Grain transportation rationalization, economic diversification, and value-added initiatives within the Saskatchewan economy has increased, and will continue to increase, commercial truck traffic on many Saskatchewan roads. As a result, the Saskatchewan Department of Highways and Transportation is investigating cold in-place recycling as a rehabilitation alternative for strengthening thin-paved roads. However, different construction practices and years of maintenance and rehabilitation have led to many of these thin-paved roads having a variable structural composition. The effect of in situ variability on cold in-place recycle designs is further exacerbated by the inherent sensitivity of stabilizers such as asphalt emulsion, foamed asphalt, cementitious blends, and/or concentrated chemicals when integrated into different road materials. As a result, the materials and structural design of cold in-place recycled thin-paved road systems can be highly uncertain. Ground-penetrating radar has been identified as an engineering diagnostic tool that can accurately quantify in situ structural composition and help reduce the uncertainty associated with the material and structural design of cold in-place recycled road systems. This paper summarizes the principles of ground-penetrating radar, discusses the use of ground-penetrating radar as an engineering diagnostic tool for cold in-place recycling of thin-paved roads, and presents two pilot case studies undertaken by the Saskatchewan Department of Highways and Transportation that demonstrate the capability of ground-penetrating radar to mitigate the uncertainty associated with cold in-place recycled road systems.

Required stopping sight distance (SSD), used to calculate the minimum rate of vertical curvature or the minimum length of a crest vertical curve (CVC), is usually calculated on the assumption that the grade of the braking section is zero (G = 0). This assumption is not the worst case and may lead to the selection of a CVC on which there is a segment with SSD restriction. On each CVC there are braking sections on one or both directions of travel, on which average grade is negative (G < 0). In the present paper a method for calculating required SSD, partly or wholly on a CVC, is developed, using the average grade over the braking distance. In addition, a computer program is compiled for calculating the value of the required SSD for all driver positions before or on a CVC. An SSD profile is drawn and it is proven that, for a significant length of the CVC, the required SSD is greater than the value used for calculating the minimum value of the rate of vertical curvature.

This paper describes improvements developed for an existing algorithm that calculates sight distance profiles based on horizontal geometry. Exact expressions are developed for vector derivatives for plane curves including clothoid spirals. Coordinate and derivative vectors are developed for partial spirals that possess nonzero curvature at both ends, frequently used as transitions between circular curves of different radii. As with complete spirals, the coordinate vectors are approximate and the derivative vectors are exact. Finally, an exact method for measuring distance along an offset curve to a clothoid spiral is developed. Taken together with the results in a previous referenced paper, this represents a complete recipe for computing sight distance profiles along arbitrary horizontal alignments. A numerical example is included to illustrate the use of the algorithm.

The headway between vehicles in a traffic stream is of fundamental importance in traffic engineering applications. Previous research in this subject has focused on modeling theoretical distributions for low and medium traffic flow conditions. Yet little research has studied congested traffic conditions—that is, the high traffic flow state. In the same context, there appears to be a lack of clear-cut boundaries for the three flow states (low, medium, and high). This study attempts to determine such boundaries on the basis of traffic conditions observed at the study sites. Although observed headways at arterial sites follow a gamma distribution, distributions that fit freeway headways differ according to the traffic flow state. The Erlang distribution provided a good fit to the observed headways at sites with high traffic flows.

The concept of design consistency has lately been gaining greater acceptance in North America. Considerable research work is being carried out and steps have already been taken to incorporate this concept into the design practices in Canada and the United States. However, a standard procedure that can be followed by designers to evaluate the design consistency of new or existing alignments is still lacking. This paper compiles different measures for evaluating geometric design consistency, as presented in available research work, to identify their potential applicability and any required future research. These consistency measures are operating speed, vehicle stability, alignment indices, and driver workload. Four fictitious alignments were presented and subjected to these measures in a step-by-step exercise of consistency evaluation. A relationship between design consistency measures and safety, which is the main objective of the design consistency concept, is also discussed. Overall, consistency measures were successful in identifying inconsistencies in the proposed alignments. However, the exercise showed the need for more research work in a number of areas for complete and accurate consistency evaluation.

In practice, the task of designing the vertical alignment of a highway is done manually by an experienced engineer. As a result, the work is both time and resource consuming and relies heavily on human expertise. This work presents a mathematical model that solves for a set of optimal highway vertical grades for a given horizontal alignment. In addition to construction costs, facts considered by this model include earthwork balance and traffic speed in both directions. Code requirements and design practice are also considered. A three-layered heuristic is developed to solve the model. In the first layer, a neighborhood search heuristic is used to determine the locations where grade can change. The second layer sets penalty terms for sections where speed is undesirable, and the third layer solves a mixed integer program that has very few or no 0-1 integer variables. Computational testing on a 2-km road segment shows that the model yields good solutions.

In traffic engineering, three computer packages have been widely used in providing coordinated signal timing plans for arterials. They are SYNCHRO, TRANSYT-7F, and PASSER. These packages were developed at different periods in time, with different backgrounds and different algorithms. This paper explores which of these packages is the best in yielding a suitable timing plan for Iowa Street, the main north-south artery in Lawrence, Kan. The timing plans produced by SYNCHRO, TRANSYT, and PASSER are compared in terms of the delay, stops, speed, fuel consumption, and emission as analyzed by NETSIM. The best plan is the one with the most desirable measures of effectiveness. The result of the study shows that PASSER provides the best timing plan for this particular arterial. SYNCHRO is very good at data entry and data transfer. NETSIM shows strong power in the evaluation of the timing plans in details and capability of displaying animation. Finally, proper steps to do arterial coordinated timing analysis using these packages are recommended.

This paper investigates the reliability of TRANSYT-7F optimal solutions from two perspectives: (1) the effect of the selected optimization criterion on the values of various system performance measures; and (2) the extent to which TRANSYT-7F signal plans remain optimal when evaluated in a microscopic and stochastic traffic environment. The well-established CORSIM model was used for the latter test. A customized code has been developed that can automatically generate statistical distributions of selected performance measures in CORSIM based on various TRANSYT-7F optimization runs. The method has been applied to a calibrated test network in Chicago consisting of 9 signalized intersections with 50 nodes and 74 links. It was found that while good correlation existed between the corresponding performance measures in TRANSYT-7F and CORSIM under light traffic, their correlation diminished under congested flow. In particular, the best signal strategy identified in TRANSYT-7F was not the best in the CORSIM environment. The discrepancies are undoubtedly due to the basic difference between the two models: TRANSYT-7F is deterministic, CORSIM is stochastic.

The Baltimore Metropolitan Area is classified as a severe nonattainment area under the Clean Air Act Amendments of 1990. Consequently, it operates on a stringent emissions budget and is mandated to embark on mitigation measures. The area has been aggressively implementing emissions control and transportation demand management programs. One of the newest emissions control schemes in the Baltimore Metropolitan Area is the deployment of electronic toll collection (ETC) technology, locally known as M-Tag, at the three toll facilities (the Fort McHenry, Baltimore Harbor, and Key Bridge toll plazas). The ETC deployment, which began in the spring of 1999, has already enjoyed a significant market penetration. The objectives of the study described herein are twofold. First, use a microscopic simulation model to simulate the existing traffic situations at the Fort McHenry Tunnel toll facility, which is the largest toll plaza in the state of Maryland. Observed field data were used to validate simulation results. Second, capture the benefits inherent in the use of ETC technology by undertaking a comparative analysis of pre-ETC and post-ETC scenarios. The primary measures of effectiveness used are (1) increased throughput and hence reduced wait time at the toll plazas; and (2) reduced mobile emissions [hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxide (NO_x)]. It was determined from the simulation and mobile emissions models that the current deployment level of M-Tag has improved the average travel speed by more than 125% and has decreased the mobile emissions rate by up to 41% at the Fort McHenry Tunnel toll plaza. It was concluded that the use of ETC is an effective tool for mitigating mobile emissions at toll plazas.

In this paper a heuristic algorithm is discussed for development of feeder routes to railway stations. The heuristic algorithm is a part of a model that has been developed for operational integration of suburban railway stations and public buses. The model has two distinct components, the first part is development of feeder routes for public buses to suburban railway stations and the second part is determination of optimally coordinated schedules of feeder bus services for the given schedules of suburban trains. The second part of the model is beyond the scope of this paper. Andheri and Vileparle suburban railway stations on a western railway line in Mumbai, India were taken as study areas, and extensive data collection was done at these railway stations. Various nodes and their potential demands from these railway stations were identified, and the demand-deviated feeder routes were developed for Bombay Electric Supply and Transport buses, which are being used as public buses in Mumbai, India.

This paper presents an integrated computer model (WNDROS2) for optimizing runway orientation at airports having two-runway configurations. In this model, mathematical formulation is applied to transfer circles and radial lines of the wind rose method into points with numeric coordinates. Details of the model development and integration are presented in this paper. The model features “evaluating” wind coverage for predefined orientations or “optimizing” runway alignments and coverage. In “optimization,” the model employs an “exhaustive search” to test evaluated coverage at small increments of orientation(s) and to determine the maximum coverage. Ten optimization options are considered in the model to account for parameters related to airport planning such as priority of runways. The model was validated using AutoCAD and FAA Software, and demonstrated in this paper through a numerical example. Results indicated that the model is a valuable tool for numerous applications in airport planning and relevant impact studies.

Computer algorithms and graphical solutions for deflection-based closed-form back-calculation of rigid pavement properties are available. However, a solution in the form of regression equations would have useful practical applications because of the speed and convenience in computation. This work presents a regression model for this purpose based on the closed-form back-calculation algorithm NUS-BACK. The input parameters remain the same as the original closed-form algorithm, with no requirements for seed values or initial guess of pavement properties. The database for the development of the regression model was established by forward computation of deflections for practical ranges of pavement properties. The verification of the regression model is presented by checking against the solutions of the closed-form algorithm NUS-BACK. The reliability of the regression equations was assessed against the closed-form algorithm for two conditions of input deflections: one for exact deflection measurements with no errors, another for deflection measurements with random errors. The analysis showed that the regression model could provide comparable reliability and accuracy to the analytical closed-form solution by NUS-BACK.