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  • Mobility and traffic research  (14)
  • 1
    Online Resource
    Online Resource
    Impact of Climate Conditions on Effectiveness of Asphalt Pavement Preservation Techniques
    SAGE Publications ; 2012
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2292, No. 1 ( 2012-01), p. 73-80
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2292, No. 1 ( 2012-01), p. 73-80
    Abstract: Pavement preservation is practiced by many highway administration agencies throughout the world. Pavement preservation also attracts much attention from agencies that have few or no such programs. How to choose the most effective treatment at a given location, however, remains a question. On the basis of data from the Specific Pavement Study 3 of the Long-Term Pavement Performance program, the study reported in this paper examined the impact of climate conditions on the effectiveness of asphalt pavement preservation techniques. Six climate zones were defined on the bases of number of wet days, freeze–thaw cycles, and number of days below 0°C. Within each climate zone, performance differences on graphical representations and paired t-tests were assessed for four types of treatment sections and control sections in terms of the international roughness index (IRI). The magnitudes of the IRI changes caused by these treatments were in general quite noticeable, but the effectiveness varied greatly with climate condition and treatment type. Statistically significant treatments at each climate zone were reported in the study. All four types of treatments significantly reduced IRI growth under two climate conditions: (a) warm and dry and (b) wet and cold. In addition, chip sealing and thin overlay treatments seemed more likely to succeed in different climates.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2292-09
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2012
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  • 2
    Online Resource
    Online Resource
    LiDAR Perception and Evaluation Method for Road Traffic Marking Retroreflection
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 6 ( 2023-06), p. 258-279
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 6 ( 2023-06), p. 258-279
    Abstract: To solve the problem of low efficiency in retroreflection maintenance of road traffic markings, in this study a vehicle-mounted LiDAR-based perception and evaluation method of retroreflection of markings is proposed. First, this method establishes a calibration prediction model for LiDAR based on a regression decision tree. Then, a marking maintenance evaluation model is constructed in combination with the decision threshold proposed by China’s national standard, and the accuracy of the maintenance evaluation model is analyzed using F1-score, recall, and precision. In this study, four marking lines were used as the calibration data source, and a dataset of an independent 1,300 m road section was used to verify the established models. The results show that the coefficient of the retroreflected luminance ( R L ) and the reflection intensity of the markings are positively correlated. During the construction of the calibration prediction model, the multiple linear regression functions, the second-order polynomial functions, and the decision tree are compared, and the result indicates that decision tree has the best fit to the data with the coefficient of determination for the established calibration prediction model better than 0.95. The agreement between the maintenance decision obtained from the maintenance evaluation model and the traditional method is more than 85%. The time cost is reduced by at least 90%. The proposed calibration prediction model can accurately predict the R L , and can quickly collect the R L values of the in-service road traffic markings. The proposed maintenance evaluation model is highly efficient and can replace the traditional evaluation method for markings.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981221145135
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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  • 3
    Online Resource
    Online Resource
    Finding Shortest Paths under Time–Bandwidth Constraints by using Elliptical Minimal Search Area
    SAGE Publications ; 2006
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1977, No. 1 ( 2006-01), p. 225-233
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1977, No. 1 ( 2006-01), p. 225-233
    Abstract: Although many studies on shortest-path algorithms have been conducted, few of them have taken advantage of the added characteristics of highway networks and, thus, have failed to become more efficient in finding shortest paths, or lowest-cost paths, for transportation problems. A new concept is proposed for enhancing most existing shortest-path algorithms. Taking advantage of the geographical nature of most transportation networks, the new concept uses a minimal search area to reduce the amount of computations that must be performed by existing algorithms. To simplify the analysis, a hypothetical network in an L1 metric was used to approximate two-dimensional roadways. Empirical results from thousands of shortest paths between arbitrary origin–destination pairs suggested that an elliptical shape is most suitable for confining the search area when seeking a shortest path. Further analysis established the formulation of the ellipse, which becomes rounder when the origin is close to the destination and more elongated when the two points are far apart. The elliptical minimal search area is stable and has a high level of confidence in containing the true shortest path, even if the cost function for each link is dynamic or stochastic. A list of future tasks is presented to further the promising findings of this research. The algorithm, which is not in itself a shortest algorithm per se, can enhance other shortest-path algorithms for transportation roadway networks.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198106197700126
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2006
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  • 4
    Online Resource
    Online Resource
    Degraded Ballast Stiffness Characterization Using Bender Element Field Sensor and PANDA ® Penetrometer
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 8 ( 2023-08), p. 428-438
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 8 ( 2023-08), p. 428-438
    Abstract: The progressive degradation of railway ballast over time increases the degree of ballast fouling and poses significant drainability concerns leading to frequent maintenance activities. To avoid such issues, an effective and continuous characterization of the physical properties of the ballast layer is deemed necessary. This paper introduces the combined use of a bender element (BE) piezoelectric field sensor and a PANDA ® dynamic cone penetrometer for periodic evaluations of ballast condition over the traffic use. To simulate various levels of ballast degradation, box tests were conducted using a dolomitic ballast material compacted in a laboratory-sized testbed with fouling indices ranging from zero to 39%. BE sensor pairs were embedded in the ballast layer to calculate the small strain modulus behavior of the ballast assessed through shear wave velocity measurements under different confinement conditions. Strength profiles of the ballast at different fouling levels were also measured using the PANDA ® penetrometer. Experimental findings from both test methods indicate the existence of a dense state of ballast linked to a certain fouling index that maximized stiffness and strength characteristics of the tested ballast in dry condition. Accordingly, the potential use of BE field sensors embedded within in-service ballasted track coupled with periodic penetration testing can be a viable approach to evaluate ballast layer degradation. Various void packing conditions associated with ballast fouling levels can be linked to important ballast layer modulus and strength behavior. Further, such smart sensing of ballasted track behavior can provide long-term performance monitoring solutions for ballast cleaning and maintenance scheduling.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981231156936
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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  • 5
    Online Resource
    Online Resource
    Deep Q-Network-Based Efficient Driving Strategy for Mixed Traffic Flow with Connected and Autonomous Vehicles on Urban Expressways
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 10 ( 2023-10), p. 324-338
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 10 ( 2023-10), p. 324-338
    Abstract: With the increase in the number of automated vehicles, roads will contain a mix of automated vehicles and human-driven vehicles. At present, rule-based driving strategy control of automated vehicles in mixed traffic flow makes it difficult to obtain optimal control. Therefore, this study proposes a learning-based driving strategy for connected and autonomous vehicles under mixed traffic flow. The proposed method differs from other driving strategies in two respects. First, both the lane-change and car-following policies are included, and the Deep Q-network algorithm is utilized to train the two policies in a mixed traffic-flow environment. Second, the proposed driving strategy considers both traffic efficiency and safety when designing the reward function. Through simulation experiments, the differences in traffic efficiency and safety of this method and the rule-based method were compared and analyzed under different traffic densities and penetration rates of connected and autonomous vehicles. Simulation results show that the driving strategy improves the average velocity (by 7.02 km/h) and traffic safety (especially in high-density traffic), compared with traditional rule-based driving strategy.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981231161355
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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  • 6
    Online Resource
    Online Resource
    Aggregate Subgrade Improvements Using Quarry By-Product Fines: A Case Study
    SAGE Publications ; 2022
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2676, No. 8 ( 2022-08), p. 386-397
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2676, No. 8 ( 2022-08), p. 386-397
    Abstract: This paper presents a case study for constructing aggregate subgrade improvement (ASI) layers using quarry by-product aggregates (QBA)—a quarry mix of large primary crushed rocks (PCR) and sand-sized quarry fines. The construction took place at Larry Power Road in Bourbonnais Township in Kankakee County, Illinois, where the Illinois Department of Transportation (IDOT) placed two QBA mixes for performance evaluation. The first mix (QBA_M1) consisted of 45% quarry by-products (QB) and 55% railroad ballast-sized PCR. The second mix (QBA_M2) consisted of 31% QB and 69% PCR. Two conventional ASI sections with only PCR were also constructed. All sections consisted of a 229 mm (9 in.) QBA/PCR layer topped with a 76 mm (3 in.) thick dense-graded capping layer. Laboratory studies preceded the construction to recommend optimum QB percentages for the QBA materials and construction practice. The quality and uniformity of the construction was ensured through field testing using dynamic cone penetrometer (DCP), lightweight deflectometer (LWD), and falling weight deflectometer (FWD). The segregation potential of the QBA mixes was monitored by visual inspection, aggregate stockpile sampling, and image analysis techniques. Short-term field evaluation of the constructed QBA layers, particularly QBA_M2 with 31% QB, showed no evidence of major segregation. The QBA ASI layers had slightly lower but comparable strength and stiffness profiles to the conventional ASI sections. The use of QBA materials in ASI was therefore field validated in this case study as a sustainable construction practice to provide stable pavement foundation layers.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981221083916
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
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  • 7
    Online Resource
    Online Resource
    Evaluation of Open-Graded Aggregates Stabilized with a Multi-Axial Geogrid Using a Large-Scale Triaxial Test Set-Up
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 10 ( 2023-10), p. 339-350
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 10 ( 2023-10), p. 339-350
    Abstract: Geogrids are commonly used in paved and unpaved roadways to stabilize base and subbase layers by laterally restraining movements of unbound aggregates under applied wheel loading, often referred to as interlocking. The geogrid-aggregate interlock is a function of the match between the geogrid aperture size and geometry and the grain size and shape characteristics of the stabilized aggregates. Open-graded coarse aggregates (OGA) are commonly used as an alternative to dense-graded materials in permeable base/subbase applications as well as in railway ballast to facilitate drainage. This paper describes an experimental study recently conducted to investigate the repeated load-deformation behavior of a geogrid-stabilized OGA material in large-scale triaxial testing. Two multi-axial geogrids with the same aperture patterns but different aperture sizes were tested. The aperture patterns include different sizes of hexagonal, trapezoidal, and triangular openings. The multi-axial geogrid with the larger apertures better matched the OGA material properties to provide a reduction in permanent deformation in the test specimen. The improved interlocking and the related local stiffness enhancement were successfully quantified using embedded shear wave transducers termed bender elements. To stabilize aggregates with relatively uniform grain sizes, for example, AASHTO No. 57 stone studied here and railroad ballast, the ratio between the aperture size and a representative particle size (i.e., D 90 ) served as a good indicator of the effectiveness of the geogrid. The findings of this experimental study therefore provided valuable information on the governing properties and mechanisms that play a role in geogrid-aggregate interaction with multi-axial geogrids.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981231161351
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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  • 8
    Online Resource
    Online Resource
    Examination of the Transferability of Safety Performance Functions for Developing Crash Modification Factors: Using the Empirical Bayes Method
    SAGE Publications ; 2016
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2583, No. 1 ( 2016-01), p. 73-80
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2583, No. 1 ( 2016-01), p. 73-80
    Abstract: In this study, crash modification factors (CMFs) for the effect of signalization at intersections in Florida were estimated. This paper applies the empirical Bayes method to develop CMFs for KABCO, KABC, and rear-end crashes by using several safety performance functions (SPFs) from various jurisdictions, adjusted by calibration factors. [In the KABCO scale, K = fatal (killed), A = incapacitating injury, B = nonincapacitating injury, C = possible injury, and O = property damage only.] Florida and Ohio data were used to develop these SPFs. Also, the SPFs suggested in the Highway Safety Manual were used to calculate CMFs. Through development of the SPFs and comparison of SPFs from different states, the study concluded that it might not be suitable to apply SPFs from other states without thorough examination. The CMF was 0.785 for KABCO with the SPF from Florida, significantly smaller than 1; this result indicated that the signalization at intersections resulted in fewer total crashes. But when the SPFs from Ohio and the Highway Safety Manual were applied, higher CMFs of 1.06 and 1.07 were obtained, respectively. These were significantly larger than 1; this result shows that the signalization brings about more total crashes. CMFs for KABC and rear-end crashes are discussed in this paper as well . The major finding of this study is that the CMF values may be significantly different when SPFs developed from other states’ data are applied. Therefore, CMFs would be biased if SPFs are borrowed from other states without proper adjustments.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2583-10
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2016
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  • 9
    Online Resource
    Online Resource
    Long-Term Effect of Universal Helmet Law Changes on Motorcyclist Fatal Crashes: Comparison Group and Empirical Bayes Approaches
    SAGE Publications ; 2017
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2637, No. 1 ( 2017-01), p. 27-37
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2637, No. 1 ( 2017-01), p. 27-37
    Abstract: A motorcyclist helmet is considered important safety equipment because it prevents or minimizes head and brain injuries, which are often fatal. Hence, in the 1960s and 1970s, most of the states in the United States enacted the universal helmet law (UHL) requiring all motorcyclists to wear helmets. Many researchers have examined the effect of the helmet law changes by using before-and-after studies and found that repealing the law had a negative effect on motorcyclists. In this study, the authors have attempted to explore the long-term impacts of repeal and reinstatement of the UHL by using 13 to 16 years of data. A before-and-after study with a comparison group and empirical Bayes methods was adopted to account for the passage of time and its effect on other factors such as exposure, maturation, trend, and regression-to-the-mean bias. A range of safety performance functions was developed on the basis of counties and parishes, and the expected fatal motorcycle crashes were calculated. The results showed that the UHL repeal still had significant effects on motorcycle fatal crash counts even 7 to 12 years after the repeal of the law. The crash modification factors showed that the UHL repeal increased the number of motorcycle fatal crashes by 15% to 41%, whereas reinstatement of the UHL decreased it by 21% to 27%. It is expected that the results from this study could be helpful for state policy makers to clearly understand the effects of the UHL on reducing motorcycle fatal crashes.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2637-04
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2017
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  • 10
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    Online Resource
    Evaluation of Airport Pavement Base Layer Stiffness Characteristics via Embedded Field Sensors
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 8 ( 2023-08), p. 462-473
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 8 ( 2023-08), p. 462-473
    Abstract: Real-time stiffness monitoring of unbound aggregate layers using embedded field sensors is crucial for advanced airport pavement design and management. This paper describes research findings on monitoring base layer stiffness characteristics for airport pavements using an embedded bender element (BE) field sensor, inductive coil sensors, and pressure cells. A full-scale pavement test section was constructed at the Federal Aviation Administration (FAA)’s National Airport Pavement Test Facility (NAPTF). A BE field sensor, inductive coil sensor pairs, and pressure cells were installed in the unbound aggregate base to evaluate the layer stiffness, applied load stress, and deformation characteristics. A triple dual tandem gear loading module applied 58,000 lb per wheel to the tested section with a wander pattern consisting of 66 passes arranged in nine lateral wander positions. Dynamic responses of coil sensors and pressure cells were collected during the traffic test, whereas BE signals were collected after completing each wander pattern. Laboratory repeated load triaxial tests with BE instrumentation were also conducted to establish a correlation for converting BE field sensor readings to layer modulus properties. The in situ modulus characteristics of the aggregate base layer were evaluated during full-scale testing using two methods: shear wave velocities from a BE field sensor, and strain and stress measurements from coil sensors and pressure cells. The moduli estimated using both approaches fell into typical ranges of crushed aggregate bases and were highly comparable. The moduli from the dynamic sensor measurements clearly showed the effect of vehicle wander on aggregate base layer measured responses.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981231156938
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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