The Pankian Metaphor 3070
Donald Tees sidd ----snipped----
I have seen highways that have been substantional rebuilt after a service lifetime on the order of 50 yrs. misc road...
It is going to depend on the load and the design criteria of the highway. If the truck is fully loaded with stone, and it is a smallish road, probably not. If you are dealing with an American truck on a Canadian highway, it probably is. It will depend on the number of tires under the load, and how the axle weighting is proportioned. There is a big difference between a truck with an axle balancing mechanism and one without, for example. Another major factor is what the maximum load the road was designed for is. Running a load of 100,000 pounds over a driveway will probably damage it beyond repair, while a car will do no damage. On the other hand, driving either on a runnway (designed for a half million pound load) will result in almost zero wear for both. Double zero is still zero. However all traffic produces *some* wear, as does time. A road with no traffic at all will gradually break up with winter cycles alone.
ref: which makes repeated reference to the earlier postings ... partial extract from the content of previous posting: misc...
Not necessarily. US 75 (the part I know, in Minnesota) has still got some of the original cement, laid down (I think) right after WWII -- maybe before, and it's still NOT broken up (of course, parts of it are).
They laid down one heck of a good base for that road. Some roads doen't even last five years before breaking up. Too cheap to put in a good base, or the cement isn't thick enough, or the grade of cement is bad, or the mixture, overloading ... lots of reasons. Gerard S.
BTW, I said "having worked in the industry all my life". I am *not* an engineer. I do program software, and large scales (particularly truck scales, including axle weight scales) have been somewhat of a specialty. I have worked with the legal weight requirements for commercial trucks extensively throughtout the eastern part of the continent. The bottom line is pounds per square inch of tire-the roadbed support figure. To claim, though, that cars do not wear out roads is a gross over-simplification. It would be far more realistic to say that any load approaching the maximum the road was designed for is going to cause the most damage. Donald
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