and consistent preferred longitudinal accelerations and decelerations during curve approach and exit. Experimental results support (a) an analytically derived square-root relationship between preferred lateral acceleration and curvature and (b) an analytically derived square-root relationship between longitudinal acceleration or deceleration and total speed change.
Evaluation of the Accuracy of a Real-Time Travel Time Prediction System in a Freeway Construction Work Zone
Authors: Zwahlen Helmut T. , Russ Andrew
Published: April 2007

The accuracy of the travel times displayed by the real-time Travel Time Prediction System (TIPS) in a construction work zone was investigated. The TIPS includes changeable message signs (CMSs) displaying the travel time and distance to the end of the work zone to motorists. The travel times displayed by the CMSs are computed by an intelligent traffic algorithm and travel time estimation model of the TIPS software, which takes input from strategically placed microwave radar sensors that detect the vehicle traffic on each lane of the freeway. Besides the CMSs and the radar sensors, the TIPS includes the computer and microcontroller computing the travel times, 220-MHz radios for transmitting data from the sensors to the computer and from the computer to the CMSs, and trailers with solar panels and batteries to power the radar sensors, CMSs, and radios. The evaluation included an accuracy analysis between the predicted and actual recorded travel times. Three crews driving independently of each other in the traffic stream recorded predicted and actual travel times at three CMSs to the end of the work zone for 12 h each day for three consecutive days, resulting in 119 trial runs. On the basis of the regression analysis of actual times versus predicted times, on the average the system does a reasonable job of predicting the travel times to the end of the work zone. About 88% of the actual times recorded for each sign, and for all the signs combined, were within a range of ±4 min of the predicted time. However, a few differences (actual versus predicted) as great as 18 min were observed. It is concluded that the realtime TIPS represents a definite improvement over any static non-realtime display system. It provides, in general and most of the time, useful and relatively accurate travel time predictions to the motoring public.
Drivers’ Understanding of Overhead Freeway Exit Guide Signs: Evaluation of Alternatives with an Advanced Fixed-Base Driving Simulator
Authors: Dutta Arup , Carpenter Rick , Noyce David A. , Duffy Susan A. , Fisher Donald L.
Published: April 2007

In the near future, Route 1A southbound as it passes around Logan International Airport in Boston, Massachusetts, will be rebuilt. The existing four-lane highway will split into three different roadways: two one-lane exits and one two-lane throughway. Drivers will have very little time to decide which lane or lanes to take for a given destination. Given the complex geometry and small warning time, there is some concern that drivers will either miss the Logan exit altogether (leading to a long and frustrating detour around Logan) or make a decision at the last moment to move into the exit lane (leading to a potential safety problem). Proposed and alternative ways of signing exits such as this one with complex multiple splits were evaluated on an advanced fixed-base driving simulator. The virtual roadways and signs were built using the actual engineering design drawings. Drivers sit in a real Saturn and operate the controls of this vehicle just as they would those of a normal vehicle. They are given Logan as their target destination. The alternative freeway guide signs were found to improve indices of driver safety and satisfaction. Specifically, drivers using the alternative signs move into the exiting lane sooner, make fewer double lane changes, and miss their exit less often. The results have implications more generally for the design and testing of highway guide signs using a driving simulator.
Reduction of Video License Plate Data
Authors: Gupta Rajeev , Fricker Jon D. , Moffett David P.
Published: April 2007

Video license plate surveys have been used for more than a decade in Indiana to help produce origin-destination tables in corridors and small areas. In video license plate surveys, license plate images are captured on videotape for data reduction at the analyst’s office. In most cases, the letters and numbers on a license plate are manually transcribed to a data file. This manual process is tedious, time-consuming, and expensive. Although automated license plate readers are being implemented with success elsewhere, their dependence on high-end equipment makes them too expensive for most applications in Indiana. Presented are the results of an attempt to use standard video cameras and tapes, readily available video processing equipment, and open-source software to minimize the human role in the data reduction process and thus reduce the expenses involved. The process of automatically transcribing video data can be divided into subprocesses. Analog video data are digitized and stored on a computer hard disk. The resulting digital images are further processed, by using image-processing algorithms, to locate and extract the license plate and time stamp information. Character recognition techniques can then be applied to read the license plate number into an electronic file for the desired analysis. The described video license plate data reduction (VLPDR) software can identify video frames that contain vehicles and discard the remaining frames. VLPDR can locate and read the time stamps in most of these frames. Although VLPDR cannot read the license plate numbers into a data file, this final step is made easier by a user-friendly graphical user interface. VLPDR saves a significant amount of manual data reduction. The amount of labor saved depends on the parameters chosen by the user.
Simulation Study of Estimation of Individual Specific Values of Time by Using Adaptive Stated-Preference Survey
Authors: Richardson A. J.
Published: April 2007

Stated-preference surveys provide a good opportunity for obtaining information for the construction of choice models, but they run the risk of asking questions that are too complex for respondents to answer meaningfully, especially when many attributes and alternatives are considered in each question. An alternative technique is the use of adaptive conjoint analysis or adaptive stated-preference (ASP) surveys, wherein simpler questions are used, each game is dependent on the answers given to previous games, and parameters are estimated at the level of the individual. A simulation study used to test the ability of ASP to produce unbiased estimates of the mean and standard deviation of the value of time (VOT) is described. It is found that this is possible under certain conditions, namely, that a seven-point rating scale is used to obtain responses, each respondent plays three games for each parameter to be estimated, the starting estimate of VOT used should be higher than the expected final mean value of VOT, and a logit model sensitivity parameter of c = 5 is used in the binary logit model used to convert probabilities of choice into utility differences. The results of this simulation give reassurance that in addition to being easier for respondents, the ASP survey method produces unbiased estimates of the distribution of VOT (or any other parameter under consideration). Given the extreme flexibility of the disaggregate results produced by the ASP survey method, the demonstration of unbiased estimates is an important confirmation of the usefulness of this method.
Use of Internet-Based Household Travel Diary Survey Instrument
Authors: Adler Thomas , Rimmer Leslie , Carpenter David
Published: April 2007

The results of an application of Internet survey methods to a household travel diary project are described. The project included a full field application of an Internet-based household travel diary instrument in a split sample design with conventional telephone or mail administration. The effects of this type of administration on survey response and on survey data are described. The work described demonstrates how Internet-based travel diary instruments can be used to complement other, more traditional survey approaches. The Internet household travel diary instrument used included several features that take advantage of the computational power provided by modern servers and the graphical user interface provided by web browsers. Among these, the most important are detailed internal consistency checks that test the continuity and completeness of the activity and trip logs and interactive geocoding of trip ends. The response rates in the split sample conducted for the Las Cruces application indicate that providing an Internet option had a small positive effect. However, there are more pronounced effects on reported trip making—more trips reported in the Internet instrument—and on item nonresponse—lower rates with the Internet instrument. Overall, respondents who used the Internet instrument found it easy to use and appreciated having the option to complete the questionnaire at their convenience. There are clear areas for further research, but it is equally clear that Internet-based household diary surveys can provide an important, cost-effective complement to computer-assisted telephone interview and mail methods.
Accessibility Indices: Connection to Residential Land Prices and Location Choices
Authors: Srour Issam M. , Kockelman Kara M. , Dunn Travis P.
Published: April 2007

Specifications of accessibility indices range from simple minimum-travel-time indices, to measures of cumulative opportunities within specified distance or time thresholds, to maximum utility measures. Models are presented that relate a variety of general accessibility indices for the Dallas–Fort Worth region of Texas to property valuations for single-family dwelling units and commercial units, and to household residential location choices. Hedonic models are used to assess how important access is to property valuations, while controlling for improvement attributes and parcel size. Multinomial logit models are used to derive logsum measures of accessibility as well as to assess the effect of access on location choices, while controlling for household demographics. Three functional specifications of access measures were used. Job accessibility (a proxy for work and other opportunities) was estimated to affect residential land values positively in statistically and economically significant ways, suggesting—as hypothesized here—that land rents track property owners’ assessments of accessibility, whereas other common accessibility measures do not perform as well. After controlling for this measure, access to park space (proxy for availability of outdoor recreational activities) and access to retail jobs (proxy for shopping opportunities) were not valued in the land market. Distances to regional central business districts and household heads’ workplace locations played important roles in location predictions, often in the presence of the more general access measures. Residential location choice model results suggested which indices are better measures of accessibility. Different functional specifications appeared useful here. Cumulative opportunities access measures were most helpful in predicting residence location, but differences in predictive power were relatively small.
Traditional Neighborhoods and Automobile Ownership
Authors: Baldwin Hess Daniel , Ong Paul M.
Published: April 2007

Many cities have traditional neighborhoods composed of diverse housing, mixed land uses, pedestrian connectivity, and convenient transit access. The effects of these types of land use patterns on automobile ownership are quantified. Using Portland, Oregon, a model is tested that explains automobile ownership on the basis of household, neighborhood, and urban design characteristics. Strong evidence is found of the effect of mixed land use on automobile ownership: as land use mix changes from homogeneous to diverse, the probability of owning an automobile decreases by 31 percentage points, ceteris paribus. Findings imply that traditional neighborhoods are more conducive to alternatives to private vehicle use, such as walking and public transit. It was concluded that inner-ring suburbs that have traditional neighborhood features provide households with the opportunity to express their preference to avoid automobile ownership and to save on the cost of owning and operating automobiles.
Effects of In-Fill Retail Center Development on Regional Travel Patterns
Authors: Shiftan Yoram , Newmark Gregory L.
Published: April 2007

Although the traditional centrifugal flow of metropolitan development continues, there is a countertrend both in the United States and abroad toward renewed real estate investment in the central business district (CBD) and in the older areas surrounding it. Construction in the non-CBD urban areas is called in-fill development. The goal of in-fill development is the rejuvenation of the urban environment through increasing densities, improving land use, and rationalizing transportation patterns. Regional transportation effects of the growing phenomenon of the in-fill mall are examined. Specifically, the focus is on changes in shopping area preference, travel mode choice, individual travel time, and vehicle hours traveled following the introduction of a new in-fill mall in the city of Haifa, Israel. Analysis is based on mall patrons’ survey responses. These responses include information on shopping travel behavior before and after the opening of the retail center. Results show that the introduction of this in-fill mall appears to have resulted in a net improvement in the regional transportation system. Specific benefits include the reduction of individual travel times for preexisting shoppers by more than 17% and the reduction of highway network vehicle hours of travel by all patrons by more than 25%. On the basis of this research, it appears that in-fill locations of retail centers can be an effective way to rationalize development and maintain the strength and vitality of existing urban areas
Microsimulation in Travel Demand Modeling: Lessons Learned from the New York Best Practice Model
Authors: Vovsha Peter , Petersen Eric , Donnelly Robert
Published: April 2007

Microsimulation is increasingly assuming a major role in the advancement of demand-modeling practice. At the same time, it is attracting growing attention from the larger transportation-planning community. Four basic advantages of microsimulation versus conventional fractional-probability models are examined. The first is the technical advantage related to computational savings in the calculation and storage of large multidimensional probability arrays. The second is the meaningful advantage gained in the explicit modeling of various decision-making chains and time–space constraints on individual travel that allows for behavioral realism in the demand-modeling procedure. The third relates to the variability of microsimulation outcomes, which can yield full information about the distributions of the travel demand statistics of interest rather than single deterministic estimates or average values. As soon as constraints are introduced into the modeling framework (which often is done at the destination choice stage), competition arises, although generally it has been ignored in standard models. Microsimulation has the potential to handle this competition over work attractions and other travel activities in a meaningful fashion, which is the fourth advantage. These four advantages of microsimulation are discussed in light of the recent development and application of the New York best practice model, a microsimulation demand-modeling system for the New York–New Jersey–Connecticut metropolitan area.