Twenty-four people on a quarry in the limestone belt
Twenty-four is a real crew rather than a two-man pit.
This is the belt of Cambrian and Ordovician limestone and dolomite running north-east across Lancaster, Lebanon and Berks counties — the Great Valley and the Conestoga lowland.
A dense grid, and an unusually restricted one
That density cuts both ways here. The market is deep — farm country with a very close road grid, within reach of Philadelphia, Baltimore and Harrisburg, and the limestone feeds lime, cement and agricultural buyers as well as construction.
But the network is more restricted than its density suggests. Within 10 miles of the Allan Myers Materials pit the National Bridge Inventory records 205 structures, twenty of them below legal loads, and the split is the ordinary Pennsylvania one rather than the county-heavy exception: five are county-maintained against twelve on township roads.
Across Lancaster County as a whole 22 of 59 county-maintained structures fail that test and 32 of 221 township-maintained ones do. So a machine from here ran a short, crowded, heavily posted network rather than a long open one, and route choice was continuous rather than occasional.
The nearest restriction is a mile and a half out
Those lanes start constrained. The closest structure coded below legal loads lies 1.62 miles from this quarry, and the lowest operating rating anywhere in the circle is 3.6 metric tonnes — under the level at which a commercial vehicle crosses at all, even empty.
The lowest that clears the commercial floor is 16.3 tonnes, about eighteen US tons, which admits roughly 5.3 tonnes of stone over the tare of an empty tandem dump. That is a fifth of a legal load, so the binding crossings cut a load rather than turning it away.
The neighbours sit close enough that a truck sees several networks in a week: Limeville Quarry about 5.9 miles east, Talmage Quarry about 6.8 miles west, Brandywine Stone about 9.3 miles east and Hinkletown Quarry about 11.1 miles north.
A machine working between the Allan Myers Materials pit and Talmage Quarry 6.8 miles west crossed posted structures continuously rather than now and then, and often part loaded. That ages the running gear ahead of the driveline — springs, hoist and pins before the engine.
- Around Hinkletown Quarry the mix is normal.
Between Silver Hill Quarry about 14.7 miles north and the Modena yard about 14.8 miles east they turn up steadily.