Project Number:
09-01
Research Project:
Accident Rates and Safety Policies for Trucks Serving the San Pedro Bay Ports
P.I. Name & Address:
Seiji Steimetz
California State University at Long Beach
Department of Economics
Long Beach, CA 90840
Email: ssteimet@csulb.edu
Website: http://www.csulb.edu/~ssteimet/
Phone: (562) 985-5078
Fax: (562) 985-5804
Co-P.I.
Steven Yamarik
California State University at Long Beach
Department of Economics
Long Beach, CA 90840
Email: syamarik@csulb.edu
Website: http://www.csulb.edu/~syamarik/
Phone: (562) 985-4634
Fax: (562) 985-5804
Project Objective:
Roughly 2,400 accidents occurred within the last year on Californias Interstate 710 serving the Port of Long Beach. Of those, about 30% directly involved trucks, in addition to those that may have been caused by debris shed from poorly maintained trucks. In contrast, heavy trucks are involved in only 4% of all highway accidents for the nation as a whole. Are trucks on highways serving the San Pedro Bay Ports especially hazardous and, as such, are safety policies that specifically target port-related travel warranted? If so, which policies are likely to be most effective?
This project has two primary objectives. First, it will empirically investigate if trucks on highways serving the ports are indeed more dangerous than on other highways. By measuring truck accident rates on each highway (defined as the number of accidents per vehicle-mile), the relative danger of port-related truck travel can be determined in a manner that controls for truck exposure. This will yield an "apples to apples" comparison for assessing the relative risk posed by inadequately-maintained trucks.
Second, the project will evaluate two policies proposed to increase truck maintenance by independent owner operators: (i) increased pay (i.e. higher freight rates) and (ii) direct maintenance subsidies. Economic theory predicts that increased pay will have an ambiguous effect on maintenance expenditures. At one extreme, all additional pay is spent on maintenance; at the other extreme, this additional pay is simply converted into operating profits. Predicting the actual outcome is an empirical matter. However, maintenance subsidies will unambiguously increase maintenance expenditures. Yet this begs the question of "how much" maintenance effort such subsidies would induce. Empirical analysis is required to estimate how a given subsidy level would translate to maintenance expenditures. Estimating these effects would ultimately allow for determining which policy, dollar for dollar, is most likely to induce the greatest return on public safety investment.
Task Descriptions
Meeting this projects objectives requires two distinct research programs: (i) an analysis of truck accident rates and (ii) an analysis of the relationship between owner-operator maintenance investment, pay rates, and costs of specific maintenance activities.
Analysis of Truck Accident Rates
The first research program is to estimate truck accident rates along highways serving the San Pedro Bay ports (such as Interstates 710 and 110), and on non-port highways for comparison. Data on accident counts and truck volumes will be drawn primarily from the PeMS Freeway Performance Measurement System and the Caltrans Traffic Accident Surveillance and Analysis System (TASAS). National accident rate data will also be compiled from U.S. Department of Transportation and National Highway Traffic Safety Administration (NHTSA) databases.
The accident rate estimates will then be used to determine marginal accident rates due to increased truck volumes along port and non-port highways. A simple linear regression model can be used to estimate marginal truck accident rates. These marginal rates can then be compared to average rates to estimate the external risk generated by trucks on port and non-port highways. A comparison of these external risks provides an economic measure of the relative hazards of port-bound truck traffic and can help guide road-pricing policies designed to manage truck accident risk.
Analysis of Maintenance Investment, Driver Pay, and Maintenance Prices
The second research program is to develop a production function framework for estimating the impact of higher pay and lower maintenance prices (in the form of maintenance subsidies) on owner-operator maintenance investment. In short, owner operators are treated as profit-maximizing firms that use maintenance as an input in the production of goods-movement services. Unfortunately, maintenance levels, such as the frequency of brake and tire replacement are difficult to observe. However, economic "production theory" tells us that observed maintenance expenditures are based on profit-maximizing levels of maintenance. Hence, a “cost function”, which defines the relationship between driver operating expenses, output and input prices, can reveal the underlying parameters of the production function. For example, a trucker would only be willing to incur additional maintenance expenses if doing so reduces the cost of moving a given amount of freight. If this is the case then the maintenance improvement must yield an improvement in the truckers productivity, such as being able to haul more freight (perhaps by spending less time driving around safety checkpoints or carving treads into bald tires). Likewise, a higher pay rate would only translate into greater maintenance investment if the profitability of this investment exceeds the additional profit from simply "pocketing" this pay increase.
As such, the second program can be broken down into three steps: (i) specifying an appropriate cost function, (ii) estimating the parameters of this cost function, and (iii) using these parameter estimates to calculate the resulting impact of higher pay and lower maintenance prices on maintenance activity.
Milestones, Dates:
August 15, 2008 – September 14, 2009
Total Budget:
$78,441
Student Involvement:
One graduate student at 500 total hours
Relationship to Other Research Projects:
Related to 06-04; and AR 04-01; part of the goods movement focus area
Technology Transfer Activities:
Project report will be posted soon
Potential Benefits of the Project:
This research will help to determine which policy, dollar for dollar, is most likely to induce the greatest return on public safety investments.
TRB Keywords:
San Pedro Bay ports, truck accident rates, highway, maintenance
