This study proposes a methodology to determine the optimal cross-sectional design of a high-occupancy vehicle (HOV) facility for safety performance by evaluating the effects of each relevant design element on safety and tradeoffs among multiple design variables. This aspect of geometric design is critical because it is often difficult to acquire sufficient right-of-way for retrofitting HOV lanes to existing freeway systems with recommended cross-sectional design. Detailed collision data of concurrent-flow buffer-separated HOV lanes, along with their geometric features and traffic flow data, were analyzed to establish collision predictive models by injury types for HOV and the adjacent general-purpose lanes. These models were used to determine the set of cross-sectional design elements that minimizes the expected collision occurrences. As a case study, a real freeway corridor where a conversion from contiguous to buffer-separated types was recently completed was selected to demonstrate the applicability of the proposed method. The evaluation through this case study shows that the proposed methodology is useful in determining the cross-sectional design of HOV facilities for safety based on selective use of available geometric space.

Horizontal curves present drivers with numerous tasks that, if not performed while approaching and negotiating the curve, may result in a roadway departure crash. A vehicle’s lateral position within the lane and its speed are two indicators of interest from safety and operational perspectives. These can and have been measured simultaneously at multiple locations along the curve. However, researchers face the challenge of collecting operational data while minimizing impacts on driver behavior, and developing robust, efficient, and accurate means to obtain the data. This paper presents the findings of a series of pilot studies on closed and open courses that investigated the effectiveness and accuracy of pneumatic road tubes and digital video cameras for collecting such data. Closed-course studies investigated a single data collection station setup, whereas an open-course study investigated multiple data collection stations on a horizontal curve. The data were reduced manually and automatically, and tests were performed to evaluate the statistical significance of the results. In general, the pilot studies show that pneumatic road tubes provide a higher level of accuracy than video data. Other findings include that drivers moved towards the centerline of the roadway overall and even more so when the presence of video equipment. It was also found that vehicle mean speeds at the center of the curve were lower with an increase amount of data site-based vehicle data collection equipment present.

Technology provides the capability to automate the collection of commercial vehicle drivers’ hours of service (HOS), and this can potentially lead to fewer errors. This study compares the use of paper-based and automated (or electronically recorded) hours of service for three motor carriers using process analysis. Potential errors are categorized by operations within an information-based process, and results demonstrate that a reduction of errors can be achieved with an electronic system. The analysis shows that some of the errors that occur with paper-based systems (e.g., verification of accurate records) still exist with electronic recordings, and there are some additional minor errors. However, data collection, entry, and storage are improved, as the system requires fewer steps and less manual requirements within the process. The study provides a systematic and structured comparison of the two methods, highlighting the error types that occur in both. Policymakers can consider this comparison when making recommended revisions to HOS documentation procedures.

Three alternative construction plans with full highway closures and limited capacity closures (partial closures) are evaluated for a large-scale freeway reconstruction project in the Sacramento metropolitan area. By using a dynamic network analysis tool, the potential impact resulting from different construction plans is estimated and analyzed measured by changes in total demand, travel delays, vehicle miles/hours traveled (VMT/VHT), fuel consumptions, and emissions. The results show that, for this Interstate 5 closure, if only user delay costs are considered, the actual full closure plan is the best. It produces considerably less total system travel delay than the two partial closure plans although it closed more lanes. This plan, however, may induce more VMT than the other two. In fact, the other two partial closure plans produce slightly fewer emissions and consume slightly less fuel. The outcome of which plan comes out on top crucially depends on two other factors, besides the chosen objective: the amount of demand reduction a plan induces and the availability of alternative routes to divert traffic away from the work zone area. Developing efficient demand management measures will be the key to improving the network performance and to reduce the emissions. Moreover, when data are available, construction costs and emissions produced by construction activities should also be included in the evaluations, in addition to the user costs considered in this study.

The majority of operating speed models reported in the literature primarily consider passenger cars and only rarely consider heavy vehicles. No study on the influence of geometry on speeds of other classes of vehicles like buses and two-wheelers, which contribute significantly to the mix of traffic in India, has been reported. This study highlights the need to develop operating speed and speed reduction models for different classes of vehicles and develops models for predicting operating speed at tangent and midcurve sections of horizontal alignment of two-lane rural highways. In addition, models for estimating the speed reduction from tangent to curve are also developed. The independent variable used to predict tangent speed is the length of the preceding tangent. The radius and length of a curve emerged as the most important variables for speed at midcurve. Speed reduction can be estimated from the preceding variables along with the approach tangent speed. The models developed in the study can be used in the design and evaluation of rural highways as well as in establishing speed limits and other enforcement measures.

A microsimulation approach is presented for evaluating the effectiveness of a transition zone connecting the rural to the urban environment using speeds computed in simulation for showing whether drivers slow down far enough below the imposed speed limit before entering the small urbanized area. The proposed approach was also applied to prove whether, both within the transition zone and on the rural roads approaching this zone, acceptable values of the traffic performance measures expressed in terms of delay time and queue length were ensured. Five design alternatives based on the horizontal deflection were tested. The results showed that the simulated mean speeds were lower than the $50\mathrm{km}/\mathrm{h}$ speed limit imposed at the start of the urbanized area for all transition zones investigated. However, a scenario with a roundabout and a T-type intersection to which two auxiliary lanes for right turns were added was also identified as having better values of the traffic performance measures. The transition zone that was built, in accordance with expert judgments, was found to confirm the effectiveness of the simulated solution. Additionally, the present paper introduces a speed-delay time model.

To implement the Mechanistic-Empirical Pavement Design Guide (MEPDG) developed by AASHTO for pavement construction and rehabilitation, it is necessary to evaluate its performance prediction models using actual pavement performance data, material properties, traffic information, and environmental factors. This paper validated the MEPDG models using the performance of typical pavements in the state of Tennessee from pavement management system (PMS). With traffic and pavement structural information collected from PMS, the performance of selected highway pavement sections was analyzed with MEPDG Version 1.100 software. The predicted present serviceability index (PSI) and rutting were compared with the actual measurement values. An initial value for the international roughness index (IRI) was suggested for Tennessee highways through investigation into the actual roughness data. The dynamic moduli of asphalt mixtures for input level 1 were obtained from laboratory testing. Those for input level 3 were estimated with the Witczak model. The results show that rutting of asphalt concrete (AC) pavements was more accurately predicted at input level 1, whereas it was overpredicted at input level 3. Traffic level was found to be an important factor affecting predicted pavement roughness. It was also found that MEPDG software was relatively conservative for highway pavements with low traffic level. However, MEPDG with nationally averaged default parameters was not sensitive enough to differentiate various climates, traffic, and materials in Tennessee for the prediction of PSI.

Using the rolling wheel deflectometer (RWD), which measures pavement deflections at traffic speeds, offers the potential to characterize the structural capacity of the road network without major delays and to do so in a cost-effective way. To optimize using the RWD at the network level, an assessment tool is needed to incorporate RWD data into a current pavement management system (PMS) and to identify pavements in need of maintenance or rehabilitation. The objective of this study is to present the development of a screening tool, referred to as the pavement-assessment triangular model, to predict overall pavement conditions on the basis of RWD deflection, roughness measurements, and surface conditions as described by a pavement condition index (PCI). Formulation of the proposed tool and its application were based on data collected during evaluation and testing of RWDs in Louisiana. This screening tool may be used at the network level to identify sites in poor condition and to conduct additional testing using the falling weight deflectometer (FWD) on the identified sites or to select a rehabilitation treatment option based on RWD measurements and PMS data.

In the railway sector, one of the sensitive issues to be borne very much in mind is the cost brought about by the energy consumption required to meet schedules, be they local trains, metropolitan systems, or long-distance trains. To reduce energy consumption, considering restrictions like traveling time or speed limits, it is necessary to find a solution for a complex problem in the domain of optimal control theory (OCT). The analytical solution for those problems is not easily carried out. A simpler alternative to that approach is presented in this paper, using a semianalytical solution that leads to a discretization and to the application of the Langrage multipliers method to solve the optimization of n-tuples of speed. With the solution introduced in this work, is possible to include all the details about train operation, such as timetable restrictions or braking types. In the full paper, the detailed solution is presented as well as some real cases to illustrate the method results.

The circulation of trains at very high speeds (higher than $300\mathrm{k}\mathrm{m}/\mathrm{h}$) leads to important vibrations in the track and its environment. Concerning the track behavior, this dynamic cyclic loading conduces to the deterioration of its geometric quality, which progressively amplifies the vibration levels in a repeated process, leading to an increase in track lifecycle costs. Within this framework, this paper presents a dynamic numerical model that was built with this concern and was consistently validated with real experimental measurements at different maximum speeds, also above $300\mathrm{k}\mathrm{m}/\mathrm{h}$. The implementation in the model of long-term estimations of plastic deformations accumulations is described and highlighted. The influence of increasing train speeds in the level of vibrations reached in different types of tracks may be evaluated, as well as the track settlement evolution along the track and throughout millions of cyclic train passages. Different design alternative solutions are simulated: softening railpads, placing under-sleeper pads or ballast mats, or using bituminous subballast as an alternative to granular subballast. Critical analyses on the results obtained in the paper enable one to draw recommendations on the mitigation of track vibrations and maintenance interventions, that is, on the possible improvements to be made to ballasted high-speed track design considering its maintenance needs.