Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 120-121). Also available via the Internet.

In recent years, the field of transportation engineering has witnessed the emergence of technological innovations linking several different application areas like human factors, computer science, communications and operations research. This research deals with automatic freeway traffic operations including ramp guidance and merging which is an important aspect of Intelligent Vehicle Highway Systems (VHS) Technology. An existing traffic flow model is utilized to generate a non-overtaking, continuous traffic stream with automatic acceleration/ deceleration characteristics of the smart cars to fulfill the needs of a high-speed flow under controlled headway and optimized density conditions. The orientation, shape, and geometry of such ramps on a high-speed highway system is investigated. It is proposed that the angle between the ramp and highway would be very acute and lane changes from acceleration lane to the cruising lane would follow a smooth trajectory. The curve would be composed of two circular curves of large radii of curvature or two spiral curves in succession. The adequacy of the existing geometric design specifications are questionable, not only for the merging section, but the entire stretch of the "smart highway”. The introduction of intelligent highway network extensively in rural areas could necessitate a complete rethinking about highway geometric design standards. An alternate method of geometric design requirements is undertaken to explore the applications of vehicle aerodynamics’ principles to the highway design, which is perceived to be essential under the high-speed conditions. The results obtained can be compared to those of the conventional geometric design formulae to yield a comparison. Though the principal aim of this research is to serve the highways, it has applicability to other forms of highspeed, controlled guideway transportation systems also. / Master of Science

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 105-107). Also available via the Internet.

Ramps are usually perceived as utilitarian objects emerging from standardized guidelines for architecture and landscape architecture. But closer examination reveals they can be quite beautiful and poetic. What we commonly call ramps, Galileo referred to as inclined planes, counting them as one of six classical simple machines in Le Meccaniche (On Mechanics) . Because inclined planes are actually static machines that do not require any energy to run. They do not discriminate among users. This thesis explores the work of the ramp in moving fragile loads, such as human beings. / Master of Landscape Architecture

Though the trucks consist of only 3% of the total registered vehicles in the United States, truck accidents have been a major concern due to the property damage and loss of lives involved. Growth trends show that the truck travel will reach 1 trillion vehicle miles by the end of the year 2000. This increase in truck travel poses a major threat to the safety of both passenger cars and trucks. To improve the safety of the trucks as well as the passenger cars, understanding of the factors affecting the truck safety is essential. Models developed in the past were mostly regression models which tried to relate the truck accidents to the geometry of the highways. But most of these models did not consider all the factors affecting the safety of the trucks. Simulation models were developed in the past to study the dynamic vehicle response to different highway geometry especially, on exit ramps where most of the rollover accidents occur every year. But not enough research was done in the past on the weather and surface conditions affecting the truck safety. The objective of this study is to develop a graphics-based computer simulation model to test the trucks for different geometric features, surface conditions, and truck characteristics on exit ramps and to gain a better understanding of the factors affecting the safety of the trucks. A high-level simulation language SIMSCRIPTII.5 was used in the study to develop a simulation model. To make the model is to understand, graphical windows and animation were included in the model. Three exit ramps were tested in this model. Two of these ramps are existing ramps in southwestern Virginia and they had rollover accidents reported on them in the past. The parameters and other surface and geometric conditions can be changed at any time during the simulation. The model indicated that deceleration lengths provided may not be sufficient for heavy trucks traveling at higher speeds to reduce their speeds to the safe speed limits on the ramps. The posted speed limits may not be suitable for heavy trucks especially when the surface is not dry. The model also indicated that the tractor-semitrailers are more exposed to rollovers than any other type of trucks. / Master of Science