What is a HAWK beacon?
A High-intensity Activated crossWalK beacon, or HAWK beacon, is much like the flashing lights commonly used to stop traffic at fire stations and railroad crossings — but applied to a crosswalk. The HAWK beacon is dark unless a pedestrian’ pushes a button to cross. Three reasons commonly given for using a HAWK beacon are:
- A traffic signal that is normally green or that turns red when nobody needs to cross may not be as effective in stopping cross traffic;
- There is no need to have an active signal unless someone actually wants to use the crosswalk;
- The HAWK beacon has a flashing red that follows the steady red. Traffic may restart if pedestrians have finished crossing, reducing delays.
A HAWK beacon for bicyclists
A HAWK beacon installation at 41st and East Burnside Avenue in Portland, Oregon, is, however, unusual, as it also applies to bicyclists. The 10-minute video here shows the HAWK beacon in operation and makes recommendations for improvements to the installation.
Recapping the video, the HAWK beacon itself is on Burnside Avenue, a heavily-traveled main street, and stops traffic to allow bicyclists on lightly-traveled 41st Avenue and pedestrians in the adjacent crosswalks to cross Burnside. So far, so good. But facing 41st, there is a traffic signal for bicyclists — and also a stop sign. The timing of the bicycle signal is odd. Motorists are required only to obey the stop sign.
The graph below shows three examples of timing of the HAWK beacon, bicycle signal and pedestrian signal. From left to right, it shows
- the timing (one of several, but this was the preferred one and the others are very different) described in a request to experiment sent to the Federal Highway Administration in 2005;
- the timing observed in September, 2008;
- a revised timing I propose.
Click here or in the image to see a larger version.
Following the timing of the bicycle signal from top to bottom, it is dark until a bicyclist or pedestrian pushes a button to start the signal cycle, then it turns red without first turning yellow; after a few seconds it turns green, then yellow, then red, then flashing red, then red again and after a while, goes dark. I note the following issues wih the timing.
- Flashing red is supposed to mean “stop”. It’s contradictory to show a flashing red signal to the bicyclists when cross traffic is starting up, changing to a steady red when cross traffic becomes lighter. Portland pared down the problem by reducing the length of the flashing red interval. But a flashing red for 41st doesn’t belong at this time in the signal cycle at all.
- The flashing red interval on Burnside also was decreased, increasing delays.
- If not activated, the bicycle signal eventually goes dark, appears broken and offers no guidance – it effectively disappears. Probably, under the law, bicyclists then need only stop and yield to cross traffic, as is usual with a signal that is not operational. But it is completely nonstandard to have both a stop sign and a traffic signal facing the same entrance to an intersection.
- The bicycle signal’s going from dark to red without first turning yellow also is nonstandard, and can be confusing to motorists as well as bicyclists.
- Must bicyclists stop for the stop sign before entering the intersection on the green light? That also is unclear.
Because only the stop sign controls motor traffic, motorists may enter or cross Burnside at any time. Motorists who enter the intersection before the bicycle signal turns green can get in the way of bicyclists. Motorists also can take advantage of the bicycle signal to cross Burnside, increasing cut-through traffic. The City of Portland nonetheless makes a bold claim that the installation eliminates cut-though traffic:
“It will have a ped/bike indication for crossing Burnside (motorists will still have to abide by the stop signs). This eliminates the threat of motor-vehicle cut-through traffic.”
Suggestions for improvement
Bicycle traffic and pedestrian traffic can use the same signalization on a multi-use path. The problems I see with the Portland HAWK installation result from using what is essentially pedestrian signalization to control bicycle traffic on a street shared with motor traffic.
The problems could be addressed with the barrier or median I suggest in the video, to prevent motor traffic from conflicting with the bicycle traffic on the green light. Or the bicyclists’ pushbutton might be placed on a median to the left of a right-turn-only lane on 41st — but I’m not sure that 41st is wide enough to allow that.
I also propose a flashing red bicycle signal starting a few seconds after the HAWK beacon goes dark. It would permit bicyclists to cross in times of light traffic without pushing the button and waiting for the signal to change. The continuous flashing red would inform bicyclists that the signal is working. The signal could serve for all traffic and would also serve to prevent motorists from overtaking bicyclists waiting for the green light. Stop signs could, then, be removed even if motor traffic still could enter the intersection from 41st.
The following references may help with further discussion.
Three BikePortland blog postings: The first one, from September 11, 2006, includes the quote about eliminating cut-through traffic. These postings are typical of the cheerleading approach taken by the BikePortland blog toward the city’s bicycle program.
The Portland HAWK Request to Experiment
Descriptions of a more-conventional HAWK beacon as used in Alexandria, Virginia.
And in Tucson, Arizona (scroll to the bottom of the page).
Video clip of the Tucson Hawk beacon in operation:
(Also on YouTube:)
Article discussing effectiveness of the Tucson HAWK beacon
Federal Highway Administration Operations Knowledge Communities discussion of HAWK beacons