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  • 1
    Online Resource
    Online Resource
    Using Empirical Data to Find the Best Measure of Travel Time Reliability
    SAGE Publications ; 2015
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2530, No. 1 ( 2015-01), p. 93-100
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2530, No. 1 ( 2015-01), p. 93-100
    Abstract: The value of travel time savings is often the largest benefit from transportation projects and has been studied extensively. Recently, additional attention has been paid to the fact that travelers also benefit from reliable travel times. The value of reliability (VOR) has usually been estimated through stated-preference data or survey-based revealed-preference data. In this research, empirical data were used to estimate VOR. One concern about estimating VOR from empirical data was the lack of a definitive measurement for reliability. Should it be the standard deviation (SD) of travel time, the 95th percentile, or another measure? Data from Katy Freeway in Texas, where travelers chose between tolled but generally more-reliable lanes and free but generally less-reliable lanes, were used in an attempt to find the best measurement of reliability that could lead to the best explanation of travelers’ lane choice. Multinomial logit models were used to estimate travelers’ lane choice on the basis of trip attributes, including travel time, many measures of travel time reliability, and tolls. Models including only travel time and tolls yielded reasonable results and values of time ($2.78/h, $9.09/h, and $10.52/h for off-peak, shoulder, and peak periods, respectively). However, adding reliability to the models caused many of them to have counterintuitive results, and concluding which measure was the best was impossible. In addition, the results of this research suggested that reliability might not be an influential factor in the lane choice decision on managed lanes, at least when travelers had reasonable knowledge of their potential travel time.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2530-11
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2015
    detail.hit.zdb_id: 2403378-9
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  • 2
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    Online Resource
    Exploring the Impact of Different Cut-off Times on Isochrone Measurements of Accessibility
    SAGE Publications ; 2018
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2672, No. 49 ( 2018-12), p. 113-124
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2672, No. 49 ( 2018-12), p. 113-124
    Abstract: Isochrone analysis and assessments of cumulative opportunities are a common way to quantify accessibility. However, different time cut-offs have been used by different researchers, with little investigation into what is the ‘best’ cut-off time. Outstanding questions remain concerning the most effective or predictive cut-off time and the potential implications of choosing one time limit over another. The primary objective of this paper is to explore how different cut-off times affect the calculation of isochrone-based accessibility measurements and their potential to predict travel-mode choice. Fifty dissemination areas (DAs) within the Greater Toronto and Hamilton Area (GTHA) are selected to test the impact of different isochrone cut-off times in 5-minute intervals for public transit, automobile, and walking accessibility. The relative predictive power of 30- and 45-minute isochrones in modeling mode choice is also examined. This paper finds that different cut-off times do impact the interpretability of accessibility measurements in the isochrone approach, but a defined cut-off time for general use cannot be determined based on the analysis.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198118783113
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2018
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  • 3
    Online Resource
    Online Resource
    Best Routing Policy Problem in Stochastic Time-Dependent Networks
    SAGE Publications ; 2002
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1783, No. 1 ( 2002-01), p. 188-196
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1783, No. 1 ( 2002-01), p. 188-196
    Abstract: The best routing policy problem in stochastic and time-dependent networks is the subject of this study. This problem can be viewed as a counterpart of the shortest-path problem in deterministic networks. A stochastic time-dependent network is one in which the link travel times are random variables with time-dependent distributions. A routing policy is a decision rule that specifies what node to take next at each decision node on the basis of the realized link travel times and the current time. The framework of the problem is reviewed, on which basis one of the variants of the problem that are pertinent to the traffic context is studied. An exact algorithm to this variant is given, and its complexity is analyzed. Since the running time of the exact algorithm is generally exponential in the number of arcs, the importance of finding good approximations to the exact algorithm is pointed out. Several approximations are presented, and their effectiveness against the exact algorithm is studied both theoretically and computationally.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/1783-23
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2002
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  • 4
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    Online Resource
    Forecasting Multiple-Period Freeway Link Travel Times Using Modular Neural Networks
    SAGE Publications ; 1998
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1617, No. 1 ( 1998-01), p. 163-170
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1617, No. 1 ( 1998-01), p. 163-170
    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 realtime 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.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/1617-23
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1998
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  • 5
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    Online Resource
    Modeling Road Link-Level Truck Travel Times Using On- and Off-Network Characteristics
    SAGE Publications ; 2022
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2676, No. 9 ( 2022-09), p. 41-58
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2676, No. 9 ( 2022-09), p. 41-58
    Abstract: Travel times of freight trucks (or trucks) play a major role in trip planning, identification of efficient routes, and allocating resources for implementation of strategies. While research on travel time estimation models for passenger cars or traffic stream is documented in the literature, their applicability for trucks remains debatable. Truck travel is influenced by the road characteristics, surrounding land use, and demographics of an area. The focus of this research, therefore, is on estimating the truck travel times using the on-network (road) and off-network (land use and demographics) characteristics. Truck travel time data for 501 road links in North Carolina from 2019 were processed for four times of the day and two days of the week. Generalized estimating equations (GEE) were used with the average truck travel time per mile (ATTTPM) as the dependent variable. Spatial proximity (buffers of 0.25 mi, 0.50 mi, and 1 mi) and spatial weights (distance decay functions like 1/d, 1/d 2 , and 1/d 3 ) were explored to check the best possible approach for capturing off-network characteristics. The office (business park and administrative areas), transportation (rest areas and parking facilities), heavy commercial, and light industrial land uses have an increasing influence on the ATTTPM. The linear model developed using data from a 0.25-mi buffer is best suited to estimate the ATTTPM. Off-peak hour delivery incentives or truck priority systems on road links near these land uses can be implemented to improve truck mobility. The methodology illustrated in this research is transferable and could be used for estimating truck travel times across a region.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981221085533
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
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  • 6
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    Online Resource
    Minimizing Transfer Times in Public Transit Network with Genetic Algorithm
    SAGE Publications ; 2006
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1971, No. 1 ( 2006-01), p. 74-79
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1971, No. 1 ( 2006-01), p. 74-79
    Abstract: This paper presents a systemwide approach based on a genetic algorithm for the optimization of bus transit system transfer times. The algorithm attempts to find the best feasible solution for the transfer time optimization problem by shifting existing timetables. It makes use of existing scheduled timetables and ridership data at all transfer locations and takes into consideration the randomness of bus arrivals. The complexity of the problem is mainly due to the use of a large set of binary and discrete variables. The combinatorial nature of the problem results in a significant computational burden, and thus it is difficult to solve with classical methods. Scheduling data from Broward County Transit, Florida, were used to calculate total transfer times for the existing and proposed systems. Results showed that the algorithm produced significant transfer time savings.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198106197100109
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2006
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  • 7
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    Online Resource
    Automated Measurement of Wait Times at Airport Security : Deployment at Indianapolis International Airport, Indiana
    SAGE Publications ; 2010
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2177, No. 1 ( 2010-01), p. 60-68
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2177, No. 1 ( 2010-01), p. 60-68
    Abstract: An anonymous Bluetooth tracking system was deployed at the new Indianapolis International Airport in Indiana from May 8 to June 2, 2009, to measure the time for passengers (a) to move from the nonsterile side of the airport (presecurity), (b) to clear the security screening checkpoint, and (c) to enter the walkway to Concourse B on the sterile side. The maximum passenger transit time between these checkpoints was observed on Monday mornings at approximately 0600, when it could take passengers up to 20 min to transit the security queue and screening and to walk to Concourse B. Depending on the day of the week, this approach was demonstrated to sample between 5% and 6.8% of passengers. This modest sample size provides a more robust measurement of screening times than the current system of manually distributing time-stamped cards as passengers enter the queue and collecting them where passengers pass through the magnetometer. Furthermore, because the final passenger reference point used in this study is on the sterile concourse, it captures the time associated with passengers repackaging their belongings and redonning their shoes. The data from this pilot study suggest the feasibility of using an automated system to provide quantitative information to managers for more effective allocation of scarce resources, as well as providing the traveling public with necessary information about the amount of time they should allocate for transiting the security screening process. The paper concludes by suggesting that additional pilot studies should be performed at several airports with alternative checkpoint configurations to develop a consensus on best practices for locating sensors to measure passage times at airport security screening.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2177-08
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2010
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  • 8
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    Online Resource
    Mathematical Model to Quantify the Impact of Accommodating Pedestrian Timings in Coordinated Signal Systems
    SAGE Publications ; 2024
    In:  Transportation Research Record: Journal of the Transportation Research Board
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications
    Abstract: This research aimed to develop a quantitative-based model for determining the delay of pedestrian timing accommodation (PTA) into coordinated signals compared with the nonaccommodation (PTN) alternative. The idea for the research came from the need for a tool sought by practicing traffic signal engineers by which empirical judgments have chosen pedestrian accommodation. Practitioners can ascertain the best option (PTA or PTN) for a series of coordinated signals using the proposed model. The model was implemented into an open-source software available for general use. The proposed delay model was validated and its accuracy demonstrated using simulation. The model and related software will make it an easier and more systematic process for practitioners to choose between PTA and PTN at coordinated signals.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981231217502
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2024
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  • 9
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    Online Resource
    Fuzzy Optimization Approach : Comparison with the Classical Optimization Method Using the Problem of Timing a Traffic Signal
    SAGE Publications ; 2007
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2024, No. 1 ( 2007-01), p. 82-91
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2024, No. 1 ( 2007-01), p. 82-91
    Abstract: The fuzzy optimization approach is known to be useful for multiobjective and multiconstraint decision situations in which the objectives and constraints are approximate. Although many transportation problems are in this category, the actual application of fuzzy optimization has been rare so far. This paper introduces the fuzzy optimization technique and tests this approach by applying it to setting the signal timing, in which the values of the parameters are not well defined. Three existing signal-timing models are reformulated into the fuzzy optimization approach to accommodate the uncertainty in the parameter values of the models. The results are compared with those obtained from the traditional formulation of the three models. The models tested are the Highway Capacity Manual approach, Webster's method, and Akcelik's method. For average delay and fuel consumption in general, the results obtained from the fuzzy optimization approach are found to be smaller than those obtained using the traditional approach of the three models. This study finds that the fuzzy optimization approach can be useful for transportation problems when objectives and constraints are many, when the boundary values of the constraints are not well defined, and when the goodness of the solution is based on acceptability or best compromise.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2024-10
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2007
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  • 10
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    Online Resource
    Estimating the Timing of Rehabilitation and Replacement of Bridge Elements
    SAGE Publications ; 2011
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2220, No. 1 ( 2011-01), p. 48-56
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2220, No. 1 ( 2011-01), p. 48-56
    Abstract: The core component of infrastructure management systems is life-cycle costing, typically used to justify the appropriate actions to the infrastructure at the best times during service life. This paper presents the results of a study on the timing of such actions, with emphasis on state-maintained highway bridges in Florida. Using historical cost data of maintenance, repair, rehabilitation, and replacement of bridge elements, the authors present and discuss basic statistical summaries of the age of bridges when the actions were applied. From the concept of age replacement models, an estimate was computed for the optimal ages at which to rehabilitate or replace some bridge elements. Weibull-type distributions were obtained as the best-fitting probability distributions of the time until a failure. “Failure time” is a term borrowed from operations research, where it implies the end of service life of items or systems, but here it means when it is necessary to repair or replace a bridge element. Optimization was then performed according to reliability models developed to minimize the average long-run costs per year on rehabilitation and replacement of the bridge elements. Advantages and limitations of the results are discussed. The proposed methodology has good potential to help the bridge manager estimate service life of bridge elements, with a consideration of the repair policy. Limitations to the direct implementation of the methodology exist, but some improvement can be achieved with future research.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2220-06
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2011
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