Cable barrier reduces the occurrence of crossover collisions.

Vehicles in a head-on crash collide at a force that equals the combined speed of each car. When vehicles hit cable barrier, the steel cable absorbs the crash.

Cable barrier is tensioned steel cable held up by weak posts. When installed properly between opposing traffic lanes, cable barrier prevents crossover collisions, which are “the most horrific crashes we can have,” says John Leonard, UDOT Traffic and Safety Operations Engineer. Often fatal or disabling, crossover collisions occur when a car veers off the road, into the median and then crashes into opposing traffic.

The steel cables protect vehicle occupants, absorb energy from the crash and keep the vehicle moving in the same direction as traffic.

UDOT started installing cable barrier in the late 1990s (Click to enlarge)

Cable barrier saves lives

UDOT has seen a steady decline of crossover collisions since the late 1990s when installation of cable barrier began. Since 2004,UDOT has installed nearly 200 miles of cable barrier. During that time, crossover collisions resulting in fatalities or serious injuries have decreased from nearly 70 to 20 per year.

The benefits of cable barrier are well known, but sometimes people outside the transportation arena don’t understand the purpose of the important safety feature that is installed between opposing traffic lanes on many Utah highways and interstates.

Myth 1: Cable barrier creates a hazard for motorists.

According to Scott Jones, UDOT Safety Programs Engineer, “putting barrier on the roadside actually does give people more opportunity to hit something.” However, cable barrier prevents head-on crashes that can be severe or fatal to occupants.

Serious and fatal crashes have declined since UDOT began installing cable barrier. (Click to enlarge)

Vehicles in a head-on crash collide at a force that equals the combined speed of each car. When vehicles hit cable barrier, the steel cable is displaced as it absorbs the crash and occupants are usually not injured severely.

Despite UDOT’s ongoing effort to educate drivers about the hazards of driving drowsy, distracted or impaired, people do end up driving into the median and into oncoming traffic, often because of driver error. For those motorists, crashing into cable barrier is much safer than crashing into oncoming traffic.

Myth 2: Cable barrier slices up vehicles.

Installed correctly,cable barrier especially is very forgiving when you hit it,” compared to concrete barrier or guardrail, says Jones. “We know that a lot of people drive into the cable barrier and then drive away – they never even report a crash.”

Like everything UDOT installs along state routes, cable barrier is crash tested. “Crash testing is really important because we want to make sure it will work the way it’s supposed to – it’s not just a guess,” explains Jones.

Myth 3: Placement of cable barrier is done arbitrarily.

UDOT engineers are very careful to identify appropriate locations for cable barrier, and to install the barrier correctly at those locations. Jones uses crash data to identify appropriate locations for cable barrier.

When it comes to installation at each specific location, placement is “extremely engineered” he explains. Cable barrier is generally most appropriate when installed on “flat or moderately sloped terrain,” according to FHWA. Engineers consider many factors, including how an errant car will react while crossing a slope between travel lanes, the distance from traffic lanes and the quality of the soil.


Getting the bond right is critical when it comes to installing a protective bridge deck overlay.

Bridges are important assets to Utah’s transportation system. Prolonging the life of bridges gives taxpayers the best bang for the buck since premature replacement can be expensive and inconvenient for road users.

A strong bond between the overlay and bridge deck helps protect the entire bridge from deterioration.

“Bridge decks are the first line of defense for the whole bridge,” explains engineer Joshua Sletten,  Structures Design Manager at UDOT. Bridges are designed to last for 75 years but the life of the deck is much shorter – about 40 years. Utah’s weather and salt, used in the winter for deicing, tends to cause decks to deteriorate.

When a bridge deck overlay is sealed improperly, water carries salt and impurities from the road where it pools between the overlay and the concrete. The freeze-thaw cycle can crack the concrete, allowing salt water to seep in and corrode the steel reinforcement. “Salt basically speeds up deterioration and corrodes steel at a ratio of about 8 to 1,” meaning that one eight inch of steel will measure one full inch if rusted through, explains Sletten. “Just a little rust will start popping off the concrete.”

UDOT uses a variety of materials to seal and protect concrete bridge decks. Research conducted by University of Utah graduate student Erica Weber, P.E. shows the role of careful application in applying polymer overlay systems to full-depth pre-cast bridge decks.

Weber conducted tests to evaluate bonding strength in a laboratory and on actual bridge decks. In the lab, she used test decks with polymer overlay material, typical of the products UDOT uses, applied according to manufacturer’s directions. Weber simulated traffic by applying static and cyclical deflection to the test decks. To check for salt penetration, test decks were submerged in a chloride bath (chloride is the culprit chemical in salt).

Weber also conducted tests to simulate lifting and placement of precast panels to evaluate how deck overlays perform during Accelerated Bridge Construction methods. ABC methods can include constructing bridges off-site and moving structures into place or using pre-cast components trucked to the site.

ABC Bridges on I-84 served as the subjects of real-world tests. Weber tested the deck overlay for bonding strength by taking samples and pulling off the overlay. Since the tensile strength of the epoxy overlay bond is greater than the tensile strength of concrete, Weber was looking for concrete failure during the pull-off tests; failure in the concrete demonstrates that the epoxy bond is not the weak point, explains Sletten.

Weber found that bond strength of the overlay on the test decks was stronger than the I-84 bridge decks. Her test results show that installers need to strictly follow manufacturer’s guidelines for bridge deck application.

“It’s an ongoing challenge for us to figure out how to protect these decks because decks protect everything else,” says Sletten. He explains that if installers aren’t careful to get the bond right, a bridge deck won’t hold up to traffic and Mother Nature, making the entire bridge vulnerable.


The UDOT lighting crew will soon start a systematic re-lamping of the I-15 corridor.

New, better performing sheeting on signs may eliminate the need for active lighting.

Starting a 10600 South in Salt Lake County and working north, soon crews will start working on Sundays to repair and secure areas where vandal have stolen  thousands of feet of copper wire from interstate lighting circuits.  First, High-mast lights, off-ramp lighting then and finally the underpass lighting will be re-lamped.

Overhead sign lighting that is located within areas of continuously lit interstate will not be re-lamped. UDOT is planning replace the sign sheeting on these signs with improved Type 9 or Type 11 retroreflective sheeting which will make active lighting unnecessary.

According to A.J. Kuhrmeyer, Government Transportation Representative with 3M, the FHWA, through the NCHRP, is currently quantifying whether higher-performing retroreflective sheeting is ample enough to eliminate overhead guide sign lighting. There is not currently a definitive study, and removing the lights is left up to the engineer’s judgment.

Kuhrmeyer points out some advantages of eliminating lighting:

  • Reduced maintenance costs and fewer lane closures
  • Improved personal safety since better performing signs are easier to see, faster to read
  • Decreased graffiti with elimination of catwalks in some areas
  • Reduced light pollution

Cost savings

The cost of eliminating lighting varies by location, but some metropolitan areas have enjoyed substantial savings. While not an official published study, the Indiana Department of Transportation eliminated 2oo signs for and anticipated savings of over $80 thousand, according to Kuhrmeyer.

Cost varies on both the energy and labor necessary to maintain overhead guide sign lighting, explains Kuhrmeyer.  State DOTs may save quite a bit when all factors are considered, such as the cost of sending out a crew to change a bulb, traffic control necessary, the per-bulb cost, all multiplied by the vast number of lights in operation.


A replacement bridge planned for US-6 will include a much-needed Mule Deer crossing.

Wildlife crossings have helped improve safety on US-6 between Spanish Fork and Price, Utah. Cameras placed at wildlife crossings record still shots and video so researchers can observe wildlife. (Photo courtesy of Dr. Patricia Cramer, USU)

Helping wildlife cross safely will make the important route safer for road users.  The current structure is a box culvert with only enough for a stream. UDOT Structures Design Engineer Mark Daniels says the project involves overcoming a “geometrical challenge.” Designing the bridge with enough vertical clearance to accommodate a stream and a path for wildlife will require raising the elevation of the new road on a new alignment and redirecting the stream at two bends.

The bridge is being replaced as part of a comprehensive effort to improve safety on US-6. In 2005, UDOT received the final Record of Decision that outlined roadway improvements between Spanish Fork and Price, Utah. Since then, UDOT has straightened the road alignment in some locations, replaced bridges and added new wildlife crossings, wildlife fencing, general purpose and passing lanes, concrete barrier, guardrail, centerline and shoulder rumble stripes and warning signs.

UDOT has worked with The US-6 Wildlife Coordination Team throughout the process to improve safety on US-6. The team members come 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. The team has worked to identify high wildlife-vehicle collision spots and make recommendations for improvements. UDOT has had good success at implementing those recommendations.

Habitat Biologist Doug Sakaguchi with the Utah Division of Wildlife Resources has helped track high wildlife-vehicle hit areas for the committee since 2005. Data shows fewer hits have occurred in areas where new wildlife crossings have been built and fences have been installed over the past five years. The graph below shows an increase in average wildlife hits near the location where the new bridge will be built.

Experts are optimistic that a new bridge with a wildlife crossing will help reduce wildlife-vehicle collisions.

Crossings and connected fencing work together to direct wildlife through crossings. The jump in wildlife hits shown on the graph is because “deer are finding that section where there’s no fence,” explains Sakaguchi.  He is optimistic that a crossing, in conjunction with fencing, will reduce the wildlife hits at the location. Since the two bridges on either side of the milepost 202 location work well for deer, Sakaguchi thinks that deer won’t be afraid to use the new crossing as well.

UDOT will keep traffic moving during construction by building the new bridge and then switching traffic to the new road alignment and structure before demolishing the old culvert.


An innovative beam design promises strength and long service life for bridges.  

A new beam that uses Fiber Reinforced Polymer, a material that is rust resistant and stronger than steel may help bridges last up to 100 years.

Conventional steel-reinforced concrete bridge girders have a useful life of about 75 years, depending on traffic loads and weather. Seemingly impervious to the elements, “concrete itself is a giant sponge,” explains Mike Zicko, an engineer with HCB Company. Water, along with impurities from the roadway or deicing chemicals, is pulled in by the concrete and failure of bridges, whether it’s the deck, girders or other components is caused in most cases “by rusting of whatever metal is in the bridge.”

Rust causes the steel to expand and crack the concrete – protect the steel from moisture and the life of the structure is prolonged.

The second reason for structural failure of bridges is fatigue. “When something goes over a bridge, it takes away some of its life,” says Zicko.  After a lifetime of bending under the weight of traffic, steel can wear out.

A new beam that uses Fiber Reinforced Polymer, a material that Zicko says is “virtually impervious to moisture” and stronger than steel may help bridges last up to 100 years. FRP is seeing increased use in the transportation and other industries partly because it does not rust. UDOT has recently used FRP to reinforce the deck of the Beaver Creek Bridge and FRP bars are being used to extend the life of concrete pavement on I-15.

Called a Hybrid Composite Beam, the design uses an FRP box to protect concrete used in the beam from moisture. What’s inside the box is innovative as well; a concrete arch gives the beam compressive strength.

More than just a covering, the box “provides shear strength and encapsulates the tension and compression elements,” according to the HCB Company website. The arch structure inside the beam is surrounded with low density foam core. A prestressing strand provides additional strength and steel shear connectors provide stiffness. Along with being very strong and durable, the beams are also light and easy to lift and place.

The beam was designed by structural engineer John Hillman, President and CEO of HCB Company. UDOT will use the beam on a bridge near Beaver, Utah. A grant from Highways for Life  will provide funding to use HCBs on the project. HFL encourages state DOTs to use innovation to build a longer lasting transportation system.


A number of trends in the asphalt pavement industry save money and use less energy.

New asphalt pavement in Washington City, Utah. UDOT's contractor used Hot mix asphalt containing recycled asphalt pavement or RAP.

Sometimes people outside of the transportation industry view pavement as a one-time use of resources. However, many of the products used for pavement can be reused or mixed in ways that use less energy. Asphalt and concrete pavement, for example, can be recycled. This article summarizes some ways asphalt pavement can be re-used or mixed using less energy.


Recycled Asphalt Pavement, old asphalt pavement that has been milled off or otherwise removed from a road or other installation, can be added to new asphalt pavement at a batch plant. In general, state DOTs allow more RAP in base courses than they do in surface courses. For example, the I-15 CORE project uses a multi-layer pavement design. The asphalt portion on the interstate uses thirty percent RAP but the surface streets use a smaller percentage of RAP.

According to Michael Kvatch, Executive Director of the Asphalt Pavement Alliance, tests show that high RAP content pavement on surface streets (10 to 25 percent RAP) can be “just as good, if not better than its virgin counterpart.”


Cold In-Place Recycling is a way to reuse asphalt on site using a long train of equipment. The process involves removing and pulverizing old asphalt, adding binder, spreading, grading and compacting the asphalt. CIR can be used to rejuvenate an old road or as a base course for new pavement. New aggregate can also be added during the process if needed.

CIR offers the advantage of being about one-third of the cost of new asphalt. CIR is a cold process, so the energy used to heat Hot Mix Asphalt is also saved. There are also many CIR processes and uses, which gives contractors and engineers at UDOT options for bidding and designing good solutions for maintaining roads.

However, regular Hot Mix Asphalt made according to a Superpave process is much stronger than CIR, so for high volume roads or cold climates, CIR may not be appropriate.

HMA is also more predictable than CIR, which is subject to many variables, such as original mix design and aggregate size, explains Kevin Van Frank, UDOT’s Engineer for Asphalt Materials. CIR is subject to many variables, including binder and aggregate type and size. Those variables make the characteristics of the final product a challenge to predict, especially when it comes to curing time. Because of the economic advantage of CIR, UDOT Research is funding testing that will establish standards for CIR.

Maintenance of Traffic is also a problem with CIR since the process requires a long train of machines that can stop traffic. UDOT places a premium on keeping traffic moving during construction, so CIR is not used in high traffic urban areas.

Sometimes people outside of the transportation industry view pavement as a one-time use of resources. However, many of the products used for pavement can be reused or mixed in ways that use less energy. Asphalt and concrete pavement, for example, can be recycled.


Warm mix asphalt pavement is produced using less energy. Hot Mix Asphalt is heated to 310 to 350 degrees Fahrenheit; the temperature range for WMA is as much as sixty degrees lower. HMA uses heat to decrease the viscosity of the asphalt in order to be able to place and roll the pavement. WMA uses Zeolite, waxes, surfactants or water to compensate for using cooler temperatures during production.

Zeolite is a “mineral sponge,” that transports water into the asphalt binder. Waxes act as thermosets that increase viscosity above the liquid phase. Surfactants can be added to coat the aggregates to make the binder workable at lower temperatures. Water injected during the mixing process causes the asphalt binder to foam so it achieves the viscosity needed to place and compact the material at lower temperatures.

WMA can be placed in the cooler months of spring or fall, which potentially lengthens the construction season. And, cooler asphalt has a milder odor, which can be good for road users and especially for workers.


An ABC approach helped UDOT keep traffic moving during construction of the Telegraph Street Bridge.

Created with Admarket’s flickrSLiDR.

The monolithic poured bridge was still in good shape for a more than 70 year old structure. But the roadway on either side was wider, witch made the bridge a traffic choke-point. Building a twin bridge to add additional capacity would have been expensive – both to build and maintain through the life of the new bridge.

“Bridges are more expensive to maintain than roadway,” says Joshua Sletten, UDOT Structures Design Engineer. Per foot maintenance costs of roadway maintenance are a fraction of the costs of maintaining a bridge – especially a long structure like the old bridge. Hydrological studies showed that a smaller structure would also be adequate to accommodate a stream under the bridge. A UDOT in-house design called for a new smaller structure to be built under the bridge deck.

The new bridge, a giant arched culvert, was built using pre-formed concrete components that were assembled on site as traffic was maintained on the old bridge. After construction, fill was placed over the new structure and the road was realigned over the top. Crews then demolished the old bridge, and the built a new wider road with two lanes in each direction and a center median.

Covering the new structure also adds a maintenance advantage; the fill provides a protective buffer between traffic and the structure.

For more, read an earlier post about how UDOT partnered with stakeholders during construction.


UDOT uses ramp meters to keep freeway traffic on an even keel.

New software to calculates meter rates to help smooth out traffic flow on I-15.

UDOT has been using ramp meters to even out freeway traffic flow and improve safety for several years. Metering breaks up bottlenecks, smooths out surges and keeps traffic on an even keel. Without metering, freeway speeds would likely be much slower, and travel times would be less reliable. Metering also improves safety because stop-and-go driving behavior is reduced and platoons are broken up, and fewer side-swipe and rear-end collisions occur.

The present way of metering takes average traffic patterns into account. But, “traffic is never average,” explains John Haigwood, Traffic Engineer at the UDOT Traffic Operations Center. “We can’t account for all the variations.” The graph below  shows variations in traffic during the evening commute, with the black line showing the average.

Sometimes metering can be too restrictive or too free. Restrictive metering allows too few cars to access the freeway, and metering that is too free can fill freeway capacity quickly and cause flow to be sluggish.

Because of variations, sometimes metering can be too restrictive or too free. Restrictive metering allows too few cars to access the freeway, and vehicles may stack on the ramps and available freeway capacity may go unused. Metering that is too free can fill freeway capacity quickly and cause mainline freeway traffic flow to be sluggish.

A new, more responsive way to control metering rates is being tried on I-15 in Salt Lake County.  UDOT is using new sophisticated software  that “automatically adjusts to actual conditions,” says Haigwood. The system is being provided by Wasatch Front Regional Council Congestion Management and Air Quality funds.

Traffic sensors measure backing on the ramp, and traffic speeds at the merge point and downstream, and the software calculates meter rates. “The system uses data collected from traffic monitoring stations that are UDOT fiber network,” says Scott Stevenson, a Traffic Engineer who works with UDOT on the new system. “These existing stations provide the raw data that is used for the travel time signs, traffic flow maps and now, corridor responsive metering.”

Engineers at UDOT’s Traffic Operations Center “are seeing a lot of success,” says Robert Clayton, Director of the TOC. Clayton anticipates having real data soon to back up the observations. In the meantime, engineers are keeping close watch on the test sections to make sure correct parameters are being set so the software can work correctly.

It’s a balancing act, explains Stevenson. “We’re trying to maintain a better flow on the freeway by adjusting the ramps, and visa verse.” By balancing the metering rate of the ramps with the flow of traffic on the mainline freeway, road users can take full advantage of available capacity, backing on ramps can be minimized and the overall operation freeway system can be optimized.


Partnering between UDOT and contractors is essential when it comes to finding solutions and providing the public with a good quality transportation product.

Complex road construction projects that occur on heavily traveled routes, especially those near business districts, are often subject to construction delay due to utility conflicts or unexpected but necessary changes in plans. UDOT works hand in hand with contractors to resolve construction issues so the project objectives can be met, stakeholders can be kept informed and the public can enjoy and improved transportation system as soon as possible.

The Monticello Main Street Project reconstructed a three mile section of US-191 and US-491 through the business district of Monticello, Utah.

A UDOT Region Four project in Monticello provides a great road map of how to partner for solutions. The Monticello Main Street Project reconstructed a three mile section of US-191 and US-491 through the business district of Monticello, Utah. The project scope included pulverizing or excavating the old pavement; compacting and grading the road base, and installing asphalt and concrete pavements; removing and replacing three miles of storm drain; installing a highway lighting system; relocating high voltage overhead power and upgrading traffic and pedestrian signals.

“On large partnered projects like this one, the issues that arise can start out small and quickly become worse if not addressed early,” says Jim Chandler, UDOT Region Four Resident Engineer for the project.  Project team members used a variety of communication and coordination strategies, common to all UDOT projects, to maintain the project scope, budget and schedule. For their efforts, project team members from UDOT and Granite Construction recently received an award for “Best Large Partnered Project” from the Utah Associated General Contractors.

Weekly team meetings – Regular meetings held at the contractor’s construction trailer allowed workers to update the rest of the team on construction processes. Participants included UDOT employees, contractor employees, sub contractors and third party stakeholders from the City of Monticello and utility companies.

Participants shared resolutions, safety concerns, and described upcoming construction impacts to the general public. The contractor reviewed all questions and concerns that were received from the general public – including road users and businesses along the corridor.

Team building – All project teams engage in formal and-or informal team building exercises. Formal team building exercises use a facilitator to forge relationships among team members and regular confidential, partnering surveys that rate communication and cooperation. Partnering surveys, with an average survey score of 19.28 out of 20, showed that the Monticello project team members valued each others’ contribution to the team.

While the project team didn’t employ formal team building, the informal team building efforts created a sense of unity and purpose among project workers.   Informal team building effort included close, purposeful collaboration among the project team members. Team members even socialized after hours.

Weekly email updates – The contractor the project sent weekly email updates to team members and area businesses to provide ongoing progress reports and to describe upcoming construction processes.

Be it resolved

Construction issues were resolved through a coordinated team effort. For example, the project team struggled with soft sub-grade and unknown, unmarked and abandoned drainage features. Old features, such as culverts and hydrants needed to be moved to make way for new drainage features. The aggressive schedule left little time for problem resolution. But, cooperation among team members prevented massive schedule delay as road features were encountered, excavated and moved. The project closed without any outstanding issues left to resolve.

Effective partnering also resulted in one half million dollars of savings. The project called for emulsion-stabilized full-depth reclamation. The contractor suggested switching to cement stabilized FDR as a value engineering change to save money without slowing down the project.

Congratulations to:

UDOT Project Manager Rustin Anderson

UDOT Resident Engineer Jim Chandler

The Moab Construction Office in conjunction with the Transportation Technicians from Moab, Monticello, Blanding and Bluff

Granite Project Manager Stephen Cordts


UDOT used a quick and modern construction approach to improve traffic mobility and keep a historic look and feel in Washington City.

The new roadway on Telegraph Street in Washington City, Utah was made to have the feel of a bridge crossing with iron work and street lights.

Traffic used to slow abruptly on the two-lane Telegraph Street Bridge where four lanes narrowed to two. The  route experiences heavy traffic during peak commute times, and supports a thriving business center. Pioneer era buildings give the area a historic look and feel, and environmental study requirements called for a design that preserved that character.

Innovative construction

An arched culvert was built under the existing bridge while traffic on top continued to use the road during construction.

An ABC approach was used to widen the road to two lanes in each direction, and keep traffic moving during construction. UDOT has used many forms of ABC – this project used pre-formed concrete arch elements to build a giant culvert under the existing bridge while traffic on top continued to use the road during construction. UDOT’s contractor was able to keep one lane moving in each direction for the duration of the project.

“A local contractor secured the job by bidding an aggressive schedule and the construction management firm’s offices were also located right on the project,” says UDOT Region Two Public Involvement Manager Kevin Kitchen.

The quick 180 day schedule limited the inconvenience of construction on road users and businesses. “One local resident who has lived in the area for decades called to congratulate us,” says Kitchen. The resident claims “it was the best run construction project he’s ever seen from a driver’s perspective with traffic always moving and work always going.”

Old school

City officials are happy with the outcome too. “We couldn’t survive with two lanes,” says Michael Shaw,Washington Cities Public Works Director. “Telegraph is our downtown.” With only one lane in each direction, traffic slowed and made travel to and through the area unwelcoming.

The Washington City Museum is in the old city school, built in 1857.

The city was involved in planning the improvement right from the start. UDOT first met with city officials and residents with the objective of improving the road and turning over ownership to the city.

According to Shaw, UDOT incorporated everything the city wanted in the project, including replacing the bridge, a new road alignment, and city funded beautification elements. All together, the project created a wider tree-lined boulevard feel that has a traffic calming effect for motorists.

Building a new bridge would have been prohibitively expensive. Widening the old monolithic poured bridge was not possible, but a UDOT in-house design called for a culvert with an arched face to be built under the existing bridge. Fill around the culvert was faced with stonework, and new roadway was made to have the feel of a bridge crossing with iron work and street lights.

The new road has four lanes with a center median. The culvert accommodates a stream and pedestrian path. The project also included a number of city beautification improvements, including lighting, welcome signs and trees.

UDOT is in the process of turning ownership of Telegraph Street over to Washington City.