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I talked to the DOT contact person for information on the HAWK prototype in Minnesota:  <o:p></o:p> They use double red lights for redundancy, which is common practice with traffic lights.  <o:p></o:p> Originally, they used double red lights that either were lit continuous meaning stop-and-wait; or flashed simultaneously meaning stop-and-yield.  But they found that many drivers went through the flashing red without stopping.  So, as a remedy, they changed the double simultaneously flashing red to the alternating flashing red like a grade crossing.   <o:p></o:p> Here is the kicker:  <o:p></o:p> The reasoning for the change was that with alternating flashing red, you always have one of the two red lights lit, so in effect, the red signal is continuous.  I am not convinced that that is an accurate conclusion, but set that aside.  The reason for presenting a driver with this presumed continuous red is to increase the restrictiveness of the signal in the hope that it will prevent drivers from going though without stopping.   <o:p></o:p> However, if it is perceived as continuous red, a law abiding driver will stop and wait, and that is not the intention of the signal.  So to convey the intention of stopping and yielding, they put up a sign that defines that meaning for the alternating flashing reds as being stop-and-yield.   <o:p></o:p> So, to get people to stop for a stop-and-yield light, they made the light say stop-and-wait, and then they put up a sign that says the light really means stop-and-yield.   <o:p></o:p> They are not worried about the alternating flashing reds diluting the warning at grade crossings because the HAWK installation does not look like a grade crossing signal installation.  Maybe so, but the point is the meaning of the signal, and the meaning is in the driver’s mind, so it goes with the driver from HAWK to grade crossing, and vise versa.     <o:p></o:p>  <o:p></o:p>
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