Consumer preferences relative to the price and network capability of small urban vehicles

Preferences of consumers for small urban vehicle concepts differing only with respect to their hypothetical purchase prices and network capabilities (i.e., whether they are capable of operating on expressways, major arterials or local streets) are analyzed using statistical techniques based on psychological scaling theories. Results from these analyses indicate that a vast majority of consumers are not readily willing to give up the accessibility provided by conventional automobiles. More specifically, over the range of hypothetical prices considered here, network capability dominates as a determinant of preferences for vehicle concepts. Also, the ability to operate vehicles on expressways is of utmost importance to consumers.     

Analyzing trade-offs between transportation,inventory and production costs on freight networks

The purpose of this paper is to determine optimal shipping strategies (i.e. routes and shipment sizes) on freight networks by analyzing trade-offs between transportation, inventory, and production set-up costs. Networks involving direct shipping, shipping via a consolidation terminal, and a combination of terminal and direct shipping are considered. This paper makes three main contributions. First, an understanding is provided of the interface between transportation and production set-up costs, and of how these costs both affect inventory. Second, conditions are identified that indicate when networks involving direct shipments between many origins and destinations can be analyzed on a link-by-link basis. Finally, a simple optimization method is developed that simultaneously determines optimal routes and shipment sizes for networks with a consolidation terminal and concave cost functions. This method decomposes the network into separate sub-networks, and determines the optimum analytically without the need for mathematical programming techniques.     

Truck backhauling on two terminal networks

Truck backhauling reduces empty truck-miles by having drivers haul loads on trips back to their home terminal. This paper 1) examines the impact on backhauling opportunities of terminal locations and directional imbalances in the flow of freight from the terminals, and 2) develops a method for determining which truckloads should be backhauled. Backhauling is studied for two terminals sending full truckloads to many customers under steady-state conditions. This research develops two backhauling models. The first is a continuous model that makes simplifying assumptions about customer locations and travel distances. It results in formulae showing that 1) savings from backhauling increase at a decreasing rate as the directional flow of freight between two terminals becomes more balanced and 2) backhauling is an important, but often ignored, factor in terminal (e.g. trucking terminal, warehouse, or plant) location and supplier selection decisions. The second model is a more general discrete model that determines which loads should be backhauled to minimize empty truck-miles.     

Decision making processes governing federal expenditures within the transportation sector of the United States

The current process for allocating federal funds within the transportation sector of the U. S. is dominated by concerns for territorial equity, administrative feasibility, technical feasibility, and national defense. Economic efficiency as a long range objective is conspicuous by its absence except insofar as it is embodied in the desire to promote the commerce of the nation.Federal allocations for highways, waterways, and maritime subsidies are declining relative to urban public transit, and Coast Guard navigation related expenditures. Environmental considerations and obvious failure in the case of maritime subsidies appear to be the major reasons. Airport and airway allocations will be subject to the same negative forces.The next massive transportation program to appear in the federal budget other than urban public transit is likely to involve the national railway system. The big question here is how the money will be handed out. Economists and planners so far appear to have had little interest or impact in this difficult and crucial area of public decision making.Former Senior Economist, Policy and Plans Development, Office of the Assistant Secretary for Policy and International Affairs, U. S. Department of Transportation. Presently Advisor to the Government of Ethiopia with the Harvard University Development Advisory Service.     

The role of accessibility in basic transportation choice behavior

Accessibility measures reflect the level of service provided by transportation systems to various locations. Basic transportation choice behavior is defined to include those decisions of how many automobiles to own and how many trips to which destinations to make by automobile and by public transit. Here, these decisions are assumed to be made jointly by urban households and are conditional upon residential location decisions. It is the purpose of this paper to explore the role of accessibility as a causal factor in such basic transportation choice behavior.An economic utility theory model of choice behavior is postulated in which the benefits from making trips to specific destinations are reflected by measures of destination attraction. Through determination of utility-maximizing trip frequencies, indirect utility functions are developed which include accessibility concepts. Behavioral implications of these concepts are proposed and contrasts are drawn to accessibility measures used in conventional segregated models of trip distribution, modal choice, and automobile ownership.Sensitivity analyses of alternative empirical definitions of accessibility in the choice model are conducted using data from the Detroit Regional Transportation and Land Use Study — covering counties in southeastern Michigan. These analyses employ a multinomial logit estimation technique and focus on definitions of trip attraction. Results of these analyses indicate that more complicated attraction measures can be replaced by measures involving the proportion of either urban area population or urban area employment within a traffic analysis zone. Also, evidence is found that decision-makers in the case study area consider trips of up to 60 or even 90 minutes duration when evaluating accessibilities offered by alternative public and private transportation systems.