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MnROAD celebrates 20th anniversary, prepares for next research phase

Researchers from around the world rely on Minnesota’s pavement testing center, MnROAD.

Minnesota alone saves at least $33 million each year, thanks to quantifiable advances made at MnROAD. The annual nation-wide savings is thought to be even larger: $749 million.

Established in 1994, MnROAD partners with the FHWA, industry and dozens of other states and countries to conduct research on two live test tracks in rural Albertville.

No other cold-weather facility offers such an array of pavement types with thousands of electronic sensors recording both environmental changes and dynamic truck testing.

“If not for MnROAD, many of our projects wouldn’t be nearly as successful,” said Highway Research Engineer Larry Wiser of the Federal Highway Administration.

At an Aug. 6 open house, this one-of-a-kind research facility celebrated 20 years of finding ways to make roads last longer, perform better and cost less.

Two separate road segments contain 51 test cells, with different combinations of surface materials, aggregate bases and subgrades, as well as variations in structural design and drainage features.

MnROAD consists of two unique road segments located next to Interstate 94.
MnROAD consists of two unique road segments located next to Interstate 94.
Annual Savings

MnROAD’s initial research on pavement life and performance (from 1994 to 2006) reduced maintenance costs, repairs and motorist delay.

In the second phase of research, MnROAD reconstructed almost 40 test cells for more than 20 different studies. The benefits derived from this work is estimated to be worth nearly nine times what the studies cost – and that’s just the benefit for Minnesota.

“We’re excited for the third phase of research, which will be mainly focused on maintenance and rehabilitation,” said MnROAD Operations Engineer Ben Worel. “We’ve seen the benefits of our past research and expect the same in the future.”

MnROAD’s facility includes:
– A test section of I-94 carrying live traffic
– A low-volume roadway that simulates rural road conditions
– Thousands of sensors that record load response and environmental data.

power broom

Chip sealing: not just for local roads anymore (video)

Chip-sealing — spraying an asphalt emulsion over existing pavement and then covering it with fine aggregate — is a cost-effective alternative to resurfacing asphalt pavements. Traditionally, however, it has only been used on rural and low-volume urban roadways.

During a recent visit to MnROAD, we filmed a road crew chip-sealing a test section on I-94 and spoke with MnDOT Research Project Supervisor Tom Wood, who explained why chip sealing can also be an effective treatment for high-volume roadways.

*Note: This story was updated on 08/12/2014 to clarify that the chip sealing shown in the video involves spraying an “asphalt emulsion” rather than “hot liquid asphalt,” as stated in an earlier version of this post.

Reducing construction pollution by skimming stormwater ponds

Soil carried away in stormwater runoff from road construction sites can pollute lakes and rivers.

Stormwater settling ponds provide a place for this sediment to settle before the water is discharged into local bodies of water. However, since stormwater ponds have limited space, a mechanism is needed to remove clean water from the pond to prevent the overflow of sediment-laden water.

MnDOT-funded researchers have designed temporary stormwater ponds with floating head skimmers that can remove clean water from the surface of the settling pond, using gravity to discharge water into a ditch or receiving body.

The Marlee Float from the SW Fee Saver is one of five currently available floating-head skimmers that researchers identified.
The Marlee Float from the SW Fee Saver is one of five available floating-head skimmers that researchers identified.

This is a new approach for MnDOT and Minnesota cities and counties, so research was needed to provide practical guidance for how to use these devices on construction sites.

“This was a small-scope implementation project for professionals to use as they design temporary stormwater ponds that meet state parameters,” said Dwayne Stenlund, MnDOT Erosion Control Engineering Specialist.

A new MnDOT study identifies five methods for “skimming” stormwater ponds that can improve a pond’s effectiveness by 10 percent. MnDOT researchers also created designs for temporary stormwater ponds on construction sites with the capacity to remove approximately 80 percent of suspended solids.

These designs will help contractors meet federal requirements for stormwater pond dewatering. Researchers also determined how often a pond’s deadpool must be cleaned, based on watershed size and pool dimensions.

“When sediment settles, it’s hard to determine when to clean out a pond. Based on the density of the sediments in the Minnesota River and the loading rates we computed, we were able to calculate how often we need to clean out a pond so sediment doesn’t reach the height of the skimmer,” said Joel Toso, principal of Wenck Associates and a consultant for the project.

Resources

Reducing Construction Pollution by Skimming Stormwater Ponds – Technical Summary (PDF, 2 MB, 2 pages); Final Report (PDF, 3 MB, 43 pages)

MnROAD five-axle truck

What it’s like to drive a 40-ton truck in circles for science (video)

The only way to test pavements is to destroy them — slowly and painstakingly, one moving vehicle at a time. At MnROAD, the state’s world-renowned pavement research facility, the bulk of this monotonous-but-necessary work is performed by live traffic passing through Albertville on I-94. But on the facility’s 2.5-mile low volume road test track, which simulates rural road conditions, more controlled methods are preferred.

Doug Lindenfelser is one of several MnROAD employees who take turns driving an 80,000-pound semi tractor trailer in laps around the closed-loop low-volume track. The truck is loaded to the maximum allowable weight limit on Minnesota roadways. As it passes over the facility’s 23 distinct low-volume test cells, an array of sensors capture data on the pavement’s performance, which researchers then use to design stronger, longer-lasting roads. The truck only drives on the inside lane; that way, the outside lane can be used as an “environmental lane” to compare  damage caused by loading  vs. damage caused by environmental factors.

He has other duties as well, but on a given day, Doug might drive the truck 60 or 70 times around the low-volume road test track. It might not sound very exciting, but as Doug explains, some days his job can be quite interesting. We interviewed him on camera during a recent visit to MnROAD. The resulting video is available above and on our YouTube channel.

For those who might be wondering, all this diligent destruction of pavement has paid off. It is estimated that MnROAD’s first phase of research (from 1994-2006) has resulted in cost savings of $33 million each year in Minnesota and $749 million nationally. Cost savings from its second phase (2007-2015) are being calculated, and the facility is scheduled to enter its third phase in 2016.

Learn More:

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LRRB web tool tracks research projects around the state

As public works employees come and go, past research efforts — and the valuable knowledge gained — often goes with them.

But a recently launched web application allows users to track innovative pavement projects for a lifetime.

“It’s something everyone has always said we need to have,” said MnDOT Research Operations Engineer Jerry Geib, who worked on the project for the Minnesota Local Road Research Board.

Using an online map, city and county engineers can enter road test sections that they want to observe for many years due to a particular construction method or material that was used. Too often, the knowledge about such projects is lost when a particular staff person leaves an agency.

Not only will the lessons learned be remembered within the organization, but the results can also be shared with others.

More than 1,400 projects (including some on state roads) previously identified by MnDOT have been entered into the system. Search fields allow users to look for a particular type of project anywhere in the state or they can zero the map in on a particular area of the state.

The website is still in beta form, but functional.

“It’s complete, we just want people to use it so we can improve it,” said MnDOT Research Project Engineer Melissa Cole, who began planning the site two years ago.

One featured project is a 1.8-mile section of dirt road in Wabasha County that had an Otta seal applied in 2007 (photo below). It is one of only a handful of lightly surfaced roads in the state (an improvement over a gravel road, but less expensive than asphalt ) so there is great interest in watching how it performs.

One of the projects being tracked is Wabasha County Road 73, one of only a couple lightly surfaced (Otta seal) roads in the state.
One of the projects being tracked is Wabasha County Road 73, one of only a handful of lightly surfaced (Otta seal) roads in the state.
More to come

The LRRB initiated the project in 2009, but it was put on the back burner for a while due to funding constraints. MnDOT ‘s technology staff began development of the current site about 11 months ago.

Anyone can look at the website, but cities and counties require permission to post projects (contact ResearchTracking.DOT@state.mn.us for credentials). They  can upload photos, plans and weblinks relating to a particular project.

“We want to track anything that is worthy of looking at a few years from now,” Geib said.

Because the website uses Google maps, users can also view archived satellite and ground-level 360-degree imagery of the roads and bridges.

The website is viewable on a tablet, but it still must be tested on smart phones. Developers hope that crews will be able to submit information right from the field.

“We’re pretty happy with it,” said MnDOT software developer John Jones. “We think we’re headed in the right direction.”

The website might eventually be expanded for other areas, such as geotechnical (foundation work), whose practitioners have already expressed an interest.

A rumble strip applied to a center line on Highway 14 near New Ulm in 2004 is being tracked.
A rumble strip applied to a center line on Highway 14 near New Ulm in 2004 is one of the projects being tracked.
Slide-in Bridge

Behind the bridge slide: dish soap and a lot of planning

Using Dawn dish soap to grease the rails, MnDOT crews inched the new Larpenteur Avenue Bridge into place two weeks ago using an innovative construction method.

As the bridge reopens to traffic tonight over I-35E, MnDOT celebrates the success of its first slide-in place bridge construction.

“The slide-in worked very well,” said David Herzog, MnDOT’s project manager for the I-35E Corridor – MnPass Project. “I think the process has given us the confidence to possibly use it again in the future.”

Slide-in technology

The slide-in method has been used in the past for railroad bridges and large bridges with high traffic and limited construction options. Now, state agencies and the Federal Highway Administration are applying the method to smaller, more routine bridges to minimize impacts to the traveling public.

Whereas the typical phased construction of a bridge builds one-half of the structure at a time, slide-in bridge technology allows the entire superstructure to be built at once, requiring just a brief, temporary closure of the highway.

Crews constructed the 3.5-million-pound Larpenteur Bridge right next to the existing bridge and then slowly slid it into place during the course of two nights. This effectively sped up construction from 110 days to 47 and reduced traffic impacts to drivers. (Watch video of the slide.)

The quality of the bridge also improves with this method, since it eliminates the deck construction joints and girder camber problems associated with phased construction, according to the FHWA. The pressure to use faster concrete cure times is also reduced.

History

With a quarter of the nation’s bridges in need of repair or replacement, the FHWA is pushing the slide-in method as a cost-effective technique that can cut construction time in half. It has previously been used in Oregon, Utah, Missouri, Michigan, Colorado and Massachusetts.

The concept has been around for more than a century, but slide-in technology is relatively new for small or medium-sized bridges, and it’s the first time MnDOT has attempted it on a state bridge.

Although MnDOT staff had flown out to Utah to view a slide-in, it was Burnsville-based Ames Construction that proposed reconstructing the Larpenteur Avenue bridge that way when it made its successful bid for the corridor project.

The slide-in method is about 15 percent more expensive, Herzog said, but it allowed the bridge to re-open in 47 days, versus 110 days.

Earlier this summer, Ames replaced the Wheelock Parkway and Arlington Avenue bridges in conventional fashion, although they were only closed for 65 days because they were constructed on a very accelerated timetable.

“Larpenteur is more of a major thoroughfare and we thought shortening the duration of its closure would be more valuable to  MnDOT,” said Steve McPherson of Ames Construction, who was brought in from Utah to oversee the corridor project.

The fast reconstructions will allow the company to complete the bridge replacements and highway reconstruction in just 120 days. Next year it’ll finish the other half of the corridor.

All three bridges are being replaced to make room for the new MnPASS lane on I-35E.

One of the drawbacks to slide-in technology is that it requires ample room to build the bridge on-site. An alternative is to construct off-site.

The new Maryland Avenue/I-35E bridge was built off-site, as was the Hastings Hwy. 61 bridge. It was then loaded onto a barge, floated down the Mississippi River and lifted into place.

Related Resources
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Changing demographics and travel choices may shape a very different future

Though no one can predict the future, thinking about how today’s changes may shape the future of transportation in our country is more important now than ever before.

“It’s critical that we understand the significance of things that are taking place and prepare for what may come,” said former Utah Department of Transportation CEO John Njord in the opening session of the 25th Annual CTS Transportation Research Conference. “For us to be relevant in the transportation business, at a minimum we have to be adaptable to change, and ideally we want to be leading change in the transportation industry.”

In his current position at Tom Warne and Associates, Njord has gained an in-depth understanding of the trends affecting the future of transportation in the United States while spearheading the Transportation Research Board’s “Foresight” project—part of the organization’s forward-looking NCHRP Report 750 Series. The project addresses a wide range of topics, including: What if the oil-fueled auto era ends and revenue from gas taxes dries up? What if engineering practices must be upgraded to ensure resiliency to natural disasters as global warming continues? What if technology such as self-driving cars eliminates or reduces the need for human drivers? What if tomorrow’s economy requires radically different freight patterns?

Perhaps most significantly, the project explores the possibility that Americans are losing their appetite for driving. Vehicle-miles traveled (VMT) per capita been dropping since 2004, without any signs of recovery. “It’s impossible to know whether that number will start growing again, stay flat, or continue to drop,” Njord said.

Other trends make the future outlook equally complex. In 50 years the United States will likely be home to 100 million more people, so even if VMT per person stays flat or declines, it’s likely total VMT will be larger than it is today. The population is also aging: by 2030, 20 percent of the population will be over 65 and will likely drive less. In addition, Millenials are staying home longer and waiting until later in life to get married and have children—all of which affects their travel behavior.

To help transportation planners consider all possible futures, the Foresight project encourages the use of multiple-scenario planning. “We need to begin considering all the possible scenarios and generating plans that are independent and distinct from one another,” Njord advised. “The act of thinking about these things is fundamentally important, because the shift that is now taking place means we’re going to have to do things much differently in the next 50 years than what we’ve done in the past 50 years.”

Following Njord’s presentation, a panel of experts discussed how the the Foresight project could relate to what’s happening in the Twin Cities region. An article summarizing their comments is available in the July issue of Catalyst.

2014 07 16 get connected

New website engages public on transportation investments

The Minnesota Department of Transportation has launched a new  website called “Get Connected” to answer Minnesotans’ most basic questions about how the state invests its transportation dollars.

The one-stop site answers these topics through interviews with MnDOT leaders, links to long-term transportation plans and graphics showing where the money goes (such as this eye-opening snow-and ice removal cost chart).

This site also highlights some of MnDOT’s most innovative projects. A “Transportation in the News” section showcases recent media coverage of MnDOT’s work and related articles from other states.

“Minnesotans have a right to know how their tax dollars are being invested and to be confident that MnDOT is spending public money effectively on transportation,” said Tracy Hatch, MnDOT deputy commissioner, chief financial officer and chief operating officer.

Tour the “Get Connected” website at www.mndot.gov/getconnected.

Bonus: here’s a video recap of 2013 projects from the new website:

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Watch MnDOT slide a 3.5-million pound bridge into place

It’s old news already, but any blog about transportation research and innovation in Minnesota would be remiss if it didn’t mention this amazing video of MnDOT workers sliding the new Larpenteur Avenue Bridge into place late last week.

The slide-in method is an accelerated bridge construction technique that allowed MnDOT to speed up the project and cut the the amount of time the bridge will be closed by more than half. It’s also cheaper and safer. This project marks the first time the slide-in method has been used in the state.

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