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On Wed, 04 Mar 2009 15:55:05 -0500, John Lansford <...@bellsouth.net
Basically, if those high poles are hit by a truck, they'll fall down.
NCDOT places them on extended height, thicker median barriers and
while they're hard to hit the way they're installed, when a truck does
hit one they get knocked down.
John Lansford, PE
--
John's Shop of Wood
http://wood.jlansford.net/
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On Wed, 04 Mar 2009 16:54:02 -0500, "Scott M. Kozel" <...@comcast.net
John Lansford <...@bellsouth.net
High-mast towers are typically mounted on a slip-base just like the
standard luminaire poles. That means that the bottom of the mast will
breakaway instead being immovable and smashing the vehicle into junk
(with deadly injuries to the people inside).
--
Scott M. Kozel Highway and Transportation History Websites
Virginia/Maryland/Washington, D.C. http://www.roadstothefuture.com
Capital Beltway Projects http://www.capital-beltway.com
Philadelphia and Delaware Valley http://www.pennways.com
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Anonymous Wrote:
But is that really the safest option? Seems there could be deadly
injuries for vehicles which suddenly have a falling high mast light to
deal with. I would think a few sand barrels or other crash absorption
devices would be better.
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On Thu, 05 Mar 2009 05:07:54 -0500, John Lansford <...@bellsouth.net
Well, the barrier mounted light poles are already on top of a concrete
shape designed to deflect vehicles away from it. The only issue is
when a large truck hits precisely where the light pole is located.
Trying to put attenuators or some other crash cushion around every
single light pole would be expensive and contribute to more crashes
then not doing anything at all.
John Lansford, PE
--
John's Shop of Wood
http://wood.jlansford.net/
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On Thu, 05 Mar 2009 07:07:10 -0500, "Scott M. Kozel" <...@comcast.net
A high-mast lighting tower typically has a large enough lighting
footprint, that it can be placed well away from any roadway or ramp,
perhaps 50 to 100 feet away, where the probability of an errant vehicle
reaching it would be near the vanishing point.
--
Scott M. Kozel Highway and Transportation History Websites
Virginia/Maryland/Washington, D.C. http://www.roadstothefuture.com
Capital Beltway Projects http://www.capital-beltway.com
Philadelphia and Delaware Valley http://www.pennways.com
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Anonymous Wrote:
On Mar 5, 7:07 am, "Scott M. Kozel" <...@comcast.net
That's the thing, Ontario's MOT put them in the middle of the 401.
If you go to the traffic cameras at http://www.mto.gov.on.ca/english/traveller/trip/traffic_cameras.shtml
select "GTA" and go for 401 near Westney, Church, right through to
Meadowvale, you can see the high masts in the median barrier.
One of these lights gets knocked down in rush hour would make a real
mess. Imagine something the size of an old-growth white pine (Ontario
reference) coming down across six or more fast-moving lanes of
traffic.
....Ed
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On Thu, 05 Mar 2009 17:46:18 -0500, "Scott M. Kozel" <...@comcast.net
Those are obviously close enough and on a low enough barrier, that a
large truck could knock one down. Of course, even a standard luminaire
pole would cause major problems if knocked down on that highway.
--
Scott M. Kozel Highway and Transportation History Websites
Virginia/Maryland/Washington, D.C. http://www.roadstothefuture.com
Capital Beltway Projects http://www.capital-beltway.com
Philadelphia and Delaware Valley http://www.pennways.com
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On Thu, 05 Mar 2009 18:03:08 -0500, John Lansford <...@bellsouth.net
Your camera link didn't work for me; are you talking the high (75' or
higher) light poles with clusters of lights at the top, or the twin
boom streetlight poles most normally placed on a concrete median
barrier?
The very high mast light poles are NOT designed to breakaway in a
collision, but they're also located away from the road far enough that
any impact would be very rare. If that's the kind placed on your
median barrier, they're probably securely mounted and wouldn't break
off if hit. The smaller, twin-beam light poles will break off and
yes, they cause a lot of problems for traffic if they do get hit. They
don't get hit all that often though, even from large trucks.
John Lansford, PE
--
John's Shop of Wood
http://wood.jlansford.net/
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Anonymous Wrote:
On Mar 5, 6:03 pm, John Lansford <...@bellsouth.net
Hmm, I don't know why the link doesn't work. You could go in through
the Ontario Ministry of Transportation site http://www.mto.gov.on.ca and
click on the TRIP link if you're interested.
But, yes, these are all the very tall masts with the cluster of six
lights at the crown. Just driving past, I can see that they're held to
the median barrier by at least six or eight very thick bolts. But we
all know what happens when the immovable object gets hit by an
irresistible force. And I do recall the occasional accident where a
transport winds up atop the median barrier. Ontario gets its fair
share of snowy and icy roads.
....Ed
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