Mass rapid transit (MRT) operators need to balance the total system costs with the level of service. The primary service of MRT systems is to provide cost-efficient mobility. Governments are responsible for establishing and regulating minimum standards to ensure that the MRT service indicators meet a specific level. Thus, approaches to optimizing MRT system service frequencies are critical concerns for MRT system operators. Previous studies on MRT operations have focused primarily on delays, energy conservation, route design, and general system operations. Conversely, few studies have focused on optimizing headway problems. This study adopts a mathematical programming method to develop a headway-oriented model for the Kaohsiung MRT (KMRT) system aiming to minimize system costs while maintaining an acceptable level of train services. The developed model systematically adjusts train headways based on time-series passengers’ spatio-temporal distribution data. A numerical case study and sensitivity analysis were conducted to test the feasibility and effectiveness of the proposed models and solution algorithms. The proposed model framework provided the KMRT operator with a flexible tool to evaluate the effects of service frequency on both operating cost and passengers’ waiting cost, which facilitates the operator to prepare a cost-efficient train service plan.

The effect of longer creep and recovery times—from $1/9$ to $2/18$ s—on the percent recoveries (R) and the nonrecoverable compliances ($J_{nr}$) of some modified asphalt binders was investigated. A $50/70$ base asphalt cement [AC, penetration grade (PG) 64-xx] was modified using ethylene vinyl acetate (EVA) copolymer, polyphosphoric acid (PPA), and a combination of both additives to produce the $\mathrm{AC}+\mathrm{EVA}$, $\mathrm{AC}+\mathrm{PPA}$, and $\mathrm{AC}+\mathrm{EVA}+\mathrm{PPA}$ formulations, respectively. These formulations have the same high PG grade in the original Superpave specification (PG 76-xx). All the materials were tested at five equally spaced temperatures ranging from 52 to 76°C. The base binder experienced a decrease in its rutting potential after the addition of modifiers because the $R$ values increased and the $J_{nr}$ values decreased at typical high pavement temperatures. Unlike the other asphalt binders, the $\mathrm{AC}+\mathrm{EVA}$ showed small increases in $R$ and slight decreases in $J_{nr}$ at lower temperatures (up to 64°C) with increasing loading–unloading times, which can be translated into minor reductions in its susceptibility to rutting when both times were doubled.

In recent years, there has been a widespread diffusion of roundabout intersections in the Italian road network; their undoubted popularity is attributable not only to their proven performance in terms of safety but also to their guarantee of smooth traffic flow. However, safety-related requirements of geometric designs are occasionally placed in a subordinate position; therefore, the success achieved by some foreign experiences has not been reached in every area. A model of potential crash rates may indicate how to modify the geometry of intersections to ensure safety. With regard to this, an example model based on the conflict opportunity technique has been developed for estimating crash rates at rural roundabouts. The model appears to respond well to traffic conditions and the geometry of roundabouts. Development of the model and results are described and analyzed in this paper.

Maintenance planning of road pavement requires reliable estimates of roads’ lifetimes. In determining the lifetime of a road, this study combines maintenance activities and road condition measurements. The scope of the paper is to estimate lifetimes of road pavements in Sweden with time-to-event analysis. The model is stratified according to traffic load and includes effects of pavement type, road type, bearing capacity, road width, speed limit, stone size, and climate zone. Among the nine analyzed pavement types, stone mastic had the longest expected lifetime with a hazard ratio (risk of needing maintenance) estimated to be 36% lower than asphalt concrete. Among road types, $2+1$ roads had 22% higher hazard ratio than ordinary roads indicating significantly lower lifetimes. Increased speed lowered the lifetime, while increased stone size (up to 20 mm) and increased road width lengthened the lifetime. The results are of importance for life-cycle cost analysis and road management.

On freeway corridors, traffic flow is limited by active bottlenecks. Weaving maneuvers (i.e., intensive lane changes) are a major cause of bottlenecks during high-demand periods. To relieve bottleneck severity, ramp metering (RM) is implemented as an active traffic control method. Ample research has been devoted to developing RM control algorithms and to exploring weaving impacts; however, RM control that is considerate of dynamic weaving impact and its evaluation has received little attention in the published literature. This paper aims to bridge that gap by proposing a proactive control algorithm that uses as inputs dynamic weaving capacity (as opposed to traditional fixed capacity values) for RM control at weaving segments. The control goals are to reduce networkwide travel time and improve traffic flow. Capacity and capacity drop were estimated through fundamental diagrams (FDs). Then, capacity drop sensitivities to on-ramp and mainline demand were analyzed within a field-data-based microsimulation model. The findings were applied to dynamically estimate weaving capacity within a macroscopic traffic flow model. The proposed traffic flow model conducted estimation in a model predictive control (MPC) framework. The RM rates were optimized by sequential quadratic programming (SQP). The proposed RM algorithm was evaluated in macrosimulation and compared with a no-control scenario as well as with a control scenario that used static (as opposed to dynamic) weaving capacity. This analysis contributes to efficient and effective field applications and freeway operational improvements.

Operating speed prediction models have been proposed as a candidate method to assess design consistency on highways and streets. A significant number of operating speed prediction models exist for passenger cars on two-lane rural highways. Few models exist for passenger cars on multilane highways, while the literature is scant for operating speed models for trucks on multilane highways. This research uses a systems modeling approach to predict passenger car and truck operating speeds on multilane highways with combinations of horizontal curves and steep vertical grades. Mean operating speeds were modeled as a function of several geometric design features and the traffic control devices present at each study site. Further, the possible endogenous relationship between passenger car and truck speeds was investigated. The findings indicate that the radius of horizontal curve appears to have a larger influence on passenger car operating speeds than truck speeds. Vertical grades appear to have a more significant influence on truck operating speeds than on passenger car speeds. Increasing the right shoulder width is associated with higher passenger car operating speeds, but the lane width was not statistically significant in the passenger car speed models. Increasing the lane width, however, was associated with higher truck operating speeds; the right shoulder width was not associated with truck operating speeds. Higher posted speed limits were associated with higher truck and passenger car operating speeds. An endogenous relationship between truck and passenger car operating speeds was found.

The use of chemicals and abrasives for highway winter maintenance operations is an essential strategy for ensuring a reasonably high level of service, yet the performance of such materials has to be balanced with their potential negative impacts on motor vehicles, transportation infrastructure, and the natural environment. In this context, this work presents a comprehensive and quantitative evaluation of snow and ice control chemicals currently used by various Idaho Transportation Department districts for highway maintenance operations, including rock salts (mainly solid sodium chloride), IceSlicer products (solid sodium chloride with trace amounts of other chlorides), and salt brines. The analysis has been enabled by the utilization of existing lab and field test data along with reasonable assumptions, in the effort to identify environmentally sustainable materials for winter highway operations. Despite its caveats, this case study is the first attempt to incorporate the most up-to-date information into a multicriteria decision making framework for the data-driven, holistic examination of various snow and ice control chemicals used by a maintenance agency.

Istanbul, the only city that straddles two continents, Europe and Asia, is one of the biggest metropolitan areas in the world with over thirteen million residents. The demand for transportation in Istanbul has been boosted considerably due to the increasing population and rising vehicle ownership. On the other hand, the transportation infrastructure has not been developing sufficiently to meet this demand. Hence, the Turkish government and local authorities sought various alternatives to the road transportation system in Istanbul and came up with the Marmaray Project, which was planned and designed to serve both intraurban and interurban passengers and freight transport. One of the main aims of the Marmaray Project is to shift the traffic demand from roads to the rail network. In this paper, a travel demand modeling framework was developed to calculate the transportation demand of the Marmaray corridor. In addition, a model including empirical modeling methods was developed for the highways to estimate the origin and destination matrices. The developed model was used to estimate freight and passenger transportation between Istanbul and other Turkish provinces. The estimated transportation demand results were used to calculate the required train numbers on a daily basis through the Marmaray corridor and some suggestions were put forward to increase the capacity of this corridor.