Journal of Transportation Engineering, Part A: Systems

Holiday passenger flow forecasting is essential to transportation plan-making and passenger flow organization in metro systems during holidays. Usually, daily passenger flow characteristics show a great difference between holidays and normal days, and the annual growth of holiday passenger flow seems more complicated. Least-square support vector machine (LSSVM) is able to handle the complex fluctuations in holiday daily passenger flow, but it suffers from critical parameter selection, and sparseness is also lost in the LSSVM solution. In an attempt to forecast holiday passenger flow accurately, this paper proposes an approach based on the modified LSSVM, in which an improved particle-swarm optimization (IPSO) algorithm is developed to optimize parameters and pruning algorithm is used to achieve sparseness, as well as a new evaluation indicator based on the $k$-fold cross-validation method to evaluate the training performance. Finally, passenger flow data for Guangzhou Metro stations in China during the National Day holiday from 2011 to 2014 are applied as numerical examples to validate the performance of the proposed approach. The results show that the modified LSSVM model is an effective forecasting approach with higher accuracy than other alternative models.

Right-turn channelization is used to improve the capacity at busy intersections with a lot of right-turns. However, under heavy traffic conditions the through lane vehicles might backup and block the channelization lane. This will affect the discharge rate of right-turning vehicles and reduce the approach capacity. If the right-turn channelization gets blocked frequently, its advantage is neglected and serious capacity problems can be overlooked. This issue is not addressed in the Highway Capacity Manual (HCM), and no separate model is provided to estimate the capacity of approaches with channelized right-turn lanes. Using conventional methods for estimating the capacity without considering the effect of potential blockage would result in overestimation of the approach capacity. This paper presents a probabilistic capacity model for signalized intersections with channelized right-turn lanes considering the possibility of the right-turn vehicles being blocked from accessing the channelization lane. The capacity model was developed as a function of the short-lane section length and the proportion of right-turn traffic by taking into account the probability of blockage. Subsequently, a model was developed to estimate the probability of blockage with respect to the possible residual queue. The proposed capacity model and the blockage probability model were validated on the basis of VISSIM simulations. For operational purposes, the recommended lengths of the short-lane section were developed to prevent blockage at a certain threshold. The recommended lengths would be useful in evaluating adequacy of the current lengths, identifying the options of extending the short-lane section length, or changing signal timing to reduce the likelihood of blockage.

Freight railroads contribute to the national economy by moving over 40% of intercity ton-miles of freight. Meanwhile, train accidents can damage infrastructure and rolling stock, disrupt operations, and possibly cause casualties and harm the environment. Understanding major accident causes is the first step in developing and prioritizing effective accident prevention strategies. The literature has predominantly focused on nationwide train accident cause analysis, without accounting for possible variation in accident cause distributions by railroad and season. This research develops a log-linear statistical model that can estimate the number of freight-train derailments accounting for railroad, accident cause, season, and traffic volume. The analysis shows that broken rails and track geometry defects are the two leading freight-train derailment causes on four major U.S. freight railroads. Fall and winter appear to have a higher likelihood of a broken-rail-caused derailment than spring and summer, given the same railroad and traffic level. By contrast, track-geometry-defect-caused derailments occur more frequently in spring and summer than in fall and winter, given all else being equal. The statistical modeling techniques in this paper can be adapted to other types of train accidents or accident causes, ultimately leading to the prioritization of train safety improvement resources on various spatial and temporal scales.

Among today’s vast data availability, traffic probe data in particular offer exceptional new opportunities for examining multistate mobility. Invaluable resources such as the National Performance Management Research Data Set (NPMRDS) allow users to assess mobility performance toward improving transportation operations and reliability at a megaregion scale. In this study performance measures are developed for interstate freight mobility consistent across Mid-America, followed by an anomaly scanner that detects significant impacts to mobility such as those from major incidents, work zones, or winter weather. The scanner functions through a process control algorithm developed to scan tens of thousands of interstate kilometers each month to identify major disruptions to passenger and freight mobility. The scanner was validated against several known disruptions, and now provides monthly feedback to coalitions collaborating on multistate mobility performance improvement.

Access density is a characteristic of two-lane highway sections whose role and significance in calculating the capacity and level of service in Serbia has not yet been researched. Because of the large number of access points per unit length (access density), direct applicability of the Highway Capacity Manual (HCM) methodology for two-lane highways has been called into question, as access density is one of the influencing factors. In this case study, realistic vehicle speed data were tracked using a global positioning system (GPS) device and used to generate a graph of speed versus distance traveled for each trip, and a methodology for calculating the time losses due to the maneuvering of a vehicle from/to access points is suggested. From the perspective of time losses, maneuvers that diverge from the main direction of travel were identified as the most critical and, as such, were used as the basis for a methodology for assigning a weighted value to every access, which is the fundamental objective of this paper. The model was verified by comparing the speed values obtained using the model from HCM based on both access density and weighted access density with real average travel speeds.

The introduction of special crossings and rail turnouts provides flexibility in the rail network as it allows for vehicles to switch between various tracks, thereby maximizing the utilization of current infrastructure. Turnouts are a costly and critical feature to a rail system as they suffer adverse operational loads, compared with a straight rail track, and thus require regular maintenance. This leads to the question of whether a turnout can be justified for flexibility against upkeep costs throughout the life of the turnout. Therefore, great consideration is given to the interaction between the turnout components and reducing wear in service, as failed components may have adverse effects on the performance of neighboring components. This paper presents a development of three-dimensional (3D) finite-element (FE) model, fostering nonlinearities in materials’ behaviors, to analyze the forces and reactions in a railway turnout system. The analysis provides new findings of critical sections in the turnout and further enables alterations to be made to the initial design of members to accommodate for the increased effects. The FE model is composed of standard concrete sleepers with $60\text{-}\mathrm{kg}/\mathrm{m}$ rail and a tangential turnout radius of 250 m. The turnout structure is supported by a ballast layer, which is represented by a deformable solid. The FE model is the first in the world to predict the torsional behavior of the turnout and its fragile support by considering multiwheel impacts, which would simulate in-service and cyclic loading and will be adapted as a set of concentrated loads to represent a coupled locomotive negotiating the turnout. The simulations demonstrate the significance of the third medium to suppress the torsional effect of the crossing forces on supporting bearers.