Eleven people on a quarry in a long narrow market
Eleven people is a small crew, and the market it serves is a particular shape.
This is the Pennsylvania Ridge and Valley, where folded rock has weathered into long parallel limestone valleys separated by sandstone ridges running north-east to south-west.
Straight along the valley, over a ridge across it
That grain is the whole of the haul economics. Routes along a valley are straight and routes across it climb a ridge, so haul distance understates haul cost in the cross-grain direction and a market that looks circular on a map is a long narrow one.
It is why the neighbours line up the way they do. The Mt Holly Quarry lies about 9.1 miles east, the Toland Sand Plant about 10.4 miles east and the Bonny Brook Quarry about 11.9 miles north-east — all of them along the valley rather than across it.
Carlisle Barracks sits about 12.5 miles north-east and Letterkenny Army Depot about 18.5 miles south-west, which puts two large installations at either end of the same run.
The local count here is not a Pennsylvania-only figure.
Six of the 156 are coded below legal loads, three of them county-maintained. The nearest is 4.95 miles out and the lowest operating rating among them is 4.5 metric tonnes, well under the level at which a loaded commercial vehicle crosses at all.
The lowest that clears the commercial floor is 13.6 tonnes, set by a structure 9.16 miles out — about fifteen US tons, which admits roughly 2.6 tonnes of stone over the tare of an empty tandem dump. And read that as an upper bound: it is a minimum inside a ten-mile circle.
A truck working out of the Penn Township Quarry towards the Bonny Brook Quarry has run a straight valley road repeatedly; one that crossed a ridge to reach the Mt. Cydonia Sand Plant about 17.6 miles south-west has worked far harder for the same distance. The second pattern shows in the driveline.
- Between Carlisle Barracks and Letterkenny Army Depot we see contractor disposals regularly, one truck or several.
One ends and a hauler who bought for it has more than the next job needs, which moves several vehicles at once rather than one.
The rest is ordinary — retirements, estates, and a truck parked since the last season it was needed. Between the Toland Sand Plant and the Silver Springs Quarry about 17.8 miles north-east they turn up steadily.