Renovation projects are characterized by their complexity, especially when they interfere with a facility's ongoing operations. These operations constrain the performance of construction in a number of ways, including scheduling, cost, safety, security, quality, regulations, etc. Renovation of airports is often associated with challenging problems because airports are normally required to remain fully functional or minimally distributed during renovation. This paper addresses these challenges and outlines a new concept, called the “disturbance concept,” to developing a prototype decision support system aimed at minimizing the disturbance elements between a construction project and aircraft operations. This is done by adopting a total disturbance cost model through the integration of stochastic airport simulation and project management packages. The disturbance model is validated in a case study, a runway reconstruction at San Francisco International Airport (SIAF). Results indicate substantial savings in renovation and facility operations costs, show important trends and tradeoffs between cost and time, and yield useful recommendations to airport authorities, contractors, airlines, and air traffic control (ATC). Only the issues associated with the airside portion of airports are emphasized in this paper, but other portions such as the landside and ground access can be addressed using the same approach.

Periodic rubber removal from runway pavement surface is necessary to keep an airport runway safe for aircraft operations. However, due to the complex relationship between pavement friction and aircraft skidding, there are no clear-cut decision rules as to when a rubber removal operation should be performed. The question is what pavement friction state should be selected as the activation level for rubber removal. A subjective approach to examining the area distribution of frictional resistance of runway pavement surface has been in use in Singapore airports for the last 15 years. This paper describes the development of a decision analysis framework based on past experience of rubber removal operations at the airport. This was carried out with the aim of reducing the reliance on a few experienced maintenance staff for such an operation, and of improving the consistency and continuity of the rubber removal decision-making process. The decision framework includes a neural network decision model for rubber removal, and a prediction model to estimate the growth of affected pavement areas for planning purpose.

A finite-element analysis was conducted of flexible pavement test sections subjected to a moving aircraft tire. The test sections failed primarily as a result of shear in the base course. Excavation of the test sections at the end of the tests revealed that there was transverse shear flow of the base as a result of repetitive loading. Deflections at various depths were recorded with multidepth deflectometers. These deflections were used to calibrate the finite-element model. Subsequently, excellent agreement was obtained between measured and predicted time histories of deflections at the various depths. Also, excellent agreement was obtained between predicted and accumulated rutting. The analysis predicted that the shear stress in the base would equal the shear strength, which confirms the mode of failure observed in the test sections.

Nonlinear finite-element analyses have been carried out to assess the effects of different trench backfill materials, pipe burial depths, and pipe materials on the amount of traffic load transferred to buried pipe. The analyses show that the use of trench backfills such as controlled low strength material (CLSM) instead of traditional materials such as sand and clay, results in significantly reduced stresses in polyvinyl chloride (PVC) pipe under traffic loading. This finding is in agreement with recent truck load tests carried out in the City of Edmonton, where strains were monitored on buried PVC water mains. The protection of buried pipes under or in CLSM backfill from traffic loading becomes more significant with the decrease in pipe burial depth and stiffness. The reasons behind the difference in load transfer between the traditional backfills and CLSM are the high elastic modulus and strength of CLSM, as well as uniform load transfer along the longitudinal axis of the pipe.

A recent freeway congestion prediction study for the Washington Department of Transportation (WSDOT) found that the sum of storage rates over time, SumSR(t), for a freeway section was a better variable for determining the best upstream ramp metering rates than the storage rate for time interval t, SR(t), which is the current WSDOT criterion. (Use of the SumSR(t) variable for this purpose requires that the summation be started during a period of low density flows.) Another finding was that the SumSR(t) variable was a better detector of loop “chattering” errors than WSDOT's current criterion, which misses chattering errors that occur at normal traffic volume levels. Since calculation of SumSR(t) is easily incorporated in the current WSDOT ramp metering algorithm, the writer recommends its use in futute WSDOT freeway metering schemes.

Traffic congestion is a major operational problem on urban freeways. In the case of recurring congestion, travelers can plan their trips according to the expected occurrence and severity of recurring congestion. However, nonrecurring congestion cannot be managed without real-time prediction. Evaluating the efficiency of intelligent transportation systems (ITS) technologies in reducing incident effects requires developing models that can accurately predict incident duration along with the magnitude of nonrecurring congestion. This paper provides two statistical models for estimating incident delay and a model for predicting incident duration. The incident delay models showed that up to 85% of variation in incident delay can be explained by incident duration, number of lanes affected, number of vehicles involved, and traffic demand before the incident. The incident duration prediction model showed that 81% of variation in incident duration can be predicted by number of lanes affected, number of vehicles involved, truck involvement, time of day, police response time, and weather condition. These findings have implications for on-line applications within the context of advanced traveler information systems (ATIS).

This paper reports the improvements in traffic operations at the electronic toll collection plazas of the Orlando-Orange County Expressway Authority. Service time, vehicle arrival times, and departure times, as well as vehicle counts were collected “before” and “after” the installation of automatic vehicle identification technology known as E-PASS. The findings indicate that, for the dedicated E-PASS lane, the measured capacity has tripled, the service time has decreased by five seconds per vehicle, the average queuing delay has decreased by one minute per vehicle, the maximum queuing delay has decreased by 2.5–3 minutes per vehicle, and the total queuing delay has decreased by 8.5–9.5 vehicle-hours per morning peak hour for that lane. Also, variability in the headway has been reduced significantly in the dedicated E-PASS lane. Capacity, headway, and service times of the mixed (manual/E-PASS or automatic/E-PASS) lanes did not change significantly. However, arrivals have shifted to the dedicated E-PASS lanes, thus reducing delays at the mixed lanes and improving traffic operations for the entire toll plaza.

This paper presents an alternative modeling framework for serviceability analysis that is conceptually based on fuzzy set theory and uses discriminant analysis as the estimation tool. The proposed approach respects the ordinal characteristics of serviceability ratings because it does not assume that the ratings are a ratio scale, which is implicitly required when using regression analyses. The practicality of the proposed approach is tested in a case study, which indicates that the proposed approach provides a consistent classification of the pavement sections, though it underestimates pavement serviceability. Since the serviceability ratings are not needed for the estimation of the model (ratings are only required for validation), assembling a panel of users is not required to create the calibration data set. This feature may produce significant savings in the data collection process.

Most highway and airport rigid pavements constructed today consist of a subbase layer, giving rise to a system of a concrete slab supported on a two-layer foundation. This paper makes use of the solution of a slab on a two-layer system to derive a closed-form procedure for back-calculation analysis of pavement parameters. A computer program called NUS-DEF3 to solve for surface deflections is developed as a subroutine in the back-calculation analysis. The algorithm for the closed-form back-calculation of this system is presented. This algorithm reduces a system of three equations with three unknowns to one single nonlinear equation. It differs from the conventional approach of searching for the best solution iteratively by means of the least-squares method, and gives unique closed-form solutions without the need to select an initial modulus to start with. Solutions to numerical examples of three typical slab-on-two-layer-foundation problems are presented.

This paper deals with the performance of mixtures of asphalt, pyrolyzed carbon black (CB_p), and two aggregates (limestone and slag). Marshall mix design was performed to determine the optimum binder content at 6% of air voids. The range of the optimum binder content was 4.2%–5.5% for limestone mixtures and 6.3%–7.8% for slag mixtures, respectively. Dynamic confined creep tests, gyratory tests, resilient modulus tests, indirect tensile tests, and Hamburg wheel tracking tests were carried out using mixtures at the optimum binder content. The test results indicate that the use of CB_p in asphalt pavements increases Marshall stability, decreases permanent strain, decreases the mix strain rate at 50°C and 138 kPa confinement, increases resilient modulus and tensile strength, and increases the stripping inflection point. These results suggest that CB_p improves asphalt pavement performance.

A viscoelastic solution of the diametral compression of short cylinders has recently been presented by Zhang et al. The solution is based on Hondros's elastic solution and applies to any load history. In this paper, the viscoelastic solution is used for analyzing the haversine load history. Expressions are derived for the real and imaginary parts of the complex compliance, as functions of phase angles and amplitudes measured in tests, and algorithms are presented for their evaluation. The theoretical solution is illustrated with a series of tests on two asphalt concrete mixtures, subjected at room temperature to haversine loading over a wide range of frequencies. It is shown that power-law creep compliance satisfactorily describes the deviatoric viscoelastic behavior of the tested materials. The volumetric behavior, on the other hand, is nearly frequency-independent and can be approximated by a purely elastic law. The results of this paper demonstrate that incorporating viscoelasticity in the interpretation of the diametral compression test is viable and provides valuable information on asphalt concrete viscosity-related properties.

A new high-order continuum model is presented in this paper. This high-order model exhibits smooth solutions rather than discontinuities, is able to describe the amplification of small disturbances on heavy traffic, and allows fluctuations of speed around the equilibrium values. Furthermore, unlike some earlier high-order models, it does not result in negative speeds at the tail of congested regions and disturbance propagation speeds greater than the flow speed. The model takes into account the relaxation time as a function of density and, in the equilibrium limit, it is consistent with the simple continuum model. A Riemann-problem-based numerical method is proposed for the solution of the new high-order model. Modeling of interrupted flow behavior such as merging, diverging, and weaving is also investigated. Based on the new high order model, the proposed numerical method and the modeling of interrupted flow, a versatile code is developed for the numerical simulation of freeway traffic flow that includes several freeway geometries. We compare the high-order model with the simple continuum model and the proposed numerical method with the Lax method based on 30-s and 5-min field data. The model is tested in interrupted flow situations (e.g., pipeline, merging, diverging, and weaving areas). A comparison of numerical results with limited field data shows that the high-order model performs better than the simple continuum model and describes better than a previously proposed method.

The interaction between vehicle and pavement is complex since pavement roughness excites the dynamic forces generated by vehicles, while these dynamic forces simultaneously increase the pavement roughness. The objective of this paper is to provide an overview of the results of recent research related to pavement and vehicle dynamics and their interaction and to evaluate their potential use in the design and management of pavements. Pavement dynamic models are capable of determining stresses, strains, and deflections in various directions when harmonic, pulse, or transient loads are applied. Vehicle dynamic models simulate the effect of pavement roughness on the inertia of various vehicle components. These models can predict the dynamic forces produced by different axles and wheels of traveling vehicles at different locations along the pavement. Pavement response computed using dynamic models matches field measurements closer than those computed using static models. The concept of vehicle-pavement interaction can be applied to weigh-in-motion, pavement design and performance, and vehicle regulations.