The pipe-soil interaction is studied by using the finite-element software ABAQUS/CAE Version 6.5-1 as a symmetric model of embankment installation to study the effect of bedding property and thickness on pipe-soil interaction with increase in the height of fill. A three-dimensional (3D) finite-element method (FEM) model of the concrete pipe and surrounding soil is developed. The FEM model is capable of simulating material, geometric, and contact nonlinearities which employs a nonlinear incremental solution algorithm. Several different element types and mesh sizes were tested to obtain the optimum converged mesh. These elements include eight-noded linear brick (C3D8R) and six-noded linear triangular prism (C3D6) for modeling of the concrete pipe and surrounding soil. The behavior of the 3D model is investigated by varying the pipe diameter, backfill height, bedding thickness, and bedding material. Three material constitutive relationships of soil involving in the model are gravelly sand and sandy silt. To study the effect of bedding thickness on the pipe wall, due to the increment of backfill soil depth, contact elements were employed in the interface between each two regions. The lateral boundaries and model length were also studied for the converged solution. A parametric study was conducted to study the effects of bedding thicknesses. The results showed that the increase in bedding thickness reduces tensile stress at crown, spring line, and especially invert of the pipe wall depending on the material property. This means the change in material property and compaction level has a greater effect on the reduction of tensile stresses than the effect from the variation of bedding thicknesses. Also, materials with lower bedding stiffness (high deformability characteristics) cause greater reduction in induced stresses. This study shows that for commonly used bedding material (coarse grained gravelly sand), the effect of the increase in bedding thickness has a minimal effect on stress reduction of the pipes studied.

Destination choice studies have been primarily carried out in developed countries. However in China, a typical developing country, few studies about destination choice exist. In this paper, we propose nonlinear-in-parameters multinomial logit models to investigate the influences of spatial factors on both work and intermediate stop destination choices. We use individual sociodemographics, travel-activity attributes, and land-use characteristics as exogeneous variables. Individual’s destination choice behaviors with different sociodemographics and travel modes are examined as well. The models are applied to data collected in the city of Shangyu, China. Compared with previous studies, this research further distinguishes the size variables influencing destination choices for work and intermediate stop in the type and the extent to which each type of size variables exerts influence. Besides, the preferences to destination choices are more clearly illustrated, resulting from the typical occupation characteristics and commuting modes of China.

There is a lack of proper travel demand forecasting tools that can evaluate and determine the impacts of pricing on travelers’ decision. The current methods use aggregated and zonal-based approaches that lack the capability of tracing individual travelers through the supply network. Transportation analysis simulation system (TRANSIMS) has unique capabilities of accessing individual records such as socioeconomic and trip characteristics and tracing vehicle as well as individual traveler movements. Although TRANSIMS environment has been significantly improved over the past few years, there are issues that still need to be improved, including the pricing of a high-occupancy toll (HOT) lane and the rescheduling of activities in case a traveler chooses time choice versus route choice. This study extends the previous work on a HOT lane system by developing a departure time choice model. The proposed method is a post-processing of route choice and represents a sequential decision-making process of travelers who want to depart early or late based on congestion, individual attributes, and activity characteristics. The paper presents the results of a departure time choice model and its impacts on a HOT lane system using Portland, Oregon as a case study. The results show that 13.9% of households did change their departure time because of congestion and/or tolls.

An important element of achieving quality in a road network is the control of vehicle vibration due to pavement roughness and road irregularities. Scientific literature and international standards suggest that we evaluate these phenomena by measuring the whole body vibration (WBV) on the road user, but, for the practical aims of road engineering, this expression has to be related to road unevenness indexes, especially the most common one (the international roughness index, IRI). This index, in turn, is obtained from measured pavement geometric data using a conventional model of a mechanical system representing part of a vehicle. To better investigate the problem of user comfort, more complex models and analyses are needed. In this paper, a model of a real and common vehicle is presented and used, after a calibration process, to perform many dynamic simulations. The obtained results, in terms of weighted vertical acceleration ( $a_{WZ}$ , that is, the WBV index, according to ISO standard), show good correlations ( $R^2$ from 0.75 to 0.93, depending on vehicle speed) with the IRI values of the examined road sections. On the basis of this correlation, authors propose threshold values for both vibration and roughness indexes; these thresholds could be used for road users’ comfort evaluation and adopted in technical standards.

Agencies are seeking a better understanding of those roadway or roadside features that affect safety. The objectives of this study were to develop a horizontal curve accident modification factor (AMF) for rural four-lane divided and undivided highways and to determine if the effect of driveway density is different for horizontal curves as compared to tangent sections. Data available for use in the evaluation included 194.8 centerline km (121 centerline mi) of rural four-lane highways. Negative binomial regression models were used to determine the effects of independent variables on crashes. Variables considered in developing the base models included driveway density, lane width, outside shoulder width, median width (which included inside shoulder width), median type, degree of curve, segment length, and average daily traffic. Five years (1997–2001) of driveway and segment crashes were examined. An AMF for horizontal curves was identified. Reviewing the findings with respect to driveway density revealed that the effect of driveway density is different for horizontal curves and tangents; however, the differences were relatively minor.

Advanced traveler information systems (ATISs) are continuously becoming key intelligent transportation system for disseminating valuable traveler information such as traffic, incident, and transit information. Developed countries such as the United States, Canada, Japan, U.K., Australia, and Germany have adopted ATIS expeditiously in comparison to developing countries that face considerable financial and framework constraints. Moreover, local traffic, roadway, signalization, demographic, topological, and social conditions in developing countries are quite different from those in developed countries. In this paper, a comprehensive framework comprising of system architecture, development methodology, and salient features of a developed ATIS for metropolitan cities in developing countries has been discussed. Development of proposed system is based on integration of two well-known information technologies, viz., geographic information systems and World Wide Web. Combination of these technologies can be used to develop an integrated ATIS that targets different types of travelers such as private vehicle owners, transit users, and casual outside visitors.

With the increase in train speed, the aerodynamics in tunnels is emerging. In recent years, we have carried out a few full-scale tests about tunnel aerodynamics, and the law of influence of train speed on pressure change, airflow velocity, and micropressure wave are obtained, and a passenger comfort survey was conducted. When a high-speed train enters a tunnel at 200 km/h, the pressure change amplitude and pressure change per second inside the vehicle are 1,036 Pa and 273 Pa/s, respectively, and 88.9% people experienced no obvious discomfort; the airflow velocity in the tunnel is 14.8 m/s, which exceeds the criterion, 14 m/s. Therefore, it is suggested that workers should not work in the tunnel when a train passes; because the micropressure wave is only 9.7 Pa at the measured point, 20 m from the exit port of tunnel, the tunnel has a cross section enlarged hood with windows, and the passing train does not impact the environment near the tunnel.