Category Archives: Maintenance Operations
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.
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.
- Minnesota Department of Transportation Metro Barrier Extraction and LiDAR Project – Final Report #2014-22 (PDF, 1 MB, 13 pages)
- Using Mobile Mapping to Inventory Barriers – Technical Summary #2014-22TS (PDF, 1 MB, 2 pages)
This blog post was adapted from an article in our upcoming issue of Accelerator, MnDOT’s research and innovation newsletter.
MnDOT saves time, money with new contracting method
Thanks to a flexible new contracting method, the cost and time of delivering small highway projects in Minnesota should go down.
The Minnesota Department of Transportation is now able to put road construction contractors on standby for certain types of projects, rather than bid each project individually, due to the adoption of Indefinite Delivery/Indefinite Quantity (IDIQ) contracts.
“IDIQ contracts give MnDOT more flexibility and the ability to get to the field quicker for work that we need repeated routinely, such as culvert repairs, overlays and seal coats,” said Kevin Kosobud, project development engineer with MnDOT’s Office of Construction and Innovative Contracting.
IDIQs also provide flexibility when needs are uncertain. Contracts are often used for multiple small projects that are similar in scope, but difficult to quantify in cost and timing.
For instance, the state of Florida awards IDIQs for hurricane debris removal, activating and paying contractors only when a hurricane necessitates the service.
Although IDIQs showed great promise, MnDOT had to develop a framework to implement them.
The federal government has used IDIQ contracts since the 1980s, but only a small number of state DOTS have used them to procure construction services. No standard procedures existed for their use by state DOTs, and federal procedures are not always applicable at the state level.
MnDOT hired Iowa State University researchers to examine IDIQ usage across the country and develop implementation procedures for Minnesota. (Read a summary of their research here.)
Researchers examined contracting practices at 14 different transportation agencies to recommend guidelines for Minnesota to follow, which allowed MnDOT to begin awarding IDIQ contracts in April 2013.
Case study analyses show clear benefits where IDIQ has been used: acceleration of the project delivery period, reduced construction costs and flexible delivery scheduling.
“IDIQs can help DOTs get better prices for routine services via an economy of scale, for instance, by awarding a contract for a larger number of culvert repairs rather than awarding a single contract for each repair,” explained Doug Gransberg, professor of construction engineering at the Iowa State University Institute of Transportation.
Agencies can award IDIQ contracts individually or collectively.
With a single-award contract, a single contractor is awarded task orders based on the pricing furnished in the initial bid package; multiple-award contracts determine a pool of qualified contractors who may subsequently bid on task orders.
*Editor’s note: This article was adapted from the September-October 2014 issue of our Accelerator newsletter. Read it online or sign up for your free subscription.
Related Resources
- Leveraging the Advantages of Indefinite Delivery/Indefinite Quantity Contracts – Technical Summary (1 MB, 2 pages); Final Report (expected Fall 2014)
New Video: “Why Aren’t They Working on My Road?”
A new video produced by the Local Road Research Board helps the public understand why some bad roads aren’t always fixed first.
The seven-minute video explains what causes road pavements to deteriorate and why, like the saying, “throwing good money after bad,” it may be more cost-effective to put maintenance dollars into roads that still have life left in them versus roads that are in the worst condition.
In it, city and county engineers discuss how they use a pavement management program to decide which roads to fix when, in order to stretch limited resources in the most effective way possible.
“We’ve learned that if we wait for things to break and fall apart, they’re much more costly to replace than if we put a little bit into it during its life cycle,” says Mark Maloney, City of Shoreview public works director.
GPS-equipped mowers to save money, reduce noxious weeds
Putting GPS units on MnDOT highway mowers is expected to speed mowing operations and cut herbicide usage by 50-percent in metro area ditches, reducing groundwater contamination.
MnDOT’s Metro District highway maintenance division will be one of the first — if not the first — state agencies in the country to equip the majority of its maintenance tractors with Automated Vehicle Location systems.
Not only will crews be able to effortlessly track their progress — reducing paperwork and freeing time for other maintenance activities — but the AVL’s live mapping software will help them avoid noxious weed patches, thereby reducing their spread.
“AVL alone enables the tracking of vehicle positions, but when combined with equipment sensors and an on-board monitor with user interface, it becomes a very innovative way to reduce operation costs,” said MnDOT Project Engineer Trisha Stefanski, who applied for funding from MnDOT’s Transportation Research Innovation Group for the pilot project.
Vehicle tracking systems have been shown to reduce chemical usage by crop farmers, improve route efficiencies in truck driving and help cities and counties track snowplows.
MnDOT Metro, which tested five AVL units last year, hopes to equip as much of its remaining fleet as possible.
In the grant application, Stefanski estimated the technology will pay for itself in about a year’s time, largely due to herbicide savings.
Noxious weeds
MnDOT is required by law to manage certain noxious weeds along its highways. Each year, weed inspectors survey one-quarter of metro ditches for weeds, which enables them to concentrate eradication efforts on the worst areas.
Touch-screen maps will contain the noxious weed locations so operators can see weed patches and mow around them.
Herbicide usage is estimated to drop an estimated $100,000 to $150,000 per year. (This estimate was based on the original funding request. Final numbers haven’t been released.)
Noxious weeds like Wild Parsnip — which can cause painful skin boils — might even be eradicated, reducing the risk for field crews, such as construction workers and Adopt a Highway volunteers.
Until now, maintenance crews have relied on paper maps to identify weed locations, which is less effective.
“What’s better, looking at a live screen when you’re going down the road and seeing where weeds are coming up, or trying to refer to a piece of paper?” Stefanski said.
Other advantages
The AVL equipment will also allow for automated reporting.
Mower operators can use the on-board AVL monitor to mark the location of guardrail hits, potholes, washed-out culverts, debris and unmarked noxious weeds.
Currently, operators must track their activities using hand-written forms or spreadsheets in the office.
The AVL system will also automatically track their location history, allowing operators to optimize their routes based on how long it took to mow segments in the past.
It will also be easier to answer questions from the public, who want to know the last time a certain ditch was mowed.
“Making everything geographically located adds so much analysis opportunity,” Stefanski said.
MnDOT also has AVL technology on an herbicide applicator to better track where it’s sprayed. Other future potential applications including pothole patching and road sweeping operations, Stefanski said.
Deicing treatments tested at Valleyfair, Canterbury Park
Excalibur and the High Roller may be closed for the season, but Valleyfair Amusement Park still has one attraction open for the season: a driving track for Minnesota snowplow drivers.
MnDOT-funded researchers are studying the effects of weather and vehicle traffic on different deicing treatments in the parking lots of Valleyfair and Canterbury Park in Shakopee, Minn.
It’s been a busy winter, but each week MnDOT Metro District snowplow drivers make one last stop before heading home, to apply different combinations of salt and anti-icing chemicals to nine 1,000-foot driving lanes. They also drive over each lane multiple times to test the effect of traffic.
“We’re running trucks up to 30 miles per hour with different speeds, wind conditions, traffic conditions and pre-wetting chemicals,” said Steve Druschel, a researcher with the Minnesota State University, Mankato. “Each lane is its own experimental unit.”
Professor Druschel’s students will review more than 17,000 photos from time-lapsed cameras to document how the snow melted in each experimental run.
“The influence of factors like pavement type and age, traffic volume, truck proportion, weather conditions and sun presence will be assessed to evaluate which techniques have special advantages for certain situations or roadways,” said Maintenance Research and Training Engineer Tom Peters.
In 2010, Druschel tested 25 anti-icing compounds in 1,500 different combinations in a laboratory to study the effectiveness of different deicers.
“Public work superintendents commented, ‘Great work. It looks good, except it’s all in the lab. Beakers aren’t what people drive on,’ ” Druschel said. “So we’re taking it from the two-inch ice cup to the real world in phase two of this study.”
With rock salt prices quadrupled, finding the most cost-effective methods of treatment is important.
This latest research will help determine the best times for applying anti-icing treatments and examine whether certain chemicals — such as a pre-storm liquid treatment that costs twice as much — melt enough snow to be worth the extra cost.
Test runs in Shakopee are strictly experimental, but in Mankato students are analyzing how real-world salting treatments are working on the North Star Bridge.
An article in the Mankato Free Press tells how Druschel’s team is collecting road melt runoff and documenting bridge traffic. (Big trucks, for instance, squeeze more water out of the snow.)
Students plan to use time-lapsed photos, along with weather data and snowplow records, to determine what chemical treatments worked best – and when.
With the multi-pronged research project, Druschel hopes to put definitiveness to what some snowplow drivers have already tried in the field.
“The key to it is not so much that we’re so smart and we have a better idea or are inventing something new,” he said. “We’re just trying to enhance what they are already doing.”
Helpful resources
Salt Brine Blending to Optimize Deicing and Anti-Icing Performance –Technical Summary (PDF, 1 MB, 2 pages) and Final Report (PDF, 11 MB, 151 pages) (previous study)
New study to shed light on environmental impacts of deicers
Even naturally derived products like corn syrup and beet juice can impact the environment when applied to salt mixtures for winter roadways.
A wide range of products, including the ones mentioned above, are added to deicing mixes to limit the amount of salt needed for Minnesota roads each winter. However, although information is available about the corrosive properties of various deicing chemicals, less is known about the toxicity of these compounds, especially to the aquatic environment.
Thanks to a recently completed project sponsored by the Clear Roads Pooled Fund, MnDOT winter maintenance personnel will better understand the relative toxicity of eight common deicing agents, which also include non-organics like Magnesium Chloride, Calcium Chloride and Potassium Acetate.
“Because the state has been trying a lot of different alternative chemicals, we wanted to get a better handle on the environmental impacts,” said MnDOT engineer Tom Peters, the technical liaison for the 26-member, Minnesota-led pooled fund for winter maintenance research.
In January, researchers plan to release a concise summary of the toxicity rankings to help winter highway maintenance managers consider both expected levels of service and potential harm to the environment when selecting a deicer.
A Dec. 3 webinar available on the Clear Roads website discusses their findings.
About Clear Roads
Minnesota is the lead state for the Clear Roads Pooled Fund, which conducts rigorous testing of winter maintenance materials, equipment and techniques. Other recent and upcoming research (see our Technical Summary on the program) includes a winter maintenance cost-benefit analysis toolkit, snow removal techniques at extreme temperatures and environmental factors that can cause fatigue in snowplow operators.
You can learn more about Clear Roads via the project’s e-newsletter.
Robotic message painter could help keep road crews safe
Using rollers and stencils to draw turn arrows and crosswalk stripes on roads seems a bit archaic to MnDOT District 3 Maintenance Superintendent Randy Reznicek, who asked researchers if they could develop an automated road message painter.
University of Minnesota-Duluth Associate Professor Ryan Rosandich has taken that vision and created an robotic arm that can spray-paint pavement signs, with the goal of saving crews time and keeping them safer.
Designed to be mounted to the front of a maintenance vehicle, the robot is operated remotely by a laptop, programmed with numerous types of messages.
In an earlier prototype, researchers developed a trailer painter that could be pulled behind a truck.
Crews currently use heavy, eight-foot by four-foot stencils and rollers to paint designs, with an estimated 75 percent of such work involving the repainting of existing markings.
“It takes two people to lift the stencils,” explained MnDOT maintenance worker Joe Gilk, whom Reznicek presented with the idea about five years ago. “This would eliminate one position. One person could just run the truck and you could use that other person in another area of our job.”
Rosandich, who heads the Mechanical and Industrial Engineering Department at the University of Minnesota-Duluth, led the initial development of a software system and trailer painter.
MnDOT has funded further research to develop the more technically difficult robotic arm, which it anticipates could be used in other aspects of maintenance work as well.
Rosandich recently demonstrated the mechanical arm to a MnDOT road crew (no paint was used during the demonstration), but additional software and mechanical tweaks remain before researchers take the machine out for final testing on the pavement this spring.
A companion vision system is being developed to identify existing markings to guide the robot in the repainting of existing messages.
The robot’s three-segmented aluminum shell arm is capable of painting up to a 12-foot wide lane and has enough battery power for a whole day’s worth of work, Rosandich said.
Once the prototype is complete, researchers hope to find a manufacturer to develop and produce a machine that could be used by maintenance crews across the state. MnDOT has already had great success in deploying automated pavement patching systems in some districts.
Not only would a robotic message painter free up maintenance crews and speed up sign-painting, but Rosandich sees worker safety as its “biggest selling point.”
The start-up cost for manufacturing such a device is estimated to be $150,000.
New videos show how frost heave ravages roads
Regardless of whether you’re familiar with the term “frost heave,” if you live in Minnesota and drive on the roads, you’re already familiar with its destructive capacity. Many of the dips, bumps, potholes and cracks that appear on our roads every spring are a direct result of frost heave, which occurs when water accumulates in the soil beneath the pavement and begins freezing and then thawing along with the changing seasons. The resulting expansion and contraction weakens the road base and leaves it susceptible to damage from traffic loading.
These new videos produced by the Local Road Research Board explain how frost heave works, and describe some of the strategies public works departments use to combat it. The top video is is the shortened, executive-summary version, while the bottom video is the full, 13-minute version meant for transportation professionals.
Patching pavement with microwaves and magnetite
On Wednesday, I had a chance to watch a demonstration of a uniquely Minnesotan pavement patching technology that combines an industrial-strength microwave with a special asphalt mix. What makes it “uniquely Minnesotan?” In addition to having been developed by University of Minnesota researchers and a Monticello-based company (and with some funding from MnDOT), this innovative method involves a special asphalt mix using magnetite, a mineral that abounds on Minnesota’s Iron Range.
It also addresses a very Minnesotan transportation problem: winter pavement repair. In the video above, Kirk Kjellberg of Microwave Utilities, Inc., highlights some of the benefits of using the 50,000-watt microwave to heat the pavement during patching. In addition to creating a longer-lasting patch, the microwave is considerably faster than many alternative techniques. The technology is still relatively new, but its supporters claim it allows for pavement repairs in the middle of winter that are as strong and durable as the ones road crews do in the summer.
The demonstration, which was organized for members of the Local Road Research Board, took place at MnDOT’s District 3 training facility in St. Cloud.
See also:
- “Three Ways to Cook a Pothole” (June 5, 2013)
- In the news: innovative U of M and MnDOT pothole repair technology (April 30, 2013)
Crossroads 