Signals

Geeking out on traffic signals

Geeking out on traffic signals

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Geeking out on traffic signals

Geeking out on traffic signals

By Julian Lopez/ADOT Communications 
June 15, 2024
A signal devide used for timing traffic signals and other training purposes hangs on a wall.

If you want to know way too much about traffic signals, you’ve come to the right place.

We’re about to go behind the scenes when an interchange signal system goes into “flash mode” – that’s traffic industry lingo for flashing red lights.

ADOT, like many municipalities that operate traffic signals, has devices that connect to these signals to ensure that they’re operating properly. If a malfunction occurs, the device sends a message to put that signal “in flash,” which keeps motorists safe by preventing a traffic signal from showing two red or two green lights at the same time on opposite sides of the road.

Without getting overly technical, this is achieved by a little blue box, which serves as the controller of the system, and a Malfunction Manager Unit (MMU) working together to ensure that two conflicting green or red lights don’t happen at the same time.    

The blue box is the manager of the signals, while the MMU is the watchdog unit that ensures the correct signals are green when they are supposed to and that no conflicting signals occur at the same time.  


Sounds like a lot of technical-speak, right? Well, you’re not wrong. That’s why ADOT’s technicians train at test sites where they learn to set up these devices.

The test panel, which you can see in the photo above, allows the technician to test and confirm that phasing and timing is correct. These test sites are essential so technicians can set up signal timing and configuration in a testing environment before it goes live at an actual intersection.

So, the next time you encounter a flashing intersection signal, you’ll know everything that goes into getting it back online.

From suggestion to improvement: 'It has made a WORLD of difference'

From suggestion to improvement: 'It has made a WORLD of difference'

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From suggestion to improvement: 'It has made a WORLD of difference'

From suggestion to improvement: 'It has made a WORLD of difference'

By Steve Elliott / ADOT Communications
May 28, 2024
Crosswalk signal showing it's safe to walk

It’s my privilege to take an occasional turn handling ADOT’s Constituent Services online system and phone line. It’s a good chance to hear what’s on our customers’ minds.

Those who handle constituent feedback work diligently to get it quickly to ADOT personnel who can either address the issues described or benefit from the information in other ways. It’s all about living ADOT’s values of being easy to work with, collaborative and results-focused. 

That’s why quite a few people at ADOT were pleased to see Kevin Hayes’ letter to the editor in Sunday’s Arizona Daily Sun, which is based in Flagstaff, praising an improvement that started when he reached out to Constituent Services.

“They did not have to take this on, but they championed this simple fix, making the streets safer for everyone,” Mr. Hayes wrote. 

His suggestion was to have the traffic signals at Interstate 40’s interchange with Country Club Road in Flagstaff automatically signal “walk” when the light is green, regardless of whether someone has pressed the button to cross. Mr. Hayes, a bicyclist, said the change would benefit not just riders but pedestrians. 

Constituent Services shared Mr. Hayes’ suggestion with ADOT’s Northcentral District, where Joe Reed and Keith Johnson with the Signal and Lighting Group, which is part of the ADOT Transportation Systems Management and Operations Division, reviewed it and made the change.

“As I bike through town, it has made a WORLD of difference,” Mr. Hayes said by email when I reached out to thank him for his kind letter.

Thanks again, Mr. Hayes. It’s always nice to hear that we’ve made a difference for Arizonans. 

 

ADOT project updates traffic signal technology and timing in Payson

ADOT project updates traffic signal technology and timing in Payson

I-17 101 traffic interchange

ADOT project updates traffic signal technology and timing in Payson

ADOT project updates traffic signal technology and timing in Payson

July 6, 2023

Goal is improving traffic flow on SR 87 and SR 260 by reducing stops at red lights

PHOENIX – The Arizona Department of Transportation has upgraded traffic signal technology and timing on State Route 87 and State Route 260 in Payson to improve travel for residents, visitors and those passing through town.

Engineers with the Transportation System Management and Operations (TSMO) Division have added nine Payson traffic signals to ADOT’s Statewide Traffic Signal System by installing radios and cell modems. This allows ADOT staff in Phoenix and Payson to monitor the signals remotely and adjust timing when there is a scheduled event or an incident such as a crash that blocks lanes. 

Engineers also used this technology to create new signal timing plans for weekdays and for weekends, when Payson sees increased traffic heading to and through town. Separate signal timing plans for Saturdays and Sundays address the different traffic demands each day.

One advantage of this technology is having all signals on the same clock, getting rid of variability that develops when individual signals operate on their own clocks. Combined with the signal timing plan, this reduces delays caused by red lights on SR 87 and SR 260. 

Payson joins several other rural communities using this combination of technology and the coordinated signal timing on state highways that are key arteries. In Bullhead City, for example, travel through town on State Route 95 now takes five minutes less on average thanks to recent ADOT upgrades.

Payson presented engineers with a greater challenge than some other communities because the speed limit drops as traffic nears downtown, traffic signals are close together and there is a busy intersection where SR 260 meets SR 87. ADOT will continue working closely with local officials and other stakeholders to enhance traffic flow.

One other benefit of upgraded technology is closed-circuit television cameras that allow for remote monitoring of traffic. Several of these cameras are already available on ADOT’s Arizona Traveler Information website at az511.gov

ADOT’s Transportation System Management and Operations (TSMO) Division focuses on operational and safety improvements that enhance the performance of the existing transportation system. To learn more about how TSMO helps Arizonans get where they need to be, please visit azdot.gov/TSMO

He keeps 1,800 highway lights and 155 traffic signals running

He keeps 1,800 highway lights and 155 traffic signals running

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He keeps 1,800 highway lights and 155 traffic signals running

He keeps 1,800 highway lights and 155 traffic signals running

By Laurie Merrill / ADOT Communications
November 8, 2021

Trevor Eltringham is one of those fortunate individuals who gets to apply his childhood fascination to his job at the Arizona Department of Transportation.

 As Signals, Lights and Technical Electrical (SLATE) Northwestern Regional Manager, Eltringham is in charge of maintaining 1,800 lights and 155 traffic signals for one-third of the state. Two other regional managers handle other areas of Arizona.

As a youngster growing up in Yarnell, Eltringham developed an interest in electricity that probably started at home with his father, a retired electrical engineer.

“I was drawn to it,” he said. “It was intriguing to see how electricity moved things and made things run. I was just attracted to that.”

Today, Eltringham oversees four area supervisors and eight technicians based in district offices in Yuma, Kingman, Payson and Prescott Valley.

To get a sense of the size of their territory, look at the red slashes on the map in this post. The area stretches from the international Mexican border to the Nevada state line.

“There is a lot of traveling, but we do just fine,” he said. “If the Kingman office gets a call about about an outage in Mohave, that’s a two-hour drive.”

ADOT is continually installing and utilizing technology that allows techs to verify, diagnose and temporarily repair issues remotely, before they travel the distance to make hands-on fixes. 

For example, ADOT recently updated traffic management technology along a 13-mile stretch of State Route 95 in Lake Havusu City.

“The ultimate goal is to ensure the safe passage of the traveling public,” he said. “The quicker we can do that remotely, the better off the public is.”

On a recent Monday in August, Eltringham was pleased to report that only 15 of the 1,800 lights were having issues.

“We pride ourselves in keeping everything up and running,” he said.  

Eltringham has held every position he now oversees. He has logged more than 17 years with ADOT, starting as a technician or “tech,” in 1996, which meant he was in the field, maintaining and repairing traffic lighting and signals.

He briefly left ADOT in 2004 to work in the private sector, then returned as an electrical inspector in 2011, became an area supervisor under Traffic Systems Management and Operations (TSMO), and in 2017, was named regional manager.

Eltringham’s supervisor, Bob LaJeunesse, Resident Engineer of the Northwest District, couldn’t be more pleased with his performance.

“Trevor is one of ADOT's finest and best and a true joy to work with. He manages the traffic signal and lighting maintenance for a very large part of the state,” LaJeunesse said.

“He is respected equally by those above and below him both for his technical ability and the way he relates to people. He is always positive and encourages. Trevor makes the job of being his supervisor an enjoyable experience.”

For his part, Eltringham said he loves his job because he appreciates both the culture and mission of ADOT.

 “I like being part of the bigger picture, being part of a group that can make a difference,” Eltringham said. “We have our hands on the outcomes of signal and lighting systems. We make a difference in the lives of the motoring public.”

ADOT activating new traffic signal at SR 69 and Spring Lane this week

ADOT activating new traffic signal at SR 69 and Spring Lane this week

I-17 101 traffic interchange

ADOT activating new traffic signal at SR 69 and Spring Lane this week

ADOT activating new traffic signal at SR 69 and Spring Lane this week

August 17, 2021

PRESCOTT – A new traffic signal along State Route 69 near Cordes Junction will be activated this week after the Arizona Department of Transportation finishes up a project to improve safety at the intersection with Spring Lane.

Those finishing touches require lane restrictions on SR 69 between mileposts 264 and 265 Tuesday, Aug. 17, from 9 a.m. to 4 p.m. Drivers should expect delays of up to 30 minutes.

The new traffic signal is set to be activated by the morning of Friday, Aug. 20.

In addition to a new signal, the $560,000 project consisted of an additional left-turn lane from Spring Lane, an advanced radar detection system and intersection lighting. A median ditch was also installed to eliminate left turns into nearby Mayer High School from SR 69 and Wildcat Way. 

The project began in November 2020, but was temporarily put on hold due to a delay in shipping manufacturer parts.

For more information on the project, please visit azdot.gov/SR69SpringLane.

ADOT improving traffic flow on SR 95 in Lake Havasu with traffic signal coordination

ADOT improving traffic flow on SR 95 in Lake Havasu with traffic signal coordination

I-17 101 traffic interchange

ADOT improving traffic flow on SR 95 in Lake Havasu with traffic signal coordination

ADOT improving traffic flow on SR 95 in Lake Havasu with traffic signal coordination

May 18, 2021

PHOENIX –  Lake Havasu City residents and visitors will start experiencing a smoother flow of traffic on SR 95. Traffic signal crews with the Arizona Department of Transportation are installing updated traffic management technology on 20 signals along a 13-mile stretch of the highway 

In 2017, ADOT installed this technology along traffic signals in a 3-mile stretch of SR 69 in Prescott Valley and a 6-mile stretch of SR 69 in Prescott. The result has been an improvement in travel times by as much as 40%. It has also been implemented in Phoenix and Tucson. Using it, engineers monitor traffic conditions remotely, adjust signal timing, and diagnose and correct problems. The signals automatically adjust timing at certain times of the day based on anticipated traffic. 

Crews will be adding the remote technology from McCulloch Boulevard South to London Bridge Road. After installation, crews will monitor and make adjustments over the next month to optimize traffic flow at different times of the day.

The cost of the project is nearly $229,000.

These changes are being made through ADOT’s Transportation Systems Management & Operations Division. This division brings together traffic-engineering resources around the state to maximize resources, technology and expertise. This includes collaborating with other transportation and public safety agencies.

Traffic signals adapt to traffic in real time to speed commutes

Traffic signals adapt to traffic in real time to speed commutes

I-17 101 traffic interchange

Traffic signals adapt to traffic in real time to speed commutes

Traffic signals adapt to traffic in real time to speed commutes

November 14, 2018

PHOENIX ‒ Drivers along one of northern Pima County’s busiest roads are now benefiting from a technology that adjusts the timing of traffic signals based on how many vehicles are on the road.

The Arizona Department of Transportation installed an adaptive signal timing system this summer to improve traffic flow on State Route 77 (Oracle Road), the primary north-south route connecting Tucson and Oro Valley. The roadway serves about 60,000 vehicles each day.

The early results are good news for area commuters. Travel times over 8.5 miles between Tangerine Road and Rudasill Road south of Orange Grove Road have been reduced by about 10 percent – about two minutes off the morning southbound commute that used to take as long as 20 minutes.

“Sensors on the corridor provide information about the speed and volume of traffic on the road,” said James Gomes, ADOT traffic engineer in Tucson. “The software uses that data to send information to each traffic signal along the route and adjust the signal timing to accommodate the traffic demand we’re experiencing at the time.”

The system can modify the length of signal cycles, including left turn signals, and can account for changes in traffic volumes and speeds.

Northbound travel times have improved by one minute during the afternoon commute and as much as three minutes earlier in the day.

Engineers also have seen a secondary benefit: Since signals are timed to the speed limit during non-peak hours, more drivers are traveling at the speed limit.

The system, funded by ADOT and the Regional Transportation Authority, is the first of its kind in Pima County. The first such system in southern Arizona was installed along SR 189 in Nogales in 2015.

Traffic signal upgrades smooth travel along SR 69 in Prescott Valley

Traffic signal upgrades smooth travel along SR 69 in Prescott Valley

I-17 101 traffic interchange

Traffic signal upgrades smooth travel along SR 69 in Prescott Valley

Traffic signal upgrades smooth travel along SR 69 in Prescott Valley

June 22, 2017

PRESCOTT VALLEY – While traffic has increased with growth, the Arizona Department of Transportation is smoothing the journey along State Route 69 through Prescott Valley using the latest in traffic-management technology.

New communication hardware installed in traffic signals along the three miles from Navajo Drive to Sundog Ranch Road allows engineers to monitor traffic conditions from afar, make adjustments to signal timing that improve traffic flow, and diagnose and correct problems. The signals automatically adjust timing at certain times of the day based on anticipated traffic.

The result: Travel time on this stretch of SR 69 has improved by as much as 40 percent.

“These new, coordinated signals move traffic more efficiently and give us more direct control than we’ve had before,” said Alvin Stump, district engineer for ADOT’s Northwest District. “This benefits local residents as well as visitors to the area.”

remote-connection
Other traffic signal features include new systems for detecting traffic and LED lights that increase nighttime visibility while using less electricity.

Later this year, ADOT plans to make these same improvements to SR 69 traffic signals from Sundog Ranch Road west to the SR 69/SR 89 interchange in Prescott.

These changes are being made through ADOT’s Transportation Systems Management & Operations (TSMO) division. While many of ADOT’s signals in the Phoenix metro area currently have remote access, the agency is bringing that technology to other regions of the state.

“As traffic demands increase due to growth, ADOT will continue to respond with different solutions to help drivers get where they need to go,” Stump said.

ADOT Transportation Systems Management & Operations brings together traffic-engineering resources around the state to maximize resources, technology and expertise. This includes collaborating with other transportation and public safety agencies.

Safety is the goal during National Stop on Red Week

Safety is the goal during National Stop on Red Week

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Safety is the goal during National Stop on Red Week

Safety is the goal during National Stop on Red Week

August 4, 2015

Red means STOP!

Red means STOP!

It’s the rule of the road most of us were taught first, long before we ever learned to drive.

Simple and straightforward, a red light means you’ve got to stop (and stay stopped for as long as the light stays red). That applies whether you’re driving a vehicle, riding a bicycle or walking…

Unfortunately, red-light running is an issue across the country, and the consequences can be deadly. The Insurance Institute for Highway Safety reports that in 2013, 697 people nationwide were killed in crashes that involved red-light running. According to the Federal Highway Association, an estimated 165,000 people are injured annually by red-light running.

ADOT’s 2014 Crash Facts Report shows that there were at least 26 fatal crashes in Arizona last year in which drivers were cited for disregarding a traffic signal, such as running a red light, and 20 additional fatal crashes when drivers were cited for ignoring a stop sign. There were at least 2,653 crashes that resulted in injuries because a driver failed to stop at a red light or a stop sign.

Those numbers are why National Stop on Red Week takes place the first week of August every year to bring attention to this serious safety issue.

For our part, we’d like to remind everyone to pay attention and focus on safe driving behaviors on the road. That includes stopping at red lights and stop signs, buckling up, obeying speed limits, avoiding distractions and never driving while impaired.

By obeying traffic signals, you’re not only keeping yourself and others safe, you’re also saving time and money.

If you run a red light (or a flashing red light) and receive a traffic citation, upon conviction of that violation you will be required to attend Traffic Survival School (TSS). MVD is required by law to order the completion of TSS for every red light conviction reported by the courts. Failure to complete the course results in an indefinite suspension of your driving privilege. You can read more about the penalties and fines associated with red-light running on our website.

Finally, since we’re on the subject of traffic signals, you might want to review what the different lights indicate. For example, a yellow light does NOT mean you should speed up to “beat the light” – that’s actually illegal and can cause a crash. For a refresher on what each light, arrow and flashing signal mean, take a look at this section from the Arizona Driver License Manual.

“Crashes caused by drivers who ignore red lights and stop signs are among the easiest to prevent,” Arizona Department of Transportation Director John Halikowski said at the start of National Stop on Red Week. “All it takes is for drivers to slow down, put distractions away and remember that red means stop.”

From the ADOT Archives: Replacing a bulb on I-15

From the ADOT Archives: Replacing a bulb on I-15

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From the ADOT Archives: Replacing a bulb on I-15

From the ADOT Archives: Replacing a bulb on I-15

January 29, 2014

This photo was taken on I-15 in December 1978.

Acrophobia, also known as a fear of heights, apparently isn’t something the man in this photo suffers from…

Working to replace a light bulb, this (we assume) ADOT employee actually looks rather comfortable suspended several feet in the air.

The photo was taken in December 1978 and, according to our notes, was snapped on I-15 near the Cedar Pocket exit.

You might remember we recently featured a vehicle that looks very similar to the one in this picture. The modern bucket truck is used primarily by ADOT’s Signal and Lighting crews to repair and maintain traffic signals and lights – same as it was 35 years ago!

Nowadays, ADOT crews wear a full-body harness and hard hat before getting lifted (it’s difficult to tell from this photo if that was the case back then). Today’s crews also go out in twos when operating a bucket truck – one person operates an arrow board/attenuator truck (to warn traffic) and one will be in the bucket making repairs to the light or signal.

It’s safe to say things have changed since 1912 when the Arizona Highway Department was first established. But you don’t just have to take our word … we’ve got plenty of pictures to prove it. We combed through our archives and decided to periodically post these photos from the past in a blog series we’re calling, “From the ADOT Archives.”