HAWK beacon

A HAWK beacon (High-Intensity Activated crossWalK beacon) is a traffic control device used to stop road traffic and allow pedestrians to cross safely. It is officially known as a Pedestrian Hybrid Beacon (PHB). The purpose of a HAWK beacon is to allow protected pedestrian crossings, stopping road traffic only as needed. Where standard traffic signal 'warrants' prevent the installation of standard three-color traffic signals, the HAWK beacon provides an alternative.

HAWK beacon
A HAWK beacon on the campus of Texas A&M University–Commerce
TypeTraffic control signal
InventorR. B. Nassi, P.E., Ph.D.
Inception2000 (2000) Experimental version.
2009 (2009) Official introduction.
For other uses, see Hawk (disambiguation) and Hawks (disambiguation).

A HAWK beacon is used only for marked crosswalks. A similar hybrid beacon, called 'emergency-vehicle hybrid beacons' are allowed at driveways of emergency service buildings such as fire stations.[1]

History

The first beacon was developed in Tucson, Arizona by Transportation Administrator R. B. Nassi, P.E., Ph.D., and installed in 2000. The bird name HAWK was suggested by his wife. Until December 2009, the HAWK beacon was categorized as an experimental device. United States transportation agencies wishing to use a HAWK signal were required to obtain approval from the Federal Highway Administration, as well as collect and submit data on the effectiveness of the device. It was finally included in the 2009 edition of the US Manual on Uniform Traffic Control Devices as a "Pedestrian Hybrid Beacon."[2]

Design and operation

Design
Diagram of the signal head of a HAWK beacon.

Manual on Uniform Traffic Control Devices guidance states that a HAWK beacon is justified and may be installed if the following conditions are met:

Guidance:

  • If one of the signal warrants of Chapter 4C is met and a traffic control signal is justified by an engineering study, and if a decision is made to install a traffic control signal, it should be installed based upon the provisions of Chapters 4D and 4E.
  • If a traffic control signal is not justified under the signal warrants of Chapter 4C and if gaps in traffic are not adequate to permit pedestrians to cross, or if the speed for vehicles approaching on the major street is too high to permit pedestrians to cross, or if pedestrian delay is excessive, the need for a pedestrian hybrid beacon should be considered on the basis of an engineering study that considers major-street volumes, speeds, widths, and gaps in conjunction with pedestrian volumes, walking speeds, and delay.
  • For a major street where the posted or statutory speed limit or the 85th-percentile speed is 35 mph or less, the need for a pedestrian hybrid beacon should be considered if the engineering study finds that the plotted point representing the vehicles per hour on the major street (total of both approaches) and the corresponding total of all pedestrians crossing the major street for 1 hour (any four consecutive 15-minute periods) of an average day falls above the applicable curve in 4F-1 for the length of the crosswalk.
  • For a major street where the posted or statutory speed limit or the 85th-percentile speed exceeds 35 mph, the need for a pedestrian hybrid beacon should be considered if the engineering study finds that the plotted point representing the vehicles per hour on the major street (total of both approaches) and the corresponding total of all pedestrians crossing the major street for 1 hour (any four consecutive 15-minute periods) of an average day falls above the applicable curve in Figure 4F-2 for the length of the crosswalk.
  • For crosswalks that have lengths other than the four that are specifically shown in Figures 4F-1 and 4F-2, the values should be interpolated between the curves.
    — "Manual on Uniform Traffic Control Devices" - Part 4 Highway Traffic Signals.
Animation demonstrating the operation of a HAWK beacon (Click to animate)

The vehicular signal head has three sections, consisting of two horizontally-arranged circular red sections over a single circular yellow section that is centered between the red lights, forming a triangle. There must be at least two HAWK signal faces facing each vehicular approach to the crossing. Normal pedestrian signal heads control pedestrian traffic. If speeds of 85% of drivers (85th percentile speed) exceeds 35 miles per hour (56 km/h), and a signal head mounted on the roadside would be obstructed from driver view, then both of the minimum signal head are required must be mounted above the roadway.

Operation

Unlike ordinary traffic signals, the vehicular signal heads of a HAWK beacon are dark until activated by a pedestrian who wishes to cross the roadway. The pedestrian signal heads operate normally, displaying an upraised hand (don't walk) aspect during the time that vehicles have the right of way.[3] When a pedestrian activates the beacon by pushing the pedestrian call button, the HAWK beacon sequence is started. First with flashing yellow, then steady yellow, and finally steady red over a period of several seconds. Pedestrian pedestrian signal heads at either end of the crosswalk display the upraised hand (don't walk) signal until the HAWK beacon displays the steady red signal, at which time, the pedestrian heads change to the walking-person (walk) aspect.

As the pedestrian phase starts to end, the walking-person (walk) aspect changes to an flashing upraised hand (don't walk) with a countdown indicator. Pedestrians in the roadway should finish crossing the roadway, and anyone who wishes to cross but has not entered the roadway should reactivate the signal and wait. At this point, the vehiclear signal heads change to display an alternating flashing red aspect. Vehicles must yield to any pedestrians still in the crosswalk. If the crosswalk is clear they may proceed after coming to a full stop.

Once the pedestrian crossing phase comes to an end, the countdown indicator reaches "0", and the pedestrian signal changes back to the non-flashing upraised hand (don't walk). Then the vehicle signal head returns to the dark state, and vehicle traffic has the right of way, until the signal is reactivated.

Sequence of signal
Signal operation sequence and driver responsibility[4][5]
Pedestrian Hybrid Beacon aspectPedestrian Signal AspectDriver responsePedestrian response
Drivers may proceed normally, without stopping at the crosswalk.Pedestrians press the pedestrian call button.
Drivers should slow down and prepare to stop soon.Pedestrians wait.
Drivers should stop, if able to do so safely. The signal is changing to red in a moment.Pedestrians continue to wait.
Drivers must stop before the crosswalk.Pedestrians may start crossing the street.
Drivers may proceed after coming to a full stop, and checking that the crosswalk is clear. (Similar to a stop sign.)Pedestrians already crossing the street should finish.
Pedestrians that have not started crossing the street, should not start.
Drivers may proceed without stopping, if the crosswalk is clear.Pedestrians press the pedestrian call button.
End of sequence.

Effectiveness

One study released by the Federal Highway Administration found that, after a HAWK signal was installed, vehicle/pedestrian crashes were reduced by 69%.[6] As many as 97% of motorists comply with the HAWK beacon, higher than signalized crossing, or crossings with flashing yellow beacons.[7]

Some motorist confusion has been reported at newly installed HAWK beacons. When first introduced to an area, enforcement and public education are needed until users understand how the beacon works. When the beacon has not been activated, some drivers have acted as if the signal is dark due to a power outage, but that has not been experienced by all jurisdictions with HAWKs in operation. The flashing red phase is sometimes misunderstood by drivers farther back in the queue, and they followed the lead driver through the crosswalk instead of stopping at the stop line as required.[6] Additionally, motorists sometimes remain stopped during the flashing red phase when the crosswalk is clear due to the similarity to a railroad crossing signal.[8] In 2016, to address this issue, the Federal Highway Administration authorized use of a new traffic sign, 'R10-23a', to better explain the steady red and flashing red aspects to drivers.[9]

Conflicting meanings of HAWK signal aspects

The design and operation of the HAWK beacon/crossing differs differ materially from the meanings and operation of the same signal aspects when used in other contexts:

  • Some motor vehicle codes require that motorists stop at dark signals, which are typically indicative of an abnormality in the normal operation of the signal, such as a power failure. However, the dark signal is a normal display at HAWK beacons, where it designates the right-of-way for vehicular traffic.
  • Traffic may fail to appreciate the conversion of a flashing yellow to a steady yellow signal, and thence fail to comprehend that the signal is about to change from steady yellow to red. Flashing yellow signals in other contexts are simply caution markers, and do not convert to steady yellow and thence to red in this way.
  • At conventional traffic signals, the entire pedestrian crossing phase, including the entire flashing upright hand (don't walk) 'pedestrian change interval' is protected from vehicle traffic of the roadway pedestrians are crossing. However, at HAWK crossings, during the flashing upright hand (don't walk) 'pedestrian change interval', vehicles may legally proceed through the crosswalk after stopping. This could create a collision risk from a pedestrian not expecting a vehicle to enter the crosswalk.

Alternating flashing red aspect

A number of conflicts come exist with the alternating flashing red aspect used with the HAWK beacon.

  • The alternating flashing red (wig-wag) aspect is used in several other applications for vehicle control in the United States.
    • At railroad crossing signals, which several jurisdictions require drivers to treat as stop and stay.
    • On School buses, all states have laws that require drivers to stop and stay upon encountering it.
    • At movable bridges, which is required to be treated as stop and stay.

The MUTCD explicitly states that use of horizontal, alternating red flashing lights should be avoided at stop signs to avoid confusion with railroad crossing signals.[10] However, at a HAWK beacon, an alternating flashing red aspect instructs drivers to stop and proceed when clear, and is not supposed to be treated as stop and stay by drivers.

  • Emergency-vehicle hybrid beacons, for emergency vehicle facilities (i.e. fire stations), use the same signal head design, and uses an alternating flashing red aspect to protect departing emergency vehicles. The only distinguishing part of the design is a different sign, R10-14, is used with the signal. Unlike at a HAWK beacon, drivers are expected to remain stopped during this time, to allow emergency vehicles to enter the roadway.[1]

See also

References
  1. Federal Highway Administration. "Manual of Traffic Control Devices - Part 4, Highway Traffic Signals" (PDF). mutcd.fhwa.dot.gov. pp. 513–515. Archived from the original (PDF) on 16 May 2020. Retrieved 27 June 2020.
  2. Federal Highway Administration. "Manual of Traffic Control Devices - Part 4, Highway Traffic Signals" (PDF). mutcd.fhwa.dot.gov. pp. 509–512. Archived from the original (PDF) on 16 May 2020. Retrieved 27 June 2020.
  3. Mike Chalmers, "New traffic signals make it safer for pedestrians". USA Today, August 9, 2010 Retrieved 2011-06-21.
  4. City of Des Moines. "What should you know about... HAWK Pedestrian Signals?" (PDF). www.dsm.city. p. 2. Archived from the original (PDF) on 26 June 2020. Retrieved 26 June 2020.
  5. Slager, Melissa (2016-12-19). "What those HAWK crosswalk signals mean for drivers". HeraldNet.com. Retrieved 2018-12-06.
  6. Fitzpatrick, K.; Park, E.S. (July 2010). Safety Effectiveness of the HAWK Pedestrian Crossing Treatment (PDF). Federal Highway Administration.
  7. http://transport.ksu.edu/files/transport/imported/Thesis/RanjitPrasadGodavarthy2010.pdf figure 21
  8. Joel Funk (October 16, 2015). "WYDOT: Signals have caused some confusion". Laramie Boomerang.
  9. Federal Highway Administration. "Interpretation Letter 4(09)-61 (I) — Use of an Alternative Pedestrian Hybrid Beacon Sign" (PDF). Retrieved 27 June 2020.
  10. Federal Highway Administration. "Manual of Traffic Control Devices - Part 4, Highway Traffic Signals" (PDF). mutcd.fhwa.dot.gov. p. 523. Archived from the original (PDF) on 16 May 2020. Retrieved 28 June 2020. Section 4L.02, Intersection Control Beacon - If two horizontally aligned red signal indications are used on an approach for an Intersection Control Beacon, they shall be flashed simultaneously to avoid being confused with grade crossing flashing-light signals.
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