This research focuses on evaluating driver visual demand on three-dimensional (3D) highway alignments, consisting of combined horizontal and vertical alignments. Using a driving simulator, nine two-dimensional and 3D hypothetical alignments for two-lane rural highways were developed following the standard guidelines of the Transportation Association of Canada. Fifteen driver subjects drove in the simulator and data on visual demand were analyzed using different processing and statistical software. The results showed that visual demand on 3D curves significantly varied with the inverse of the horizontal curve radius and the inverse of the vertical curvature. Meanwhile, the subject age had a significant effect on visual demand. Models for evaluating visual demand on 3D highway alignments were developed for both curves and tangents. The developed models were verified and applied to 3D alignments to carry out a design consistency evaluation.

In British Columbia, many highways are located in mountainous terrain and the costs of highway construction in these areas are high. One method of controlling construction costs is narrow medians but the safety consequences of using narrow medians were never determined. Recent research on safety in geometric design has focused on establishing quantitative relationships between collisions and cross-sectional elements using collision prediction models (CPMs) and collision modification factors (CMFs). In some situations, such as the use of narrow medians, it is difficult to find CPMs and CMFs that adequately describe the design scenario. In other instances, it is difficult to measure the safety in terms of collision reduction because of a lack of data or difficulty isolating the impact of a single design element on collision frequency. In these situations, reliability analysis can be used to evaluate the risk associated with a particular design feature. Reliability analysis is not intended as an alternative to quantify safety using collision frequency but represents a complementary method of measuring safety in terms of risk. In this paper, reliability analysis was completed on a series of horizontal curves with varying horizontal sight distance restrictions and the probability of being unable to stop within the available sight distance was calculated. The results of the study found that narrow medians combined with tight horizontal curves did not provide sufficient sight distance that vehicles would be expected to stop if an object was in a vehicle’s path. The analysis was applied to a case study of two constrained alignments in mountainous terrain of British Columbia.

Optimal coordination of traffic signals requires proper activation of timing plans to match current traffic conditions. One of the greatest challenges in configuring a traffic responsive plan selection control mode is how to select only $n$ number of timing plans (restricted by traffic controller memory limitations) to address possibly all traffic conditions/states that can be encountered in the field, for a specific site, but most importantly, how to associate each of these traffic conditions to one of the $n$ timing plans stored in the traffic controller. This paper uses a multiobjective nondominated sorting genetic algorithm to (1) select the best $n$ timing plans to be stored in the controller and (2) group traffic states into $m$ number of clusters, and associate each of the $m$ clusters with one of the stored timing plans. A new performance measure, degree of detachment, developed by the writers to address the clustering requirements, is described in this paper.

Various accessibility measures, differing in terms of their definitions and formulations, have been proposed over the past $40\text{years}$ and been applied to a wide range of problems. This paper extends previous research by developing a new functional form to represent accessibility using real transportation data from the New York/New Jersey metropolitan area. The accessibility function is used as an input to develop an employment function in terms of several socioeconomic variables. Two main hypotheses are tested: (1) that improved accessibility, with all other factors remaining the same, will positively affect individuals’ tendency to enter the labor market; and (2) that this effect will vary across employment types and industries. Both functions are estimated simultaneously with county-level data for the year 2000 using two-stage and three-stage least squares analysis (2SLS and 3SLS). Because the results of 3SLS were statistically more robust than 2SLS while the parameter estimates remained similar in magnitude and sign, the proposed model mainly used the 3SLS estimation results. Main results show that the changes in accessibility have a noticeable effect on employment in the studied area. Depending on skill requirements, offered wage rates, household’s income, and children of specific age groups, participation in the employment sectors considered were proved to be responsive to accessibility improvements.

This paper focuses on a case study concerning the evaluation of the mechanical characteristics of high modulus asphalt mixtures (HiMAMs) for base layers, especially with regard to its permanent deformation resistance. This type of mixture has been used successfully for almost two decades in several countries. However, for Portuguese climatic conditions, which are quite severe during summer in terms of pavement temperature, a better understanding of HiMAMs behavior is needed. Because HiMAMs are produced with low penetration (hard) asphalt cement, the writers expected that these mixtures would make an important contribution to reducing rutting in the structural asphalt layers of Portuguese pavements. The 16 km length of the EN14 (Portuguese National Highway 14) rehabilitated near Porto has supported the research described. Slabs extracted from trial sections were submitted to a traffic simulation test (wheel-tracking). Cylindrical specimens compacted by vibrocompression in the laboratory and cores taken from trial sections were submitted to repetitive loading axial tests at three different temperatures. This made it possible to derive several permanent deformation resistance parameters for HiMAMs. The values for these parameters enable prediction expressions to be developed for those characteristics, and these can be useful for designing HiMAMs, based on performance criteria.

A series of finite element (FE) simulations are carried out to evaluate the benefits of integrating a high modulus geosynthetic into the pavement foundation. The simulations are conducted under a parametric study to investigate the beneficial effects of geosynthetic reinforcement to the fatigue and rutting strain criteria, and to determine how such effects are influenced by the base quality and thickness as well as the subgrade quality. Three locations of the geosynthetic reinforcement are studied, namely the base–asphalt concrete interface, the base–subgrade interface, and inside the base layer at a height of 1/3 of its thickness from the bottom. It is found that placing the geosynthetic reinforcement at the base–asphalt concrete interface leads to the highest reduction of the fatigue strain (46–48%). The placement of geosynthetic reinforcement in thin bases is particularly effective; the highest decrease of rutting strain (16–34%) occurs when the reinforcement is placed at a height of 1/3 of the base thickness from the bottom. The study is carried out with the finite element program ADINA using a three-dimensional (3D) dynamic modeling technique with implicit solution scheme.

Even though the concepts of pavement reliability and risk-based design have been recognized for a long time, probabilistic pavement design methods are often limited to the application of Monte Carlo simulation or Taylor expansion to evaluate reliability measures. This paper presents a comprehensive framework for establishing pavement reliability functions that consider various uncertainties associated with a pavement, starting from design assumptions to construction process and finally to utilization. With the recent development in the theory of structural reliability, in particular, the introduction of the standard normal point-estimate method for approximation of moments of the limit state function and the standardized functions for obtaining moment reliability indices, analytical evaluation of the probability integral for reliability has become feasible. The primary advantage of the analytical approach is its suitability for implementing optimization models of classical nonlinear algorithms. Finally, a numerical study was conducted to demonstrate the applicability of the method of moments for predicting pavement reliability.

An experimental analysis of response data from actual aircraft passes at Denver International Airport was conducted to determine the effect of the slab-base interaction on concrete pavement responses. This analysis was divided into three parts: gap analysis from deflection data, interface analysis from paired strain data, and comparison between predicted and measured strains. The gap analysis showed that gaps exist between the slab and base, depending on the temperature differential and slab location. The gap analysis also indicated the existence of an effective built-in temperature difference. Despite the indication of gaps beneath the slab, the paired strain data analysis indicated contact friction or bonding action under wheel loading. The greatest contact friction occurred at the slab interior, followed by doweled transverse joints and transverse dummy joints, whereas an unexpected full-slip condition was found at tied longitudinal joints. The comparison between measured and predicted strain confirmed contact friction is developed under aircraft gear loading.

Accessibility, proximity, and land-use changes over time are important considerations in highway route selection. Highway users while benefiting from living closer to highways also pay a price for living close to them due to increased noise and pollution. Although noise and air pollution considerations have long been emphasized in land-use planning, their relative impacts in selecting a highway route are not fully understood. This research is motivated by a recent Federal Highway Administration initiative in which a national workshop involving participation from Departments of Transportation is proposed to understand current practices of including noise and air pollution in land-use planning. Formulations for accessibility, proximity, and land-use changes are developed and incorporated into a previously developed highway alignment optimization model by our research team. An example problem is presented to check the sensitivity of alignments to accessibility, proximity, and land-use change. The results indicate that accessibility, proximity, and land-use changes can greatly influence the selection of highway routes.