PedalMN Bicycle Conference Seeks Presenters

The 2015 PedalMN Bicycle Conference will be held in Minneapolis May 4-5, 2015.  The conference theme is “Building a Bike Friendly State.”

The conference sponsors invite individuals, communities and partnerships to share stories of how they are building better places to bike through planning, policies, infrastructure, events and strategic funding.

For more details or to submit a presentation idea, visit  https://survey.vovici.com/se.ashx?s=56206EE369B6F330.

Proposals are due Monday, Dec. 1, 2014

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How those little blue lights make intersections safer

A story from WCCO-TV last week answered a question that has likely been puzzling many commuters passing through Ramsey County: what are those new blue lights for that are popping up on traffic signals?

The report explains that the blue lights illuminate when a traffic signal changes to red, allowing a patrol officer to witness and enforce a signal violation more easily and safely. What the report doesn’t explain is the safety benefits to be gained from increased red light enforcement.

In Ramsey County, the proposal for a recent large deployment of blue lights came from traffic engineers, not police.

“Our county safety highway program conducted by MnDOT indicated a lot of right-angle crashes related to people running red
lights,” said Ramsey County Planner Joseph Lux. “These are typically the accidents with the severest injuries.”

As part of the statewide Towards Zero Deaths (TZD) initiative in July 2013, MnDOT worked with counties to develop safety plans that emphasize low-cost, high-value safety improvements.

A federal grant is helping fund the installation of 128 blue lights at 49 intersections in Ramsey County (see locations) over the next two weeks. Deputies will begin enforcement later this month, but the hope is that the blue lights will be so effective,  active enforcement won’t be necessary long-term.

A blue light, positioned on each of the four corner intersection poles, turn on whenever the opposite signal light turns red.

“The comments we’ve received from local police is they don’t want to write tickets; they just want people to quit running red lights,” Lux said.

IMG_2431
Blue light indicators were affixed to existing signal poles at Lexington Avenue and Larpenteur Avenue in Roseville.

The blue light indicators allow a police officer to view an infraction from many viewpoints, instead of having to pursue the offending vehicle through the intersection. Also only one squad is required to patrol an intersection; not two.

The blue light indicators have been shown to increase traffic safety. In Florida, crashes due to people running red lights fell by 33 percent, according to a low-cost safety improvement pooled fund study conducted on behalf of MnDOT and 37 other states.

Unlike Florida’s blue lights, Ramsey County’s are being placed on the signal pole, instead of the masthead. They’re more prominent than a couple indicators the county tried previously at accident-prone intersections in Little Canada and Maplewood.

“They’re bright and noticeable to the public, but not distracting, like the ones Florida puts on the masthead,” Lux explained.

According to WCCO-TV, the blue lights are funded by a $120,000 federal grant, with $13,000 in matching local funds.

Temporary signs will be put up by Ramsey County to notify the public of the new indicators.

A few other Minnesota communities — including Blaine, Crystal, Olmsted County and Dakota County — have also installed blue light indicators in recent years.

Lux explained that Ramsey County is installing blue lights on intersections that are easily enforced by law enforcement, as well as those that aren’t, in hopes that the public will obey them all because of the heightened presence.

Continuous Scour Monitoring Improves Bridge Safety

A leading cause of bridge failure is bridge scour, which occurs when rapidly moving water erodes riverbed soil around abutments or piers.

Monitoring bridge scour with traditional inspection methods can be dangerous and difficult, so MnDOT has been working with researchers from the University of Minnesota’s St. Anthony Falls Laboratory to develop a continuous monitoring system to test certain bridges more safely and efficiently.

MnDOT currently monitors 45 scour-critical bridges — and local Minnesota agencies monitor 360 more — using visual inspections or water data websites during flooding events. Once a predetermined threshold is exceeded, portable scour monitoring equipment is deployed to measure scour depth.  If scour has undermined the foundations of a bridge, inspectors close it for repair.

But portable scour monitoring systems can be difficult and dangerous to deploy from the bridge deck or boat in fast-moving water. It can also be difficult to get inspectors to sites quickly enough in areas subject to flash flooding.

A better alternative for such situations are fixed scour monitoring devices that continuously monitor scour and send data wirelessly to bridge personnel, alerting them when scour reaches a dangerous level.

The Highway 43 Bridge in Winona was affixed with continuous bridge scour monitoring equipment.
The Highway 43 Bridge in Winona was affixed with continuous bridge scour monitoring equipment.
New technology

MnDOT has not historically made use of fixed scour monitoring equipment, but as advances in technology have made these devices more affordable and reliable, the agency  became interested in exploring the use of fixed monitoring equipment at locations where the use of portable equipment is problematic. ( A major concern for fixed scour monitoring is damage from debris and ice.)

Researchers have installed fixed remote monitoring stations on four such bridges.

Stations on the first two bridges (Highway 14 over the Minnesota River in Mankato and Highway 43 at the Mississippi River in Winona, pictured at top) ran successfully for three years, with outages due to primarily to power and communication issues.

Researchers learned valuable lessons from these bridges and have now installed monitoring equipment on two more: The Old Hastings Bridge (Highway 61 over the Mississippi River), on which float-outs were installed; and the Dresbach Bridge (Interstate-90 over the Mississippi River), which had a tilt meter and underwater sonar device installed.

“The less familiar personnel are with technical equipment, the less they tend to use it,” said Andrea Hendrickson, State Hydraulics Engineer, MnDOT Office of Bridges and Structures. “This research project gave us the familiarity and technical information we need to be comfortable using fixed scour monitoring equipment on bridges that warrant it.”

Related Resources

*Editor’s note: This article was adapted from an article in the latest issue of our newsletter, Accelerator. Read it online, or sign up to receive it by mail. 

Video: Load Testing for the Winona bridge

New video, below, shows how explosions are used to test the bedrock for the new Highway 43 bridge in Winona.

Bridge engineers use “pile load testing”  to find out how much weight and resistance the ground will bear. It not only saves time and money, but helps design a bridge that will sit securely on the bedrock, below the river.

The statnamic test used in the video is one part of this process.

Winona Bridge Statnamic Test

 

How load testing works: 

It begins with digging and pounding.

Two different kinds of piles are put into the ground:

  • A hollowed shaft, which is filled with rebar and concrete. It goes 30 to 50 feet below the bedrock to create a solid pillar that can assess how much weight and sway the ground will bear.
  • A steel pipe that is hammered into the ground. Since the bedrock is about 100 to 150 feet below the river, these pipes are welded together end-to-end to reach that length.

Once the piles are in, they’re tested two different ways.

  • Pile Dynamic Analysis, with gauges affixed to the top of the pile to read the pressure put on it when hit with a pile driver.
  •  A Statnamic test (shown in videos), which involves accelerating a heavy weight by setting off a controlled combustion reaction. This shows how much resistance the pile can take.

Once the data is collected for the bridge design, the piles are cut off two feet below the river bed.

Mobile imagery, LiDAR help MnDOT maintain its assets

How do you quickly and cost-effectively get an accurate inventory of transportation assets spread out along more than 1,100 miles of roadway?

That was the problem facing the Minnesota Department of Transportation’s Metro District, which needed an inventory of its plate beam guardrail and concrete barriers.

To accomplish this, engineers in the district launched an innovative research implementation project using a pair of mobile mapping technologies — Light Detection and Ranging (LiDAR) and mobile imaging — that can collect vast amounts of geospatial data on highway infrastructure in a safe and efficient manner.

Mobile imaging uses a camera mounted on a vehicle driving at highway speeds to take high-resolution photos at regular intervals. It’s accurate to within 1 foot, which makes it suitable for use in preliminary (30 percent) design plans without additional field surveys. In this project, researchers collected mobile images of roadway barriers and extracted data from them along Metro District roadways, including all ramps, overpasses, interchanges, weigh stations, rest areas and historical sites.

A MnDOT worker replaces a section of broken guardrail.
A MnDOT worker replaces a section of broken guardrail on I-94 near the Lowry Tunnel in Minneapolis. (Photo by Dave Gonzalez, MnDOT)

Researchers also collected LiDAR data at three Metro District sites. LiDAR uses a laser range finder and reflected laser light to measure distances. It provides survey-grade data accurate to within 0.1 foot, but it is significantly more expensive to collect than mobile imaging.

“Mobile imagery and mobile LiDAR are relatively new technologies, but this research shows that they are options that we can use. Collecting this information manually would have taken a lot more time and money,” said MnDOT Asset Management Engineer Trisha Stefanski.

MnDOT’s barrier inventory will provide invaluable information for design, planning and maintenance. The data will be published on MnDOT’s Georilla map server, where it will be beneficial to a variety of projects and recurring tasks. For example, if a vehicle hits a barrier, maintenance staff will be able to check the database to see the type of barrier and end treatment to ensure they bring the right equipment to make repairs. Although the project focused on barriers, the imagery contains data on other assets as well. MnDOT has already used the imagery to extract noise wall and sign data.

This blog post was adapted from an article in our upcoming issue of Accelerator, MnDOT’s research and innovation newsletter.

3D-vertical
Thousands of data points can be extracted from this image of a Highway 61 roadway segment created with LiDAR Technology.

‘High Bridge’ study yields insights on bridge deck maintenance

One of St. Paul’s most iconic landmarks is helping the Minnesota Department of Transportation find the most cost-effective methods of maintaining concrete bridge decks.

For the last three years, the Smith Avenue High Bridge, which connects downtown St. Paul with the city’s west side, has served as a test bed for a variety of products used to seal cracks on bridge decks. Through MnDOT-funded research, various sealant products have been applied on different areas of the bridge deck, with their performance tracked over time.

“This project will help MnDOT make cost-effective maintenance decisions to preserve its current bridge infrastructure,” said Sarah Sondag, a senior engineer with MnDOT Bridge Operations Support.

The bridge was chosen in part because of its large deck area, which allowed for the application of 12 sealant products and three control sections.

Sealing deck cracks is a routine preventive maintenance task for bridge crews. Left untreated, cracks can allow moisture and chlorides to penetrate the bridge deck, which can lead to the corrosion of reinforcing steel, deck deterioration and the need for early deck replacement.

researcher testing permeability of a deck crack on the Smith Avenue Bridge
A researcher tests the permeability of a crack on the deck of the Smith Avenue High Bridge in St. Paul.

MnDOT maintains a list of approved bridge deck crack sealing products, but until now had little data on how well each one performs in the field. The recently published report also examined several products that are not currently on the Approved Products List.

Among the study’s findings: some of the products on MnDOT’s Approved Products List did not perform as well as other products that are not currently on the list. MnDOT is using the results of the study to update its qualification process for products to get on the approved list. Insights gained from studying application techniques will also be used to update MnDOT’s bridge maintenance manual.

*Note: This blog post was adapted from an article and technical summary that will be featured in the upcoming issue of the Accelerator newsletter.

More:

How roadside drainage ditches reduce pollution

Stormwater can pick up chemicals and sediments that pollute rivers and streams. Roadside drainage ditches, also known as swales, lessen this effect by absorbing water. But until recently, MnDOT didn’t know how to quantify this effect and incorporate it into pollution control mitigation measures.

In a recently completed study, researchers evaluated five Minnesota swales, measuring how well water flows through soil at up to 20 locations within each swale.

“There’s a big push in Minnesota, and probably everywhere, to do more infiltration,” Barbara Loida, MS4 Coordinator Engineer, MnDOT Metro District, said. “We know that our ditches are doing some of that, but we wanted to look at how much infiltration these ditches are providing.”

A key finding: grassed swales are significantly better at absorbing water than expected, which may reduce the need for other, more expensive stormwater management practices, such as ponds or infiltration basins.

This could save MnDOT and counties significant right-of-way and construction costs currently expended on more expensive stormwater management techniques. While swales were recognized in the Minnesota Pollution Control Agency’s new Minimal Impact Design Standards, there was a need to quantify the amount of water a swale can absorb so it could receive the appropriate MIDS credits.

Researchers also tested the ability of carbon, iron chips, steel wool and other materials to remove pollutants as ditch check filters—material put into swales to enhance removal of pollutants.

Gradations on a Modified Philip Dunne infiltrometer allow the measurement of stormwater infiltration.
Gradations on a Modified Philip Dunne infiltrometer allow the measurement of stormwater infiltration.
What’s Next?

A follow-up project, which the MPCA is participating in, will seek to clarify the impact of swale roughness on infiltration rates. The goal is a calculator for real-world infiltration rates that MnDOT and local agencies would be able to implement.

MPCA, MnDOT and the city of Roseville are also partnering on a project to install and test the effectiveness of ditch check filters in real-world locations.

Maintenance recommendations should help MnDOT and local agencies ensure that swales operate at maximum efficiency. These recommendations should continue to be revised as knowledge evolves.

Related Resources

*Editor’s note: This article was adapted from our upcoming edition of the Accelerator. Read the newsletter online, or sign up to receive by mail. 

Access Across America: University of Minnesota ranks accessibility to jobs by transit

New research from the Accessibility Observatory at the University of Minnesota ranks 46 of the 50 largest (by population) metropolitan areas in the United States for accessibility to jobs by transit.

The new rankings, part of the Access Across America study begun last year, focus on accessibility, a measure that examines both land use and transportation systems. Accessibility measures how many destinations, such as jobs, can be reached in a given time.

“This project provides the most detailed evaluation to date of access to jobs by transit,” says Andrew Owen, director of the Observatory. “We directly compare the transit accessibility performance of America’s largest metropolitan areas.”

The findings have a range of uses and implications. State departments of transportation, metropolitan planning organizations, and transit agencies can apply the evaluations to performance goals related to congestion, reliability, and sustainability. In addition, detailed accessibility evaluation can help in selecting between project alternatives and prioritizing investments.

“It can help reveal how the costs and benefits of transportation investments are distributed,” Owen says.

Top 10 metro areas: job accessibility by transit (January 2014)

  1. New York
  2. San Francisco
  3. Los Angeles
  4. Washington
  5. Chicago
  6. Boston
  7. Philadelphia
  8. Seattle
  9. Denver
  10. San Jose

The report—Access Across America: Transit 2014—presents detailed accessibility values for each of the 46 metropolitan areas, as well as detailed block-level color maps that illustrate the spatial patterns of accessibility within each area. In addition, time-lapse map videos for each area are forthcoming and new analysis of the data from the accessibility to jobs by transit rankings will be published periodically. Upcoming reports in the Access Across America series will explore more detailed aspects of transit accessibility to jobs, including accessibility to jobs of different wage levels and a comparison with accessibility by car.

In the study, rankings were determined by a weighted average of accessibility, giving a higher weight to closer jobs. Jobs reachable within 10 minutes were weighted most heavily; jobs were given decreasing weight as travel time increases up to 60 minutes. Travel times were calculated using full transit schedules for the 7:00 to 9:00 a.m. period. The calculations include all components of a transit journey, including “last mile” access and egress walking segments and transfers.

“Accessibility is the single most important measure in explaining the effectiveness of the urban transportation system,” says David Levinson, University of Minnesota civil engineering professor and principal investigator on the project.

According to Owen, accessibility can be measured for various transportation modes, to different types of destinations, and at different times of day. “There are a variety of ways to define accessibility,” Owen explains, “but the number of destinations reachable within a given travel time is the most directly comparable across cities.”

The research is sponsored by the Center for Transportation Studies at the University of Minnesota. Accessibility Observatory reports, including the analysis of job accessibility by auto published last year and interactive maps, are available on the Access Across America: Transit 2014 web page.

RailVolution showcases Minnesota transit successes

Before a national audience of 1,400 urban planners and transit enthusiasts, Hennepin County Commissioner Peter McLaughlin and others told the story of how the Twin Cities metropolitan area was transformed into a community that embraces “livability” and mass transit, including light rail.

“The growth was horizontal and there were lots of people who were saying it wouldn’t work in Minnesota,” said McLaughlin, during the opening plenary of the RailVolution conference in Minneapolis.

But the metro region bucked years of infighting and helped pass a transportation bill in 2008 that allows counties to tax for the expansion of transit in the metro area. Anoka, Ramsey, Hennepin, Dakota and Washington Counties decided to pool their resources from the quarter-cent transit sales tax, which is why the Southwest Light Rail Line is able to move forward.

“They had to believe their day would come,” McLaughlin said of the counties.

MnDOT Commissioner Charles Zelle, who ran a regional bus company before being appointed to MnDOT, said it was faster for him to bike to the conference than to take his car.
MnDOT Commissioner Charles Zelle, who ran a regional bus company before being appointed to MnDOT, said it was faster for him to bike to the conference than to take his car.

This was the first time the annual conference has been held in the Twin Cities, allowing Minnesota leaders to share their success stories.

Minnesota Department of Transportation Commissioner Charlie Zelle, who biked the Greenway trail to get to the conference, spoke of MnDOT’s commitment to multi-modal transportation and maximizing the health of Minnesota’s people and economy.

“MnDOT is more than a highway department,” he said. “We have a statewide bike plan and we will probably be the second state in the union to have a statewide pedestrian plan.”

Michael Langley of Greater MSP said a mix of transportation types is critical to attracting  talented workers to the Twin Cities, especially millennials.

“Nearly every area of the world is facing a future workplace shortage,” he said. “It’s fueling a competition for talent like we’ve never seen.”

Federal Highway Administration Secretary Anthony Foxx on Tuesday addressed conference attendees about the need for a bipartisan compromise on funding. He proposed moving away from the Highway Trust Fund to a more inclusive transportation account (named the Surface Transportation Trust Fund) that also addresses rail needs, with $19 billion in proposed dedicated funding. He also discussed the recent announcement of $3.6 billion in resiliency funds for transit systems.

During his comments, he wore a red bicycle pin that the MnDOT commissioner frequently wears at multi-modal events.

During the five-day conference, attendees toured the recently completed Green Line and attended dozens of workshops on topics ranging from street walkability to bus-rapid transit to the use of mobile phones to enhance bus service. On Sunday, the Northstar commuter train traveled for the first time to St. Paul’s Union Depot and conference attendees took it back to Minneapolis.

Minnesota transportation research blog

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