Check out 11foot8.com If you find trucks running into bridges interesting. Some guy has a bunch of video cameras rolling 24/7 on the same bridge in Durham, NC. Great commentary. His youTube channel has at least 100 different videos of trucks hitting the same poor bridge.
jg2828 - 11foot8 They don't hit the bridge - the railroad put a beam across, a little shorter than the bridge so that anything that fits beneath the beam clears the bridge. They now have a height sensor and a huge sign and still drivers fail to understand the height of the vehicle they are in.
11foot8, yup, lots of car-nage, or I guess, truck-nage ;-)
Seems to me that the cost of just cleaning up the debris for each collision with the bar would pay for a sensor that measures the height of the oncoming truck and force the light to stay red until the truck turns off to one of the side streets.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!
IRstuff - If it stayed red, how would anyone ahead of the truck get through/how would it trigger in time to stop a truck if it's measured just as the truck gets to the light?
The current height sensor setup triggers a sign with "TOO TALL, TURN NOW" or the like, but people still think it doesn't apply to their vehicle. Maybe they need to add a counter with the number of hits the protection beam has taken. "HIT 145 TIMES."
At least it's not like the other, nastier buddy, 11Foot8's Evil Little Brother (10Foot6) that includes the collide-o-matic sidewalk:
Never be amazed or surprised by a driver's ability to hit something with his vehicle. When I was still operating wreckers I saw all manner of bridges and signs get hit, and also one car that fell off a transporter.
Thanks for the link 3DDave. I hadn't seen the 10 foot 6 bridge video. That one seems to do a lot more damage, completely ripping the boxes off the trucks instead of just peeling them open.
Yes but why? Is it because if you simply dropped a screen or curtain it would be harder to reset? Bearing in mind that presumably some wagon is going to have to spend some time backing up anyway.
I'm guessing that there is a sound case for using that technology but I wonder what the reasoning is.
A screen wouldn't need a projector (unless the driver wasn't using his lights) and how visible is a projection onto a curtain of water when the sun is shining brightly?
I will concede that it's very cool though!
"I love deadlines. I love the whooshing noise they make as they go past." Douglas Adams
As a kid, I thought the Army's bazooka was the world's coolest weapon.
Now, rig one with a trigger hooked to a "you are still too tall" sensor behind the overhead beam .... 8<)
A Star Wars horizontal light sabre would work too.
Not going to save much money or time that way; there'll still be debris on the roadway.
Might be better to make use of the curvy curb in the 10ft6 bridge, which seems to be really good at diverting vehicles, so the trigger shifts the curb and force the truck into a right turn.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!
Stopping sight distance for a passenger car is ~500 feet (150m) at 55 mph (80 km/h). A loaded truck needs more than that, so let's assume the screen is triggered when the truck is 700 feet (200m) from the tunnel portal. At 2.5 second headways, there could be three vehicles between the portal and the overheight truck. Probably ten vehicles if they drive like NY City drivers.*
So, several of those vehicles are going to be closer than stopping sight distance to the portal when the system is activated. They can go through the water curtain without damaging anything except perhaps their undershorts. A physical screen would be damaged when the car collided with it.
I was wondering how well it shows up in daylight, too, especially when the sun is low on an east-west roadway.
*I was told the NYC standard is, if you can see the back tires of the vehicle in front of you, you're not tailgating.
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