Reliable, complete, and up‐to‐date information concerning the state of pavement surface is necessary for any cost‐effective highway pavement management program. An automatic imaging system based on state‐of‐the‐art video imaging technology using the shadow moire method for the quantitative inspection of highway pavement surface has been developed which includes image‐analysis software for performing image enhancement and the analysis of the moire fringe patterns. The pavement surface reconstruction algorithm presented herein uses two moire interferograms of any point on the surface to obtain overlapping information for surface‐elevation determination. The prototype system possesses a high degree of automation and gives enhanced pictures and accurate results. Also, such surface geometry information as profile, rut depth, and washboard depth may be obtained efficiently and effectively.

Traffic data, essential for the detection of freeway incidents, are often corrupted by impulsive noise and short‐term traffic inhomogeneities that may impair detection performance. Rigorous data filtering can reduce the undesirable noise and enhance the incident signal. A new incident detection algorithm is developed that employs short‐term time averaging (low‐pass filter) to reduce the adverse effects of short‐term traffic fluctuations and impulsive noise in the detection process. The detection algorithm traces the filtered spatial occupancy difference between adjacent detector stations through time, and detects an incident when this difference changes significantly in a short time period. The new algorithm was evaluated with data from a congested freeway in the Minneapolis‐St. Paul metropolitan area and compared against major existing algorithms. Test results indicate the ability of the Minnesota algorithm to significantly alleviate the false‐alarm problem, while preserving high detection performance, as compared to existing algorithms.

Maintenance activity on two‐lane highways often requires the closure of one travel lane. Vehicles in both directions of travel are served via the one remaining lane. Under such conditions, alternating right of way into the highway's work zone is provided to each direction of travel. This so‐called “one‐way traffic control” typically creates significant motorist delays. This paper describes a proposed technique for estimating vehicle delays and queue lengths on two‐lane highways operating under one‐way traffic control. Using parameter estimates derived through empirical data, the procedure estimates the average amount of time right of way is extended to each direction of travel during a given time period of operation. Average motorist delays and queue lengths occurring over the given time period are then computed using deterministic queueing theory. The proposed technique can aid highway agencies in determining the appropriate physical lengths and/or hours of operation for two‐lane highway work‐zone segments.

This paper presents a new framework for the analysis of infrastructure performance and the planning of inspection, maintenance, and rehabilitation (M&R) activities. The main facets of this framework are: explicitly modeling the errors in measurement of facility performance indicators; treating the key variable in the process, facility performance, as a latent variable that manifests itself through measured condition indicators; and explicitly analyzing and including in the decision process the uncertainties in infrastructure condition measurement and performance forecasting. Our approach recognizes the errors inherent in the measurement of the condition indicators; these errors are quantified through the use of measurement error models. A model system relating the latent facility performance to explanatory variables and to observed indicators is developed. Our M&R activity planning model accounts for the presence of uncertainty in the output of the inspection of facility condition and the forecasting of facility performance. An application example is presented.

The U.S. Department of Transportation and most of the state transportation agencies have identified a growing problem with deficient and obsolete bridges throughout the country. This paper summarizes the results of a study undertaken to help alleviate these problems. The result of this effort was a generic computer bridge management system to help bridge engineers and administrators manage and improve their bridge networks. The software developed through this study organizes and analyzes bridge inventory, inspection, and appraisal data to assist management in making decisions that will give the maximum benefits from bridge maintenance, rehabilitation, and replacement activities on a network of bridges. The software consists of six major modules: data base module, level of service module, improvements module, maintenance module, system upkeep module, and help module. These modules interact to perform the basic functions of bridge management.

The single‐point urban interchange (SPUI) is a relatively new type of diamond interchange. Its reported advantages are improved operational efficiency, improved safety, and reduced right‐of‐way requirements as compared to other interchange forms. This paper focuses on the efficiency and right‐of‐way requirement issues by examining the relationships among the various SPUI design elements. In particular, constraints placed on the SPUI geometry by the bridge‐abutment locations and offset left‐turn paths made it possible to develop a geometric model relating turn radius, cross‐section width, number and width of turn lanes, and skew angle to bridge length and clearance path length. A sensitivity analysis using the geometric model developed in this paper indicates that skew angle, cross‐road median width, and ramp‐major road clearance distance have a significant effect on the length of the bridge and the duration of the all‐red clearance interval. An illustrative application of the model indicates that it can be used to develop relationships among SPUI design elements that yield the most cost‐effective design.

A unified method for designing complex horizontal curves and all traditional categories of horizontal curves is presented. The unified method is applicable to complex curve geometry involving any number, combination, and configuration of circular arcs. Traditionally, complex curves have to be solved on an individual basis because they do not exhibit a consistent pattern suitable for mathematical analysis. This difficulty is overcome in the unified method by the use of (0, 1, −1) variables to designate the types and configuration of arcs of the horizontal curve. The solutions of traditional curves are special cases of the unified solution. By setting the proper values of these variables, the known solutions of the simple, compound, and reverse curves are obtained. Application of the method is illustrated using practical examples involving street widening, median design for a Y‐intersection, a cul‐de‐sac, and a three‐centered asymmetric compound curve. The method should be of interest to highway professionals who are concerned with achieving computational efficiency in designing highway horizontal curves.

The American Association of State Highway and Transportation Officials (AASHTO) and other models for evaluating the lateral clearance on horizontal circular curves are applicable only to simple curves. Employing these models for compound curves will underestimate or overestimate the lateral clearance needs, depending on whether the analysis is based on the flatter or the sharper arc of the compound curve. In this paper, the available sight distance on compound horizontal curves is formulated. The available sight distance is related to the parameters of the sharper and flatter arcs, the lateral clearance of the obstacle, its location within the sharper or flatter arc, and the locations of the driver and object. The minimum sight distance $S_m$ and sight distance profile of the compound curve may be considerably different from those of the simple curve. To facilitate practical use, values of $S_m$ are established for typical parameters of the compound curve.

Permanent deformation in the layers of a full‐scale flexible pavement test section that was subjected to heavy fighter‐aircraft loading (F‐15) is presented as background information for designing a laboratory study of asphalt concrete subjected to realistic (but very slow moving) highway vehicle load simulation. A hollow cylinder specimen was used in the laboratory study. The correction factor for “dynamic effects” used in the Shell Pavement Design Manual, published in 1978, is explained in terms of rotation of principal planes of stress using hollow cylinder test results. A statistically significant difference is illustrated between the permanent strain resulting from laboratory testing with no principal‐plane rotation and that resulting from testing with principal plane rotation. The tests were also able to identify statistically significant differences between two levels of wheel loading, two aggregates, and two asphalts. Dilatational, Bauschinger, and time‐dependent effects were observed either directly or indirectly.

This paper discusses the problem of loss of jointing sand in block paving, how to avoid attendant loss of interlock, and possible damage to the pavement structure from ingress of water. Reasons for the erosion of jointing sand so far identified are: (1) Action of jet blast and propeller wash from aircraft engines; (2) Use of vacuum sweepers for cleaning block‐paving areas; (3) turbulent water flow over pavement surface; and (4) degradation and pumping of laying‐course materials. Various materials have been used to try to stabilize the jointing sand; some have provided a temporary solution to the problem. However, the most effective means of preventing erosion problems has been found to be the use of a specially formulated liquid prepolymer that retains elasticity after curing and is thus able to sustain the essential flexible nature of the block‐paving system.

This paper reports on the admixture stabilization of problem laterite using portland cement as the stabilizer and sodium chloride $\left(\mathrm{NaCl}\right)$ as the admixture. Results of unconfined compressive strength (UCS) tests show that this form of admixture stabilization is unsuitable for problem laterite using the conventional 1.73 N/mm² evaluation criterion for the economical range of cement content specified by Nigeria's General Specifications—Roads and Bridgeworks. However, the strengths of this admixture are comparable to those recorded in an earlier work on soil‐lime‐cement stabilization for the same soil for which a UCS value of 1.38 N/mm² was proposed as evaluation criterion. This UCS value of 1.38 N/mm² seems an appropriate evaluation criterion for soil‐sodium chloride‐cement stabilization for problem laterite. Adoption of this form of admixture stabilization for problem laterite is thus recommended. A reaction mechanism in which calcium silicate hydrate, sodium calcium silicate hydrate, calcium aluminate hydrate, and calcium aluminate chloride hydrate are formed in soil‐sodium chloride‐cement stabilization of laterite is proposed for further investigation.

Submarine oil pipelines carry hot crude oil obtained from offshore oil wells to an onshore location. As the flow proceeds, the crude oil progressively cools down, drastically changing its kinematic viscosity. This cooling increases the surface resistance to flow considerably. Analysis of such a pipeline is complicated because it involves a large number of variables representing fluid, flow, thermal properties, and geometry. Furthermore, as the liquid cools down the flow may change from turbulent to laminar. This paper reports a unified friction factor equation valid in laminar as well as in turbulent flow that deals with this complex flow situation. This equation can aid development of a methodology for analysis and design of offshore pipelines.