Traffic Signals

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What does that FLASHING YELLOW ARROW mean?

The 4-section traffic signal head with the flashing yellow arrow gives the driver the opportunity to turn left after opposing traffic and pedestrians have cleared the intersection.  In some cases the 4-section will replace the current 5-section heads and on other cases they will replace existing 3-section heads where left turns are only permitted on a green arrow.

On S Washington St for example there used to be 3-section left turn signal heads which only permitted left turn when there was a green arrow.  With the realignment of the left turn lanes ( to provide sufficient sight distance) drivers will now be able to make a left turn either on a green arrow or a flashing yellow arrow after tuning. 

The Flashing Yellow Arrow also gives us the capability of only proving a green arrow during heavy traffic.  You may not get a flashing yellow arrow every time you come to the intersection.  If the flashing yellow does not appear left turns can only be make on the left green arrow.

Several jurisdictions have already installed flashing yellow arrows.  The following link provides a visual explanation.

 Studies done all over the US have shown that the flashing yellow arrow for permissive left turns is safer than with the green ball.  

https://www.youtube.com/watch?v=w9coaImuzqk

or

https://www.youtube.com/watch?v=5C05DZNd9Zo

How do I report a problem with a traffic signal, lane markings or traffic signs?

If you see a problem with traffic signals or missing stop signs, please call the Engineering Department (701) 746-2640 during regular working hours, nights, holiday and weekends call (701) 787-8000.

If you see a problem with lane markings, traffic signals and other traffic signs that are not in the nature of an emergency, please call the Engineering Department at (701) 746-2640

What is traffic signal coordination?

Traffic signal coordination is when two or more traffic signals are working together so that cars moving through the group of signals will make the least number of stops possible.

Does traffic signal coordination mean that I will never have to stop for a red light?

No. There are many reasons why you will still have to stop at red lights. Each of the reasons has to do with the amount of time available for the green light in your direction.

- Pedestrian Crossings: For safety, enough time must be allowed for a pedestrian to cross the street from curb-to-curb, walking at a pace of about three to four feet per second.

- Cross Traffic: Like pedestrian crossings, enough time must be allocated to clear the waiting traffic on the cross street. The heavier the cross traffic, such as experienced near schools and businesses, the more time that is needed to clear them through the intersection and the less time that is available for the green light in the "coordinated" direction.

- Left-Turn Signals: Where left-turning traffic is especially heavy and/or the amount of opposing traffic is so heavy that there are not enough gaps in the traffic to safely complete a left-turn, protected left-turn signals are usually installed. The amount of time for protected left-turning traffic also limits the time permitted for the "through" traffic flow in the opposite direction.

- Two-Way Traffic Flow: The distance between traffic signals and the speed of the traffic determine the way in which the green lights at the next traffic signal line up. When the spacing is not equal between traffic signals, the green lights may only line up well in one direction. When this happens, the city tries to line up the green lights in the direction that has the most traffic. The traffic in the other direction may have to stop occasionally as a result.

- Off-Peak Traffic Periods: Traffic signals are not coordinated 24 hours a day. During times when traffic is light, traffic signals are usually allowed to run independently. Traffic signals are most often coordinated during the "peak" travel times when traffic is heaviest, usually between 7 - 9 a.m. and 4 - 6 p.m.

Why do I have to wait so long for a green light on a side street?

In order to have coordinated traffic signals, each traffic signal in the group must be able to allow the green light for all movements during a common fixed time period. The time period chosen is usually determined by the largest intersection with the most different movements. This will most often be an intersection that has protected left-turn arrows for all directions and wide cross streets. For that reason, the time period that is fixed for each traffic signal (the cycle length) may be rather long. So, if you are waiting for a green light to cross the "coordinated" street where there are protected left-turn arrows and there is very light traffic on the side street, chances are good that you will feel like you are waiting for a long time, even though you should rarely have to wait any longer than about two minutes.

What should a driver do when approaching an intersection in which the traffic signal is not working?
This question is answered by North Dakota Century Code which states: If a vehicle approaches an intersection that has traffic-control signals that usually exhibit different colored lights and the signals are not lit, the driver of the vehicle shall stop and yield as required under subsection 2 of section 39-10-24.

39-10-24 states: Stop signs and yield signs.

  1. Preferential right of way may be indicated by stop signs or yield signs as authorized in section 39-07-03.
  2. Except when directed to proceed by a police officer, every driver of a vehicle approaching a stop sign shall stop at a clearly marked stop line, or, if none, then at the point nearest the intersecting roadway where the driver has a view of approaching traffic on the intersecting roadway before entering it. After having stopped, the driver shall yield the right of way to any vehicle in the intersection or approaching on another roadway so closely as to constitute an immediate hazard during the time when such driver is moving across or within the intersection or junction of roadways.
  3. The driver of a vehicle approaching a yield sign shall be in obedience to such a sign and slow down to a speed reasonable for the existing conditions and, if required for safety to stop, shall stop at a clearly marked stop line, or, if none, before entering the crosswalk on the near side of the intersection, or, if none, then at the point nearest the intersecting roadway where the driver has a view of approaching traffic on the intersecting roadway before entering it. After slowing or stopping, the driver shall yield the right of way to any vehicle in the intersection or approaching on another roadway so closely as to constitute an immediate hazard during the time such driver is moving across or within the intersection or junction of roadways. Provided, however, that if a driver is involved in a collision with a vehicle in the intersection or junction of roadways after driving past a yield sign without stopping, such collision is deemed prima facie evidence of the driver's failure to yield the right of way.

 How is the placement of traffic signals determined?

Traffic signals don't always prevent accidents. In some instances, total accidents and severe injuries increased after signals were installed. Usually, in such instances, right angle collisions were reduced by the traffic signals, but the total number of collisions, especially the rear-end type, increased.

There are times when the installation of signals result in an increase in pedestrian accidents. Many pedestrians feel secure with a painted crosswalk and a red light between them and an approaching vehicle. The motorist, on the other hand, is not always so quick to recognize these "barriers."

When can a traffic signal be an asset instead of a liability to safety? In order to answer this, traffic engineers have to ask and answer a series of questions:

  • Are there so many cars on both streets that signal controls are necessary to clear up the confusion or relieve the congestion?
  • Is the traffic on the main street so heavy that drivers on the side street will try to cross when it is unsafe?
  • Are there so many pedestrians trying to cross a busy main street that confusing, congested or hazardous conditions result?
  • Are there so many school children trying to cross the street at the same time that they need special controls for their protection? If so, is a traffic signal the best solution?
  • Are signals at this location going to help drivers maintain a uniform pace along the route without stopping unnecessarily?
  • Does the collision history indicate that signal controls will reduce the probability of collisions?
  • Do two arterials intersect at this location and will a signal help improve the flow of traffic?
  • Is there a combination of the above conditions which indicates that a signal will be an improvement rather than a detriment?

To aid them in answering these questions, engineers compare the existing conditions against nationally accepted minimum guidelines. Experienced traffic engineers established these guidelines (warrants) from many observations at intersections throughout the country. Where the guidelines were met, the signals generally were operating effectively with good public compliance. Where the guidelines were not met, public compliance was reduced, and additional hazards resulted.

A traffic signal that decreases accidents and improves the flow of traffic is an asset to any community. On the other hand, an ill-advised or poorly designed signal can be a source of danger and annoyance to all that use the intersection; pedestrians, cyclists and drivers alike.

What IS a Traffic Signal Warrant?

The use of the word "warrant" in the Manual on Uniform Traffic Control Devices (MUTCD) is unfortunate since this word implies the idea of "sanctioned, needed and approved". However these adjectives do not apply to the warrant guidelines in the MUTCD. Page 3, The Traffic Signal Book, Fred L. Orcutt, Jr. Prentice Hall, 1993)

The MUTCD has eight guidelines (called warrants), which establish certain minimum thresholds below which a traffic signal should not be installed. Satisfying one or more of these warrants does not mean that the city must or should install a traffic signal. In fact, the MUTCD states the following:

A traffic control signal should not be installed unless one or more of the factors described in here are met.

- A traffic control signal should not be installed unless an engineering study indicates that installing a traffic control signal will improve the overall safety and/or operation of the intersection.

- A traffic control signal should not be installed if it will seriously disrupt progressive traffic flow. (Page 4C-1, MUTCD, Millennium Edition, Federal Highway Administration)

What ARE the Traffic Signal Warrants?

The following warrant titles and the general supplemental information below them provide some indication of what parameters are looked at by traffic engineers, and are taken from the MUTCD. Refer to the latest edition of the MUTCD for all of the specific information required and when the criteria for each warrant, or guideline, have been met.

Warrant 1, Eight-Hour Vehicular Volume
This warrant looks at the major and minor total street volumes per hour for eight hour periods, when the volumes of intersecting traffic are the principal reason for consideration of signal installation. In general, average day volumes of more than 500 vehicles per hour (vph) total on the major street, and/or more than 150 vph on one approach from the minor street will result in this warrant being met.

This warrant also looks at the major and minor traffic volumes for eight hour periods, for that instance when the traffic volume on the major street is so heavy that traffic on minor streets suffers excessive delay or hazard in entering or crossing the major street. In general, volumes of more than 750 vph total on the major street, and/or more than 75 vph on one approach from the minor street will result in this warrant being met; providing that the signal would not seriously disrupt progressive traffic flows.

Warrant 2, Four-Hour Vehicular Volume
A traffic signal may be warranted at some intersections when each of any four hours of an average day has a total traffic volume on the major street and an approach traffic volume on the minor street, which if plotted would fall above the curve of Figures 4C-1 and/or 4C-2 of the MUTCD.

Warrant 3, Peak Hour Volume
The peak hour volume warrant is intended for application when traffic conditions are such that for one hour of the day minor street traffic suffers undue traffic delay in entering or crossing the major street, as determined on where the plotted traffic volumes would fall with respect to the curves of Figures 4C-3 and 4C-4 of the MUTCD.

Warrant 4, Pedestrian Volume
This warrant looks at pedestrian volume crossing the major street at an intersection or at a mid-block location during an average day. In general, pedestrian volumes of more than 100 pedestrians per hour for any four hours, and/or more than 190 pedestrians during any one hour period will result in this warrant being met.

Warrant 5, School Crossing
A traffic signal may be warranted at an established school crossing when a traffic engineering study of the frequency and adequacy of gaps in the vehicular traffic stream as related to the number and size of groups of school children indicates that the available time for the school children to cross the street is inadequate.

Warrant 6, Coordinated Signal System
A traffic signal may be warranted at intersections where they would not otherwise be warranted in order to maintain proper grouping of vehicles (to establish and maintain platoons of vehicles for effective traffic signal coordination) and to effectively regulate group speed.

Warrant 7, Crash Experience
A traffic signal may be warranted at some intersections when less restrictive remedies and enforcement has failed to reduce the vehicular collision rate; and five or more correctable collisions have occurred within a 12 month period; and there are volumes of vehicles and pedestrians of not less than 80 percent of the requirements specified in Warrant 1; and the new signal will not seriously disrupt progressive (coordinated) traffic flows.

Warrant 8, Roadway Network
A traffic signal may be warranted at some intersections to encourage concentration and organization of traffic flow networks when there is an entering traffic volume of at least 1000 vph during the peak hour of a typical workday, and which has five year projected traffic volumes – based upon an engineering traffic study – that meet one or more of Warrants 1, 2, and 3 during at average workday; or which has a total entering volume of at least 1000 vph for each of any five hours on a weekend.

What is the justification for a left turn arrow?

Left Turn Signal Phasing
Left turn signal phases facilitate left turning traffic and usually improve the safety of the intersection for left turning vehicles. However, this is done at the expense of the amount of green time available for through traffic and will usually reduce the capacity of the intersection. Left turn arrows also result in longer cycle lengths, which will in turn have a detrimental effect by increasing stops and delays. Pedestrian delays may be increased, resulting in pedestrians ignoring the pedestrian signal.

While phases for protected left turning vehicles are the most popular and most often added phases, other methods of handling left turn conflicts should be considered first. Potential solutions include prohibited left turns and geometric improvements.

Left Turn Phase Criteria
The left turn phase criteria suggested below are a combination of left turn phasing used in several states in the United States and the result of considerable research and study. These warrants are not mandated by the Manual on Uniform Traffic Control Devices (MUTCD) and are provided for information purposes only. Suggested warrants are as follows:

Volumes – Consider left turn phasing when the product of left turning and opposing volumes during peak hours exceed 100,000 on a four lane street, or 50,000 on a two lane street (one approach lane). Also, the left turn volume for two or more approach lanes should be greater than two vehicles per cycle during the peak hour period. Volumes meeting these levels indicate that a left turn phase may be justified and further study of the intersection is recommended.

Delay – Consider installing left turn phasing if a left turn total delay of two vehicle hours or more occur in a peak hour on a critical approach. Also, there should be a minimum left turn volume of greater than two vehicles per cycle during peak hour, and the average delay for left turning vehicle should be at least 35 seconds.

Accident Experience – Install left turn phasing if the critical number of left turn accidents has occurred. For one approach, the critical number is four left turn accidents in one year, or six in two years. For both approaches, the critical number is six left turn accidents in one year, or 10 in two years.

Protected/Permitted Left Turn Phasing
Protected/permitted left turn phasing is a left turn movement of traffic at a signalized intersection having a separate left turn phase in the signal cycle to provide a protected green arrow interval, as well as non-protected circular green interval. Use of the protected/permitted left turn phasing technique is based on the assumption that the need for a protected left turn interval has been established. One of the basic precepts of the protected/permitted left turn phasing, is that the protected green arrow is displayed only when needed in a traffic demand condition. It is therefore emphasized that the protected/permitted left turn phasing technique is an efficient concept as opposed to an accident reduction concept although it will probably offer safer operation than permissive only operation.

Protected Only Left Turn Phasing
When a separate interval is provided to accommodate a left turn without conflicting traffic, and left turns are prohibited during the rest of the cycle, protected only left turn phasing occurs. Although the MUTCD provides no left turn phasing warrants, the traffic control device handbook offers suggested guidelines for separate left turn phasing.

Unprotected Left Turn Phasing
Unprotected left turn phasing occurs when an exclusive phase is not provided for left turn vehicles. Left turns are permitted to occur through gaps in the opposing traffic flow. Separate left turn lanes may or may not be provided.

How do pedestrian signals work?

The pedestrian signal provides time for the pedestrians to enter the street on the steady walk signal or walking person symbol and to finish crossing the street on the flashing don't walk or upraised hand signal. The signal is normally activated by a push button, which causes the traffic signal controller to operate a pre-programmed timed sequence of walk and flashing don't walk indications.

Pedestrian signals consist of walk and don't walk signals or the international symbols displaying a person walking for the walk indication, and a hand for the don't walk indication. The walk indication is displayed in white, and the don't walk indication is displayed in Portland orange.

The pedestrian signal sequence begins when the walk indication is illuminated, and this sequence is typically four to seven seconds long. This sequence should be long enough for a pedestrian to leave the curb and begin crossing the street before the clearance interval begins.

The pedestrian clearance interval consists of the flashing don't walk indication. During this interval the pedestrian is expected to complete their crossing of the street. The pedestrian should not, however, begin crossing the street on the flashing don't walk indication. The pedestrian clearance interval is typically calculated by dividing the street width by an assumed walking speed of four feet per second, unless a special study indicates that a longer time interval is needed for all pedestrians to safely cross the street, i.e. a slower walking speed of 3.5 feet per second is often used for elderly pedestrians. The actual distance used to calculate the clearance interval is usually the distance from the curb on the near side of the street to the center of the last traffic lane on the far side of the street.

The don't walk indication, steadily illuminated, means that a pedestrian is not to enter the street in the direction of the pedestrian signal.

WARNING: While pedestrians have the right of way at both marked and unmarked crosswalks, both pedestrians and motorists should be very alert when pedestrians are present at a pedestrian signal, since right turn on red movements are allowed unless otherwise prohibited.

Is it really necessary for me to push a button to activate the pedestrian signal, or can I just wait for the light to change?

YES!  Where buttons are available to pedestrians, it is because the traffic signal is timed for cars, not for people on foot.  If you don't activate the pedestrian signal by pushing the button, the traffic light won't give you enough time to safely cross the street.  You only need to push the button once for it to be activated.

It is also state law and included in the North Dakota Century Code:

39-10-06. Pedestrian control signals. Whenever special pedestrian-control signals

exhibiting the words "Walk" or "Don't Walk" or the symbols of a walking person, symbolizing "Walk", or an upraised hand, symbolizing "Don't Walk" are in place, such signals must indicate as follows:

1. "Walk": Pedestrians facing such indication may proceed across the roadway in the direction of the indication and must be given the right of way by the drivers of all vehicles.

2. "Don't Walk" (steadily illuminated): A pedestrian may not start to cross the roadway in the direction of such indication.

3. "Don't Walk" (flashing): A pedestrian may not start to cross the roadway in the direction of the indication, but any pedestrian who has partially completed a crossing during the "Walk" signal must proceed in the direction of the indication to a sidewalk or safety island.

(Back to the Top)

Why does it always say, "DON’T WALK" before I've completed crossing the street?

The flashing "DON’T WALK" or upraised ORANGE hand is a warning to people not to start across the street who have not yet entered the intersections.  There is not enough time to safely cross the street before the traffic signal changes allowing cars to proceed in the opposite direction. Signals are timed to allow plenty of time for people who start walking during the “WALK” phase to safely cross the street.

Can I safely cross the street if I carefully follow the pedestrian signals?

The “WALK” pedestrian signals will tell you when you should start to cross the intersection. However, it is important to be cautious when crossing busy intersections.  Do not start crossing the street once the “DON’T WALK” or RAISED HAND begins to flash.  At that point that is not enough time to cross the street before the signal changes. 

The following suggestions are offered in the interest of safety: Cross intersections defensively when crossing the street. Regardless of the availability of signals  cross as quickly as possible. Minimize your time in the roadway. Always watch for turning vehicles. You have the legal right to be there, but that doesn't protect you from a motorist who doesn’t see you.

Why are the words "walk" and "don't walk" being replaced by symbols?

Transportation engineers world-wide are moving toward the use of symbol signs in place of word signs because they are easier for people to comprehend in a shorter amount of time. Easily recognized symbols also accommodate people who can't read English.

In the case of pedestrian signals, both "word" and "symbol" signs are currently in use. Here's what they mean. "Walk" or walking pedestrian symbol means you may begin crossing. A flashing or steady "Don't Walk" or an upraised hand symbol means it's too late to begin crossing. Don't enter the street but finish crossing if you have already started.  In the near future all of the pedestrian signals in Grand Forks will also have a “COUNTDOWN” head.  This will let the pedestrian know how many seconds are left before the traffic signal will turn YELLOW.  Once the COUNTDOWN begins a pedestrian should not start to cross the street.

What are the pedestrian rights and responsibilities when walking along, or crossing a street?

Pedestrian rights and responsibilities are found in the North Dakota Century Code Section 316.130 of the Florida Statutes, but a list of some of those rights and responsibilities is given below. The following list is not represented as being exhaustive, and the reader is directed to the statutes for more complete information.

39-10-27. Pedestrian obedience to traffic-control devices and traffic regulations.

  1. A pedestrian shall obey the instructions of any official traffic-control device specially applicable to the pedestrian, unless otherwise directed by a police officer.
  2. Pedestrians are subject to traffic-control and pedestrian-control signals as provided for in sections 39-10-05 and 39-10-06.

39-10-28. Pedestrian's right of way in crosswalk.

  1. When traffic-control signals are not in place or not in operation, the driver of a vehicle shall yield the right of way, slowing down or stopping if need be to so yield, to a pedestrian crossing the roadway within a crosswalk when the pedestrian is upon the half of the roadway upon which the vehicle is traveling, or when the pedestrian is approaching so closely from the opposite half of the roadway as to be in danger.
  2. No pedestrian may suddenly leave a curb or other place of safety and walk or run into the path of a vehicle which is so close as to constitute an immediate hazard.
  3. Subsection 1 does not apply under the conditions stated in subsection 2 of section 39-10-29.

4.   Whenever any vehicle is stopped at a marked crosswalk or at any unmarked crosswalk at an intersection to permit a pedestrian to cross the highway, the driver of any other vehicle approaching from the rear may not overtake and pass such Stopped vehicle.

39-10-29. Crossing at other than crosswalk.

  1. Every pedestrian crossing a roadway at any point other than within a marked crosswalk or within an unmarked crosswalk at an intersection shall yield the right of way to all vehicles upon the roadway.
  2. Any pedestrian crossing a roadway at a point where a pedestrian tunnel or overhead pedestrian crossing has been provided shall yield the right of way to all vehicles upon the roadway.
  3. Between adjacent intersections at which traffic-control devices are in operation, pedestrians may not cross at any place except in a marked crosswalk.
  4. No pedestrian may cross a roadway intersection diagonally unless authorized by official traffic-control devices; and, when authorized to cross diagonally, pedestrians shall cross only in accordance with the official traffic-control devices pertaining to such crossing movements.

39-10-30. Driver to exercise due care.

Notwithstanding other provisions of this chapter or the provisions of any local ordinance, every driver of a vehicle shall exercise due care to avoid colliding with any pedestrian and shall give warning by sounding the horn when necessary and shall exercise proper precaution upon observing any child or any confused, incapacitated, or intoxicated person.

 When is a marked crosswalk unsafe?

A number of years back, the City of San Diego published some startling results of a very extensive study of the relative safety of marked and unmarked crosswalks. San Diego looked at 400 intersections for five years (without signals or four-way stops) that had a marked crosswalk on one side and an unmarked crosswalk on the other. About two and one half times as many pedestrians used the marked crosswalk, but about six times as many accidents were reported in the marked crosswalks. Long Beach studied pedestrian safety for three years (1972 through 1974) and found eight times as many reported pedestrian accidents at intersections with marked crosswalks than at those without. One explanation of this apparent contradiction of common sense is the false security pedestrians feel at the marked crosswalk. Two painted lines do not provide protection against an oncoming vehicle and the real burden of safety has to be on the pedestrian to be alert and cautious while crossing any street. A pedestrian can stop in less than three feet, while a vehicle traveling at 25 miles per hour will require 60 feet and at 35 miles per hour approximately 100 feet.

Crosswalks exist at all intersections unless signs prohibit pedestrian crossing. Some of these crosswalks are marked with painted lines, but most of them are not. Pedestrian crosswalk marking is a method of encouraging pedestrians to use a particular crossing.

Therefore, crosswalks should be marked only where necessary for the guidance and control of pedestrians, to direct them to the safest of several potential routes.

Do marked crosswalks provide better pedestrian safety than unmarked crosswalks?

Not always. The city receives frequent requests to install marked crosswalks at uncontrolled intersections or at some mid-block location between uncontrolled intersections. An uncontrolled intersection is one without stop signs, yield signs, or traffic signals. These requests almost always come from the sincere belief held by some citizens that a marked crosswalk provides some kind of additional protection to the pedestrians who use them. Unfortunately, this is a common misconception that can be extremely hazardous.  There have been many site studies of pedestrian safety at marked and unmarked crosswalks at uncontrolled intersections.

The primary thrust of these studies is that marked crosswalks give pedestrians a false sense of security. While the crosswalk markings are very obvious to the pedestrian, they are often much less visible to the motorists who drive over them. Pedestrians must always act defensively when motorists are in close proximity to them, but some pedestrians think that white pavement markings will somehow stop, or slow down, a moving vehicle, and this is obviously just not the case.