It’s not shocking that bridges built without thought to earthquakes wouldn’t make it through a big quake unharmed. More surprising, however, is how much damage even a relatively small earthquake would cause to Oregon’s bridges.

In an exhaustive OTREC project, researcher Peter Dusicka looked at the most common bridge types in the Oregon highway system. Those bridges weren’t just fragile, he found—they were even more fragile than other researchers and technical guidelines had suggested.

Dusicka published his preliminary findings in a draft report last year. The final report, “Bridge Damage Models for Seismic Risk Assessment of Oregon Highway Network,” is out now. Click here to download.

Most Oregon highway bridges were built before the 1980s, when designers started to consider seismic activity. Dusicka set out to see what would happen to the most common bridge type, continuous concrete multi-beam or girder, during quakes of varying degrees.

To find that out, he had to first know how the ground in the Pacific Northwest moves during and earthquake and second, model how the bridge type would react to these motions. Historical and geological evidence show a catastrophic earthquake will occur sooner or later in the region, Dusicka has said, as the Cascadia subduction zone stores up energy that will be released at some point. (...

Read more

Although specialized equipment and vehicles make up a large portion of state transportation budgets, an OTREC research report found little consistency in how states decide to replace this equipment.

Researchers David Kim and David Porter of Oregon State University surveyed 25 state departments of transportation to determine how they made replacement decisions. Nearly all consider the age of the vehicle or piece of equipment, with many considering how much use it gets.

Around half use thresholds, such as number of miles or months in service, to identify candidates for replacement. Some consider the equipment’s repair cost or operating cost, while others rely on physical inspections. None explicitly considers greenhouse gas emissions or other environmental concerns in its replacement criteria.

Given the huge range of approaches, Kim and Porter wondered if modeling could lead to better decision-making. They ran various models against the simple approach of using equipment age as a threshold value.

As it turns out, the simple approach isn’t too bad. In fact, it does better than one complicated mathematical model and about the same as a second model.

Click here to learn more about the project and download the report.

That may...

Read more

Transportation models keep growing more sophisticated. But complicated isn’t necessarily better, Rick Donnelly said during the inaugural seminar in OTREC’s spring 2012 transportation seminar series April 6.

“Better is contextual,” Donnelly said.

Donnelly, who leads the modeling and simulation practice at engineering consultancy Parsons Brinckerhoff, opened the spring seminar series with an introduction to models. Seven more free seminars follow in the series, produced in partnership with the Oregon Modeling Collaborative.

Donnelly detailed questions that model builders and users should ask and offered his thoughts on building more useful and informative models. Click here for a link to the archived presentation.

Although transportation models consider increasingly more information, simpler models can often get the job done with a smaller investment of time and money, Donnelly said. Sometimes the simplest approach actually produces the best results.

“’Better’ is only relevant in the context of what the model is going to be used for,” he said.

The modeling series continues Friday, April 13 with another seminar geared toward non-modelers. The seminar, by Ben Stabler, also of Parsons Brinckerhoff, builds on Donnelly’s opening installment.

Stabler will discuss two approaches to travel modeling and give...

Read more

Even as complex visual representations of data become common, many people still don’t understand what land-use and transportation modelers do. In April, state and local planning directors met to address that and other issues they’ll increasingly face in the coming years. The Oregon Modeling Collaborative convened the Oregon Transportation Policy Forum for guidance in developing the tools agencies will need and to keep agencies talking about transportation issues.

Giving a complex topic such as global warming the video game treatment could make it easier to grasp, said Angus Duncan of the Oregon Global Warming Commission. “I have yearned for something that’s the greenhouse gas equivalent of a ‘Sim City,’ “ Duncan said at the forum. “Something simple enough that kids can play with it, but something you can use for communication.”

Developers have gotten much better at representing data, said Tom Schwetz, director of development services for Lane Transit District, but leaps in handheld devices such as iPhones have raised expectations still higher. Transportation models are getting more complex and, at the same time, people are demanding their information quicker and quicker.

Modelers struggle, Schwetz said, both because people don’t understand the complexity of the models and because modelers themselves don’t explain themselves clearly. The models then become easier to attack than to defend. “There is a credibility issue,” he said. “It’s too easy to...

Read more

It’s a common occurrence: a digital signboard over the freeway tells you to expect a 15-minute trip, but traffic clears and you arrive in 10 minutes. Or, worse, you hit a clog and arrive in 30 minutes.

Sometimes those signboards, called dynamic message signs, are way off, Portland State University researcher Kristin Tufte found. But sometimes that doesn’t matter.

Tufte examined the signboards, called dynamic message signs, along Portland-area freeways in an OTREC project. Drivers typically reach their destinations earlier or later than the signs told them to expect when a so-called “shock wave” forms or dissipates; that is, when traffic suddenly bunches or clears up.

Currently, only three of the 30 or so message signs in the Portland metro area display travel times. Detectors at freeway onramps feed those signs. As a result, large swaths of freeway without onramps also have no data. To be most useful, new message signs would require more detectors in certain areas.

Take the busy Marquam Bridge in Portland, where busy freeways merge and there is no signboard. “There’s no detection for the whole length of the bridge,” Tufte said. “If you really want to have accurate travel times, you have to have detection there.”

As expected, Tufte found that traffic bunching or clearing in blind zones can throw off the accuracy of travel times displayed. Surprisingly, that inaccurate information is...

Read more

Even residents of a gingerbread candyland can't get around with holiday magic alone. After all, Santa's elves still need a reliable way to get from their cozy homes to the workshop.

Sadly, transportation planners have turned a frosty shoulder to sugar-based transit systems. Until now.

On Dec. 3, Portland State University's Students in Transportation Engineering and Planning held the first gingerbread transit station competition. Four teams of students pulled their attention away from human transit to focus on the needs of gingerbread people and misfit toys.

Dealing with building materials of unknown structural properties, students field engineered solutions. Licorice sticks stood in for steel rails, candy canes for bicycle racks. For a binding agent, students mixed cream of tartar and egg whites instead of portland cement.

The resulting transit system has already resulted in fewer traffic gum-ups and a drastic reduction in ultrafine powdered-sugar emissions. Sleigh-travel-time reliability has also improved.

Researchers are now assessing the durability of corn-syrup-reinforced composites in candy bridges, the potential for alkali-silica reaction in gingerbread pavement and the possibility that someone hungry will stumble in and eat the infrastructure.

The winning design team was Transit Wonderland, composed of Jesse Boudart, Sara Morrissey, Mark Haines and Meeyonwoo Lim.

Good transportation decisions rely on good models. Yet, despite advances in transportation modeling, there had been no dedicated training ground for the next generation of modelers. That all changed with the launch of the Oregon Modeling Collaborative Nov. 12. The collaborative will serve as a living laboratory to put the research from some of America’s top modelers into practice across Oregon.

On Nov. 12, we welcomed Peter Appel, administrator of the federal Research and Innovative Technology Administration, to Portland to kick off the collaborative with researchers, practitioners and policymakers from across the Northwest. Appel, confirmed by the U.S. Senate as administrator in 2009, has worked on U.S. Department of Transportation initiatives aimed at getting researchers and professionals to address safety, efficiency and environmental sustainability across all forms of transportation.

Groundbreaking research at the Oregon Transportation Research and Education Consortium has already produced models to account for bicycle trips and greenhouse gas emissions and to predict earthquake risk to highway bridges. However, models don’t do any good if agencies can’t afford the staff time and resources to use them. The Oregon Modeling Collaborative helps fill this gap by educating the next generation of...

Read more

The video begins at 0:34.

View slides

Speaker: Joseph Broach, Ph.D. Candidate, Portland State University
Topic: Trick or Treatment? Impact of Route-Level Features on Decisions to Walk or Bike
Summary: Some travel routes attract people walking and cycling, while others may scare them away. What features of street environments are most important, and how do available routes affect decisions to bike or walk on a specific trip? 

Research to date has focused on either large-scale areal measures like "miles of bike lane nearby" or else has considered only shortest path routes. Neither method is suited to capturing the impact of targeted route-level policies like neighborhood greenways. This session will present a new technique for measuring bike and walk accessibility along the most likely route for a given trip. The method is applied to travel data, and results provide new insight into the relationship between route quality and travel mode choice.

The video begins at 2:09.

Abstract: The ability to fully understand and accurately characterize freight route choice is one that will support freight modeling frameworks, and regional and state transportation decisions. This ability, when combined with regional and state commodity flow data, can compose an effective statewide freight modeling framework. Typically, transportation network models take a shortest path assumption for truck routing both for strategic and operational routing decisions. The goal of this research was to determining how different subgroups of shippers, carriers, and receivers make route choices, and to understand how these approaches vary across types of routing decisions. We consider route changes of both a spatial and temporal manner. This talk presents the results of a survey of over 800 shippers, carriers, and receivers in Washington State, and recommends a framework for improving the modeling of routing decisions in existing network models.

Speaker Bio: Professor Anne Goodchild has worked and studied in the transportation field for more than 15 years. Her initial experience in management consulting for transportation providers was followed by the completion of a PhD at UC Berkeley and research experience while developing the freight transportation program at the University of Washington. In addition to a BS in mathematics and an MS and PhD in Civil Engineering, Dr....

Read more

Abstract: We study the impact on productivity of a specific operating practice currently adopted by some demand responsive transit (DRT) providers. We investigate the effect of using a zoning vs. a no-zoning strategy on performance measures such as total trip miles, deadhead miles and fleet size. It is difficult to establish closed form expressions to assess the impact on the performance measures of a specific zoning practice for a real transportation network. Thus, we conduct this study through a simulation model of the operations of DRT providers on a network based on data for DRT service in Los Angeles County.

The video begins at 2:26.

Pages