Pavement maintenance planning and programming requires optimization analysis involving multiobjective considerations. Traditionally single-objective optimization techniques have been employed by pavement researchers and practitioners because of the complexity involved in multiobjective analysis. This paper develops a genetic-algorithm-based procedure for solving multiobjective network level pavement maintenance programming problems. The concepts of Pareto optimal solution set and rank-based fitness evaluation, and two methods of selecting an optimal solution, were adopted. It was found that the robust search characteristics and multiple-solution handling capability of genetic-algorithms were well suited for multiobjective optimization analysis. Formulation and development of the solution algorithm were described and demonstrated with a numerical example problem in which a hypothetical network level pavement maintenance programming analysis was performed for two- and three-objective optimization, respectively. A comparison between the two- and three-objective solutions was made to highlight some practical considerations in applying multiobjective optimization to pavement maintenance management.

Porous pavements are widely used for local disposal of storm water. This paper presents the results of a full-scale study of ground temperatures in porous pavement during periods with prolonged freezing conditions and during snowmelt. The pavement construction was situated in a housing area in Lulea in northern Sweden, and it consisted of porous asphalt over an aggregate base of macadam. It was found that the cooling of the porous pavement was governed by variations in ambient air temperature and that freezing of the soil below the subgrade was related to the freezing index. The porous pavement was more resistant to freezing than a conventional impermeable pavement due to higher water content in the underlying soil, which increased the latent heat in the ground. Thawing of the porous pavement was a rapid process, which depended on meltwater infiltration. The thawing process in a comparable impermeable pavement was slower.

The objective of this research is to investigate the deformation behavior of asphalt concrete mixtures containing four phosphate waste fillers (12.7-mm reject, 4.5-mm reject, slime, and phosphogypsum) as compared to the behavior of a standard mixture containing limestone filler. The Marshall test results revealed that, generally, there was improved Marshall characteristics for the mixtures containing these wastes when compared to the standard mixture. The immersion wheel tracking machine results revealed that the 12.7- and 4.5-mm reject fillers increased resistance to deformation by 2.2 and 1.5 times, respectively, as compared to the standard mixture. As measured by the immersion wheel tracking machine, the effect of water on the slime and phosphogypsum indicated poor behavior of the mixtures containing both fillers. It is recommended that the slime and phosphogypsum fillers should not be used in wearing course mixtures. It was further concluded that the Marshall test method provided misleading conclusions with respect to the effects of water on the mixtures containing slime and phosphogypsum fillers and in terms of ranking mixtures in the order of their ability to resist deformation.

The design of signal timings for diamond intersections is well documented in the literature, and there are a variety of software packages to assist one in generating timing plans. However, the actual implementation of diamond intersection control procedures on modern dual ring actuated controllers is not documented in the literature, primarily because early implementations used vendor specific features on modern controllers. Consequently, none of the implementation procedures were transferable. In recent years, vendors have greatly increased the flexibility of their traffic controllers and now provide configurable ring structures, overlaps, detector modes, and detector mapping. This paper synthesizes current practice and defines procedures for implementing both three-phase and four-phase diamond control logic using common features on modern traffic controllers. The procedures introduced in this paper should allow this important area to mature and gain widespread implementation, leading to more efficient traffic signal operation at signalized diamond interchanges.

A CORSIM-based microscopic simulation model is developed, which provides transit planners and operators with the ability to simulate bus operations on transit routes. Several modules in CORSIM for processing bus operations are modified to calculate bus dwell times at stops. The bus dwell time is dynamically determined by the passenger arrival rate, average boarding time, and vehicle interdeparture time (headway). Bunching of buses—due to variations in passenger demand at stops, travel times on streets, and delays at intersections—deteriorates the quality of service and operating efficiency, which can be observed from the simulation results. The input requirements and the modular nature of the proposed model are highlighted. Outputs, including bus arrival and departure times, dwell time, and average passenger waiting time at each stop, are generated for the evaluation of bus operations. The proposed simulation model is calibrated and validated by two sets of data collected from bus route 39 of the New Jersey Transit Corporation.

This study is an examination of the daily dynamics and system stability of pedestrian movement within an extensive, indoor walkway system. Temporal and spatial stability in the distribution of pedestrians was established using an efficient census-taking technique. It was found that the spatial distribution of pedestrians was weakly related to the integration of the Underground system. Centrally located links were marginally more attractive to pedestrians. Relatively minor differences in pedestrian distribution were discovered between weekday and weekend day. The absence of directional flows over time was also observed. The highly stable dynamic structure of the Underground is in direct relationship with a describable urban environment. This paper concludes with recommendations for research into other explanatory environmental factors.

This paper is a follow-up study to the dynamic user-optimal departure time/route choice problem, by imposing hard time-windows on origin departure times and on destination arrival times. However, by an appropriate network representation, the dynamic user-optimal departure time/route choice problem with hard time-windows is mathematically equivalent to the dynamic user-optimal route choice problem and can be solved accordingly by the nested diagonalization method. The enhancements of the proposed model are that off-peak and peak phenomena within the analysis period can be properly differentiated and that the influence of earlier departures on latter ones can be naturally presented. A numerical example is provided for demonstration.

This paper considers transportation service of a bus route with a capacity constraint. The conventional demand-supply equilibrium model is adopted to determine demand, service quality, and profit of the operator and total social welfare in terms of the bus fare and bus fleet size. A simple numerical realization and graphical characterization of a wide variety of industry equilibria in a bus fleet-fare 2D space are presented. The 2D representation in this study allows for intuitive visualization of the various possibilities of profitability and welfare gain of the bus route under competition and regulation. It thus provides a convenient way to help the private sector identify how, and under what circumstances, a bus route service is feasible and profitable and to assist the public sector in understanding how the bus route service will benefit the private operator, the passengers, and the whole society.

The EPA specifies that level-of-service D intersections must undergo detailed microscale carbon monoxide modeling using the recommended software such as CAL3QHCr, which requires an in-depth knowledge of microscale dispersion modeling of pollutants. In this study, a new statistical framework is introduced that is intended to replicate the microscale modeling results achieved with CAL3QHCr. The new framework provides an important means for assessing air quality impacts during the design phase of a transportation project, without having to acquire the modeling skills and/or dispersion modeling knowledge necessary to execute CAL3QHCr. To develop the framework, approximately 23,000 CAL3QHCr simulation scenarios were generated by varying the input values of the major design and dispersion modeling factors. The input values, together with the corresponding output values of CAL3QHCr simulations, were used to specify a statistical model for predicting carbon monoxide concentrations. The statistical model was then validated using field meteorological conditions for five cities in California. The study results show that the proposed model can be easily and reliably used by traffic engineers to predict potential carbon monoxide exceedances at the planning stages for transportation projects.

This paper documents a study of the feasibility of using sign blanks constructed of reclaimed materials in roadside applications instead of conventional high-grade plywood and aluminum. Various types of recycled materials were solicited from commercial manufacturers and subjected to an array of laboratory tests and numerical simulations. Materials tested include high-density polyethylene, polycarbonate, polyvinyl chloride, and calcium carbonate. Properties and performance of a total of seven recycled materials that were tested in flexure, uniaxial tension, creep, free vibration, and exposure to ultraviolet radiation are discussed.

In this paper, the classical work of Spangler is revisited to derive a modified Iowa formula for estimating vertical deflection of flexible pipe. During the derivation process, the approach suggested by Spangler is faithfully followed. No new assumptions or empirical elements are introduced beyond those originated by Spangler. Once the vertical deflection formula is established, its reliability is verified against field deflection measurement data supplied by Spangler. Then, a few parametric studies are conducted using the horizontal and vertical deflection modified Iowa formulas to gain further insights into the pipe-soil interaction problem as revealed by the work of Spangler. Finally, the paper concludes by offering a summary and then pointing out a few key issues that need to be remembered when applying the classical approach pioneered by Spangler.

A generalized chart is presented to determine the spread in composite gutters given the gutter discharge. The use of this chart eliminates the tedious trial-and-error calculations to determine the spread in routine pavement drainage problems. The chart is also different from those available in the literature in the sense that it is limited neither to a specific unit system nor to specific gutter dimensions. The use of the chart is demonstrated through a practical application.