• Contents
• Message from the Co-General Editors
• Transportation Economics
• Willingness-to-Pay Values
• Spring Load Restriction Policy
• U.S. Air Carrier Returns
• Intercept Surveys
• High Severity Crashes in Rural Areas
• Traveler Characteristics
• Freight Transportation Demands
• Aviation Accidents
• Handbook of Transportation Science
• Mobility

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A Message from the JTRF Co-General Editors

This issue marks the second time that JTRF has published a summer issue under the new publishers, the Upper Great Plains Transportation Institute. The Summer 2006 issue contains the usual wide variety of transportation topics that distinguishes JTRF from the other transportation journals. Topical areas include:

• Post-1970 developments in transportation economics
• Willingness to pay for attributes of bus travel
• Costs and benefits of heavy truck weight restrictions during spring thaw season
• Impact of financial leverage on airline profitability
• Using intercept surveys to generate data for freight planning
• Factors affecting severity of vehicle crashes in rural areas
• Urban commuter traveler characteristics
• Transportation demand on U.S. inland waterways
• Effect of milestone accidents on aviation safety policy, regulation, and technology

Kenneth Button discusses some developments in transportation economics focusing on regulation, congestion, and travel demand in "Transportation Economics: Some Developments Over the Past 30 Years." Button noted that until the late 1970s transportation economists were mainly concerned with traffic congestion, developing investment decision mechanisms for prioritization of highway and public transportation expansion, and the pricing of regulated and state-owned transportation modes. He then discusses changes from the late 1970s in economic regulation, the economics of congestion, and travel demand modeling. Button suggests current research problems such as the interface of transportation and business logistics, transportation security, and the importance of transportation to the economy. He concludes with the observation that the contribution of economics to solving transportation problems has been positive, but with more impact on decision making, it could have been greater.

In "Modeling Willingness-to-Pay Values for Rural Bus Attributes Under Different Trip Purposes," C.V. Phanikumar and Bhargab Maitra estimate willingness-to-pay (WTP) values for attributes of bus travel in rural regions of a developing country. They employ stated choice data, multinomial logit, and random parameter logit models to measure the WTP values. The authors found that WTP values varied by trip purpose. For example, they discovered that WTP values associated with comfort and travel time were higher for job trips, while recreation trip makers value travel time, comfort, and headway slightly less than job trip makers, but more than business trip makers.

Brian Smalkoski, Ning Li, and David Levinson investigate the benefits and costs of spring load restrictions in "Economic Effects of Lifting the Spring Load Restriction Policy in Minnesota." The spring load restrictions (SLR) regulate the weight per axle carried by heavy trucks during the spring thaw period. The authors note that the SLR policy aims to reduce pavement damage caused by heavy trucks and extend the useful life of the road. To evaluate the policy, Smalkoski, Li, and Levinson conduct a cost/benefit study based on results of surveys of industry costs, a pavement performance model, and a freight demand model. They conclude that the benefits of eliminating the SLR policy are greater than the additional costs.

In "Operating, Financial, and Total Leverage and the Effects on U.S. Air Carrier Returns, 1990-2003," Richard D. Gritta, Brian Adams, and Bahram Adrangi quantify the impact of excessive financial leverage on air carrier profitability. The authors examine three types of leverage which are degree of operating leverage (DOL), degree of financial leverage (DFL), and degree of combined leverage (DCL). DOL measures the changes in operating profit in response to changes in operating revenues. DFL reflects the responsiveness of net profit to changes in operating profit. DCL is DOL multiplied by DFL. The authors calculated these leverage measures for the major U.S. air carriers for the 1990-2003 period. Gritta, Adams, and Adrangi found that the high degree of leverage is responsible for the "boom and bust" profitability cycle in the U.S. airline industry. They also discovered that the majority of the carriers had small but positive returns on assets (ROA), but with the exception of Southwest, all the carriers had negative returns to equity (ROE) during the sample period.

Eric Jessup, Ken Casavant, Catherine Lawson, and Alan Kirk demonstrate the utility of intercept surveys for freight planning in "Intercept Surveys Productivity in Collecting Truck Trip Data: A Case Study of Portland, Oregon." The objective of the study was to examine and contrast the use of intercept surveys at different locations (highway roadside, ports, and warehouses) to generate data useful to states' modeling and freight planning for truck movements. They found that truck data collected at roadside interview locations provided complete trip detail for all interregional truck movements, and for almost all intraregional truck movements (warehouse/distribution center locations). Jessup et al. concluded that interviews at the warehouse/distribution center and interstate highway weigh station provided the highest commodity type response rates, while the preponderance of container traffic at the port limited responses regarding payload information.

In "Identification of Factors Leading to High Severity of Crashes in Rural Areas Using Ordered Probit Modeling," Sunanda Dissanayake and Indike Ratnayake used crash data from a Kansas database to analyze crash severity. Using ordered probit models to identify critical crash severity factors, the authors found that alcohol involvement, lack of seatbelt use, excessive speed, and driver being ejected due to the crash contribute towards the increased severity of rural area crashes. They concluded that other factors that contribute to increased crash severity include single vehicle crashes, sharp curves, and steep grades.

Mark W. Burris and Carlos F. Figueroa analyze the characteristics of urban commuters using HOT (high occupancy-toll) lanes in Houston, Texas in "Analysis of Traveler Characteristics by Mode Choice in HOT Corridors." They note that high congestion and tight transportation budgets have increased the attention given to value pricing. However, given the few empirical studies of value pricing, it is difficult to predict how drivers will react to value pricing options. Using combined revealed and stated preference surveys, the authors contributed important empirical information regarding characteristics of travelers using value pricing options. They found that travelers using the value pricing option (Quick Ride) were more likely to be over 65 years old, have a post-graduate degree, have an income greater than $100,000, and are on a trip to school. They were significantly less likely to be male, between 25 and 34 years old, and living alone.

In "Freight Transportation Demands on the Upper Mississippi and Illinois Rivers," Tun-Hsiang (Ed) Yu, Jin Zhang, and Stephen Fuller use Seemingly Unrelated Regression (SUR) techniques to estimate structural barge transport demands. The authors note that a detailed analysis of river freight demand is a necessary precursor of a defendable study into the economic feasibility of improving the lock and dam systems on the two waterways. The authors estimated the short run own price elasticity to be -0.427 and -0.213 for the Upper Mississippi River and Illinois River respectively. The corresponding long run elasticities were -0.803 and -0.312. Yu, Zhang, and Fuller also found that foreign and domestic grain demand, season of the year, floods, and river water levels influenced barge demands.

Alfredo Lagos, Vahid Motevalli, Majid Motevalli, and Nobuyo Sakata analyze the effect of milestone accidents on aviation safety policy, regulation, and technology in "Review and Analysis of the Effects of Major Aviation Accidents in the U.S. on Safety Policy, Regulation, and Technology." The authors describe the process for identifying aviation accidents that have had significant impacts on the development of aviation safety in the U.S. These accidents are termed milestone accidents. Lagos et al. identified 14 milestone accidents that occurred in the 1988-2002 period, and had a major impact on safety policy, regulation, and technology. Among the indicators of change in the three areas are U.S. Congressional and Federal Aviation Administration (FAA) records. The impacts of milestone accidents are shown using a timeline format to demonstrate various sets of outcomes and their interrelation over time.

Michael W. Babcock
Co-General Editor - JTRF

Kofi Obeng
Co-General Editor - JTRF

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