modeling | Transportation Research and Education Center

Report: travel-time data lacking at key spots on Portland-area freeways

Mar 16, 2011

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...

Transit stations operate in sweet microenvironment

Dec 06, 2010

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.

USDOT official visits Portland to launch transportation modeling initiative

Nov 10, 2010

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...

TRB Highlights: 3 PSU Student Presentations

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View slides: Bell Presentation (PDF)

Moore Presentation (PDF)

Ma Presentation (PDF)

Summaries:
Identification and Characterization of PM2.5 and VOC Hot Spots on Arterial Corridor by Integrating Probe Vehicle, Traffic, and Land Use Data: The purpose of this study is to explore the use of integrated probe vehicle, traffic and land use data to identify and characterize fine particulate matter (PM2.5) and volatile organic compound (VOC) hot spot locations on urban arterial corridors. An emission hot spot is defined as a fixed location along a corridor in which the mean pollutant concentrations are consistently above the 85th percentile of pollutant concentrations when considering all other locations along the corridor during the same time period. In order to collect data for this study, an electric vehicle was equipped with instruments designed to measure PM2.5 and VOC concentrations. Second-by-second measurements were performed for each pollutant from both the right and left sides of the vehicle. Detailed meteorological, traffic and land use data is also...

Integrated Models: What They Are and How They Help

The video begins at 0:43.

Abstract: Integrated land use transportation models simulate the behavior of the spatial economic system and the interactions between the transportation system and the rest of the economic system. The essential elements of these models are explicit treatment of space in economic production and consumption behavior, both the space that is the physical areas that contain production processes and the space that separates different production locations and gives rise to the demand for travel and transport. They put travel within an economic context, and thus facilitate simulation of the impacts of transportation policy and planning actions and transportation conditions on the wider economic system. As such, integrated models can be used address complex policy questions that more limited transportation models cannot address, or cannot address well.

This seminar will set out the basic scope and form of integrated models and discusses several of the key advantages they provide for planning. Experiences gained in the practical applications of the Oregon SWIM and Sacramento MEPLAN and PECAS integrated models will be described. These experiences will be used to illustrate the added benefits arising with such models in terms of more efficient land use forecasting, more complete analysis of cumulative and indirect impacts and more holistic consideration of policy in general, more...

The Effects of Data Aggregation on Measuring Arterial Performance

The proliferation of information technology in the transportation field has opened up opportunities for communication and analysis of the performance of transportation facilities. The Highway Capacity Manual relies on rules of thumb and small data samples to generate levels of service to assess performance, but modern detection technology gives us the opportunity to better capture the dynamism of these systems and examine their performance from many perspectives. Travelers, operations staff, and researchers can benefit from measurements that provide information such as travel time, effectiveness of signal coordination, and traffic density. In particular, inductive loop detectors show promise as a tool to collect the data necessary to generate such information. But while their use for this purpose on restricted‐access facilities is well understood, a great many challenges remain in using loop detectors to measure the performance of surface streets.

This thesis proposes 6 methods for estimating arterial travel time. Estimates are compared to simulated data visually, with input/output diagrams; and statistically, with travel times. Methods for estimating travel time are applied to aggregated data and to varying detector densities and evaluated as above. Conclusions are drawn about which method provides the best estimates, what levels of data aggregation can still provide useful information, and what the effects of detector density are on the quality of estimates....

Modeling Injury Outcomes of Crashes involving Heavy Vehicles on Texas Highways

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Summary: A growing concern related to large-truck crashes has increased in the State of Texas in recent years due to the potential economic impacts and level of injury severity that can be sustained. Yet, studies on large truck involved crashes highlighting the contributing factors leading to injury severity have not been conducted in detail in the State of Texas especially for its interstate system. In this study, we analyze the contributing factors related to injury severity by utilizing Texas crash data based on a discrete outcome based model which accounts for possible unobserved heterogeneity related to human, vehicle and road-environment. We estimate a random parameter logit model (i.e., mixed logit) to predict the likelihood of five standard injury severity scales commonly used in Crash Records Information System (CRIS) in Texas – fatal, incapacitating, non-incapacitating, possible, and no injury (property damage only). Estimation findings indicate that the level of injury severity outcomes is highly influenced by a number of complex interactions between factors and the effects of the some factors can vary across observations. The contributing factors include drivers’ demographics, traffic flow condition, roadway geometrics, land use and temporal...

Activity and Transportation Models: An Introduction to Travel Models for Non-Modelers

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Abstract: This seminar will introduce travel models to non-modelers. It will build off the previous seminar, which introduced models in general, and discuss two primary approaches to travel modeling – four-step aggregate models and activity-based disaggregate models. The inputs, basic model methodology, and outputs of each approach will be discussed. An example of each approach will be discussed as well. The goal of the seminar is to introduce key concepts, basic differences between the two approaches, and discuss the benefits and shortcomings of each approach, with a focus on application.

Speaker Bio: Ben Stabler is a supervising planner with Parsons Brinckerhoff who specializes in planning modeling systems development. Ben has worked locally, as well as internationally, on numerous four-step and activity-based travel demand and land use modeling systems and has presented at various conferences, including TRB, the TRB Planning Applications Conference, and the Innovations in Travel Modeling conference. He is a certified GIS Professional and has worked in travel forecasting for Oregon DOT as well as PTV – the makers of VISUM and VISSIM. Ben is a member of the TRB Urban Transportation Data and Information Systems Committee (ABJ30) and is an active member of the Oregon Modeling Users Group.

200th Seminar! Travel Time Estimation for Traffic Management and Traveler Information

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Transportation Analysis Informing Transportation Planning and Policy at ODOT

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Summary: The Transportation Planning Analysis Unit (TPAU) at ODOT helps to provide information to a large variety of transportation plans, projects, and policy questions. This allows customers to make better informed decisions and to maximize limited resources. In order to fill this role TPAU and the Oregon modeling community have a fairly large "toolbox" of models and analysis tools and procedures. This transportation seminar will give an overview of the role and services that TPAU provides and the different tools and processes used to fulfill that role.

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