The diverging diamond interchange (DDI) is growing in popularity as an interchange treatment, yet there is rather limited guidance available on signal timing practices. One particular area of concern is the coordination of a DDI along with neighboring intersections in an arterial. This study examines three different cycle length strategies for DDI coordination: (1) using the full cycle length of the corridor; (2) using a half-cycle; and (3) using a previously described three-phase scheme intended to manage queues within the DDI. Six different origin-destination (O-D) scenarios are tested in a microsimulation study. Results are presented in terms of the number of stops, movement delays at the DDI, queue lengths, and delay by O-D path. The outcomes show that the half-cycle strategy yielded lower total and average delays yet resulted in more stops along the arterial and higher arterial O-D path delays. The full-cycle option, meanwhile, tended to achieve fewer stops and lower delays for arterial routes but increased total and average delays for other movements. The three-phase strategy often reduced delays and queue lengths for the arterial movements exiting the DDI, but increased these for other movements.

Abstract Congestion has become highly recognized as a worldwide traffic problem, as traffic demand has grown steadily over the past few decades. Variable speed limits (VSLs) are an intelligent transportation system (ITS) measure that limits mainline flow to mitigate bottleneck congestion. Currently, VSLs have become proactive based on short-term prediction. Proactive VSLs succeed in simulation evaluations, but few have been deployed in the field and their real-world effectiveness has not been proven. Various factors may lead to this limitation, such as the absence of reliable field application software, accuracy of prediction models, and high computation time for proactive control. To address this research gap, this study reports a preliminary VSL test and details its implementation results on Whitemud Drive, Edmonton, Canada. First, based on field traffic measurements before VSL control, recurrent bottleneck locations are identified. Second, the proactive control algorithm is briefly introduced. Then, a s...

Abstract In this paper, for a quarter-car model, root-mean square response variables are calculated for roads classified by the international standard organization, based on the straight-line spectrum models. Covariance expressions are derived for vehicle response variables assuming that the road spectrum is that of a Motor Industry Research Association (MIRA) spectrum and compared with the existing results in the literature. The international standard and the MIRA spectra are then compared with the models delivered by high resolution frequency-domain subspace identification algorithms. The IRI statistic of the quarter-car response is calculated for the road models built by the curve fitting and the identification methods from the measured road spectrum assuming that the road excitation is a zero-mean Gaussian process

Abstract Insulated rail joints (IRJs) are widely used in signaling and broken rail identification systems. Track deterioration adjacent to IRJ is frequent due to excessive dynamic forces generated at IRJs by the repetitive passage of the ongoing traffic. Hence, they exhibit low service life and are considered high-risk elements and maintained through high standards. With a view to increase operational speed and the annual operational throughput, many improved structural designs have been proposed, of which inclined IRJs are the focus of this paper. To compare noise, vibration, and adjacent sleepers’ vertical displacement of square and 30° and 45° cut joints, a series of field tests have been carried out in the Tehran-Karaj urban metro track. Results show that sleepers in the vicinity of 45° cut joint have less vertical displacements compared to that of 30° and square cut joints. Peak root-mean square (RMS) values of acceleration signatures of 30 and 45° cut joints are almost half the value for square joint...

This paper investigates the effects of segment length, line types, and imputed retroreflectivity values on pavement-marking retroreflectivity and crash frequency analyses. Road data, crash data, pavement condition data, and pavement-marking retroreflectivity data from Iowa Department of Transportation (DOT) databases were acquired and spatially integrated. Data sets for 1-, 3-, and 5-mi segments were prepared to investigate the effect of segmentation. Additional data sets with imputed and measured retroreflectivity data were prepared for comparison. A series of negative binomial regression analyses were run to estimate the expected number of crashes on varying segment lengths and data subsets based on the two retroreflectivity collection methods. The findings show that using smaller segments and data sets with measured retroreflectivity rather than imputed retroreflectivity leads to a more significant relationship between the retroreflectivity of longitudinal pavement markings and crash frequency. The findings also suggest that keeping longitudinal pavement markings in good condition has significant positive effects on safety. The results further suggested that the expected number of annual crashes significantly decreased with the increasing retroreflectivity of white-edge lines (WELs) and yellow-edge lines (YELs) for four-lane road segments. In addition, a significant relationship between pavement condition, measured with the International Roughness Index (IRI) and the expected number of crashes was found for all data sets.

Abstract Tours are increasingly being considered as an appropriate unit of observation of mobility behaviors and are one of the key ideas underpinning contemporary activity-based modeling approaches. Identifying typologies of tours would benefit both modelers and decision makers, striving to set up more tailored actions aimed at promoting environmentally benign travel choices. Different a priori classifications based on activity kinds have been proposed, none of which seems clearly preferable on empirical grounds. This paper takes a complementary approach and defines a data-driven segmentation through a cluster analysis of tours that were derived from the trip records from a United States national survey. The socioeconomic characterization of each cluster is finally carried out to link travelers’ profiles with specific kinds of tours. Four main tour clusters have thus been identified: nonwork tours for compulsory activities done by young individuals, tours done by elder or retired persons, short and second...

Abstract The research uses a database of urban noise data collected continually from April 2013 to March 2014 at 10 sites in Dublin, Ireland. The first objective of the paper is to investigate if the morning daily noise level peak is related to transport characteristics of households, such as car ownership levels, the mode by which people travel to work, and morning work trip departure time. Data from the 2011 Irish census is used to provide the information on households and this is tested against noise measurement levels. The second objective is to examine the relative importance of the spatial and temporal variables of location, month of the year, weekday, and hour of the day in predicting urban noise levels using a multinomial logistic regression model. The results show that the transport household characteristics examined do not appear to influence noise levels. The outcome from the regression model demonstrates that location is the most important variable followed in order by hour of the day, month of...

Abstract Accurate traffic state information is essential for both travelers and transportation agencies. In the past, traffic condition data were usually collected by a government agency using its own sensors. Recently, a number of private sector companies have started selling travel-time and speed data collected using probe vehicles, which provides a viable opportunity to outsource traffic data collection. Because these data sources and their related algorithms are proprietary, the reliability and accuracy of this private sector data is often an important issue for transportation agencies. Previous studies have examined the accuracy of private sector data on freeways, but arterials have not been examined extensively. Arterials represent a fundamentally more challenging environment for probe vehicle data given the larger variance in travel times created by traffic signals and other intermediate access points. In the research, the quality of private sector data on arterials is evaluated by utilizing Bluetoo...

Abstract Increasingly, sustainability is a key indicator for planning transportation projects. As a result, evaluating the applicability of various transportation sustainability rating systems (TSRS) for adoption is important for the transportation industry in general, and for specific transportation organizations in particular. Several contending TSRSs are emerging, and provide various methods of guidance with regard to sustainability for infrastructure projects throughout project delivery. Different TSRSs, for example, employ different methods to determine or quantify sustainability and emphasize different sustainability factors. As a result, comparing the various systems and their suitability for implementation by a specific transportation organization can be a challenge. In this research, the authors apply the Analytical Hierarchy Process (AHP) as the method to assist in such an evaluation according to the Colorado Department of Transportation’s (CDOT’s) preferences. Application of AHP in previous rese...

To increase freight efficiency, trucks are allowed to transport heavier loads without adding extra axles. The impact of this practice on infrastructure damage needs to be evaluated. This involves evaluating the fatigue life of asphalt pavements under multiple axle configurations. In mechanistic pavement design, the asphalt thickness is generally determined using a fatigue model calibrated in the laboratory by applying a continuous sinusoidal signal with different strain levels. The classical fatigue relationship gives fatigue life as a function of the strain level. However, results from literature show the influence of the loading wave shape on the fatigue life of bituminous mixtures. Real loading signals under multiple axle configurations are more complex in shape than sinusoidal pulses. Moreover, real strain signals have different shapes in the longitudinal and transverse directions. This paper presents an approach using a multilinear fatigue model that takes into account the shape of the loading signal coupled with a viscoelastic pavement model. Using this approach, a parametric study is made to evaluate the effect of loading variables on fatigue life, as well as comparisons between the aggressiveness of different truck configurations including European Modular Systems (EMS).