Using published field data on accidents in crowds involving either the trampling or crushing of pedestrians, a theory has been developed to model similar dangerous situations. Whether a particular situation is fatal is statistical, but general rules may be established. In cases involving trampling, which occurs when pedestrians are moving, it was found that the density of pedestrians is an important isotropic quantity that appears to determine the probability of a fatal accident. Previous studies have also identified the density of a crowd as determining the probability of crushing within a stationary crowd, although different densities are involved in the initiation of these two types of accidents. In a moving crowd, trampling will occur before crushing, but trampling does not occur in a static crowd. The cross-sectional size of pedestrians within the crowd is important in determining whether a particular density is dangerous in both types of accidents. Consequently, comparisons of accidents involving different groups of pedestrians, possibly in different countries, need to be standardized for the characteristics of the group.

Visual information is one of the vital elements that affect driver workload. Previous studies have modeled driver visual demand on simple horizontal curves and have found that it is significantly affected by the curve radius. This paper models driver visual demand on complex horizontal alignments that may include simple, compound, and reverse curves. Two sets of visual demand models were developed (curve models and tangent models) using visual demand data collected on 18 highway alignments on a driving simulator. The results show that visual demand is affected by the characteristics of not only the current element but also the preceding element. The characteristics of the preceding element included curve radius, curve direction (right or left), deflection angle, and lane width. As such, the developed models represent important tools for accurately evaluating driver workload on complex horizontal alignments.

Modern road profilers deliver long sequences of measurements on road characteristics including a road’s longitudinal and transversal unevenness. These measurements represent adjacent parts of the physical road, and interest focuses more on the overall pattern of these measurements than on each single value. In order to systematically assess the information contained in these measurement series, one typically wishes to partition a given series into segments, where each segment contains measurements which are “similar” to each other but “dissimilar” to the elements in the neighboring segments. An algorithm is suggested that combines a recently developed Bayesian identification of transitions between two homogeneous road sections with a heuristic approach that uses this technique iteratively to find multiple homogeneous sections in arbitrary long measurement series. The approach is demonstrated with narrowly spaced measurement series of the international roughness index as well as rutting.

In an attempt to better understand and predict rigid pavement behavior, the incorporation of material and climatic factors in mechanistic-empirical design methods are fast becoming standard in the United States. With the wide variety of climatic regions found in California, the inclusion of localized factors can have a profound effect on the critical distresses and life of the pavement. Permanent built-in curling from construction temperature gradients and differential shrinkage can have a considerable effect on the location and magnitude of concrete fatigue damage. A mechanistic analysis was developed employing an influence line approach in conjunction with Miner’s Hypothesis to calculate the fatigue damage at numerous locations in the concrete pavement slab for typical California rigid pavement sections. Concrete fatigue transfer functions which account for stress range or maximum stress, were used to predict the location and magnitude of critical damage. Results show that the critical cumulative damage levels and locations are highly influenced by factors such as effective built-in temperature difference, steer-drive axle spacing, load transfer level, lateral wheel wander distribution, and climatic region. For slabs with built-in curling and a combination of the aforementioned variables, top-down and bottom-up transverse, longitudinal, and corner cracking can occur. These predicted fatigue failure modes correspond well to the wide variety of observed fatigue cracking on existing California rigid pavements.

The study presented in this paper analyzed the development patterns of fatigue cracking shown in flexible pavement test sections of the long-term pavement performance (LTPP) program. A large number of LTPP test sections exhibited a sudden burst of fatigue cracking after a few years of service. In order to characterize this type of LTPP cracking data, a survival analysis was conducted to investigate the relationship between fatigue failure time and various influencing factors. After dropping insignificant influencing factors, accelerated failure time models were developed to show the quantitative relationship between fatigue failure time and asphalt concrete layer thickness, Portland cement concrete base layer thickness, average traffic level, intensity of precipitation, and freeze-thaw cycles. The error distribution of the accelerated failure time model was found to be best represented by the generalized gamma distribution. The model can also be used to predict the average behavior of fatigue failures of flexible pavements.

This research was conducted to study subsurface drainage issues surrounding an asphalt overlay. The type of pavement that was examined in this study was a Superpave overlay on top of a Broken and Seated Jointed Reinforced Concrete Pavement (B&S JRCP). A finite-element model of the pavement was developed and a number of numerical analyses were performed to evaluate the movement of water in the pavement. The pavement drainage modeling was conducted using the SEEP/W 2002 in GEO-SLOPE program. A steady-state saturated flow analysis was used to obtain the flow path of the infiltrated water and flux quantity through the cross-sectional area in the pavement. This analysis was done for the pavement models with different layer arrangements and different drainage practices. The findings of this research revealed that high water permeability in the asphalt base and Superpave surface layers contributed to water flow into the pavement. This infiltration of water into the pavement structure is a serious issue that must be addressed in pavement drainage design. The broken and seated layer functions as an efficient drainage layer.

The Highway Development and Management model (HDM-4) is a support system for decision making for highway administrators and engineers to predict the economic, social, and environmental impacts that might occur while making investment decisions. The road deterioration models contained in HDM-4 attempt to model the complex interaction between vehicles, the environment, and the pavement structure and surface. The road deterioration models predict the deterioration of the pavement over time and under traffic, which is manifested in various kinds of distress. But as each mode of distress develops and progresses at different rates in different environments, it is important that the HDM-4 relationships be calibrated to reflect local conditions and to ensure their relevance to technico-economic analysis of maintenance and rehabilitation alternatives for a road network constructed in a particular geographical region. This study has attempted to calibrate the HDM-4 pavement deterioration models for a National Highway Network located in the Uttar Pradesh and Uttaranchal states of India. The data have been collected for cracking, raveling, potholing, and roughness, analyzed, and used for calibration of the HDM-4 pavement deterioration model. To test the efficacy of the calibrated model, models have been validated that can be adopted for prediction of distress and development of maintenance management strategies for the Indian National Highway Network. It is expected that the HDM-4 deterioration models calibrated for the Indian National Highway Network can be used for other developing countries with similar traffic characteristics, soil types, climatic conditions, terrain type, and pavement composition.

The design of ultra-deepwater offshore pipeline is often based on the wall thickness and material grade selection to resist the local buckling due to bending, axial tension, and external pressure. Typically, this load combination occurs at the sagbend region during pipeline installation. With the economics of ultra-deepwater pipeline systems being highly dependent on the installation considerations, it remains difficult to see how this design methodology with no reference to installation loads, can lead to an economical solution. By means of extensive numerical studies, over a range of pipe diameters and water depths, it is shown that installation parameters are sensitive to wall thickness and the level at which the maximum allowable bending strain is set. By appropriately combining pipe strength and stiffness characteristics with the pipelay installation parameters, a bending strain limit is defined that is shown to lead to the most economical solution.

The number and type of bus stops provided on a road significantly influence the flow characteristics of traffic on the road. The study of the influence of bus stops on traffic flow under homogeneous traffic conditions has been attempted by several researchers. However, studies on the influence of bus stops on traffic flow under heterogeneous traffic conditions, are found to be absent. This paper is concerned with the study of heterogeneous traffic flow characteristics using a simulation technique with specific reference to the influence of bus stops on the traffic flow. First, an overview of the microscopic traffic-flow simulation model used to study the flow characteristics of nonlane-based heterogeneous traffic on urban road links is given. Then, the validation of the model based on field observed data is described. Finally, the application of the model to study the impact of curbside bus stops and bus bays on the speeds of other vehicles in heterogeneous traffic streams is dealt with. The effects of variation of the basic parameters, such as bus dwell time, road width, and traffic flow level, are examined for both curbside and bus bay type of stops. The usefulness of the model in fixing the traffic flow levels for replacing curbside stops with bus bays, as example, has also been highlighted.