Traffic-responsive plan selection (TRPS) control is one of the largely underutilized control features in National Electircal Manufacturers Association traffic controllers. This control feature allows the controller to change timing plans in arterials or networks in response to changes in traffic patterns automatically, and can therefore result in better performance of the signal system. However, there is limited number of studies that document the procedure of TRPS configuration. The authors have previously published general guidelines on TRPS system setup and configuration, laying out a comprehensive approach that assumes general traffic patterns, a standardized arterial network, and some generic system detector locations. This paper fills a significant gap in literature by providing an illustrative procedure of actual field implementation of a TRPS system in Mexia, Texas. The paper demonstrates the configuration methodology on an arterial network that does not conform to the standardized guidelines. This implementation resulted in up to 75% reduction in delay and up to 33% increase in the lower arterial speed. In this paper, the authors provide some findings and insights into the TRPS configuration process, highlighting some solutions for potential field problems that the engineer might face when configuring a TRPS control system.

The flexible pavement system consists of layered structures. Each layer is composed of different materials and represents different response to loading. Successful pavement design, therefore, requires proper evaluation of mechanical properties for the sublayers, which can realistically describe the behavior of pavement substructures. The resilient modulus is an important mechanical property widely used for the analysis and design of flexible pavements. In this study, a normalized resilient modulus model applicable to both subbase and subgrade materials is proposed. A series of laboratory test results for subbase and subgrade materials are collected and analyzed to investigate effects of the confining and deviatoric stresses on the resilient modulus. Based on test results, a normalized degradation relationship of the resilient modulus as a function of normalized stresses is developed. Values of model parameters for the proposed model are also evaluated and presented. To check validity of the model, a finite element analysis is performed and compared with measured responses of pavement structures.

The primary objective of this research is to develop a practical model for evaluating the effects of traffic management on fuel efficiency. The relationships between the real-world driving activities, the vehicle specific power, and the corresponding fuel consumptions are analyzed based on the data of 26 gasoline and liquefied petroleum gas-fueled light-duty vehicles (LDVs). Then, an indicator for evaluating the level of fuel consumption is designed by dividing the normalized fuel consumption by the fuel use in the most economic scenario. An aggregate model is developed following the design of the indicator that features minimal input requirement and meaningful output for LDVs. In the case studies, the proposed model is applied to estimating and comparing the fuel efficiency of several driving cycles, evaluating the fuel efficiency improvement resulting from the electronic toll collection system, and developing temporal variations of fuel efficiency for a road in Beijing by using floating car data. Finally, the merits of the proposed model are discussed, and the limitations and recommendations are provided for further model improvement.

Transportation management policies and practices are currently experiencing evolving trends such as funding limitations, aging facilities, greater travel demand, increased number of visible stakeholders, and higher user expectations. As a result, transportation agencies currently grapple with how to best incorporate a wide range of performance criteria in investment evaluation and decision making. Often, a key prerequisite to multiple criteria decision making is to establish the relative importance of different performance criteria as perceived by decision makers, facility users, and other stakeholders. This paper reviews methods that exist in the literature for weighting and illustrates the applications of some of these methods. For the bridge management case study, the direct-questioning weighting technique was found to yield results that indicated high levels of agreement among bridge experts. For the overall highway asset management case study, the analytical hierarchy process was used to derive the weights across performance criteria. The findings show that the distribution of weights across various highway performance criteria based on the agency perspective can differ from that based on the road users’ perspective. The relative weights of the different performance criteria can help agencies establish the overall combined desirability or otherwise of each alternative transportation action in terms of all performance criteria, identify the best action in a balanced and rational manner, or analyze trade-offs between the alternative actions.

This paper details the development of a fully customizable population synthesis program designed to be used for almost any geographic area or input variable. The design addresses several important issues that have been raised regarding other population synthesis methods, including the false-zero cell problem. To address this problem, a routine was developed that allows for the aggregation of control variable categories during execution at the subregional level based on a user-controlled aggregation threshold parameter input, which reduces the areas where false-zero cells are most likely to occur. This procedure also greatly eases the task of data preparation. As part of the study, new validation methods were developed and used to compare the new procedure against other procedures and known test variable distributions. Finally, detailed analysis regarding the trade-off between complexity and computational effort was also undertaken. The use of these new routines and validation methods along with an understanding of the trade-off between complexity and computational effort will allow for the development of more realistic synthetic populations.

This article presents a multiobjective approach to long-term interurban multilevel road network planning. In addition to the efficiency objectives dealt with in most of the literature where the subject is addressed, the approach takes into account robustness and equity objectives. For achieving the objectives, two types of action can be performed: the construction of a new road of a given level; and the upgrading of an existing road to a higher level. The approach is consistent with the planning framework of the highway capacity manual, using the concept of level of service to assess traffic flow conditions. The application of the approach is illustrated for a case study involving the main road network of Poland.

Sight distance at the intersection of a minor road (controlled by a stop sign) and a major road is an important element of road safety. Several models have been recently developed for the analysis of sight distance at intersections involving horizontal curves on the major road. All these models assume that the intersection lies within the horizontal curve. There are situations, however, when the intersection lies within one of the tangents of the horizontal curve. This case would adversely affect sight distance, especially when the horizontal curve is sharp and the minor road is close to the horizontal curve. This paper develops a new mathematical model for sight distance analysis that explicitly addresses the case where the intersection lies within the tangents of the horizontal curve. The obstruction may be located within the tangent or within the horizontal curve, or located inside or outside of the horizontal curve. Using the model, graphical aids for the required obstruction distances from the major and minor roads, to satisfy sight distance requirements, are developed. The developed model can be used to evaluate sight distance for existing or new intersections.

The paper develops a short-term space-time traffic flow forecasting strategy integrating the empirical-based seasonal autoregressive integrated moving average (SARIMA) time-series forecasting technique with the theoretical-based first-order macroscopic traffic flow model—cell transmission model. A case study in Dublin city center which has serious traffic congestion is performed to test the effectiveness of the proposed multivariate traffic forecasting strategy. The results show that the forecasts at the junctions only deviate around 10% at a maximum from the original observations and seem to indicate that the proposed strategy is one of the effective approaches to predict the real-time traffic flow level in a congested network especially at the locations where no continuous data collection takes place.

A previously published solution for the minimum temperature for which a periodic laterally buckled solution is possible introduced an unnecessary restriction on the solution. Removing this restriction gives a true minimum that is slightly lower and not more difficult to calculate.

Capacity can be derived by fitting a relationship between the three fundamental traffic variables: flow, speed, and density. The study uses a dual-regime model with the consideration of all three variables. Different forms of functions were specified for congested and uncongested conditions. An optimization based estimation procedure was developed to minimize the distance between the theoretical functions and the traffic stream variable measurements. The optimal procedure was coded into a computer program and applied to three data sets representing different roadway classifications. The results indicate that the proposed method can produce good estimates of the key traffic stream parameters including the roadway capacity.