September 2009

The number of oversize or overweight (OSOW) permits in Wisconsin is rising, but the test vehicles used to analyze the state’s bridges assume a regular distribution of weight along a regular number of axles. The weight distribution of trucks, as well as the actual force exerted by each axle, has a significant effect on fatigue experienced by infrastructure, such as bridges. Even if an OSOW vehicle is below the permit vehicle’s weight, it may have a more damaging effect on the bridges it crosses due to its configuration.

To determine the validity of this risk, the Statistical Analysis of Heavy Truck Loads Using Wisconsin Weigh-In-Motion Data (CFIRE 01-02) project acquired data on a wide range of Wisconsin trucks and used Monte-Carlo simulations (which run many trials with random variables) to determine their possible effects over bridges of various sizes. This project was coordinated by CFIRE affiliate researcher Habib Tabatabai.

Data for this project was sourced from the 17 weigh-in stations located around Wisconsin. Only the heaviest five percent of the measured trucks were used, in order to maintain an accurate measurement of the trucks with the most significant effects on the state’s bridges.

The heaviest five percent of the data for each class of truck were simulated moving over bridges with spans ranging from 20 feet to 250 feet, and the maximum shear and moment forces were recorded. In addition, the moment and shear force limits set by the permit vehicle (which weighs 250,000 lbs) was recorded, and found to only account for 99.8 percent of the trucks in the simulation. This suggests that a portion of real-world trucks exceed the permit vehicle in applied forces, even if they weigh less.

This project showed that current practices for determining maximum permitted weight do not entirely limit the effect a truck has on the bridges it crosses. Expanding this work to include all trucks, instead of just the heaviest five percent of each class, would create a profile of the marginal fatigue that each truck exerts. These fatigue studies would be valuable in measuring the performance of different roadway and bridge materials, as well as making maintenance decisions for heavily-traveled corridors.

To learn more about this project and to read the final report, visit the CFIRE 01-02 project page

Most public transportation agencies have valuable employees who were born in the early post-WWII era, and now those agencies will face a wave of retirements over the next decade. For some agencies, up to 50 percent of their workforce will be eligible for retirement sometime in the next 10 years.

In response to this looming loss of skills, as well as to address the technological shift that has accelerated in the most recent decades, the 21st Century Workforce Development Summit (CFIRE 01-10) was convened. This summit included representatives from state DOTs, educational institutions, and consulting firms and sought to cooperate on growing the current workforce of transportation professionals. The summit was organized by CFIRE Executive Director Teresa Adams and was hosted in Madison, Wisconsin.

The representatives concluded that the future workforce must include a wider range of skills in order to respond flexibly to agency needs, including financial management and team communication. Many of the needed skills are not directly taught in university programs, such as ethics and leadership.

Addressing the insufficient number of potential employees in the market, the summit found that more involvement in the K-12 schooling period might be necessary to encourage young people to focus on engineering skills. This includes more participation of the transportation industry in ongoing efforts to promote Science, Technology, Engineering, and Mathematics (STEM), as well as improving the image of the transportation workplace.

Recruiting new employees is only one facet, however. Other strategies discussed at the summit included improving the skills of existing employees through training programs and increasing workplace flexibility to encourage older employees to remain.

Five steps to address the workforce deficit were decided on:

  1. Creating a professional development network to continue education outside the classroom.
  2. Expanded partnership between members of the transportation industry for better efficiency and better relationships.
  3. Improving the visibility and attractiveness of the transportation industry, as well as science and engineering in general, in K-12 institutions.
  4. Research to understand workforce needs and the skills acquired throughout K-12 and further education.
  5. Promoting alternative leadership that emphasizes employee empowerment and alters institutional structures to be more communicative and open to innovation.

To learn more about this project and to read the final report, visit the CFIRE 01-10 project page.