Originally Posted by
genec
But he wasn't going 60 mph... it sounded like a dark residential neighborhood... and in fact the reflectors served their need, perfectly.
Bottom line, they worked... stop trying to set up some screwed up scenerio that the OP did not describe.
Reflectors work... lights work better, reflective tape adds to that and bright blinkies add more...
Frankly I light up like a UFO... and I also have reflectors. Big ones... from the trailer store... where they sell reflectors for vehicles... cause... they work.
But really, reflectors do work. Lights are just better.
I chose 60 mph because that's a worst case scenario to prove my point and the OP noted his location as KS. Had the driver been in a residential neighborhood and the driver's speed been 30 mph (45 ft/sec), reflectors would have been less even useful.
As noted, the reflectors were spotted when the car was 300 feet from the potential point of impact. That translates to 6.7 seconds. The bicycle would have traveled 100 feet (@ 10 mph) during those 6.7 seconds at 30 mph. The cyclist would have traveled even further had he been going 12 or 15 mph.
Missing a cyclist by 100 feet or even 50 feet (had the driver been going 60 mph) isn't a near miss. It's a non-issue. The wheel reflectors provided no information that would be vital to collision avoidance. It was only a false alarm.
This would be the end of the story, had the driver gone straight. The OP stated he turned onto the same street. That turn would take an additional 5 seconds. by which time the cyclist would have been an additional 75 feet up the road. That's a total of 175 or 125 feet in front of the turning car, depending on whether the car were traveling at 30 or 60 mph.
The point is that in a T-Bone situation, the cyclist has to travel 10 to 14 feet for a lane width plus 7 feet for the bicycle length to avoid a collision. That's a total of 17 to 21 feet. The time to traverse that distance is 1.1 to 1.4 seconds @ 10 mph and proportionately less at higher cycling speeds.
Any warning to the driver more than 1.4 seconds from the point of collision is superfluous. The cyclist at his normal, slow travel speed would have passed through the collision zone by the time the driver reached it.
Collision avoidance requires that a warning be given, if there is a danger of collision. The cyclist is in the collision zone for 1.1 to 1.4 seconds. Therefore, the warning should be given when both the cyclist and driver are 1.1 to 1.4 seconds from the collision point. This would place the cyclist 10 to 14 feet to the left (assuming the cyclist is traveling left to right) of the roadway's left edge. It would place the driver 50 to 125 feet behind the collision point, depending on the driver's speed (30 or 60 mph). The tangent of the angle between driver and cyclist at this point is between 0.08 and 0.28 or incidence angles of 4.6 and 15.6 degrees. The wheel reflectors are responsive to incidence angles up to 0.2 degrees.
The wheel reflectors will not reflect back to the driver, when he is within 1.1 to 1.4 seconds of a potential collision because the incidence angle between driver and wheel reflector is too great.
Wheel reflectors perform as follows as a collision warning. The will give a warning, when there is no danger of a collision. They will not give a warning, when there is a danger of a collision. As a collision warning system, what's the definition of "useless."