Signal Spotlight: Optimizing Yellow Clearance Intervals: A Proven Safety Countermeasure

traffic_signal_spotlights_logoSignal Spotlight: Optimizing Yellow Clearance Intervals: A Proven Safety Countermeasure

ss.8.20.1At a signalized intersection, the yellow clearance or yellow change interval is the length of time the yellow signal indication is displayed following a green signal indication. The yellow signal confirms to motorists that the green has ended and that a red will soon follow.

Since red-light running is a leading cause of severe crashes at signalized intersections, it is imperative that the yellow change interval be appropriately timed. Clearance intervals are a function of operating speed, the width of the intersection area, lengths of vehicles, and driver operational parameters such as reaction, braking, and decision-making time.

When a yellow change interval is too short, drivers may be unable to stop and unintentionally run the red light. If the interval is too long, drivers may treat the yellow as an extension of the green phase and intentionally run the red light.

ss.8.20.2Municipalities can improve signalized intersection safety and reduce red-light running by reviewing and updating their traffic signal timing policies and procedures concerning the yellow change interval on a regular basis. The MUTCD does not require specific yellow or red intervals but provides general guidance that the yellow change interval should be approximately 3 to 6 seconds.

Current CTDOT practice is to use the kinematic equation outlined in the ITE Traffic Engineering Handbook for the yellow change interval, and a modified version of the kinematic model for the red clearance interval. Yellow change intervals of three seconds to five seconds are typically used.

The yellow change interval for each phase is computed using the following formula:
Y = t+V/(2a+2Ag)

Y = Yellow change interval in seconds
t = reaction time (use 1 second)
V = 85% percentile approach speed in ft/sec or m/sec
a = deceleration rate of a vehicle (use 10 ft/sec2 or 3 m/sec2)
A = Acceleration due to gravity (32.2 ft/sec2 or 9.81 m/sec2)
g = percent grade in decimal form (+ for upgrade, – for downgrade)

ss.8.20.3While providing an appropriate yellow clearance interval improves safety, it should be noted that there is no additional benefit to making the interval longer than it needs to be. Longer clearance intervals increase lost time at the signal and will reduce the intersection’s capacity.

Connecticut DOT Traffic Control Signal Design Manual

NCHRP Report 731 Guidelines for Timing Yellow and All-Red Clearance Intervals at Signalized Intersections

Guidelines for Determining Traffic Signal Change and Clearance Intervals: An ITE Recommended Practice

Recorded Webinar: Introducing ITE’s Guidelines for Determining Traffic Signal Change and Clearance Intervals

Making Intersections Safer: A Toolbox of Engineering Countermeasures to Reduce Red-Light Running

If you have traffic signal systems questions, please contact: Theresa Schwartz, P.E.,
P.T.O.E. – Traffic Signal Circuit Rider (860) 486-4535 or

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Safety Matters: Sign Visibility and Retroreflectivity

safety_matters_logo Sign Visibility and Retroreflectivity 

Every day, no matter where we go or what we do, we see signs. Whether it’s the STOP sign at the end of a street, a pedestrian warning sign or the sign directing you to the beach, all of the signs we see are regulated by the Federal Highway Administration’s Manual on Uniform Traffic Control Devices (MUTCD). The size, shape, color and messaging are all specified in the MUTCD and allow for a person to travel from a small rural community in Connecticut to a city like Los Angeles, CA and recognize each and every sign. This is most important when it concerns traffic control signs – it would be nearly impossible to move around safely if regulatory signs weren’t uniform!

Almost as important as their uniformity is their visibility. A sign can only provide information to the roadway users if those users can see it. The MUTCD has the following language with regard to sign design and retroreflectivity.


Some visibility issues are easy to identify and resolve. A low-hanging branch that blocks a sign can be identified and cut rather quickly. A sign that has been vandalized can be repaired or replaced. More difficult, though, is determining if a sign is no longer retroreflective. During the day, a sign may look worn, but does that make it no longer retroreflective at night? Since Public Works crews work during the daytime, it can be hard to conduct proper nighttime visual inspections of signs. Ensuring that the proper signs are installed and maintained has a measurable impact on roadway safety. Signs that are visible in the day provide information to drivers but may be one of many visual cues to aid the driver in their decision making. At night, when many of those other cues may not be visible, signs become even more important.


  • Daytime
  • Many cues available 
  • Driver task relatively easy




  • Nighttime 
  • Few cues remain
  • Task more difficult



A sign inventory is an effective way to keep track of the life of signs, which aids in assessing their retroreflectivity. Using an established method to assess and/or manage regulatory and warning signs for retroreflectivity is also an FHWA requirement. The different ways that sign retroreflectivity can be determined are listed below:

  • nighttime visual inspections using comparison panels
  • nighttime visual inspections using calibration method
  • nighttime visual inspections using consistent parameter method
  • measured using retroreflectometer

Many local agencies do not have the ability to bring staff in at night to conduct visual inspections. Another option is to anticipate the expected life of a sign and replace signs on a rotating basis, but this can be costly if signs are needlessly removed. A retroreflectometer can be used during the day and provides an objective measurement; however, they are cost prohibitive for most local agencies. The T2 Center does have two retroreflectometers, as part of the Equipment Loan Program, which can be borrowed by a municipality to conduct sign inspections. More information can be found on our website by clicking here.

Maintaining sign visibility is an important and necessary part of keeping our roadways safe for all users. The better the information is that we provide, the easier it is for the driver to complete the task needed to navigate the road.

Additional information on retroreflectivity requirements can be found in the MUTCD and on FHWA’s website at:

For more information and assistance with local road safety in your community, contact Melissa Evans, Safety Circuit Rider, at


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Warren’s Words of Wisdom: OSHA’s Fatal Four

warren_words_wisdom_LogoOSHA’s Fatal Four


Public Works folks are so valuable because they are known to be jacks-of-all-trades; driving a dump, operating a chainsaw, digging holes, filling the holes they just dug, chipping tree branches, running a front-end loader, spreading sand, welding are just a few of the fun and snappy jobs which they do daily. So, just based on being like Jack, PW’s have multiple opportunities to make one or more of the Fatal Four a reality every day on every job.

The OSHA FATAL FOUR could also have the title PUBLIC WORKS FATAL FOUR.www.8.2020.1

Of these four, which one has happened to you the most? Probably the Falls, right? You wouldn’t get many second chances if you were electrocuted! The others could be close calls and you’d still be alive, maybe with life-altering injuries, but still alive.

PW’s are typically very good with recognizing when a situation is “gut feeling” not right. Trust your gut, take a step back, give the job or situation a long look, talk it over with your co-worker; if you’d don’t feel comfortable with the job, stop. There is scientific proof the reason you’re having the “gut feeling” is that your subconscious is processing what’s happening faster than another part of your brain, causing a mental imbalance, sending signals saying something’s not right, you just haven’t been able to verbalize it yet. Trust the gut! Note: Size of gut does not play a roll…Get it?…Roll?

www.8.2020.2This is my right ankle after slipping on ice during a storm in NH. I should have had on ice grippers, like Yaktrax. It wasn’t fatal, but I will forever be packing the screws and plates from one little slip and fall. Worse, my dream of winning “Dancing with the Stars” was crushed, maybe my delusion is a better word.

Terrible numbers on this chart about Work Zones.www.8.2020.3

The above is an adaption from the article, “Annual National Work Zone Awareness Week.” For more information, please visit

Daily, I receive a utility safety report on incidents over the previous 24 hours. Every week there are multiple distracted/impaired/elderly drivers entering a work zone, even with Police present. Luckily there have been no serious injuries to anyone, so far, but pulling a car out of an open 4 foot deep trench cut in the road can really mess up a transmission/oil pan. In my book, work zones are the absolute most dangerous things PW’s are exposed to. CTDOT holds contractors and tree people to high standards when working on a public roadway for signage, traffic control devices (cones) and flaggers doing their job. Just because PW’s are the “A Team” doesn’t mean your work zone should be any less well done than the contractors. Those signs and cones are out as a warning to drivers that there are workers ahead in the road and to SLOW DOWN!!

Everyone who’s worked on the road has scary stories about close calls. I would find crews who had gotten a little lazy and set all the cones and signs way too close to the job—meaning drivers, even the sober and alert ones, came up to the work zone with very little warning, especially over hills or around corners, and had little time to react. If your work zone’s cause screeching tires, locked-up brakes and people yelling compliments about how well you look, I would spend time expanding your work zone before someone gets hurt.

Ever been tempted to do this?


Stay safe my friends!

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Signal Spotlight: On-Demand Learning: Basics of Traffic Signal Operations Course Launch

traffic_signal_spotlights_logoOn-Demand Learning: Basics of Traffic Signal Operations Course Launch

The T2 Center is pleased to announce the launch of the first on-demand Traffic Signal Academy course. This new course, Basics of Traffic Signal Operations, provides an overview of traffic signals and how they operate. It is recommended for new signal technicians, engineers, and other municipal employees interested in an introduction to traffic signals. An on-demand format offers the flexibility of completing the course on one’s own schedule, as well as having it available at any time of the year for new hires.


ss.7.2020.2The course consists of a video lecture with knowledge checks, a downloadable Basics of Signal Operations Learning Guide for future reference, and an online participant evaluation. It covers the advantages and disadvantages of installing a traffic signal, the main components of a signal, and the basic terminology used to describe the operations of a traffic signal. Standard NEMA phasing and the Ring and Barrier Diagram are also discussed.

This and future Traffic Signal Academy on-demand courses will be hosted on Vimeo and may be accessed from links on the Traffic Signal Academy page of the T2 Center’s website. A direct link to the Basics of Traffic Signal Operations course video is here.

ss.7.2020.3.useAfter completing the on-demand module, participants may access a participant evaluation from the link below the video on Vimeo. Results of the evaluation are automatically reported to T2 Center Staff. Upon finishing the course and successfully completing the evaluation, participants will receive one credit hour toward the Traffic Signal Champion certificate.

We hope this proves to be a useful learning opportunity for your staff during these unprecedented times, and we look forward to providing you with additional on-demand course materials. Please feel free to reach out and let us know what you think and if there are other topics you would like to see in this format.

If you have traffic signal systems questions, please contact: Theresa Schwartz, P.E.,
P.T.O.E. – Traffic Signal Circuit Rider (860) 486-4535 or

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Safety Matters: Taking STEPs to Boost Pedestrian Safety

safety_matters_logoTaking STEPs to Boost Pedestrian Safety

With warm weather comes outdoor activity, and one of the most popular activities is walking. Over 110 million Americans walk for exercise, transportation to work or school, or just for fun! With that many pedestrians out there, who are vulnerable users of the roadways, it’s important to keep them safe.

Pedestrian fatalities escalated 53 percent between 2009 and 2018, according to the National Highway Traffic Safety Administration. Crashes with vehicles killed 6,283 pedestrians in 2018, the highest number since 1990. The Federal Highway Administration has made pedestrian safety a priority through their Every Day Counts (EDC) initiative Safe Transportation for Every Pedestrian or STEP.

sm.7.2020.1STEP promotes proven safety countermeasures for addressing pedestrian safety, and ranges from low-cost measures such as enhanced signage and markings to larger-scale projects such as Rapid Rectangular Flashing Beacons (RRFBs). The entire list, often referred to as the Spectacular Seven, along with additional information on each can be found here.


Many of these countermeasures may be familiar to you, as Connecticut has been proactive in installing them at both the State and local level. The CT Department of Transportation (DOT) has taken a programmatic approach to pedestrian safety, including it the State’s Complete Streets policy, the Active Transportation Plan and the Highway Safety Plan. ss.7.2020.2CTDOT also created a pedestrian safety countermeasure tool for marked uncontrolled crosswalks, which was featured in the March Connecticut Crossroads Safety Matters.
On a local level, many cities and towns have been working to improve pedestrian safety by installing many of the Spectacular Seven countermeasures. You can see some of them on the T2 Center’s Safety Examples website,

FHWA has recently added more resources to help agencies improve pedestrian safety. One of these is STEP Studio, which is, according to FHWA’s website, “a comprehensive compilation of resources, design guidance, research, and best practices for practitioners to identify appropriate countermeasures for improved pedestrian safety.” They also have instituted a STEP UP campaign, focusing on key pedestrian safety issues. More information can be found on their website at

For more information and assistance with local road safety in your community, contact Melissa Evans, Safety Circuit Rider, at

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Warren’s Words of Wisdom: Back to Basics – Electrical Boot Camp – Part 2

Backwarren_words_wisdom_Logo to Basics – Electrical Boot Camp

Part 2: Back to Basics Series

Last month we reviewed how electricity can kill you, mainly because you’re full of it. I mean water, salt and chemicals are over 80% of your body weight, which unfortunately makes you the best conductor of electricity on earth. But unlike a copper wire, you will burn up when the electricity flows through you—never a good thing. Linemen call dying by Primary contact a closed casket death. Dying by Secondary contact will probably be open casket, having caused less physical damage. But heck, you’re just as dead either way. Be smart, never trust any wires, primary or secondary, to be safe unless someone with the training and equipment is standing there tell you it’s safe to grab that wire. When they do that, you tell them to “You grab it first.” Your momma didn’t raise a fool!

This month we’re looking to recognize the electrical equipment in the field you could encounter while cutting grass, trimming trees, or clearing storm debris.

Substations are the locations where Transmission voltages (115,000 to 345,000 volts) get turned into Distribution Primary voltages, which could be 4,800 volts up to 23,000 volts.www.7.2020.1.use

The Distribution lines carry the Primary voltages at the top of the poles in either three wires (each wire is called a phase, this would be a 3-phase primary) or a one wire Primary, called a single phase. Utilities use the three phases as the backbone of the Distribution system and single-phase distribution as small customer load lines, for residential customers like in the picture below.


Speaking of transformers, almost all electrical equipment in the electrical grid has oil inside the equipment as an insulating fluid to prevent electrical arcing. Ninety-nine percent of the equipment in the field is Non-PCB oil. Still, some old equipment could contain PCB’s, so if you see anything electrical leaking oil, contact the local utility to investigate. Avoid the oil, don’t walk in it or get it on you. It tastes terrible (kidding, don’t do that).

You’ve probably had small children ask you, “How do electric utilities get the electrical primary and secondary wires to underground equipment from the overhead?” Well, now you’ll be able to give a coherent answer instead of saying, “Magic purple unicorns!” The secret is plastic PVC pipes called Risers attached to the side of the pole. Inside the Riser are electrical wires that are shielded so you can touch the outside of the riser without any risk. Big problems will happen if you drive a nail, snow plow, grass trimmer, saw blade, or any other pointy thing through the Riser into the wires inside.

A prime example of what not to do is to attempt to install important signs with nails and pop rivets into Primary cables. There is a reason the cable was covered. We don’t know what happened to the individual doing the work, but at least they knew where to go.www.7.2020.3

Risers have Primary or Secondary wires going underground. Primary goes to a padmount transformer (converts Primary to Secondary), and Secondary comes up to the meter.www.7.2020.4

Moral of the story: everything is hidden underground!! Use Call Before You Dig—even if you only plan on using a shovel, it’s a good safe thing to do. Enough for today. It may be not exciting, but it’s very important to recognize the deadly electrical hazards waiting for you to mess up.

When the right PPE includes gloves, make sure everyone has a pair!www.7.2020.5

Stay smart and stay safe! 

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Traffic Signal Academy: Basics of Signal Operations Learning Guide

Basics of Signal Operations Learning Guide

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Signal Spotlight: Upcoming Workshop Series: Developing a Traffic Signal Management Plan

traffic_signal_spotlights_logoUpcoming Workshop Series: Developing a Traffic Signal Management Plan

As blueprints for the future, TSMPs identify the staffing, funding and equipment necessary to provide good basic service to residents.  But with all the day-to-day tasks necessary to keep traffic signals and other public works operations running smoothly, developing a traffic signal management plan (TSMP) can seem like a daunting and time-consuming task. We’ve broken the process down into a four-part series of workshops to assist municipalities in tailoring a plan to fit their organization’s needs, whether a vendor maintains a handful of signals or a dedicated team of professionals manages hundreds.

ss_june_2020_1In Part One of the series, we’ll discuss the benefits of having a written traffic signal management plan as well as some existing activities that should be documented. Participants will come away with a worksheet to guide the initial information-gathering process of inventorying existing activities.

Next, in Part Two, we will discuss how having clear objectives can allow an agency to make the most of limited resources. Participants will brainstorm objectives for the traffic signal system in the context of the municipality’s overall transportation goals. Take-homes from Part Two of the series will include sample objectives that can be used to build a TSMP.

In Part Three, participants will review their existing traffic signal maintenance, operations, and design strategies within the context of the objectives identified during Part 2 of the series. We will explore whether the current strategies help to meet stated objectives, identify any gaps, and brainstorm additional strategies. A worksheet for linking strategies to objectives will be included in the participant learning guide.

ss_june_2020_2After completing Parts One through Three, participants will have a documented set of traffic signal management strategies that support their agency’s objectives. Part Four will focus on developing ways to evaluate progress toward those objectives, as well as documenting an action plan with steps toward meeting the objectives. Templates for maintenance and inspection checklists and quarterly and annual reporting forms will be included in the learning guide.

We’re excited to develop the curriculum for these and other future workshops. If you have suggestions for learning topics, email Tess Schwartz at

For more information on traffic signal management plans, visit the Traffic Signal Circuit Rider webpage at:

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Warren’s Words of Wisdom: Back to Basics – Electrical Boot Camp

warren_words_wisdom_LogoBack to Basics – Electrical Boot Camp

Part 1: Back to Basics Series 

It’s time to review the elements of electricity and the electrical distribution systems so that you know absolutely what you must do to protect yourself, your co-workers, the public and your family. There are many important things we need to go over, but in this series I’ll keep the sections in each issue short so that you can memorize them or get tattoos of the best parts to refer to. There will be a test—using this information every day to stay safe!

Part 1

Electricity is always trying to go to ground, or zero volts. That’s what makes electrical things work—the electricity going from a higher voltage to a lower voltage. 120 volts at the plug (Hot), going through a motor to get to the zero-volts side of the motor (Neutral), going to ground.

Electricity will always take the path of least resistance to flow from high to low voltage. Anything that will conduct electricity is called a conductor, and some are lower resistance than others, like copper. The perfect conductor for electricity is water mixed with a little salt and chemicals. Since the human body is 80+% water, salt and chemicals, anytime there is damage in a wire, tool, cord, etc. where the electricity has options, it will always choose you over any other conductor to flow through. (Not to be gross, but if you’ve ever tasted your blood, cut-finger time, did you notice it’s slightly salty tasting? You vampire you!)

The moral of the story: If you give electricity a choice between using you or any other conductor to flow from high to low voltage, it will always choose you and it will always be a very bad for you—from heart-stopping shock to internal organs being severely damaged. Your blood is the conductor, and the blood vessels are the wires the electricity is going to use to travel through your body causing serious damages/burns.

Home electrical systems that are typically 120/240 volts, 100–200 amps, called Secondary voltages, kill more people than encountering the 4,800–23,000 volts, thousands of amps, called Primary voltages. Primary-carrying conductors are normally 40–45 feet off the ground at the top of the pole and tough for you to get close to, unless you are in a bucket truck or freakishly tall. But the secondaries are only 12 feet off the ground coming to your weatherhead, and please trust me when I say, secondaries are NOT insulated wire. They may have been the day they were installed fresh out of the box, but don’t trust them with your life. Let a qualified electrician or your utility mess with your secondaries. You can supervise from the ground.

Do you need to do some work near the secondaries or around your weatherhead? Call your utility and ask them to install some insulation from the weatherhead out 10–12 feet or more if you need it. (It’s a FREE service.) Utilities will not trim tree limbs off the secondaries between your house and the street. You will need a qualified tree crew, but ask the utility to shut the power off during the time you schedule for the tree work.

As a utility safety person, I sadly had two occasions to investigate tree people who died while trimming limbs around secondaries. One contacted the energized secondaries with his aluminum pruning tool, and the other, working in uninsulated bucket truck, cut a limb which became hung up on primaries and then grabbed the limb with his bare hand. Very sad…because both were so easily preventable.

Guess which job had an ambulance carry away the shocked worker?www.6.2020.1



This gentleman did not pay attention to last month’s article!! Should we be concerned the life insurance beneficiary took time to snap the picture before rushing out to stop him?


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Safety Matters: Sharing the Road and Trail Safety

safety_matters_logoSharing the Road and Trail Safety


Roadway safety used to mean vehicular safety, but we have come a long way as a society in learning how to share the road with all users. Pedestrians and bicyclists are more and more prevalent on our roadways, especially during the current pandemic. People are working from home, there is less vehicular traffic on the streets, and walking and biking are a way to get outside at a time when many other options remain unavailable. This will only increase as the weather gets warmer and people venture out more and more.

Here are some tips to remember for all users.


  • Slow down! With less traffic, it may be appealing to drive faster but remember, a pedestrian hit by a car going 40 mph has an 85% chance of being killed; at 20 mph, the risk is reduced to 5%.
  • Avoid distractions. Driving is a serious responsibility and requires your attention and focus. When your attention is on the road, you’ll be prepared for any unexpected events.
  • Yield to pedestrians in marked and unmarked crosswalks.
  • Give cyclists their space – 3 feet is the law! If you need to pass a cyclist, slow down and give them the required distance.



  • Follow the rules of the road – the same rules that apply to drivers apply to you!
  • Be visible – wear bright or reflective clothing and use a light if conditions are dark.
  • Wear a helmet! If a crash is unavoidable, a helmet can be the difference between life and death. Over half of all bicycle fatalities are the result of a head injury.


  • Always use a sidewalk if available. If one isn’t available, walk as far to the edge of the road as possible facing traffic.
  • Use crosswalks when present, and obey pedestrian signals.
  • Be visible – wear visible clothing and carry a flashlight if walking in dark conditions.

Multi-use trails are a great way to walk and bike without exposing oneself to vehicular traffic, but trail safety is important too. On many trails, pedestrians and cyclists of all levels of experience are sharing a limited amount of space.

In their June newsletter, Watch for Me CT shared some information from the Farmington Valley Trails Council about survey results from their membership. The following are the most common safety issues those trail users experienced.

  • Users moving too fast for conditions
  • Users not thoughtfully sharing space
  • Coming upon someone unexpectedly
  • Interactions with vehicles at intersections

To safely share the trial, here are some tips to follow.

  • Cyclists should keep their speed down.
  • Stay on the right side of the trail and do not take up more than half of the trail.
  • Indicate when passing, if you are a runner or cyclist, and as a walker be alert and aware of trail users coming up behind you.
  • Where a trail crosses a road, be cautious of vehicles and stop at the intersection.


All users of the roadway and multi-use trails should expect the unexpected. If everyone is doing their part to pay attention, follow the rules and look out for others, crashes can be avoided and everyone can get home safely.

For more information and assistance with local road safety in your community, contact Melissa Evans, Safety Circuit Rider, at

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