This paper presents a method of addressing stochastic variation at closely spaced signalized intersections to provide secondary coordination to “minor” movements with significant traffic volumes. A neurofuzzy signal control system was designed in this study to manage a noncoordinated movement to avoid queue spillback. Building on the conventional actuated-coordinated control system, the neurofuzzy controller does not lose the benefit of the primary coordination of the conventional controller but establishes a “secondary coordination” between the upstream coordinated phase (through phase) and the downstream noncoordinated phase (left-turn phase) on the basis of a real-time traffic demand. Under the neurofuzzy signal control, the traffic from the upstream intersection can arrive and join the queue at the downstream left-turn lane and be served in a timely fashion and thus reduce the likelihood of being delayed at the downstream intersection. The simulation results indicate that the neurofuzzy signal control consistently outperformed the conventional actuated-coordinated controller in terms of reduction in systemwide average delay and number of stops per vehicle under a wide range of traffic volumes by nearly 20% under heavier demand conditions.

The use of nontraversable median cross sections and directional median openings has generated increased numbers of U-turning vehicles at signalized intersections. A procedure is needed to help transportation professionals determine the impacts of proposed median-modification projects on traffic operations at downstream signalized intersections. This study is a continuous effort following previous studies to evaluate the impacts of indirect driveway left-turn treatments on traffic operations at signalized intersections. In the present study, a total of 80 h of traffic data were collected at 66 roadway segments in the Tampa Bay area of Florida. On the basis of the data collected in the field, the research team developed a negative-binomial model to estimate the expected number of U-turning vehicles on a left-turn approach at a signalized intersection during weekday peak periods. The model has only five independent variables, and all of these variables can be easily measured in the field. By combining the research results of this study and previous studies, a procedure is provided to help transportation professionals evaluate the impacts of proposed indirect driveway left-turn treatments on traffic operations at downstream signalized intersections.

The available design guidelines indicate a lack of proper methodologies for determining the length of left-turn lanes at signalized intersections. This is largely attributable to the alternating nature of stopped and unstopped approaches as a result of cyclic signal phases. The existing design guidelines recommend the design length of left-turn lanes as a sum of two components: queue storage length and deceleration length. This is appropriate for unstopped approaches at unsignalized intersections, but it is inapplicable to signalized intersections, in which the approaches switch between stopped and unstopped by phase. This paper introduces a new methodology that coordinates the requirement of each component with signal timing for the proper design of left-turn lanes. With the underlying assumption of Poisson arrivals, the model developed is limited to uncoordinated intersections or approaches. Compared to the existing guidelines, the proposed methodology provides a rational approach for determining left-turn lane lengths and generally results in shorter left-turn lanes that necessarily meet both safety and operational needs.

Car-following behavior forms the kernel of traffic microsimulation models and is extensively studied for similar vehicle types. However, in heterogeneous traffic having a diverse mix of vehicles, following behavior also depends on the type of both the leader and following vehicles. This paper is an attempt to modify the widely used Gipps’s car-following model to incorporate vehicle-type dependent parameters. Performance of the model is studied at microscopic and macroscopic levels using data collected from both homogeneous and heterogeneous traffic conditions. The results indicate that the proposed modifications enhance the prediction of follower behavior and suggest the need of incorporating vehicle-type combination specific parameters into traffic simulation models.

Specific service (or logo) signs provide information on attractions, camping, lodging, food, and gas services on the mainline of limited-access highways in advance of the interchange that provides access to the services. At present, to ascertain the distance to a particular establishment, motorists depart from the mainline and read the distance on the logo signs on the ramps. The purpose of this study was to determine the effectiveness or usefulness of adding distance information on mainline logo signs. A pilot study of adding distance information on mainline logo signs at three interchanges in Virginia was conducted. The Virginia Department of Transportation requested permission to experiment with these signs and the Federal Highway Administration granted the permission. The study examined legibility, motorist opinions, and crash history related to adding the distance information. The results of the study indicated that the legibility distance for the added information on the mainline logo signs was adequate in that it exceeded the rule of thumb of $4.8\mathrm{m}/\mathrm{cm}$ ($40\mathrm{ft}/\mathrm{in}.$) of letter height. Most legibility study participants found the distance information easy to read, although some found the information “cramped” on the signs. Most respondents to the motorist opinion survey found the signs “OK” or “easy to read” and the distance information useful. The presence of the distance information on the mainline logo signs did not affect the number of crashes at the sites used in the pilot study.

This paper formulates, structures, and analyzes a model to optimize the staffing levels at a border checkpoint from the perspective of a person in charge of staffing, accounting for both wage costs for staff and border waiting times for travelers. This model adapts existing queuing theory systems previously applied in other disciplines to the customs process and uses the adjusted model to develop a staffing plan for a representative day at the Peace Arch border crossing in Blaine, Washington. The sensitivity analysis suggests model outputs are heavily dependent on inputs including staffing costs and waiting costs. This paper concludes that the border crossing under consideration is currently operating near its maximum capacity and that future increases in traffic volumes of 40% could warrant expansion of the checkpoint. The model also confirms the benefits of the NEXUS, frequent, low-risk traveler program in decreasing the wait times and costs of operating a customs facility.

Many sources of uncertainty are inherent in pavement design. These uncertainties must be incorporated systematically in a reliability analysis to compute their combined effects on the probability of failure of a given pavement structure. Monte Carlo simulation has been the technique of choice in the past to simulate the effects of uncertainties in input parameters on pavement distress and the resultant reliability analyses. The impractical computational time associated with a Monte Carlo scheme, however, has prompted the deferral of the implementation of similar techniques in the current Mechanistic-Empirical Pavement Design Guide (MEPDG). Instead, the reliability analysis implemented in the current MEPDG is performed on the basis of a simple assessment of the overall standard error of the predicted distress compared to the observed distress of the long-term pavement performance (LTPP) sections. It relies on a set of predetermined variability values obtained from a performance database instead of the site-specific input parameters that induce such uncertainty in distress predictions. Past efforts found that techniques (such as the Latin hypercube method) that require a substantially reduced number of simulations compared with Monte Carlo accuracy still suffered from the need for repeated execution of the MEDPG calculations. This study proposes to combine an efficient numerical scheme to conduct statistical simulations with the MEPDG calculations. It makes use of the concept of the representative linear elastic (LE) structure to minimize the number of repeated executions involved in simulations. The numerical scheme can be combined with any simulation technique of random variables to perform a reliability analysis of flexible pavements. The relative merits of Monte Carlo simulation, Latin hypercube simulation, and Rosenblueth’s $2K+1$ point-estimate method are compared. The simulations show that the Latin hypercube method is an efficient alternative to the computationally intensive Monte Carlo technique. On the other hand, although Rosenblueth’s $2K+1$ point-estimate method is much simpler, it is not capable of capturing the important attributes of the distribution of either input or output variables.

The failure of expansion joints is a leading cause for structural damage to bridge decks and concrete pavements. A fundamental requirement for sealant is that it should always apply a compressive stress to the concrete wall so that adhesive failure can be eliminated; also, the sealant must contract transversely (in the vertical direction) as temperature rises so that the sealant does not squeeze out of the channel. In addition, it is desired that the sealant has some self-healing capabilities so that cohesive failure can be healed. In this study, a shape memory polymer–based (SMP-based) self-healing syntactic foam sealant was prepared and tested. Special two-dimensional (2D) programming or training (compression in one direction and tension in the transverse direction) and free-shape recovery tests were conducted on the foam to evaluate its capability to serve as a sealant for expansion joints. The functional stability of the foam sealant was evaluated by repeated thermomechanical cycles. Furthermore, mechanical properties tests, including uniaxial compression, uniaxial tension, and interfacial shear, were also conducted. Results show that the smart foam sealant can eliminate the squeezing-out problem if programmed properly, and it has the potential to be used in expansion joints.

In response to rising energy costs, there is increased demand for efficient and sustainable transportation of people and goods. One source of such transportation is the railroad. To accommodate the increased demand, railroads are constructing new track and upgrading existing track. This update to the track system will increase its capacity and make it a more reliable means of transportation compared to other alternatives. In addition to increasing the track system capacity, railroads are considering an increase in the size of the typical freight rail car to allow larger tonnage. An increase in rail car loads will, in turn, require the design of track components to accommodate these loads. This design change is especially pertinent to crossties that support the rail and serve to transmit loads down to the substructure. Today, the use of concrete ties is on the rise in North America as they become an economical alternative, competitive with the historical wood ties used in industry, providing performance that surpasses its competition in terms of durability and capacity. Because of the increased loads heavy-haul railroads are considering applying to their tracks, current designs of prestressed concrete railroad ties for heavy-haul applications may be undersized. In an effort to maximize tie capacity while maintaining tie geometry, fastening systems, and installation equipment, a parametric study to optimize the existing designs was completed. The optimization focused on maximizing the capacity of an existing tie geometry through an investigation of prestressing quantity, configuration, stress levels, and other material properties. The results of the parametric optimization indicate that the capacity of an existing tie can be increased most efficiently by increasing the diameter of the prestressing and concrete strength. Findings of the study demonstrate that additional research is needed to evaluate the true capacity of concrete ties because of the impacts of deep beam effects and inadequate development length in the rail seat region.

In recent decades, the spreadsheet and computer-aided mapping are the major tools for track alignment design. These traditional methods can meet the design criteria, but when the design factors and the change order must be satisfied at the same time, the process is always complicated and redundant. Building information modeling (BIM) is mainly applied on the generation and management of building data. It utilizes the object-oriented concept to increase the efficiency of information management in the building life cycle. The track-alignment data also have topographic relation that is similar to the building. There is a much closer relation between the topological, sharp, and position of track entities than that of the building components. This paper discusses the feasibility of applying a real-time, dynamic, three-dimensional building information model to design the alignment; compares the traditional alignment method with the BIM alignment method to find out the differences; and analyzes the precision by using alignment data of east and west main tracks of Qidu Switchyard of Taiwan Railways Administration. Moreover, the paper proves that the BIM can simplify track-alignment design, increases the abilities of computer-aided design and automation, and greatly shortens the design period.

This paper analyzes the motorcycle usage and policies in Huizhou, China. Two sets of survey data were used in the study: one is Daily Trip Survey of Huizhou that was taken in 2004, and the other one is Resident Travel Preference and Behavior Survey of Huizhou that was taken in 2006. It was found that men are more likely than women to use motorcycles. The average annual household income for motorcycle users is less than for car users but higher than bike and transit users. Two types of motorcycle policies (active policies and passive policies) are considered in the study. Approximately 50% of motorcycle users would be willing to switch to transit if corresponding active policies were in operation. However, if only passive policies were in operation, approximately 7% of motorcycle users would be willing to switch to driving a car. So, to lead motorcycle users to switch to more sustainable travel mode, a group of policies should be used in Huizhou instead of a single policy forbidding motorcycle use.

A critical factor in highway design is maintaining a good consistency with a road geometry that fits the drivers’ expectations. Presently, highway geometric design consistency is usually evaluated on the basis of operating-speed profile analysis, which requires the use of operating-speed models. This paper presents research carried out in Colombia consisting of a study of vehicle speeds on tangents and curves of two-lane rural highways. Car speeds were measured on the approach tangent and at the beginning, middle, and end points of curves by using two radar meters. The operating-speed prediction models that were developed are described. The speed change experienced by drivers from tangent to curve was also studied, and a model is presented that predicts this change. Finally, the model developed for operating-speed prediction at the midpoint of curves was compared with equivalent models calibrated in other countries and applied to a Colombian highway. This comparative study highlights the importance of using speed-prediction models calibrated according to local conditions.