On 30-Jan-12 21:39, Adam H. Kerman wrote:
Stephen Sprunk wrote:
On 29-Jan-12 17:57, Adam H. Kerman wrote:
Stephen Sprunk wrote:
On 29-Jan-12 14:09, wrote:
On Jan 29, 11:07 am, Stephen Sprunk wrote:
Movement of tanks. That is the origin of the clearance, lane width and
bridge-strength requirements--and in turn limits the height, width and
weight of new US tanks.
I'm not sure that's true. Tanks are not very kind to concrete roadway
surfaces, nor do they move very fast, and of course drink up fuel. I
would think if tanks have to be moved any sort of distance they would
be loaded onto trains.
The tanks would not be directly on the roadway unless they were actually
deployed for battle on US soil, in which case I doubt anyone would care
about what it did to the pavement.
Otherwise, the tanks would be on transporters, which is why the
Interstate vertical clearance requirements are so high.
Transport is designed to current standards, not the other way around.
The "standards" of the day varied significantly from state to state and
were, in many places, completely insufficient for the Army's needs. The
entire purpose of the Interstate system was to unify and raise those
standards _to match the transport needs_.
Here in Chicago, which may have more elevated railroads than anywhere
else, the required elevation standard was based on trucks of that era.
It sounds like you're asking about civilian trucks, which are completely
irrelevant to the discussion; we're discussing highway standards to meet
_military_ needs.
Why would any state have had lower vertical clearance standards than
required for trucks of that era?
Because the local (not even state, at that point) authorities had no
reason to spend extra money building bridges and such to handle military
equipment that, until that point, had never attempted to use them.
Why do you think it took Lt. Eisenhower two months to cross the country?
Were there any significant number of trucks sold that exceeded 12' 6",
a common vertical height limit prior to 1956? Expressways in my area
prior to 1956 didn't have 13' 6" clearances until they were reconstructed.
I've seen bridges with clearances under 10ft. And it's not just about
height; it's also about width and weight.
In theory, the Army _could_ have tried to redesign their tanks, etc. to
the size, height and weight of a Model T or horse-drawn wagon--what much
of the US road infrastructure of the day could handle--but they probably
wouldn't have fared too well in battle.
Now you're moving the goal posts from vertical clearance to weight
Moving the goalposts? Look at the very first quote at the top of this
thread, Adam. You're the one that focused only on height; the rest of
us have been talking about _all_ dimensions.
The concept that roads and bridges would be designed for trucks that
don't exist is awfully odd.
The trucks _did_ exist: in the Army.
S
--
Stephen Sprunk "God does not play dice." --Albert Einstein
CCIE #3723 "God is an inveterate gambler, and He throws the
K5SSS dice at every possible opportunity." --Stephen Hawking