Kathleen Hancock

Estimating Truck Equivalencies for Freeway Sections

In the Highway Capacity Manual (HCM), passenger car equivalents (PCEs) are used to convert a mixed-vehicle stream into an equivalent passenger car stream. The 2000 edition of the HCM reports PCEs for basic freeway segments as a function of the proportion of heavy vehicles, grade section steepness, and grade section length. These PCEs are reported for a typical truck with a weight-to-power ratio of 76 to 90 kg/kW (125 to 150 lb/hp). The HCM procedures are extended by using INTEGRATION software to develop PCEs for a broader range of vehicle weight-to-power ratios. In addition, the effects of pavement type and condition, truck aerodynamic treatment, number of freeway lanes, truck speed limit differential, and level of congestion are considered in the development of these PCEs. The calculation of PCEs for multiple-truck weight-to-power ratio populations is also examined and found to be not significantly different from PCE factors for single-truck weight-to-power ratios. The PCE values are tabulated in a format compatible with that used in the HCM 2000 capacity and level-of-service procedures.

Highway Freight Flow Assignment in Massachusetts Using Geographic Information Systems

Goods movement is an important aspect of the transportation system. Freight flow, complemented with the much-researched passenger movement, provides a way for understanding the complete vehicle flow scenario on the highways. Commodity movement prediction has not received much attention because of the lack of sufficient and easily accessible data sources. Most data sources give aggregated commodity movements and, because of the heterogeneity of freight, accurate predictions of truck flows have not been possible. A methodology for calculating the truck flows on the various highways in Massachusetts from interstate commodity flow data is presented. Freight tons originating and ending in Massachusetts have been converted to truck numbers by using a quantitative procedure and distributed to different areas in the state by using employment as an economic indicator variable. The truck flow is assigned to the important highways and validated against existing survey counts. On comparison, a large percentage of the roads show the estimated truck counts are within a tolerable error margin. The research also shows that statewide analyses need to be refined near urban areas because of a variety of complexities involved.

Simulation of regional freight movement with Trade and Transportation Multinetworks

A simulation model called Trade and Transportation Multinetworks (TTMNet), constructed for the purpose of studying the effects of highly developed information technologies and logistic strategies (e.g., electronic commerce and real-time information) on freight transportation, is described. TTMNet is formulated as a multilevel product supply chain system that integrates the financial, informational, logistical, and physical aspects of transportation networks and allows interactions between each of these networks. Several simulators, including a freight traffic simulator, a supply chain decision-making simulator, and a pseudo-real-time information simulator, are involved. The freight traffic simulation is the focus of the present study. As part of this simulator, a learning model is set up to help decision makers estimate transportation costs on the basis of past experiences. Given the stochastic nature of these transportation costs and of the freight demands simulated by the system, the route for an origin–destination shipment may not remain optimal during a trip and may change along the way. A vehicle redirection procedure that handles this is presented. A numerical example is designed to compare a set of freight movements under two scenarios, one supported by and the other not supported by pseudo-real-time information on traffic conditions.

On path anomaly detection in a large transportation network

The purpose of anomaly (outlier) detection is to find a small group of objects that are numerically distant from the rest of the data set. It is generally applied to identifying anomalies from normal patterns and events in urban traffic flow, trends in air quality change, human activities in urban environments, route quality assurance and control, etc. Traditional research in this field has focused on cases where objects can be represented as points or sequences, and popular methods include clustering, distribution, and distance-based methods. In this paper, we present a new type of outlier detection, path outlier detection, in a large spatial graph typically representing a transportation network. Two types of abnormal paths are presented and their corresponding applications are discussed. To perform path anomaly detection, we propose two fundamental distance metrics, spatial-region-based and perimeter-based, along with path segmentation based metrics to capture local feature differences and to jointly combine similarity and dissimilarity. Search algorithms for three distance metrics and outlier detection algorithms are provided to detect abnormal paths and potentially assist with identifying abnormal events or phenomena which occur during a trip. Experiments were performed on synthetic data sets that correspond to two real-world scenarios, and the results show that the efficient perimeter-based distance metric is very effective when used with path segmentation to capture local features and global features, and to combine similarity and dissimilarity.

VIDEOLOG ASSESSMENT OF VEHICLE COLLISION FREQUENCY WITH CONCRETE MEDIAN BARRIERS ON AN URBAN HIGHWAY IN CONNECTICUT

In-service performance evaluation is the process of assessing the performance of roadside safety hardware under real-world service conditions. The purpose of in-service evaluation is to determine and document the manner in which a safety feature performs during a broad range of collision, environmental, operational, and maintenance situations for typical real-world site and traffic conditions. An in-service performance evaluation of the concrete median barrier (CMB) in Connecticut was undertaken to determine how often CMBs are struck and how often such collisions are reported to the police. The method used to perform the inservice performance evaluation of the CMB is described, and the results are presented. Data were collected for a section of CMB located on I-84 in Hartford, Connecticut. Accurate information about impacts with CMBs is difficult to obtain because so many collisions are unreported. Even for severe collisions, damage to the barrier is rare, and little maintenance is required. In many cases, police reports are the only means of monitoring when, where, and how severe the CMB collision was. Videologging was used to accomplish the in-service performance evaluations of CMBs to document the extent of unreported collisions.

Conversion of Weight of Freight to Number of Rail Cars

Multimodal freight vehicle assignment models require numbers of vehicles to generate origin-destination matrices. Most current freight flow data are provided as total volume or value. Presented are the development and results of conversion models for converting weight to number of rail cars as one component of a multimodal planning activity. The 1992 rail waybill sample was used for developing the conversions. Only loaded cars were used for conversions. Therefore, empty cars are not included in the models. Evaluation of these conversions was performed by using 1993 Commodity Flow Survey data. On the basis of the evaluation, recommendations on conversion models are made.

Incorporating Costs of Life-Cycle Impacts into Transportation Program Development

Ensuring sustainability is necessary for balancing economic viability, the environment, and the social system. Because transportation infrastructure projects have direct and indirect impacts on this balance, transportation agencies must consider the sustainability and environmental impacts of transportation investment during the planning and programming phase. An integrated life-cycle analysis approach (ILCA2) that integrates life-cycle assessment and life-cycle cost analysis is developed through the establishment of a reasonable life-cycle time frame, representative elements, largely homogeneous transportation facilities with representative cross sections, and accepted construction, maintenance, and rehabilitation practices. The methodology quantifies life-cycle environmental impacts for the carbon footprint of materials in carbon dioxide equivalent, quantity of wasted materials, and quantity of stormwater runoff along with associated costs. The use of the ILCA2 is demonstrated for a case study of urban roadway projects in a sample transportation state transportation improvement plan. A case study shows that initial costs represent approximately 20% of life-cycle costs; environmental impact costs are higher than direct operational costs, energy costs, and resurfacing costs. The use of the ILCA2 for transportation programming allows decision makers to evaluate the larger impacts of transportation investments as well as provides opportunities for considering programmatic changes to practices that support sustainability.

Enterprisewide Information Management System for Transportation Right-of-Way Activities

Given the current state of technology–with service-oriented architecture, decentralized information, and desktop access to cloud computing and data management–enterprise systems for managing the information associated with business operations are necessary for improving efficiency and quality while optimizing resources. In transportation agencies, this situation is particularly true in the data-intense real estate offices that purchase and manage right-of-way property before construction. A structure is presented for a logical model of an enterprisewide information management system for transportation right-of-way activities. The business processes are based on the federal requirements as mandated by law and outlined in the Project Development Guide of FHWAs Office of Real Estate Services for appraisal, acquisition, relocation, and property management. The logical model is developed with the use of unified modeling language, which is considered to be a standard computer system modeling language rich in well-defined graphical notations for representing complex systems and provides the structure for developing an operational information management software program.