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  • 1
    Online Resource
    Online Resource
    Elsevier BV ; 2017
    In:  Journal of Traffic and Transportation Engineering (English Edition) Vol. 4, No. 5 ( 2017-10), p. 423-435
    In: Journal of Traffic and Transportation Engineering (English Edition), Elsevier BV, Vol. 4, No. 5 ( 2017-10), p. 423-435
    Type of Medium: Online Resource
    ISSN: 2095-7564
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2017
    detail.hit.zdb_id: 2817145-7
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  • 2
    Online Resource
    Online Resource
    SAGE Publications ; 2015
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2484, No. 1 ( 2015-01), p. 165-172
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2484, No. 1 ( 2015-01), p. 165-172
    Abstract: The purpose of this paper is to report the results of a study on the effectiveness of implementing the carousel method on a multilane freeway. When compared with other average vehicle occupancy (AVO) data collection methods, the functionality of the carousel method allows for the most accurate vehicle occupancy data to be collected on multilane freeways. With the power of a spreadsheet macro user-generated form, the carousel method has the capability to collect observation data, such as AVO data and vehicle type data, instantaneously. As data are collected, a power analysis can be executed to track the progress of the data collection process and can provide intermediate vehicle occupancy results. A 2014 Utah Department of Transportation study outlines how the carousel method was successfully implemented for multilane freeways. The results of the data analysis validated the carousel method as an acceptable method for collecting average vehicle occupancy data. The results of an AVO study in Utah are reported on the basis of the application of the carousel method. Results show that the AVO on express lanes is between 1.55 and 2.23 persons per vehicle and between 1.11 and 1.36 persons per vehicle for general purpose lanes. The details included in this report provide the basic building blocks of information that will allow municipalities and research teams to use the carousel method in multilane freeway studies.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2015
    detail.hit.zdb_id: 2403378-9
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  • 3
    Online Resource
    Online Resource
    SAGE Publications ; 2024
    In:  Transportation Research Record: Journal of the Transportation Research Board
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications
    Abstract: At the start of the 2019 to 2020 snow season, vehicle-to-everything (V2X) systems using dedicated short-range communication (DSRC) were placed on Utah Department of Transportation snowplows and traffic signal controllers on selected state routes. This study was conducted to understand the overall impacts of snowplows using V2X DSRC to request signal preemption. Roadside units (RSUs) were deployed on five corridors throughout the Salt Lake metropolitan area. Similar routes without RSUs were selected as a control and were used in the analysis to quantify results. Each snowplow on these corridors was equipped with an onboard unit (OBU). Based on data collected, analysis was performed on both traffic signal performance and vehicle performance data. Within the traffic signal performance analysis, it was found that the V2X DSRC system was utilized often, with snowplows requesting preemption in more 50% of the occasions they approached a signalized intersection. Of those requests, signal controllers granted preemption in over 80% of cases. On average, signal controller coordination was affected for less than 5 min. The vehicle performance analysis found that the snowplows on equipped routes had travel speeds that were less affected when there was snow than on corresponding not-equipped routes. Vehicle crash data also showed that there was a greater decrease in crashes on equipped routes than not-equipped routes. Anecdotal evidence gathered from snowplow drivers indicated that snowplows stopped less when using signal preemption. Drivers also noted a benefit to overall snow removal operations on corridors equipped with the V2X DSRC system.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2024
    detail.hit.zdb_id: 2403378-9
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  • 4
    Online Resource
    Online Resource
    American Society of Civil Engineers (ASCE) ; 2007
    In:  Journal of Transportation Engineering Vol. 133, No. 10 ( 2007-10), p. 564-571
    In: Journal of Transportation Engineering, American Society of Civil Engineers (ASCE), Vol. 133, No. 10 ( 2007-10), p. 564-571
    Type of Medium: Online Resource
    ISSN: 0733-947X , 1943-5436
    Language: English
    Publisher: American Society of Civil Engineers (ASCE)
    Publication Date: 2007
    detail.hit.zdb_id: 2011420-5
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  • 5
    Online Resource
    Online Resource
    SAGE Publications ; 2021
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2675, No. 5 ( 2021-05), p. 149-163
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2675, No. 5 ( 2021-05), p. 149-163
    Abstract: An analysis was performed to evaluate the impact of changing the transit signal priority (TSP) requesting threshold on bus performance and general traffic, using field-generated data exclusively. Route 217, a conventional bus route that uses a dedicated short-range communication (DSRC)-based TSP system as part of its normal day-to-day operations, was analyzed over a three-month period from May 2019 through August 2019. The requesting thresholds evaluated for Route 217 were 3, 2, and 0 min, which stipulate how far behind schedule the bus must be to request TSP. For each requesting threshold, bus performance was evaluated through on-time performance (OTP), schedule deviation, travel time, and dwell time, while the traffic analysis was performed by evaluating split failure, change in green time, and the frequency at which TSP was served. A combination of observational and statistical analyses concluded with convincing evidence that OTP, schedule deviation, and travel time improve as the requesting threshold approaches zero with negligible impacts on general traffic. As the requesting threshold changed from 3, to 2, to 0 min, OTP increased 2.0% and 2.5%, respectively; mean schedule deviation improved by 15.9 s and 20.9 s, respectively; and travel time decreased at 75% of timepoints. Meanwhile, negative impacts to traffic occurred if an increase in split failure was measured after TSP was served, a phenomenon observed a maximum of once every 43 min. Thus, it is concluded that bus performance improves as the requesting threshold approaches zero with inconsequential impacts on general traffic.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2021
    detail.hit.zdb_id: 2403378-9
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  • 6
    Online Resource
    Online Resource
    SAGE Publications ; 2018
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2672, No. 17 ( 2018-12), p. 120-128
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2672, No. 17 ( 2018-12), p. 120-128
    Abstract: In a traditional safety impact analysis, it is necessary to have crash data on existing roadway conditions and a few years must pass before accumulating additional crash data to evaluate the safety impact of an improvement. This is a time-consuming approach and there remains uncertainty in the crash data integrity. The surrogate safety assessment model (SSAM) was developed for resolving these issues. With SSAM, a conflict analysis is performed in a simulated environment. A planned improvement alternative is modeled and no physical installation of the alternative is needed. This study evaluated if SSAM can be used to assess the safety of a highway segment in terms of the number and type of conflicts and to compare the safety effects of multiple access management alternatives. An evaluation of the effect of converting a two-way left-turn lane (TWLTL) into a raised median on a section of an urban street was performed using SSAM working on VISSIM simulation’s trajectory files. The analysis showed that a raised median would be much safer than a TWLTL median for the same level of traffic volume, with approximately 32 to 50 percent reduction in the number of crossing conflicts. The analysis showed that about 34,000 to 38,000 veh/day would be the demand level where the median conversion is recommended for the four-lane study section. The study concluded that the combination of a simulation software program with SSAM could be a viable surrogate analysis approach for evaluating and comparing the safety effects of multiple access management alternatives.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2018
    detail.hit.zdb_id: 2403378-9
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  • 7
    Online Resource
    Online Resource
    MDPI AG ; 2023
    In:  Future Transportation Vol. 3, No. 4 ( 2023-10-02), p. 1175-1194
    In: Future Transportation, MDPI AG, Vol. 3, No. 4 ( 2023-10-02), p. 1175-1194
    Abstract: Automated traffic signal performance measures (ATSPMs) have garnered significant attention for their ability to collect and evaluate real-time and historical data at signalized intersections. ATSPM data are widely utilized by traffic engineers, planners, and researchers in various application scenarios. In working with ATSPM data in Utah, it was discovered that five types of ATSPM data anomalies (data switching, data shifting, data missing under 6 months, data missing over 6 months, and irregular curves) were present in the data. To address the data issues, this paper presents a method that enables transportation agencies to automatically detect data anomalies in their ATSPM datasets. The proposed method utilizes the moving average and standard deviation of a moving window to calculate the z-score for traffic volume data points at each timestamp. Anomalies are flagged when the z-score exceeds 2, which is based on the data falling within two standard deviations of the mean. The results demonstrate that this method effectively identifies anomalies within ATSPM systems, thereby enhancing the usability of data for engineers, planners, and all ATSPM users. By employing this method, transportation agencies can improve the efficiency of their ATSPM systems, leading to more accurate and reliable data for analysis.
    Type of Medium: Online Resource
    ISSN: 2673-7590
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 3112260-7
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