What is traffic signal coordination?
Does traffic signal coordination mean that I will never have to stop for a red light?
Why do I have to wait so long for a green light on a side street?
How do I report a problem with a traffic signal, lane markings or traffic signs?
What should a driver do when approaching an intersection in which the traffic signal is not working?
How is the placement of traffic signals determined?
What is a traffic signal warrant?
What are the traffic signal warrants?
What is the justification for a left turn arrow?
How do pedestrian signals work?
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?
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.
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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.
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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.
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Please call (904) 630-CITY.
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This question is answered by Florida Statute 316.1235 which is given below in its entirety.
Florida Statute 316.1235, Vehicle approaching intesection in which traffic lights are inoperative.
The driver of a vehicle approaching an intersection in which the traffic lights are inoperative shall stop in the manner indicated in s. 316.123(2) for approaching a stop intersection. In the event that only some of the traffic lights within an intersection are inoperative, the driver of a vehicle approaching an inoperative light shall stop in the above-prescribed manner. A violation of this section is a non-criminal traffic infraction, punishable as a moving violation as provided in chapter 318. (Chgd by L. 1999 ch. 248(120). Eff. 6/8/99)
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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:
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.
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?
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.
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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.1
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 this section 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.2
1 Page 3, The Traffic Signal Book, Fred L. Orcutt, Jr. Prentice Hall, 1993
2 Page 4C-1, MUTCD, Millenium Edition, Federal Highway Administration
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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 the all of the specific information required and when the criteria for each warrant, or guideline, has 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.
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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 turning 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.
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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 pedestrian 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.
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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.
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Pedestrian rights and responsibilities are found in 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.
Florida Statute 316.130. Pedestrian obedience to traffic control devices and traffic regulations.
(1) A pedestrian shall obey the instruction of any official traffic control device specifically applicable to the pedestrian unless otherwise directed by a police officer.
Pedestrians shall be subject to traffic control signals at intersections as provided in s. 316.075, but at all other places pedestrians shall be accorded the privileges and be subject to the restrictions stated in this chapter. Where sidewalks are provided, no pedestrian shall, unless required by the circumstances, walk along and upon the portion of a roadway paved for vehicular traffic. Where sidewalks are not provided, any pedestrian walking along and upon a highway shall, when practicable, walk only on the shoulder on the left side of the roadway in relation to the pedestrian's direction of travel, facing traffic which may approach from the opposite direction. No person shall stand in the portion of a roadway paved for vehicular traffic for the purpose of soliciting a ride, employment, or business from the occupant of any vehicle. No person shall stand on or in proximity to a street or highway for the purpose of soliciting the watching or guarding of any vehicle while parked or about to be parked on a street or highway. When traffic control signals are not in place or 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. 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. No pedestrian shall suddenly leave a curb or other place of safety and walk or run into the path of a vehicle which is so close that is impossible for the driver to yield. Whenever any vehicle is stopped at a marked crosswalk or at any unmarked crosswalk at an intersection to permit a pedestrian to cross the roadway, the driver of any other vehicle approaching from the rear shall not overtake and pass such stopped vehicle. 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. Between adjacent intersections at which traffic control signals are in operation, pedestrians shall not cross at any place except in a marked crosswalk. No pedestrian shall, except in a marked crosswalk, cross a roadway at any other place than by a route at right angles to the curb or by the shortest route to the opposite curb. Pedestrians shall move, whenever practicable, upon the right half of crosswalks. No pedestrian shall 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. Notwithstanding other provisions of this chapter, every driver of a vehicle shall exercise due care to avoid colliding with any pedestrian or any person propelling a human-powered vehicle and give warning when necessary and exercise proper precaution upon observing any child or any obviously confused or incapacitated person.
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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. Such marked crossings may not be as safe as an unmarked crossing at the same location. 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.
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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.
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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.
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