Cooper County
Ten posted, ten below, and they are not the same ten
Within ten miles of it the national bridge file counts 98 structures, and two different columns each put ten of them under a restriction.
They are not the same ten, and that is the whole difficulty with reading Missouri’s bridge data. One column says a structure is posted for load. The other says it will not carry legal loads. Across the state the first flags 3,196 of 24,647 structures and the second 2,206, and only about three in five of the posted ones also fail the load test.
So the two are independent codings rather than one sitting inside the other. In Cooper County the load test actually finds more than the posting column does, nine against eight, and the same inversion turns up in Ray County at 29 against 27 and in Saline County at 15 against 14. The posting column does not merely overstate restriction in the cities; in country like this it misses some.
We read the load test, because it is the column that asks the question a loaded truck asks. Across Cooper County 9 of 124 county-maintained structures fail it, against a Missouri county-maintained rate roughly half again as high. By that measure this is easier ground than most of the state.
So the circle round the pit is the tighter measure
Those county figures average a whole county, so the ten-mile circle is the one that describes a haul. Of the ten crossings inside it that fail the load test, nine are Cooper County’s own and the nearest is 2.71 miles out.
The lowest operating rating among them is 4.5 metric tonnes, well under the 11.0-tonne tare of an empty tandem dump. Nothing commercial crosses that one in either direction, loaded or not.
The lowest that does admit a commercial vehicle is rated 14.4 tonnes, about 15.9 US tons. Over the tare that leaves roughly 3.4 tonnes of stone, against the twenty-five a legal 80,000 lb truck carries. Below 11.0 tonnes nothing commercial crosses at all; between 11.0 and 36.3 it crosses part loaded; at or above 36.3 a legal load goes over whole.
A truck working out of a pit like this one has spent its life picking routes around those numbers, and that is worth saying out loud when you come to sell it.
Grain trucks and farm trucks off the Cooper County bottoms.
- Why do you read one bridge column and not the other?Because they measure different things. In Cooper County the load-test column finds more restricted crossings than the posting column does, nine against eight, so taking the postings alone would undercount what a loaded truck meets.