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Eastbound and Down
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Discussion Starter #1
The other day while riding to work I had an a$$ pucker 11 moment. I was traveling northbound on a 2 lane road and was approaching a 4-way intersection with stoplight (green for me) There was a left turn lane at the intersection. I noticed a car up ahead going the same direction as me get into the left turn lane. As I got closer to the intersection that car cut back into the lane I was in.

My only option was to evasively counter steer to the left of that vehicle due to the ditch off to the right. What I didn't see or hear for that matter was the fire truck approaching from my left to turn south. I had to get on the brakes pretty good and I felt the back end slide out from under me. To be honest I'm not sure what I did (I think I let off the brakes and gassed it). Whatever I did it worked and I didn't lay the bike down.

This got me thinking about the Doppler effect of sirens and our ability to hear those sirens while riding.

Most sirens operate at about 115 decibels. Now, if you are traveling down the road at about 35 mph the road noise along with a helmet that covers the ears, the siren will not be audible until the emergency vehicle is within 300 ft. Now take into account that Harley's have louder exhausts and that distance is decreased to 98 ft.

Take that one step further for those that ride with earbuds in for music and most wont hear the siren until the vehicle is within 3-6 ft. Now these distances were studied at only 35 mph. Many of us drive faster than that this reducing out reaction time.

This portion of the study was the effect on the emergency vehicle and the civilian vehicle heading towards each other. They noted, "there was a marked reduction in the audible intensity of the siren between the two vehicles when the approach angle was altered by a 90 degree intersection. This angled approach resulted in no sirens sound being audible from the other vehicle."

The reason for this is when an emergency vehicle travels at 60 mph the siren sound only precedes the emergency vehicles front bumper by 3-6 feet.

Just something to think about while we're out there. Be safe.
 

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Village Idiot
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2,300 Posts
interesting data. I'll have to keep that in mind. I really just try to have my eyes and ears trained way ahead to try to avoid hazards.
 

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260 Posts
If you have USAA insurance, they have a new program available to train the brain for faster reaction time. I just started it today, and found it pretty interesting. You should get an email about it, if you have USAA ins.
 

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712 Posts
DC was changing their siren systems on the police squad cars a couple of years ago. It was to include a change in pitch, as well as a change in percussion level. Thus causing a cage driver to literally "feel" the siren while sitting in the car. Not sure exactly how well this would work on a bike. But i imagine it would be an improvement.

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