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.
Why would any state have had lower vertical clearance standards than
required for trucks of that era?
Can you tell us what the hell state you are talking about that wouldn't
have had standard clearances for bridges being built for trucks currently
being sold?
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.
btw, you are wrong: To this day there is no FEDERAL vertical height
standard on trucks. That's in state law. There are federal standards on
length, width, and weight of trucks. I found that on truckinfo.net. Don't
consult Wikipedia, which merely ripped off that Web site.
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
that bridges can support. Of course bridges in rural areas were designed
for the vehicles that would cross them typically, straight-bodied trucks
that farmers might own.
The concept that roads and bridges would be designed for trucks that
don't exist is awfully odd.