May 2012 Research E-News

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Final issue of the Research E-News

This is the final issue of the CTS Research E-News. It has been delivering the latest research project milestones, published reports, and seminar coverage to the transportation community since 2003.

But don't worry—the transportation research coverage that has been the hallmark of the CTS Research E-News will continue in a brand-new publication that will be merged with the CTS Report.

Why the change? Because CTS is continually striving to improve our outreach efforts to transportation researchers, professionals, and practitioners, and this new signature CTS publication will be just the latest evolution of that work. 

CTS is proud of the work we have done in the CTS Research E-News, but we're not resting on our laurels. The times change, and so must we.

The first issue of the new CTS publication will be available in July. Please stay tuned.

Policy & Planning

Using accessibility to evaluate future planning scenarios

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Understanding the interdependent relationship between transportation and land use is important for planning the future growth of cities. Recognizing how this relationship affects accessibility—the ability of people to reach the destinations that meet their needs and satisfy their wants—can help policymakers and planners make decisions that optimize a city's efficiency, livability, and economic competitiveness.

In a study funded by the Minnesota Department of Transportation, researchers from the Department of Civil Engineering compared a set of planning scenarios for the Twin Cities metropolitan area using accessibility as a performance measure. Associate Professor David Levinson, undergraduate research assistant Paul Anderson, and graduate student Pavithra Parthasarathi used the scenarios to evaluate the accessibility of various land use and transportation network combinations.

The researchers analyzed the accessibility of 60 different scenarios, including combinations of six land-use scenarios and 10 highway and transit networks. The land-use scenarios included existing 2010 conditions, projected 2030 conditions, and various combinations of centralized and decentralized population and employment conditions.

Highway networks used in the scenarios included 2010 conditions, projected 2030 conditions, an ideal freeflow network with no congestion, and a hypothetical diamond lane network that added high-occupancy toll lanes to all freeways inside the I-494/694 beltway. Transit networks ranged from 2010 conditions to projected 2030 conditions to a "retro" network that added all 1931 rapid transit streetcar routes to the 2030 network. 

In terms of land use, results show that centralized employment and centralized population had the highest accessibility across all networks, resulting in more access to jobs and labor as well as shorter commute times. The researchers found that fully centralized growth produced about 20 to 25 percent more accessibility than the projected 2030 scenario, depending on the accompanying transportation network.

Of the transportation networks, the researchers found that the freeflow network had the highest accessibility—20 percent more than the projected 2030 network—followed by the diamond lane network.

At first, the researchers say, it would be easy to choose the land use and transportation network combination with the highest accessibility as the future planning goal. However, the scenario of centralized population and employment on a freeflow network—while ideal for accessibility—is not likely to be cost-effective or feasible under current conditions.

Instead, the researchers say, these study results could be used to help prioritize future investments and land-use strategies based on how accessibility-effective they are—how much accessibility they deliver per dollar of investment.

A final report on the project, Using Twin Cities Destinations and Their Accessibility as a Multimodal Planning Tool (MnDOT 2012-05), is available on the CTS website.

Examining the dynamics of the UPA collaboration

Researchers from the Humphrey School of Public Affairs have completed the final phase of a three-part study on the Urban Partnership Agreement (UPA) in Minnesota. Overall, the study examined how technology and collaborative processes can be combined in such programs to achieve important transportation goals, catalyze institutional change, and create public value.

The final phase of the ITS Institute-sponsored study focused specifically on the dynamics of the UPA collaboration, including the factors that contributed to its successes and difficulties. The research team included Professor John Bryson, Associate Professor Barbara Crosby, Professor Melissa Stone, and research fellow Emily Saunoi-Sandgren.

Minnesota's participation in the UPA program required many transportation-focused groups in the Twin Cities area to collaborate on 24 individual projects aiming to improve traffic flow on the I-35W corridor between Minneapolis and the city's southern suburbs. Study findings indicate this collaboration was facilitated by existing relationships among key stakeholders, a general agreement on I-35W congestion as a significant problem, and the presence of powerful project sponsors and champions at the federal, state, and local levels.

The research team also highlighted the critical role of neutral conveners—including the Citizens League, CTS, and the State and Local Policy Program at the Humphrey School—in the collaborative process. Specifically, the researchers cited the value of carefully managed forums that promoted and stabilized relationships across public, business, and nonprofit entities.

The researchers also say that a number of lessons can be learned from the UPA effort that could help Minnesota and other areas address transportation challenges in the future. For instance, the researchers recommended developing a comprehensive toolkit to assist potential collaborators. This toolkit could combine existing strategies—such as storyboarding, strategy mapping, and role-playing—into a useful framework for thinking about collaboration.

A final report on the project, Dynamics of Cross-Sector Collaboration: Minnesota's Urban Partnership Agreement from Start to Finish (CTS 12-04), is available on the ITS Institute website.

Intelligent Transportation Systems

Evaluating the usability, potential distractions of in-vehicle signing

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Example of IVS information showing an upcoming change in speed limit

In a recently completed study, researchers from the HumanFIRST Program examined the use of in-vehicle signing (IVS) for presenting information about changes in speed zones to drivers. This information is intended to help drivers better detect transition points in the roadway by providing them with visual notifications on a smartphone or other personal navigation device.

HumanFIRST director Michael Manser and research fellow Janet Creaser examined the use of IVS notifications for changes in speed limits in four driving zones: along a straight segment of roadway, in school zones or construction zones, and before upcoming curves. They then evaluated the utility and potential distractions associated with presenting this IVS information to drivers. The study was sponsored by the Minnesota Department of Transportation.

The study was completed in the HumanFIRST driving simulator using a route that included freeway driving, two-lane rural road driving, and town driving. All IVS information was presented graphically to drivers—primarily through images of various roadway speed limit signs—on a smartphone mounted on the center console of the vehicle.

Study participants were divided among three system conditions when driving the simulated route. In the first group, drivers received both IVS information and a continuous visual navigation function on the device. In the second and third groups, drivers received only continuous navigation information and only the IVS information, respectively. These varying conditions allowed the researchers to compare the effect and usability of IVS information with navigation information and to examine the effect of multiple sources of information on driving performance. 

Overall study results indicated that for some zones and conditions, minimal distraction might have been occurring, especially when navigation information was being presented. However, results also showed that transition zones requiring drivers to adjust their speeds could result in an increased workload for the driver in general, without any information presented. According to the researchers, this finding supports the goal of the IVS application—to help drivers be more attentive to the driving environment when transitioning to a new speed zone.

The researchers also found that providing only IVS information resulted in drivers having their eyes on the screen of the device for shorter time periods than in the two conditions with continuous navigation. This suggests that the more information there is available on a display, the more time drivers are likely to spend looking at it.

Comments from study participants indicated that they found the IVS speed warning information useful in transitioning to new zones and adopting appropriate new speeds. Drivers also preferred the IVS information to the continuous navigation condition.

Overall, the researchers say the study results justify the goals of the IVS application. Although the information could provide a small amount of additional workload or distraction prior to entering a transition zone, it might be outweighed by the benefit to drivers of advanced notification.

Connected Vehicles Program: Driver Performance and Distraction Evaluation for In-Vehicle Signing (CTS 12-05), a final report on the project, is available on the ITS Institute website.

Effects of occasional hazard warning signs on vehicle speed

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Occasional hazard playground warning sign

Warning signs are typically installed along roadways to inform drivers about hazards that may affect their decision making. Some of these signs are installed for hazards that occur sporadically, such as the potential activity associated with playgrounds or parks located near a roadway. In general, these warning signs are designed to elicit specific driver responses, such as increased awareness or reduced speeds.

In this study, sponsored by the Minnesota Department of Transportation and the Minnesota Local Road Research Board, researchers evaluated the vehicle speed impacts of occasional hazard playground warning (OHPW) signs at three sites in Bloomington, Minnesota. The research team included civil engineering professor Gary Davis, Minnesota Traffic Observatory Director John Hourdos, and Keith Knapp of the Iowa Local Technical Assistance Program.

The researchers collected vehicle speed data at three residential sites in the Bloomington area. At each site, data were collected one month before and again one week to one month after two OHPW signs were installed. The team also recorded manual observations of the amount and location of on-street parking and park or playground activities at each site during the collection periods.

Overall results indicate that the vehicle speed impacts of the OHPW signs are small and site-specific. After the OHPW signs were installed, average speeds were about 1.5 miles per hour (mph) lower at the first study site, 0.9 mph lower at the second site, and had no noticeable difference at the third site.

According to the researchers, one explanation for the limited changes in speed is that the signs could be successfully increasing driver awareness without producing any changes in vehicle speed. The researchers also found that vehicle speed in these areas is highly dependent on the amount of activity at the nearby park or playground as well as on the amount of on-street parking. For example, at one study site, the researchers saw 10 to 15 mph reductions in speed when there was more activity at the nearby park.

The researchers recommend completing additional research that incorporates study sites with and without OHPW signs to help better understand their potential vehicle speed impacts. They also suggest conducting further analysis on how the layout of parks and their proximity to the roadway affects vehicle speeds.

A proposed second phase of this study would include a vehicle speed and eye-scanning evaluation of drivers in a simulated environment to help researchers determine the attention value of OHPW signs. The study would include an examination of drivers' responses to both traditional and enhanced OHPW signs.

Vehicle Speed Impacts of Occasional Hazard (Playground) Warning Signs (MnDOT 2012-05), a final report on the project, is available on the ITS Institute website.

Safety & Security

Primary seat belt law saves lives and money

Heavy Equiptment

According to a new study by the Center for Excellence in Rural Safety (CERS), Minnesota's primary seat belt law resulted in 68 fewer deaths and 320 fewer severe injuries from 2009 to 2011.

CERS researchers Frank Douma and Nebiyou Tilahun conducted the study on behalf of the Minnesota Department of Public Safety (DPS) Office of Traffic Safety. They analyzed the impacts of the new law, examining the changes in roadway crash fatalities, seat belt use data, and public opinion survey results. 

The primary seat belt law, which went into effect in June 2009, allows law enforcement officers to ticket drivers for not wearing a seat belt without any other law being broken. Prior to the law, not wearing a seat belt was a secondary offense in Minnesota. This allowed law enforcement officers to ticket for failure to wear a seat belt only when there was another moving violation. Currently, 32 states have primary seat belt laws.

To assess the effects of the new law on crash-related injuries and deaths, the researchers compared actual crash data from June 2009 to June 2011 with expected crash data based on trends from 2004 to 2009. Results indicated that there have been 68 fewer deaths, 320 fewer severe injuries, and 432 fewer moderate injuries since the law went into effect. This reduction in deaths and injuries has saved $45 million in hospital charges, the researchers say, including nearly $10 million in taxpayer dollars that would have paid for Medicare and Medicaid charges.

"The primary seat belt law has advanced traffic safety in Minnesota by saving lives and preventing serious injuries," Minnesota Public Safety Commissioner Mona Dohman said. "The findings of this study remind us again how vital it is for Minnesotans to buckle up—every seat, every ride."

The researchers also examined seat belt use data and survey results that measured support for the primary seat belt law. Findings suggest that more Minnesotans are buckling up since the primary law went into effect. Observed seat belt use has increased from 87 percent in 2008 to 93 percent in 2011. In addition, a survey of Minnesotans shows the support of the law has increased to 70 percent, up from 62 percent just before the law was passed.

"The stronger seat belt law is keeping a lot of Minnesotans out of hospitals and morgues, and it will continue to do so for years to come," CERS director Lee Munnich said. "But we still have too many Minnesotans injured or killed every year because they are not wearing seat belts, so we have more work to do."

A final report on the project, Impacts of Minnesota's Primary Seat Belt Law (CTS 12-06), is available on the CERS website.

Transit, Bicycling, and Walking

TCRP research publications available online

The federal Transit Cooperative Research Program (TCRP), administered by the Transportation Research Board, provides practical transit research to address technical and operational issues. TCRP emphasizes putting research results into the hands of organizations and individuals that can use them to solve problems.

Recent TCRP publications include:

Upcoming Events

August 14
TERRA Innovation Series: Expanding What We See—Remote Sensing Applications in Transportation, Great Lakes Research Center, Michigan Technological University, Houghton, MI

September 6-7
2012 Mid-Continent Transportation Research Forum, Madison, WI