The performance of Australia’s unbound granular pavements with a wearing surface of stone aggregate embedded in a thin bituminous binder seal is highly dependent on maintaining a serviceable surface for the road users. Experimental pavement deterioration data gathered by means of accelerated load testing (ALT) was used to estimate relative performance factors for cumulative rutting and roughness deterioration for various surface maintenance treatments. The ALT experiments were on various surface treatments over separate test pavements undertaken in an enclosure to control the environment, which was either dry or continuously wet. The experimental deterioration data was also used to establish the limit of gradual pavement deterioration prior to the onset of rapid deterioration. The relative performance factors can be applied to the observed deterioration of given surface treatments to develop network level road deterioration (RD) models that predict the influence of various surface treatments on deterioration. Several long term pavement performance studies, including a study directed specifically at maintenance treatments, have collected observational data for the purpose of network level RD model development.

Image segmentation is the crucial step in automatic image distress detection and classification (e.g., types and severities) and has important applications for automatic crack sealing. Although many researchers have developed pavement distress detection and recognition algorithms, full automation has remained a challenge. This is the first paper that uses a scoring measure to quantitatively and objectively evaluate the performance of six different segmentation algorithms. Up-to-date research on pavement distress detection and segmentation is comprehensively reviewed to identify the research need. Six segmentation methods are then tested using a diverse set of actual pavement images taken on interstate highway I-75/I-85 near Atlanta and provided by the Georgia Department of Transportation with varying lighting conditions, shadows, and crack positions to differentiate their performance. The dynamic optimization-based method, which was previously used for segmenting low signal-to-noise ratio (SNR) digital radiography images, outperforms the other five methods based on our scoring measure. It is robust to image variations in our data set but the computation time required is high. By critically assessing the strengths and limitations of the existing algorithms, the paper provides valuable insight and guideline for future algorithm development that are important in automating image distress detection and classification.

In pavement engineering, good estimation of layer moduli from nondestructive methods is an important tool for scheduling and designing rehabilitation projects. The falling weight deflectometer test is perhaps the most commonly used nondestructive method for the evaluation of the structural performance of pavement systems. These measurements are then used to back-calculate the properties of the layered pavement materials. A new method based on constrained extended Kalman filter (EKF) is proposed for back-calculating layer moduli. The method uses a transformation to constrain the “searchable” domain for determining the optimal estimates of material parameters and a weighted iteration algorithm that enhances the speed and convergence of the iterative procedure. In numerical examples, the proposed method converges to the actual layer moduli with high accuracy for three-, four-, and five-layer pavement systems even though very different initial values are used. The paper also compares the performance of EKF with other methods published in the literatures. The proposed method shows excellent performance in terms of speed and stability while providing highly accurate estimates of material properties including cases in which nonlinear layers were considered. It is concluded that the constrained EKF is a fast, stable, and consistent algorithm used in back-calculation of layer moduli.

Asphalt mix design involves a number of tasks culminating in a laboratory estimation of suitable asphalt binder content which is recommended for bulk manufacture of the mix. Generally, the suitable binder content is that which on an average satisfy the specification limits. However, due to inherent material variability, there exists a possibility that all samples (or batches) of a mix designed with a suitable binder content may not always satisfy the specification requirements. The present paper aims to highlight this variability involved in the asphalt mix design process and develop a procedure to estimate the reliability of a particular mix design. This study is based on Indian specifications, where mix design, like in many other countries, is performed in accordance with Marshall method. As an example, experiments have been conducted to determine the reliability of an asphalt concrete mix. Using the same approach, reliability of asphalt mix design for any other mix and mix design procedure can be suitably derived.

In the Mechanistic Empirical Pavement Design Guide (MEPDG), rather than producing a quantitative overall evaluation index, several performance measures are used to separately evaluate the pavement performance condition for rehabilitation design. Due to the characteristics of information on parameters being partially known during the evaluation process, there exist several limitations of the current evaluation methods. In this paper a gray clustering-based methodology is proposed to comprehensively evaluate existing pavements following the MEPDG framework. Gray clustering method is one pillar part of the gray system theory, which was proposed in the 1980s to solve problems with partially known information. The performance criteria used in this study are selected from those defined in MEPDG. The analysis data sets are obtained from the long-term pavement performance (LTPP) database for three types of pavements: flexible pavement, jointed plain concrete pavement, and continuous reinforced concrete pavement. Many LTPP pavement sections are evaluated using the proposed methodology and comparisons are made between gray clustering-based method and extension theory-based approach. It is shown that the proposed gray clustering-based method is able to quantify pavement performance and is suitable to be used as a practical pavement evaluation tool for highway agencies.

This study presents both a laboratory test and a model for simulating the polishing phenomenon of road surfaces when subjected to traffic. In laboratory tests a machine called “Wehner-Schulze machine” is used which performs polishing and friction measurements on road specimens. The tests are done inside the laboratory and try to reproduce the variation of road friction when it is subjected to traffic. On the other hand, the presented model shows the possibility of computing the Wehner-Schulz polishing effect on the microtexture. The model itself uses an approach which mixes the calculation of contact parameters and some characteristic of the used aggregates. The here used aggregate characteristic is the capability to resist wear and is measured by another world wide used device different then the Wehner-Schulz machine. The model remains to be improved because of some assumptions, but this approach provides encouraging results regarding the ability to predict the evolution of road microtexture due to the polishing effect of traffic.

This paper proposes a modified origin-based partial linearization method for solving the logit-based stochastic user equilibrium traffic assignment problem formulated by a strictly convex minimization model in terms of origin-based link flows. As a feasible descent direction method, it first generates a feasible descent direction in terms of the origin-based link flows by Bell’s second logit-based stochastic network loading algorithm without path enumeration, and it proceeds to improve the descent direction according to the Fukushima’s strategy and the PARTAN technique which haven been successfully applied to accelerate convergence of the link-based Frank-Wolfe method for solving the deterministic user equilibrium traffic assignment problem. To tackle the numerical overflow or underflow issue of the exponential function calculation arising in the computerized logit-based stochastic network loading algorithms, this paper develops a scientific notation based engineering approach for large-scale problems. Two numerical examples are carried out to compare the proposed solution method with the conventional origin-based partial linearization method and the method of successive averages in computational time and accuracy of solution.

The Highway Capacity Manual 2000 indicates that the capacity of two-lane two-way highways (TLTWHWs) is 1,700 pcph for a single direction and 3,400 pcph for both directions. There are no capacity estimates provided for different traffic conditions such as varying percentages of no-passing zones and varying traffic distributions between the two directions of travel. Previous research has reported that capacity conditions for TLTWHW are very difficult to observe in the field while none of the existing simulation models can report capacity for TLTWHW. This paper briefly describes a new TLTWHW simulation model called TWOSIM that is developed, verified, compared to TWOPAS and highway capacity software (HCS) and used for the estimation of capacity for TLTWHW under a variety of prevailing traffic and geometric conditions. These include percentage of traffic per direction, presence of a passing zone, a horizontal curve, a driveway, an upgrade, and heavy vehicles. Capacity of TLTWHW under base conditions is estimated to be 1,800 pcphpl at 64 kph (40 mph) average free-flow speed, 2,000 pcphpl at 80 kph (50 mph), and 2,100 pcphpl at 96–112 kph (60–70 mph). The presence of passing zones was not found to have an effect on capacity. When a driveway or horizontal curve or upgrade is present, the capacity reduction ranges between 3 and 30% when there are no trucks and may reach up to 40% when trucks are present in the traffic stream.

A simple real-time merging traffic control concept is proposed for efficient toll plaza management in cases where the total flow exiting from the toll booths exceeds the capacity of the downstream highway (or bridge, or tunnel), leading to congestion and reduced efficiency due to capacity drop. Merging traffic control aims at maintaining the number of vehicles in the merge area close to a critical value that maximizes throughput; to this end, an algorithm known from local ramp metering operations is proposed (ALINEA). The potential control concept efficiency is demonstrated by use of microscopic simulation applied to a particular toll plaza infrastructure with and without merging traffic control. It is shown that the employed feedback regulator is little sensitive to various settings which indicates easy applicability with low fine-tuning needs in potential field applications. The case of partially uncontrolled lanes (e.g., for high-occupancy vehicles, buses or other vehicles) is also addressed.

The Boussinesq theory for the distribution of stresses in a half-space resulting from surface loads is largely used in road engineering. It is based on the assumption of linear-elastic homogeneous isotropic half-space for the soil media. Since the soil exhibits nonlinear and irreversible behavior, it is of major interest to study the validity of this theory for nonlinear response of soils. This paper investigates this issue by comparing the elastic stress distribution to that obtained using respectively nonlinear elastic and elastoplastic finite difference analyses. Results show that nonlinear elasticity does not influence significantly the stress distribution while plasticity reduces the attenuation of the vertical stress in the soil mass, which means that Boussinesq solution underestimates the stresses in an area which contributes to the soil settlement. An important discrepancy is also observed in horizontal stress for the case of homogeneous and multilayered soil when plasticity is considered.