Traditional Transportation Systems Research Articles

Effects of traffic information provision strategies to mitigate traffic ongestion for within day and day-to-day dynamic environments

Modeling interactions between congestion and travel decisions (mode, route, and departure time) has been one of the hottest research agenda since early initiation of the travel modeling practices. Recently, with the intelligent transport systems (ITS) components available on top of existing traditional transportation systems, information has become to play a more important role by affecting drivers choosing travel options and thereby modifying their travel behavior. Such being the case, the inclusion of effects caused by traffic information into the modeling framework has been expected both to reflect the actual ITS condition and to more effectively use the model to control and manage the congested traffic network. Therefore, the objective of this paper is to assess the effects of the pre-trip and en-route traffic information provision based on the dynamic models. For this, both day-to-day dynamic and within day traffic assignment models have been formulated and their solution algorithms have been proposed, respectively. To test the models applicability, some information providing strategies such as user optimal based, system optimal based, and mixed in-between strategy have been proposed to identify which scheme is best in attaining certain goal such as minimum traffic congestion. The implementation has been made using a sample road network and some discussions have also been made along with some future research agenda.

Freeway Facility Methodology in Highway Capacity Manual 2000

The next edition of the Highway Capacity Manual (HCM 2000) will contain for the first time an operational analysis procedure for directional freeway facilities up to 20 to 25 km long. At the simplest level, this procedure integrates the proposed HCM 2000 methods for the analysis of basic, ramp, and weaving segments to enable the analysis of an entire facility. But the proposed facility methodology goes much further. It allows the user to analyze multiple, contiguous time intervals with timevarying demands and capacities. It can handle both undersaturated and oversaturated traffic conditions (with some limitations). In the latter case, both the spatial and time extent of congestion are estimated. Finally, the method permits the investigation of the effect of many traditional and intelligent transportation system–based freeway improvement strategies such as full or auxiliary lane additions, ramp metering, incident management, and a limited set of high-occupancy-vehicle designs on facility performance. Described here is the conceptual model for and computational steps of the methodology, with emphasis on the components for analysis of oversaturated conditions. The scope and limitations of the methods are also highlighted. Reference is given to a companion paper that describes how the results of the method were validated in the field and how they compared with those obtained from widely used freeway simulation models.

Cable‐Based Lunar Transportation System

The establishment of an efficient transportation system is key to any human development on Earth or in space. Different technologies for transporting humans and goods have been developed, the diversity of which indicates that individual concepts have specific strengths and weaknesses. So far, transportation on the Moon has utilized a wheel-based vehicle, the lunar rover. Present concepts for transporting goods and people in a lunar base of the future are generally based on using wheels and traction. While such systems have many advantages for a variety of applications, the hauling of heavy goods will require the preparation of stable and trafficable roadways, a challenging and potentially expensive undertaking. This paper presents an alternative based on using one of the fundamental means to move objects, namely ropes and cables. Because of their inherent characteristics, ropes have been used to lift and haul heavy loads for long distances with high levels of reliability. This mature and constantly perfected technology, not well known in this car-oriented society, has been investigated for its use as a true alternative to the traditional wheel-based transportation systems. As will be shown, innovative applications of cable-based technologies may in effect provide many opportunities to leverage the differences between the Earth and the Moon for the purpose of creating efficient engineering products.

Response of the cyanobacterium, Oscillatoria tenuis, to low iron environments: the effect on growth rate and evidence for siderophore production

Cyanobacteria vary in their ability to grow in media contaning low amounts of biologically available iron. Some strains, such as Oscillatoria tenuis, are well adapted to thrive in low-iron environments. We investigated the mechanism of iron scavenging in O. tenuis and found that this cyanobacterium has a siderophore-mediated iron transport system that differs significantly from the traditional hydroxamate-siderophore transport system reported from other cyanobacteria. Unlike other cyanobacteria, this strain produces two types of siderophores, a hydroxamate-type siderophore and a catechol-type siderophore. Production of these two siderophores is expressed at two different iron levels in the medium, suggesting two different iron regulated uptake systems. We compared the production of each siderophore with the growth rate of the culture and found that the production of the catechol siderophore enhances the growth rate of the cyanobacterium, whereas the cells maintain lower than maximal growth rates when only the hydroxamate-type siderophore is being produced.

Transportation systems for meeting Just-In-Time materials delivery requirements

Abstract An increasing number of manufacturing firms in the US are developing and implementing just-in-time (JIT) purchasing. A unique aspect of JIT purchasing is an organizational commitment to eliminating raw material and work-in-process (WIP) inventories, and replacing them with frequent deliveries of a given part or parts. With WIP inventories greatly reduced, there has been significant concern about the effectiveness of the traditional transportation systems to meet JIT's delivery requirements. Unless new transportation systems have been developed by the buyer to meet JIT purchasing practices, the implementation of JIT will be unsuccessful or inefficient at best. In this article we present several essential factors which need to be considered by the buyer companies to meet these delivery requirements. These steps were developed from an empirical study done at Nissan Motor Manufacturing Corporation USA (Smyrna Plant), Hewlett-Packard (Greeley Division), General Motors Corporation (Buick Division), and...