The aircraft gate reassignment problem occurs when the departure of an incoming aircraft is delayed or a delay occurs in flight. If the delay is significant enough to delay the arrival of subsequent incoming aircraft at the assigned gate, the airline must revise the gate assignments to minimize extra delay times. This paper describes a genetic algorithm approach to solving the gate reassignment problem. By using a global search technique on quantified information, this genetic algorithm approach can efficiently find minimum extra delayed time solutions that are as effective or more effective than solutions generated by experienced gate managers.

This study used the TRANSYT-7F simulator to examine changes in performance measures of through buses and adjacent traffic following the introduction of reserved lanes in an urban arterial. In addition, the TRANSYT-7F simulator was used to examine the specific impacts on modal performance of two policy measures implemented in conjunction with lane introduction. The results showed that TRANSYT-7F provided relatively accurate estimates of bus delays and auto speeds. However, the study identified one area of improvement for TRANSYT-7F to model priority treatments on arterials more effectively. The simulation results showed that the performance of the average bus improved after project implementation, whereas the performance of the adjacent through traffic deteriorated. However, the deterioration exceeded the improvement. Other aggregate estimates of performance were examined and discussed. The simulations also showed that modifications to left-turn movements would have a minor impact on both bus and adjacent traffic performance, whereas the removal of taxis from the reserved lanes would cause far more performance deterioration to the adjacent traffic than the performance improvement this policy measure would bring to buses.

This paper presents multivariate correlation analyses of truck drivers' opinions on speed, hazards, roadway features, and traffic control devices in work zones (WZ). About 90% of truck drivers considered the WZ to be more hazardous than regular sections. A higher proportion of less-experienced drivers said so. Less experienced drivers and drivers who considered WZs more hazardous preferred one-lane closure layout. Speeds were correlated with driver age or experience. Half of drivers admitted exceeding WZ speed limits. About three-fourths said arrow boards were too bright and either too high or too low. More-experienced drivers were concerned about visibility, but less experienced ones were concerned with the clarity of the flagger's message. Pavement edge drop-off, loose construction materials, lack of shoulder, and lane width made over 85% of drivers and a higher proportion of less experienced drivers more uncomfortable. About 70–85% of the drivers considered the traffic control devices helpful. Impact attenuators were ranked highest, followed by cones and a third group containing barrels, tubes, and barricades. Of concrete barriers, 70% said they were helpful, but 28% said they do not like their use.

This paper attempts to consider some key elements of the transport assessment process in order to present and compare the most commonly applied multicriteria methods to be used in the assessment of transport projects. This comparative analysis is based on the performance of the methods with respect to transparency, simplicity, robustness, and accountability. To assist the comparison, an application example consisting of three transport projects in Greece is used. Finally, the methods' advantages and disadvantages are systematically presented so as to allow for the decision maker to draw definite conclusions on the appropriateness of each method for the different fields of transport appraisal.

The Indiana Department of Transportation and Purdue University have been investigating and implementing a novel traffic control system at two-lane freeway work zone entries to reduce the number of aggressive lane changes close to the lane taper. The system creates a variable no passing zone through a series of dynamic “DO NOT PASS” signs activated in response to congestion detected on the continuous lane. The Purdue team investigated the operational effect of the system to develop preliminary guidelines for system deployment. The research results indicate that the system improves drivers' behavior toward more safety and reduces travel time in the continuous lane. The simulation model developed at Purdue was used to generate data and formulate rules for system deployment.

A problem often arising in engineering applications of computer models is to determine the importance of each data item in the large pool of required input factors. This paper explores a statistical approach for investigating factor sensitivities. The methodology is demonstrated with the HDM-III highway life-cycle cost analysis model. Specifically, the net present value (NPV) of life-cycle costs predicted by the HDM-III model is analyzed, and sensitivities of NPV to the link characterization input factors are investigated. In the statistically designed experiment, combinations of the input factors are chosen using a method called Latin hypercube sampling, which is well suited to the deterministic HDM-III model. Two analyses of the output data are performed, based on a first-order regression approximation and a Gaussian stochastic-process model. For NPV, the factor rankings are similar, but the sensitivities obtained from the two techniques show some marked differences. This demonstrates the greater flexibility of the stochastic-process model in dealing with nonlinearities and factor interactions in complex input-output relationships.

Hoosier Helper is an Indiana Department of Transportation sponsored roving freeway service patrol, providing free assistance to motorists stranded on portions of Interstate 80-94 and Interstate 65 in Northwest Indiana, which started on August 30, 1991. This paper presents a detailed evaluation of the Hoosier Helper freeway service patrol. Specifically, the study results will include a benefit-cost ratio for each of two distinct Hoosier Helper operating scenarios: Daytime patrol and 24-h patrol. The calculation of agency cost concerns an aggregation of equivalent annual investment cost, employee salaries and benefits, overhead cost, and maintenance cost for Hoosier Helper. The following components comprise the estimation of Hoosier Helper benefit: Nonrecurrent congestion delay savings, secondary crash reduction, and vehicle operating cost savings. The study yielded a 4.71:1 benefit-cost ratio for the daytime program operation and a 13.28:1 benefit-cost ratio for the 24-h program operation. The increase in benefit-cost ratio magnitude, brought about by Hoosier Helper's change to 24-h operation, clearly supports the program's operating strategy as it exists today.

Subgrade resilient modulus is highly dependent on water content, which can vary significantly with a number of environmental factors. Four sites across the state of Tennessee were instrumented with comprehensive monitoring systems that collect meteorologic, subgrade water content, infiltration, and temperature data. These data will be used to develop a rational method to account for environmental effects (e.g., seasonal changes in subgrade water content, in flexible pavement design). Multiple-segment TDR probes were placed horizontally in the soil subgrade, in the stone subgrade, and in the asphalt stabilized base, and single-segment probes were placed in the asphaltic concrete of the roadway sections. Tension-free pan lysimeters were installed at three of the test sites to measure infiltration through the pavement layers. Temperature sensors were installed in the soil subgrade and in the stone base at the same elevations as the TDR probes, and at three elevations in the top 200 mm of the pavement. Each site was instrumented with a weather station that monitors relative humidity, air temperature, rainfall, wind speed, and solar radiation. The preliminary data indicate changes in water content in the stone base layer that correlate with rainfall, and a small seasonal change in subgrade water content. Data from a test site where the pavement surface layer is not in place indicate that the asphaltic layers below the surface layer are permeable during significant rainfall events and that water appears to move freely through the asphalt stabilized base layer.

This paper derives an analytical solution for a three-slab system resting on a Pasternak foundation. Joint transfer between slabs is considered in the analysis. The basic equations are based on Reissner's thick-plate theory, and modified to include the Pasternak foundation model. The transverse shear deformation in the slabs and the transverse connection in the foundation are considered in the three-thick-plate model. The solution of the three-thick-plate system are arrived at by considering the solutions of three elemental plates, one with four “guided support” edges and two with two “guided support” edges and two free edges. For each slab of the three-slab system, its solution is obtained by superposing the solutions of appropriate elemental plates. The central slab can be represented by superposing three elemental thick plates, while the two-edge slabs by four-elemental-thick plates each. The derived solutions were verified using numerical examples against solutions by finite-element methods.

A method to determine the optimal groups of road segments to be simultaneously treated during road widening programs is described. This methodology specifically addresses a prioritizing system and the closure strategy considering the disutility due to rehabilitation. The dynamic programming methodology is utilized for the optimization procedure where the problem has been formulated as a utility maximization problem. The mathematical modeling of the problem and its solution technique are described. An example is included. The results indicate that the proposed method is useful for multistage optimization problems such as road network planning. The proposed method differs from the conventional design method for the determination of reconstruction sequence because the closure strategy is simultaneously determined by the multistage optimization.

The current practice in India for thickness design of roads with bituminous surfacing is based on limited experience of road performance in the late 1970s. Extrapolation of the design method to the present day heavy traffic is not valid because of the empiricism in the original method. This paper describes the details of an investigation undertaken by the writers to develop a mechanistic design method by correlating the performance data of bituminous pavements from different parts of India to the critical stress-strain parameters of the pavement composition leading to the failure of pavements. Also indicated are the evaluation of fatigue and elastic properties of pavement materials, analysis of field performance data, determination of fatigue and rutting criteria from laboratory and field data, and development of thickness design charts for bituminous pavements.