Category Archives: Uncategorized

QUALITY CONCRETE

The I-15 CORE project team does its homework before placing concrete.

A concrete curing/tinning machine on the I-15 CORE project.

At a month past the half-way point, workers on the Utah County I-15 Corridor Expansion project have placed over 1.7 million square yards of concrete. “Since concrete pavement is smooth, requires less maintenance and resists potholes, it’s often a good choice on high-volume roads,” explains John Butterfield, UDOT Materials/Pavement Engineer for the project. But regardless of pavement type, “the main thing that drives pavement design is traffic.” I-15 CORE pavement is built for longevity and strength.

During the bidding process, UDOT asked for 30-year pavement. Provo River Constructors included a 40-year pavement design as a value-added feature in their winning proposal. The entire pavement section, bottom to top, consists of four layers: granular borrow, drainable granular borrow, asphalt base and 12 inches of Portland Cement Concrete Pavement on top. Together, the layers in the pavement achieve a structural value that is predicted from the road’s expected traffic volume.

Making sure the top layer of concrete meets final acceptance — and lasts that expected 40 years — starts with an understanding of how the specific concrete mix design will cure. For that important task, the I-15 CORE project team uses maturity meters — electronic sensors embedded in concrete and handheld readers. Using maturity meters has become standard practice in the building construction industry and is common in road construction.

Do the math

Before concrete is placed on the I-15 CORE project, “there is some homework that’s required,” says Butterfield, who explains the process. Because the compressive strength of a specific concrete mix design has a relationship to time and temperature, a maturity curve that shows that relationship can be charted. When inserted into core cylinders, maturity meters can be connected to a reader to access information on time and temperature, making the process very precise.

Data is collected by casting concrete cylinder samples and tracking the time and temperature of the concrete as it cures and gains strength. Then, the cylinders are broken at pre-set intervals to determine compressive strength, and that data is recorded and correlated to the time and temperature data.

Progressing work or allowing traffic on the pavement

Once data is collected and plotted, the “homework” maturity curve becomes an appropriate basis to measure the strength of in-place concrete. Workers assess concrete strength simply by taking a quick electronic reading in the field from data loggers embedded in the pavement. When the correct concrete strength is reached, work can progress or traffic can be allowed on the pavement.

For final acceptance, traditional cast cylinders made from the same batch as in-place concrete are still broken to measure 28 day compressive strength. However, for determining interim strength for the purpose of progressing subsequent work, maturity meters are a more efficient, precise and less expensive method than casting and breaking several additional cylinders.

“One of the greatest benefits of maturity meters is that they provide the strength of the actual ‘in-place’ concrete,” Butterfield says. “We no longer have to break cylinders, either lab-cured or field-cured, and speculate how closely they correlate with the strength of the actual structure.”

CURING CONCRETE

SLIDE SHOW: Concrete is monitored and tested for strength in order to progress work, allow traffic on the pavement or to determine final acceptance.

The compressive strength of concrete has a relationship to time and temperature specific to the mix design. As concrete hydrates, it cures and gains strength. Hydration occurs as the cement becomes fully saturated by the water in the concrete. The hydration process produces heat. Taking time and temperature readings of the concrete as it cures and gains strength allows workers to track the curing process.

(Click on the large images to see captions. Choose images by placing cursor in the black area below.)


Created with Admarket’s flickrSLiDR.

MASH UP

The Manual for Assessing Safety Hardware updates the size of test vehicles to more closely match what’s on the road today.

All permanently installed and temporary roadside hardware – including sign bases, crash cushions, traffic control devices, and various kinds of barriers, is crash tested according to standards established by the National Cooperative Highway Research Program. New standards for crash testing have recently gone into effect, and are detailed in AASHTO’s Manual for Assessing Safety Hardware. The new manual replaces NCHRP Report 350.

This video shows crash testing using MASH standards.

The MASH updates protocol for vehicles that are used in crash tests to more closely match what’s on the road today. The new crash test criterion is being used on all roadway hardware being produced since January 2011. NCHRP Report 350-tested hardware is appropriate when replacement is necessary, and re-testing is not required. UDOT will update roadway hardware with MASH tested products as necessary – the old hardware in place now is safe.

Although crash testing took place as early as the 1930’s, standards that establish criteria for tests have been in effect since 1962 with sedans specified as a test vehicle. As crash testing has continued through the years, understanding about the practice has improved and updates that add more criteria and different procedures have been added. For example, a 1974 NCHRP update added a small car and also added tests for transitions, terminals, crash cushions and breakaway supports. A 1980 update added evaluation criteria and modernized procedures to conform to available technology and practices. In 1993, a pickup was added as a test vehicle to represent small trucks and minivans in use.

The Texas Transportation Institute is one of the first organizations to crash test hardware, including sign bases and crash cushions. The TTI facility, a decommissioned military air base, has long concrete runways that make a good setting for the tests. The modern TTI crash test video below shows a crash test of a concrete barrier on a mechanically stabilized earth wall using the larger truck specified by the new MASH standards for vehicles.

For more:

Download the MASH.

Read a recent post about tests on MSE walls.

See an interactive timeline about crash testing at TTI.

Watch a presentation about how crash test standards have changed.

 

SAFE MOVE

UDOT’s use of an innovative traffic control system has earned national recognition for improving safety in an urban construction zone.

Using moveable barrier helped UDOT balance the needs of road users and workers by keeping traffic flowing and providing a large, safe work zone. Here, moveable barrier being adjusted to give west-bound evening commuters an additional travel lane.

The Federal Highway Administration and the Roadway Safety Foundation will recognize UDOT as a winner of the 2011 National Roadway Safety Award for using moveable barrier on the 3500 South reconstruction project. The annual award program honors “high achievers in the field of roadway safety” for using and documenting safety best-practices. The award will be presented on Tuesday, November 15 in Washington D.C.

While common on interstate highways across the nation, urban use of moveable barrier is less common. The flexible lane use system can be adjusted frequently to accommodate traffic flown by providing more lanes in the peak travel direction.  UDOT’s pioneering use of the innovative technology on an urban travel corridor will help other departments of transportation employ the effective safety strategy on projects with similar characteristics.

Moveable barrier helped improve safety, accommodate commute traffic, and shorten the duration of the project. The barrier improved safety by eliminating left turns, except at major intersections. Twenty to 25 fewer crashes occurred during the project, resulting in a safer roadway, less expense to road users and less delay due to crashes.

Traffic delay, which causes inconvenience, also has an associated user cost. Because morning and evening traffic flow was not severely mired, road users saved time and money. A conservative estimate shows that using the moveable barrier saved road users between $1.7 to 2.4 million by reducing travel delay and crashes during construction.

Reducing  the duration of projects is one of the most important ways UDOT limits the inconvenience of construction on road users. Using the moveable barrier provided a large, safe work area where construction could progress more efficiently. Partly as a result of the barrier, the project was completed 7 months ahead of schedule, leaving road users and businesses with a wider, high functioning roadway free of excessive delay.

HIGHWAY SAFETY BLOG

A new blog uses many voices to tell Utah road users how to stay safe.

For some serious fun, take a motorcycle safety class. Rachel Leiker did so and wrote about her experience for the Highway Safety Office Blog.

The Utah Department of Public Safety, Highway Safety Office has a new blog that uses a variety of authors to promote safety. Experts when it comes to safety on the road, blog authors are personally involved in a number of important efforts. “Our office’s program managers are passionate about their programs and it shows in their writing,” says Derek Miller, Highway Safety Program Specialist and one of the authors.

The Office of Highway Safety has 13 programs aimed at all types of road users – cyclists, motorists and passengers. The programs emphasize knowing the rules of the road and making the best choices, like wearing approved protective gear when riding a motorcycle.

Many posts are also backed up by studies or statistics with punch. A Click It or Ticket post by Kristy Kay cites how high visibility enforcement of safety belt laws helps save lives: “…the Click It or Ticket mobilization is credited with helping to increase the state’s belt usage rate from 67.4 percent in 2000 to an observed rate of 89.0 percent in 2010. Belt use saves thousands of lives each year across America and seatbelts have saved an estimated 1,355 lives in Utah since 2000.” That direct message is a great example why everyone needs to buckle up!

Even though the topics are serious, authors convey messages in an entertaining way. Author Helen Knipe’s post  explains how being a cyclist helps her drive with respect, and observe the rules of the road: “When I see cyclists in the road, I see myself  (except they’re usually riding faster than I do…) I have no problem waiting to pass a cyclist, giving cyclists extra room, exercising greater caution whenever they’re around – because that’s exactly what I would want drivers to do around me when I’m on my bike.”

Many of the posts have great images and videos that speak volumes. High school student Jake Barube won an iPod touch for his visually appealing motorcycle safety video using stop motion animation.

Jake’s on-camera narrative also uses humor. He urges motorcycle riders to wear approved protective gear “unless you enjoy the taste of asphalt.” His parting sentiment, “The safer you are the more fun you’ll have” are words any parent would want their teen to understand.

Guest posts give some good safety narratives too. Rachel Leiker attended a motorcycle safety training class. In her post she says, “This is seriously one of the most fun ways to spend a weekend, and the skills you learn don’t hurt either.”

Bookmark the site and check back often!

SALT

Recent cold weather is a reminder that snow is on the way. One way UDOT prepares for winter weather is by stocking road salt at maintenance facilities around the state.

Redmond, Incorporated operates this salt mine in Central Utah. The salt is a remnant of an ancient sea. A variety of products, including road salt are produced from the mined salt.

Road salt deliveries have occurred in some of the high mountain areas and soon all UDOT Maintenance Station storage facilities, in areas where snow is expected, will have plenty of salt on hand.  UDOT uses 215,000 tons of salt per year —  two-thirds solar salt, one-third rock salt.

“As essential to life as water – ubiquitous – so precious anciently that Roman Legionaries were paid their wages with sal, which is Latin for Salt,” says UDOT Maintenance Methods Engineer Lynn Burnham. “Hence the English word salary.” Bernhard earns his salary planning maintenance methods that keep UDOT roads safe and clear.

Wet salt will re-crystallize with a hard crust that’s difficult to break up, so most salt is stored in covered salt sheds that keep salt dry during stormy weather. Salt is stored at 80 maintenance facilities and 26 other storage areas around the state. There is no central stockpile.

Salt is purchased on contracts set up at UDOT headquarters, and station supervisors order the amounts and type needed for the roads in their area. Most stations place their orders in September and have their salt sheds full by mid October.

UDOT buys reddish-brown rock salt from an underground mine in Central Utah and white evaporated or solar salt from the Great Salt Lake. Both types work well, but salt types have different properties so station supervisors order what works best in each specific climate.

“Utah has an advantage over other snow-belt states,” says Bernhard. “Our salt sources are literally in our own backyard, so we do not have to order a full year’s supply at one time.” Other states anticipate the amount of salt needed and order a year’s worth at one time. If accurate estimates are not made, salt may run out, and leave workers in the lurch.

A truck is loaded with salt from the Great Salt Lake

 

“We could place an order one day and expecting delivery by the next afternoon,” says Bernhard, who adds that UDOT supervisors keep very close watch on inventory so one-day delivery is not needed. “Our goal is to end the snow season with no salt left in our stockpiles.”

 

WILD AWARD

FHWA has given UDOT and partner agencies an award for successful wildlife mitigation efforts on U.S. Highway 6.

First to be photographed at Beaver Creek Bridge

Beaver Creek Bridge on US-6

A diverse team of experts from federal and state government joined forces in 2005 to find better ways to help wildlife get across US Highway 6 between Spanish Fork and Price, Utah. Members from the Wildlife Coordinating Committee, drawing from FHWA, UDOT, U.S. Fish and Wildlife Service, Utah Division of Wildlife Resources, the Bureau of Land Management, Uinta National Forest Service, and Utah State University, collaborate to identify high wildlife-vehicle collision spots and make recommendations for improvements.

“Their efforts are showing measurable success,” says Brandon Weston, UDOT Environmental Manager and chairman of the committee. FHWA has recognized that success with a Exemplary Ecosystem Initiative Award.

The committee has been successful by studying wildlife habitats, building cross-agency partnerships and using innovative solutions backed by the best science available, according to Rebecka Stromness, past UDOT Environmental Manager.  Stromness wrote the nomination for the award, which points out that many past activities, including  construction of the original road and railroad, logging, fur trapping, livestock grazing, agriculture, and urban development, have served to eliminate or degrade wildlife habitat. “With the implementation of mitigation for each specific project, vehicle-wildlife collisions are being reduced and wildlife movement across the highway is gradually being restored.”

Professor Patricia Cramer, a wildlife research assistant professor with Utah State University, is tracking the success of crossings by placing cameras to record images of wildlife. Cramer joined the committee years before research started. Knowing UDOT was planning an ambitious and challenging effort to improve safety on US-6, she saw the potential for the highway to be the “crown jewel of wildlife crossings in Utah.” Her research started with a UTRAC grant and continues with funding from Utah Division of Wildlife Resources.

Doug Sakaguchi, Habitat Biologist with the Utah Division of Wildlife Resources, has served on the committee since 2005. The success of the committee in collaborating to reduce the number of wildlife killed is “exciting to me,” says Sakaguchi. His graph (below) shows a reduction in the number of carcasses before and after two bridges were replaced with new bridges that accommodate wildlife movement.

Before and after (click to enlarge). A new bridge planned at Mile Post 203 will allow wildlife to cross.

Weston, Cramer and Sakaguchi point to a railroad bridge replacement project at Mile Post 200 as an example of a successful outcome. The old structure, a three-span steel girder bridge, needed to be replaced. The new bridge that accommodates the rail lines limits the ability of wildlife to cross. Through the committee’s efforts, a wildlife crossing was added to the project just west of the new bridge. The new crossing allows over 800 Mule Deer each year to cross under US-6.

The committee provides a model that shows how agencies can work together to improve highway safety and reduce animal-vehicle collisions, explains Weston. The committee’s job with US 6 is nearly complete, but members will continue to meet to discuss research and wildlife mitigation efforts in other parts of the state.

“We are not starting from scratch anymore,” says committee member Ashley Green, UDWR Wildlife Coordinator for Statewide Projects. He is confident that other areas of the state can benefit from cross-agency cooperation even though wildlife crossing areas pose problems that are “difficult, complex and not easy to fix,” he explains. “We have seen some really awesome success.”

In addition to improving wildlife crossings, UDOT has added new bridges, general purpose and passing lanes, concrete barrier, guardrail, centerline and shoulder rumble stripes, warning signs and improved the road alignment on US 6.

Read more:

FUN RUN OPENS MOUNTAIN VIEW CORRIDOR

The first portion of the Mountain View Corridor opened first to runners, then motorists.


Created with Admarket’s flickrSLiDR.

The first three-mile section of Mountain View Corridor (MVC) in Utah County opened to motorists at 2100 North in Lehi. Hundreds turned out for a charity 5K, Fun Run and community BBQ to mark the occasion. All proceeds raised at the event will support four local charities including North Point Elementary School, Hess Cancer Foundation, Boys and girls Club of Utah County and Anything for a Friend.

PAVEMENT MARKINGS IN CANYONS

New pavement markings in Echo and East Canyons will improve visibility and safety at night and during storms.

This slide show provides a few images of work done this week in Echo and East Canyons. Click on the large images to see captions. Place your cursor in the bottom portion of the show to select another image.


Created with Admarket’s flickrSLiDR.

A past UDOT Blog post gives more information about how UDOT is testing beads and grooving pavement.

SIGN UPDATE

New I-15 Sign in Cedar City, Utah

Interstate signs are updated to improve safety and provide better readability and directional help for road users.

New signs have been placed on Interstate 15 near Cedar City. The signs meet new Federal standards and the messages on the signs have better relevance to the local area.

As interstate signs age and Federal standards change, UDOT identifies interstate segments that could be improved by a sign facelift. Sometimes single signs need to be replaced due to fading or other damage, but replacing a sequential group, as exemplified by the Cedar City project, gives UDOT the chance to update a series of signs that work together to provide clarity and consistency for road users.

Evaluation of old signs is based many factors. Current Federal standards are outlined in the Manual on Uniform Traffic Control Devices (MUTCD). Here are three broad areas engineers consider when prioritizing sign replacement projects:

Retroreflectivity: Light that bounces back to a light source instead of being generally diffused is retroreflective. “It’s right back at you,” says Wes Starkenburg, Sign Engineer at UDOT. Signs use sheeting and tape with prismatic reflectors that send headlight beams back to drivers.

Federal requirements determine the level of reflectivity of all signs on roads with public access. The level of retroreflectivity is evaluated by a trained sign inspector who visually inspects sings. Wear from weather and sun can decrease the level of retroreflectivity making signs harder to read. A trained eye taking a look at signs at night is a good start. Using a retroreflectometer allows an objective evaluation.

According to FHWA, approximately three times as many crashes occur at night, making retroreflectivity of signs an important safety feature.

Readability: Lettering used on interstate signs, sometimes informally called “Highway Gothic” is simple and easy to read. Spaces between letters, the shape and size of lettering are consistent from sign to sign which helps avoid confusion.  The number of words should be limited so signs can be read quickly.

Messaging: As cities grow and small towns become more urban, messages on signs can become outdated. To make sure a series of signs helpful to road users, UDOT works with local elected or transportation officials to develop new messages to provides good directional help.