In this paper, the statistical distribution of railway track geometry data is investigated using a significant volume of field data. Analyzing the results yields a general pattern for the statistical distribution of the track geometry data. This is used to develop new indexes for track geometry parameters including gauge, profile, alignment, and twist. An overall track geometry index is established by combining the new parameter’s indexes. This combination is made by assigning a coefficient to each geometry parameter based on its role in the overall quality condition of the track. In comparison with the approaches previously used for the development of the track geometry indexes, this method has three distinguishing features. First, the mean values along with the SD of data are incorporated into the calculation of the new indexes. Second, the new indexes indicate not only the condition of the individual parameters but also the overall track geometry condition. Third, the track classification is considered, and an index is developed for each class of the tracks. A practical use of the new indexes is presented and discussed in the paper.

The rail industry spends billions of dollars each year on maintenance and renewal of its track infrastructure. The scheduling of these maintenance projects is extremely complex, with numerous hard and soft cost trade-offs and job scheduling constraints. Scheduling requires consideration of efficient maintenance production “gang” routing around the rail network while paying close attention to any train delay such maintenance projects might cause. Despite this importance and complexity, the subject has been largely ignored in the literature. We evaluate two formulations (time-space network mixed integer program and job scheduling) and three modeling formulation and solution methodologies (integer programming, constraint programming, and genetic algorithms) for scheduling rail gangs to annual renewal projects and discuss their relative merits in terms of parsimony of model formulation, solution time, and solution quality. The purpose of this paper is to identify the most fruitful avenues for further research on this novel application.

This paper presents a theoretical application of multibody dynamics with unilateral contact to model the friction wedge interaction with the bolster and the side frame. The objective of the proposed approach is to produce a stand-alone model that can better characterize the interaction between the bolster, the wedge, and the side frame. The new model allows the wedge four degrees of freedom: vertical displacement, longitudinal displacement (between the bolster and the side frame), pitch (rotation about the lateral axis), and yaw (rotation about the vertical axis). The new model also allows for toe variation. The stand-alone model shows the capability of capturing the dynamics of the wedge which was unnoticed in previous models. The inclusion of unilateral contact conditions is integral in quantifying the behavior during lift-off and the stick-slip phenomena. The resulting friction wedge model is a three-dimensional, dynamic, stand-alone model of a bolster–friction wedge–side frame assembly.

This paper presents an application of multibody dynamics with unilateral contact to model the friction wedge interaction with the bolster and the side frame. The new friction wedge model is a three-dimensional, dynamic, stand-alone model of a bolster–friction wedge–side frame assembly. It allows the wedge four degrees of freedom: vertical displacement; longitudinal (between the bolster and the side frame) displacement; toe in and toe out; and yaw (rotation about the vertical axis). The dedicated train modeling software NUCARS (Transportation Technology Center, Inc., Pueblo, Colo.) has been used to run simulations with similar inputs and to compare—when possible—the results with those obtained from the new stand-alone MATLAB (MathWorks, Natick, Mass.) friction wedge model. The stand-alone model shows improvement in capturing the transient dynamics of the wedge better. Also, it can predict not only normal forces going into the side frame and bolster, but also the associated moments. Significant simulation results are presented and the main differences between the current NUCARS model and the new stand-alone MATLAB models are highlighted.

For the most part, optimal signal timing is the most effective and economical method for mitigating traffic congestion in urban areas. In this study, a new mixed integer nonlinear programming model is proposed to develop an optimal arterial-based progression algorithm. The proposed algorithm is designed to optimize the bandwidths for contiguous signals along a signalized arterial. The traffic conditions for examining the proposed algorithm are extracted from moderate to high saturated traffic conditions. The main objective of the proposed algorithm is to allow traffic to traverse through the maximum number of downstream intersections without a stop. According to measures of effectiveness $\left({\text{MOE}}_{\text{s}}\right)$ acquired by TSIS-CORSIM 6, the signal timing generated by the proposed model yields lower stops (%) when compared with the signal timing optimized and generated by Synchro. In addition, the proposed model yields lower network-wide average delays (sec/veh) and higher average travel speeds (km/h) under moderate to high saturated traffic conditions. The performance and applicability of the proposed model have been validated.

Stabilization of granular materials with low percentage of slow setting binders, such as slag lime, for constructing new pavements and/or rehabilitation of existing granular pavements has economical and environmental benefits. The fatigue life of a lightly stabilized granular material under traffic type repeated or cyclic loading is an important consideration for pavement design involving this material and it is the focus of this paper. In particular, this paper examines the use of indirect diametrical tensile (IDT) testing with internal displacement measurement for determining stiffness and fatigue life of a granular base material lightly stabilized with slag-lime cementitious binder. An extensive laboratory investigation involving monotonic and cyclic load IDT testing was carried out to determine the strength, stiffness, and fatigue life of a granular material stabilized lightly with 3–5% slag lime and to establish relationships for predicting the fatigue life. Fatigue life was established using two methods, namely, the approach of determining the number of cycles for 50% reduction in the stiffness compared to the initial stiffness and the energy ratio method, and they both showed similar results. Based on the experimental results, a general fatigue model is proposed for determining the fatigue life using the static or dynamic stiffness modulus and maximum tensile strain, which is useful for mechanistic-empirical pavement design involving such materials. Empirical equations are proposed to relate the fatigue life with tensile strain and stress ratio similar to those proposed in the literature. A new model to determine the fatigue life from strain ratio is also proposed in this paper that was found to closely match the experimental data. Empirical relationships are also proposed to predict the fatigue life based on IDT strength and/or static stiffness modulus which are particularly useful in situations where resources are not available for conducting cyclic load IDT testing.

A significant portion of nonrecurrent freeway congestion is caused by incidents. This nonrecurrent congestion negatively impacts safety and mobility. It produces enormous travel delay and results in secondary incidents, which cause additional delay and injury. The simulation-based secondary incident filtering (SBSIF) method is proposed for identifying secondary incidents from archived incident data. The proposed methodology is computationally efficient and overcomes deficiencies of existing techniques. It is evaluated on incident data from a 6-month period along a segment of I-287 in the New York state. Results of the evaluation show that the SBSIF method has a significantly reduced misclassification rate (e.g., a reduction of 58 percentage points and greater) as compared with static methods commonly used in practice, despite that, it requires comparable computational effort.

Two-lane rural highways attract trips between traffic generators such as residential villages or small commercial areas and are generally uninterrupted flow facilities that provide a high level of mobility with high posted speeds limits. When passing through developed areas, the posted speed limit may be lowered to encourage reduced vehicle operating speeds. No published guidelines currently exist for the design of transition zones that connect high- to low-speed operating environments on two-lane rural highways. The objective of this research was to collect operating speed and roadway characteristic data along two-lane rural highway transition zones in Pennsylvania to explore the roadway, roadside, and traffic control factors that are associated with driver speed differentials. Single- and multilevel models were estimated and compared. The posted speed limit reduction as well as a change in the paved shoulder width, total number of driveways, various advance warning signs, the transition zone length, and the presence of horizontal curves were shown to increase the expected speed reduction in transition zones in the models. Additionally, drivers entering transition zones at higher speeds were found to have greater speed reductions than drivers entering the transition zone at lower speeds.

Pavement condition indexes are numerical indicators of the structural and material integrity of a pavement. Because these indexes appear to be similar (essentially a 0–100 scale, with 100 indicating ideal condition), it can be tempting to use different indexes for comparing the performance of pavement networks in different states or jurisdictions within a state. To ascertain the level of agreement among these condition indexes, six pavement condition indexes from five DOTs in the United States are discussed and compared using distress and ride quality data obtained from the Pavement Management Information System of the Texas Department of Transportation. The computed scores were compared visually (using scatter plots) and statistically (using paired $t$ -test). The results provide empirical evidence that there are significant differences among seemingly similar pavement condition indexes.

This paper addresses the impact of bead density on paint pavement marking retroreflectivity. The writers collected retroreflectivity data and glass bead images on 40 segments of two-lane highways. Bead density is defined as the surface percentage of glass beads exposed above the paint marking material. Numerous methods for determining bead density were considered and studied. A new approach, referred to as a computer-aided counting method, was developed and a bead density analysis program was written. The program was used to analyze 108 images to obtain a bead density value for each image. A correlation study was conducted between pavement marking retroreflectivity and bead density. The findings of the study show that the normal range of glass bead density for older markings is 9–24% of the paint marking surface area. Furthermore, bead density values have a positive correlation with marking retroreflectivity readings; higher bead density leads to higher retroreflectivity. White paint markings have significantly higher retroreflectivity values than do yellow markings when the bead density values are the same.

Like in many other countries, Malaysian road users are facing problems with traffic congestion. In urban areas roundabouts are becoming more popular like in Shah Alam but had limitations, among others, such as a geometric design and traffic flow characteristics. The lane changing behavior due to the drivers’ driving “habit” which creates problems, such as delays, because of intolerable and impatient driving while selecting and changing lanes. Due to such factors, congestion will occur and at the same time it will reduce the safety of the drivers either at entry, exit, or in weaving the section of the roundabouts. There is a lack of knowledge of Malaysian driver behavior and of corresponding methods for calculating impacts of geometric design and other factors on traffic performance at the weaving section of conventional roundabouts. A study of vehicle interactions at the weaving section of Malaysian conventional roundabouts needs to be done in order to close this knowledge gap and to enable development of model to support the design and traffic operation processes. One approach of evaluating roundabout performance based on traffic parameters is by video taping techniques. Generally, traffic parameters that are normally considered and measured are gap, entry flow, and conflicting flow at the entry of the conventional roundabout, whereas, this paper focuses on the weaving section of the conventional roundabout. Samples of data reduction and analysis taken at the weaving section of the Malaysian conventional roundabout were presented, discussed, and became an input for weaving the section flow model under stable flow condition. The model developed was then validated with other weaving section of the Malaysian conventional roundabout.