April 30th, 2012

DDI DESIGNER

No Comments, Optimize Mobility, by Catherine Higgins.

National DDI expert and advocate Gilbert Chlewicki will give the keynote address at the UDOT Research Workshop on May 10.

Gilbert Chlewicki

Chlewicki developed the design for the Diverging Diamond Interchange as a graduate student. After designing the innovative interchange, he visited France and on a bus tour, was surprised to see that the design was already in existence.  While disappointed that he was not the first, he continued to work on the DDI. Chlewicki has pioneered other designs as well, including the Continuous T Intersection, which he will discuss in detail at the workshop.

As a forward to his keynote address at the workshop, he answered some questions about non-traditional transportation designs.

What prompted you to want to develop non-traditional designs?

“I’ve been designing roads since I was a little kid.  I used to draw long stretches of highway on old dot-matrix computer paper that had each sheet of paper attached to the next.  I used to make the lanes wide enough for my hot wheels to drive on my roads.  The drawings had full signing and traffic controls.  When I would finish a drawing, I would stretch it out across the house and have my younger sisters drive on them to find certain destinations.  In high school, I made my lanes narrower so that I could fit more into a drawing and eventually created a new highway (which I called I-74) that went from New Jersey, through southern Pennsylvania, Ohio and finally to Indiana.

My drawings were always in pen, so when I would make a “mistake”, I would incorporate the mistake into the final design.  Anytime I drew a more complex design, I would always try to figure out how both the geometrics and traffic operations would work and then think about what I could do to improve the design for the future.  I came up with several designs on my own before I even knew they existed such as a roundabout and a single point urban interchange (SPUI).  There were other designs that I still believe are original concepts.  So I’ve been developing unique geometric designs for nearly 30 years now and am still continuing to come up with new designs.”

Are transportation agencies/engineers initially resistant to the DDI or other non-traditional designs? Why, and what has to happen for that resistance to be dropped?

“There has been a lot of resistance to non-traditional designs.  Just as an example, the modern roundabout has been around

An aerial photo of I-44 / Kansas Expressway Diverging Diamond Interchange in Springfield, Missouri. First of its kind in the U.S. Photo from Missouri Department of Transportation.

nearly 50 years but it has only gained partial acceptance in the US over the past 10-15 years even though it is a great design.  There are over 40 unique documented non-traditional designs but about half of these designs have never been constructed even though they show promise.  Of the 20+ designs that have been constructed, many of those you can only find sporadically in the country (ex. one echelon in Florida) or prominently in one state (ex. the jughandle in New Jersey, the median u-turn in Michigan).

The DDI has been very fortunate to gain acceptance very quickly across a lot of the transportation world and my hope is that the DDI will be the main example that helps stimulate building other non-traditional designs.  However, there is still resistance to the DDI in a large part of the transportation world.”

“There are many different reasons for the resistance of non-traditional designs.  Some are due to not wanting to change when a more well-established design could work almost as well.  Some are due to consultants not thinking that their clients will accept something different and “unproven”.  Some don’t want to try something new.  Some are worried about liability.  Some are scared to fail.  Some think that these designs cost too much.  Some don’t even know that these designs exist and most of those that know they exist don’t understand which design is best.  And some are scared of the politics and/or community acceptance.

I think three big things need to happen for this resistance to change.  One, we need to educate every one of these designs.  There’s enough information out there now and the more people know and understand, the more willing they will be to try these designs.  Two, we need champions of non-traditional designs in both the consulting world and in transportation agencies.  When we have the right people promoting these designs, the resistance will begin to fall.  And three, we need to create a more innovative culture in the transportation industry.  When we promote innovation, we will be more likely to accept it.”

How has the driving public accepted DDIs?

“For the most part, the public has been very accepting of DDIs, perhaps even more accepting than the transportation industry.  When the public sees how easy it is to navigate in the DDI and then they see the benefits of the design in terms of the traffic operations, costs, and safety improvements, it becomes a no-brainer to most of the public.

I worked on a planning project back in 2005, where we had a DDI as one of our options.  This might have been the first project that was considering a DDI in the country.  All of the alternatives had the interchange operating at a LOS A or B in the design year, so there was little benefit from an operations point of view of the DDI versus any other alternative.  The public still voted for the DDI over the other alternatives.  Ultimately the DDI was not selected because the agency did not think it was the proper location to put the first DDI in the state and since it was a new interchange, the DDI did not show any inherent benefit over the other alternatives in terms of traffic operations or costs.”

In your opinion, what is the future of the DDI in the US?

“The future is extremely bright for the DDI in the US.  I wrote a paper that was published in Transportation Research Record last year that showed that the DDI will likely be the best option for a multi-lane arterial of any diamond form regardless of turning movements, when considering costs and traffic operations.  I think the DDI will replace the need to build any more SPUIs, except in a few situations where it might be better geometrically.

In my opinion, the DDI should be considered as an alternative for all interchange projects because of the many benefits of the design.  It may not be the best solution in every case, but it has enough benefits to merit consideration.  We have a similar policy in Maryland concerning roundabouts.  All projects in Maryland must consider a roundabout for any intersection improvement.

I can easily see there being over a hundred DDIs across the country by the end of the decade.  And when you consider that the DDI on average costs roughly $10 Million less than the next best alternative, the country should be saving over $1 Billion in transportation costs!”

Your new Continuous T sounds interesting! Can you send an explanation and maybe refer me to some information online?

“The Two-Way Continuous-T Intersection allows non-stop flow of thru traffic in both directions of a T-Intersection without any grade-separation, while at the same time vastly increasing the percentage of green time for the left turn movements.  How is this possible?  The design takes concepts from three other innovative intersections (the Continuous-T Intersection, Continuous Flow Intersection, and Double-Wide Intersection) to create this new design.  You can get more information on this design from the materials in the 2012 TRB annual meeting where you can find my paper and poster that I presented.  If time permits, I will be talking about this design during the keynote address as an example of how innovation is developed.”

April 27th, 2012

CHANGING LIVES

No Comments, Uncategorized, by Catherine Higgins.

Public transit is more about people than buses.

Todd Beutler, Cache Valley Transit District General Manager had a “changing moment” that prompted him to consider a career in public transit. As a student, he worked as a bus driver and became acquainted with an elderly man who rode the bus every day. One day, Beutler had a conversation with the man and became acutely aware of how important bus service was to his independence and quality of life.

Eight agencies in Utah provide public transit and para-transit public transportation in service areas across the state. However, some parts of the state are not covered by those service areas. The Federal Transit Administration, part of the US Department of Transportation, sponsors 21 grant programs, 6 of which are specific to special rural areas and low income, elderly and disabled citizens. In Utah, those programs are administered by the UDOT Public Transit Team staff that assist qualifying local communities to apply for and obtain funding to meet operational and capital needs.

According to the PTT Annual Report, the program allocated more than $4,733,886 in FTA grant funds to public and private agencies and organizations across the state. Many of the funds help support existing services by purchasing additional buses or equipment, such as GPS systems, that help communities expand public transit routes. The funding helps support “improved access and quality of service in urban and rural areas statewide.”

Thousands of citizens in Utah have benefited from improved public transit services. A new video details how the work of the UDOT PTT is really about people. In addition, local economies have benefited when people can connect to services, education and employment.

April 26th, 2012

NEW CROSSWALK

No Comments, Uncategorized, by Catherine Higgins.

A new cross walk with multiple signal phases is now in operation in North Salt Lake.

A new cross walk is in operation on Highway 89 at 800 West in North Salt Lake, Utah. A Federal Highways Administration study of the HAWK showed “yielding percentages above 95 percent."

The new crossing, a High intensity Activated crossWalk – called a HAWK – was designed in Tucson, Arizona appropriate for use at high volume or wide arterial streets with minor street intersections. HAWKs gives drivers “multiple cues to emphasize the potential presence of a pedestrian,” according to a Federal Highways Administration study that tested the effectiveness and safety of the HAWK. The study found that the yield rate is high due to those multiple visual cues.

The HAWK crossings include prominent pavement markings, signage and red and yellow lights on an over-the-roadway arm. When not is use, the lights are dark. Just like regular crosswalks, HAWKs are triggered when a pedestrian pushes a button. First, double yellow flashing lights, then solid yellow lights are activated to warn drivers to stop. The yellow phase is followed by two solid red lights to signal traffic to stop.

Pedestrians are then given the walk symbol followed by a countdown showing how many seconds remain in the walk phase. During the count-down, a flashing red light warns oncoming motorists to come to a full stop – motorists can proceed after a full stop if pedestrians are out of the crosswalk.

The FHWA study of the HAWK showed that “yielding percentages above 95 percent for the HAWK treatment, even on major streets with multiple lanes or higher speeds.”

Although the study also mentions that drivers are most likely to fail to yield during the flashing red phase. “Some drivers don’t seem to know what to do,” during the flashing red phase says Larry Montoya, a Traffic and Safety engineer at UDOT. Drivers encountering a flashing red signal on any roadway location should first come to a full stop, make sure the way is clear, and then proceed.

At a HAWK, drivers should come to a full stop and make sure pedestrians have cleared the crosswalk before continuing on. The flashing red phase is a way to balance the needs of pedestrians while limiting traffic delay.

April 25th, 2012

ZONE DEFENSE

2 Comments, Uncategorized, by Catherine Higgins.

Three out of four work zone crashes are caused by drivers.

UDOT limits construction delay as much as possible but some delay is inevitable. Use UDOT Traffic to check your route and leave early or take an alternate route.

It’s road construction time, and UDOT has over 200 active work zones.  The most important thing drivers should remember is to “slow down and pay extra attention when driving through a work zone, especially this year when we have so many projects,” said UDOT spokesman Nate McDonald in an article in the Standard Examiner.

An Associated General Contractors of America survey found that 68 percent of contractors said that motor vehicles crashed into their construction work zones during the past year. The same study also found that work zone crashes are more likely to kill construction workers than vehicle operators.

“Any time your job site is just a few feet away from fast moving traffic, things can get a little too exciting,” said Tom Brown, chairman of AGC’s national highway and transportation division. “Since construction workers don’t get the option of wearing seatbelts, they are more likely to be killed in a work zone crash than motorists are,” he stressed.

When driving in work zones, remember to manage your speed, your space and your stress. Here are some great tips:

  1. Slow Down when approaching all work zones. You will be in the work zone quicker than you think.
  2. Follow Posted Speed Limits, especially within construction zones, and try to maintain a consistent speed with the traffic flow. And adjust your speed for weather conditions.
  3. Don’t Resume Normal Speed until you see roadway signs indicating it’s safe to do so.
  4. Leave braking room, at least two car lengths, between your vehicle and the one ahead of you. The most common crash in a highway work zone is a rear-end collision.
  5. Keep a safe distance between your vehicle and traffic barriers, trucks, construction equipment and workers.
  6. Don’t pass on the shoulder or drive across the median – doing so creates a very dangerous situation for you, workers and other motorists.
  7. Watch out for tailgaters and don’t force tailgaters to back off by slamming on your brakes or reducing your speed significantly.
  8. Stay calm and don’t rush. Construction zone inconvenience means that improved roads are soon to come.
  9. Pay attention and avoid distractions like cell phones or the radio.
  10. UDOT limits construction delay as much as possible but some delay is inevitable. Use UDOT Traffic to check your route and leave early or take an alternate route.

April 24th, 2012

DOCTOR SEEKS SLOW CURE

No Comments, Preserve Infrastructure, by Catherine Higgins.

Prolonged internal curing promises to help concrete resist shrinkage and cracking.

Concrete designed for internal curing resists shrinkage and cracking. The small plywood square in the foreground is a temporary cover for a sensor embedded in the concrete that will help researchers gather data.

BYU researcher Dr. Spencer Guthrie is comparing and evaluating the performance of concrete on two concrete bridge decks – one is made of regular concrete and the other is made with “pre-saturated lightweight aggregate fines,” explains Guthrie.  “My particular task is to quantify the differences between this type of concrete and conventional concrete in bridge deck applications.”

Adding the wet, fine aggregate causes prolonged internal curing which has been shown to reduce shrinkage and cracking in concrete.* Internal curing also makes the concrete less porous and therefore delays the intrusion of water and dissolved chemicals and minerals that eventually cause the steel reinforcement to corrode.

A detailed explanation of internal curing can be found in a YouTube video of a presentation given by Dr. Jason Weiss of Purdue University School of Civil Engineering. According to Weiss, “internal curing increases hydration and ‘densifies’ the system.”

Concrete (basically cement and aggregate) cures through a chemical reaction, called hydration, which occurs when water saturates the cement. Internal curing is especially useful when it comes to high performance concrete that has a very dense aggregate matrix. Concrete mixes that are designed to be dense and structurally robust restrict water movement during the curing process.

Pre-wetted aggregate temporarily holds water in the concrete mixture without increasing the water-cement ratio.  As the hydration unfolds, tiny pockets of water in the aggregate continue to react with the cement. “When we get more internal curing water, we keep the system moist, we keep the system reacting, we keep hydrating the cement which means we’re going to have lower overall porosity in the system,” says Weiss.

Guthrie and engineers at UDOT will eventually have objective data that will show the differences between conventional concrete and concrete designed for internal curing. Sensors embedded in the concrete measure time, water content, temperature, and electrical conductivity, which is a good representation of permeability. Guthrie and others will also conduct strength and durability tests in the lab.

Weiss claims that internal curing can effectively double the life of bridge decks, making it possible to use transportation resources more wisely.

 *According to Guthrie: “Shrinkage always happens before cracking (and is often the cause of the cracking).”

April 23rd, 2012

I-15 CORE’S “OLD FAITHFUL”

1 Comment, Uncategorized, by Catherine Higgins.

By Aaron Mentzer, I-15 CORE Social Media Manager

Drivers on I-15 in Springville may have noticed a large fountain of water gushing into the air like a geyser west of the freeway in early March.

Water from Hobble Creek is pumped into the air near I-15 in Springville. Photo courtesy I-15 CORE.

All of the water flowing into Hobble Creek — approximately 20,000 gallons per minute — was pumped through five 12-inch-diameter pipes a few hundred feet downstream while I-15 CORE construction crews installed a new box culvert to allow the creek to pass under I-15.

“The existing culvert was just too small to handle the quantity of water in the creek,” said Ray Stillwell, Environmental Compliance Manager for I-15 CORE contractor Provo River Constructors (PRC). “It was almost always full, with no additional capacity to deal with runoff or heavy rainfall. The new culvert is much wider and includes two additional overflow culverts adjacent to the main box to accommodate higher-than-normal flows.”

Rerouting a creek or canal is common in construction, but this was not a typical case. Hobble Creek is a key spawning site for the endangered June sucker, which is only found in Utah Lake and its tributaries. Farther downstream, the creek

Five pumps were used to reroute Hobble Creek during construction: four operating at all times and one spare in case of high water flows. Photo courtesy I-15 CORE (Click to enlarge)

channel had recently been reconstructed by the Utah Transit Authority, in cooperation with the Utah Department of Natural Resources (UDNR) and Bio-West, to create the Hobble Creek Wetland Mitigation Site. PRC needed to divert the creek in a way that (a) followed the existing channel as much as possible; (b) prevented erosion and sedimentation within the wetland mitigation site downstream; and (c) preserved the June sucker’s spawning habitat.

To solve this problem, the CORE team developed a creative solution. They installed five pumps in the creek with 12-inch outlet pipes to route Hobble Creek around the new box culvert and into the existing channel. Ninety-degree elbows were attached at the end of the five pipes so the high-pressure flow of water exiting the pipes would be directed upward, minimizing erosion and sediment generation.

During design and construction of the new channel, PRC coordinated with UDNR and Bio-West, and the resulting design limited wetland impacts to a much smaller area. “Working with these other agencies, we were able to re-build the channel in a way that minimizes impacts and maintains or enhances the spawning areas for the June Sucker,” Stillwell said.

Workers installed carefully selected, native rock at different locations in the channel as well as in the box culvert itself to restore the habitat in the new creek bed. With the channel reconstruction and rock placement completed, workers removed the temporary upstream dam, and water began flowing through the new culvert last month.

“This new culvert is a great example of the cooperation and innovation taking place throughout the I-15 CORE project,” said Mike Brehm, I-15 CORE Environmental Manager. “Parties from several agencies worked together to construct this culvert in a way that actually benefits the environment.”

The completed culvert with Hobble Creek flowing in its new permanent location. Photo courtesy I-15 CORE.

April 20th, 2012

LIGHT ROCKS

No Comments, Preserve Infrastructure, by Catherine Higgins.

Lightweight concrete proved to be a good solution for a deck replacement project in rural Utah.

Lightweight concrete is not commonly used for constructing bridge decks according to Joshua Sletten, Structures Design Manager at UDOT. Some of the barriers to using lightweight concrete are availability of aggregate and slightly higher cost. Additionally “many engineers simply aren’t familiar with it and may shy away from it for that reason.”

However, light weight concrete was a good choice for the Taggart Bridge. The twin structures that carry I-84 over the Union Pacific Railroad were originally built in 1967. Lightweight concrete allowed the bridge deck to accommodate a thicker deck and asphalt overlay to meet the adjoining freeway profile and not exceed the load capacity of the older, pre-stressed concrete girder bridges.

 


Created with Admarket’s flickrSLiDR.
The bridge geometry, along with the need to keep the freeway open during construction, presented challenges that were met by UDOT, Hanson Structural Precast and Granite Construction Company Inc. Design was the project’s first hurdle.

Both bridges are three-span structures on a curved alignment. A total of sixty individual deck panels were designed, and “no two panels were the same,” according to UDOT Design Engineer Robert Nash. He kept the outside dimensions the same where possible but “the location of shear blockouts and leveling devices were different for every panel.” Each panel was designed utilizing reinforcing bars grouted into the top flanges of the concrete beams.

Hanson created precise shop drawings for each pre-cast panel. An indoor pre-cast yard made Hanson immune to weather delay, and a rigorous internal quality control process eliminated fit issues at the construction site. Panels used concrete with Expanded Shale Lightweight Aggregates from Utelite Corporation, a local supplier.

Granite Construction achieved UDOT’s aggressive construction schedule requirements while keeping traffic moving during construction. Workers even kept pace during snow flurries and low temperatures that would have stopped a cast-in-place deck pour.

In addition to the deck replacement, Granite also completed extensive substructure repair work on columns, pedestals, bent caps, wingwalls beam ends and backwalls. The project was completed ahead of schedule and under budget and won Granite’s project of the year award among entries costing up to $5 million and UDOT’s Rural Project of the Year.

The lightweight concrete deck panels seem to be performing well, according to Sletten. “I think you will see it utilized more frequently in the future.”

April 19th, 2012

PROJECT ROADWAY

3 Comments, Uncategorized, by Catherine Higgins.

A UDOT engineer with an eye for safety wants construction workers to wear his attention-getting shirts. 

Hexagons retro-reflect light and minimize a barrel chest.

Workers who build maintain roads and bridges are required to wear clothing that is brightly colored with retroreflective bars meant to make workers visible to drivers during the day and especially at night. Sam Grimshaw, a UDOT Field Engineer, has come up a new idea for clothing that he thinks will make workers even more conspicuous.

The issue as he sees it is that the commonly used clothing makes workers look similar to traffic control devices – the cones and barrels that delineate a construction zone. Instead of the typical horizontal and vertical stripes, Grimshaw placed retroreflective hexagons on bright orange fabric.

To prove his point about how workers can look barrel-chested, he took photos of workers wearing the typical shirts and his shirts at night.

Commonly worn clothing has bars and colors that make workers look similar to traffic control devices. Grimshaw's photos show the contrast between the typical and his design on the left.

He showed his prototype shirts to fabricators who said the new designs could be put into production without any trouble.

Grimshaw’s idea seems to have merit – however, the new clothing needs to have the appropriate review and approval before workers can make the switch.

The UDOT Research Workshop allows participants to prioritize research projects. Register by May 3 to participate.

Cameron Kergaye speaks at 2011 UTRAC

Usually held yearly, the Research Workshop is organized by the UDOT Research Division as a way to allow researchers and transportation experts from UDOT, FHWA, universities, private sector firms and other transportation agencies meet, network, share solutions and most importantly, prioritize research topics.

The May 10 2012 Research Workshop is approaching quickly and Kevin Nichol, Research Project Manager and workshop organizer hopes all who can be involved in the process will register  by May 3 to participate. Good participation – that is having a broad cross section of experts and a high number of participants makes for a healthy process – all involved can bring a different point of view or expertise to the table.

For researchers, that participation means presenting problem statements that detail proposed research. It’s a way for researchers to “engage their expertise,” says Nichol. This year, research problem statements are being accepted in six specialty areas:

  • Structures and Geotechnical
  • Environmental and Hydraulics
  • Construction and Materials
  • Maintenance
  • Traffic Management and Safety
  • Pre-construction

Problem statements need to be submitted by April 26.

A national expert on the Diverging Diamond Interchange will be the keynote speaker at the Research Workshop. Pioneer Crossing was UDOT's first DDI.

UDOT employees can participate in the workshop by registering for one of the specialty areas. At the conference, groups will meet separately to hear and prioritize problem statements.

It’s always exciting to see how the groups view and prioritize the research problem statements, according to Nichol. The Workshop draws a vibrant, intelligent community of transportation experts who take an important step in putting research in motion.

Ultimately, the knowledge and understanding gained by research will make for a better transportation system. For example, the 2011UTRAC Workshop produced studies that examined cost effective snow plow blade selection, sign management, and design of integrated abutment bridges.

General session

This year, workshop attendees will have a chance to hear from Gilbert Chlewicki — a national Diverging Diamond Intersection expert and advocate. Chlewicki is a leading expert on DDIs with respect to “geometric design, signal placements, traffic design, driver acceptability, pedestrian and bicycle issues, and locations for implementation,” according to his website.

April 17th, 2012

SHAKE OUT UDOT

1 Comment, Uncategorized, by Catherine Higgins.

To test readiness for dealing with damage from a quake, UDOT participated in a scripted simulation along with the state Emergency Operations Center at the State Capitol.

As simulated earthquake damage was reported, GIS experts at UDOT began building an online map showing the damage to the transportation system. Emergency Operations Center participants at the state capitol could view the map in real time as changes were made.

In the aftermath of an earthquake, UDOT employees will be responsible to make sure the transportation system is safe. The first step in that process is assessing damage to roads and bridges. As part of the Shake Out earthquake drill, UDOT used a United States Geological Survey Earthquake Hazards software program called ShakeCast to generate estimated damage information for roads and bridges.

GIS, Electronic Asset Management and communication experts gathered in one room to interact with the state EOC at the state capitol. Minutes after the quake drill at 10:15 today, scripted calls and email started arriving at the UDOT Traffic Operations Center. As simulated damage was reported, GIS experts began building a map showing the simulated damage to the transportation system. EOC participants at the state capitol could view the map in real time as changes were made. The UDOT participants used a color coded system to identify critical routes and the status of each route.

While UDOT does not anticipate extensive damage to the transportation system, some damage will occur. And, uncertainty exists when it comes to events, such as crashes or power outages and how those events will affect the transportation system.

“We are one of the critical infrastructure owners,” says Chris Siavrakas, Emergency Management Coordinator at UDOT. Transportation, along with other critical systems, including energy, water and health care, is part of an interdependent system. The simulation was good practice for what would occur in the first several hours after an earthquake.