7/28/2011:
Victorian baby buggy parts, corset stays, and pre-Prohibition bottle stoppers might sound like treasures found on Antiques Roadshow, but they are actually a sampling of the items pulled from the gravel roads of Langdon, North Dakota by a magnetic "nail picking" truck during the last week of July, 1931.
In the Nineteen-Thirties, car tires were still rubber treads with an inner tube. Weaker tires and rougher roads made blowouts a greater hazard for driving than today, and a minefield of nails and iron scrap hiding in gravel roads only made things worse. The North Dakota highway department decided to purchase a nail picker in the summer of 1930 after hearing of South Dakota's success using magnets to clean the roads.
The nail picking machine consisted of a one and a half ton truck with three electro-magnets mounted below the chassis. The magnets were powered by a generator mounted in the box. Each magnet had a lifting power of two hundred pounds per square inch, enough to pull iron and steel from deep beneath the road surface.
The driver of the nail picker would turn on the electro-magnets and make three passes over each stretch of road. Then the driver parked the nail picker over a tarp, the magnet was turned off, and all the scrap fell onto the tarp. Railroad tracks posed a special problem for the nail picker. The electro-magnets would temporarily magnetize the steel tracks when the truck passed over, pulling metal away from the picker and leaving the rails bristling with nails and iron.
In the first few years of the nail picker's operation it pulled as much as twelve pounds of metal out of every mile of road. By 1938, the amount of metal pulled from the roads had dwindled and the nail picker was taken out of service. The scrap metal drives of World War Two encouraged the state to put the nail picker back to work, picking up metal for the war effort, even sweeping up a few steel pennies among the bottle caps, tire chains, and lost wrenches that stuck to the truck's magnets. Unfortunately, the nail picker's revival did not last long. Over the years, North Dakota gradually paved all its state-maintained highways, making the magnetic nail-picking truck a relic of the dirt road days.
Dakota Datebook written by Derek Dahlsad
Sources:
“Much Hardware Taken From Langdon Streets,” Turtle Mountain Star, Jul 30, 1931
“North Dakota's Highway Nail Picker,” Municipal journal & public works, Volume 63, 1932
“Road Department Begins Scrap Metal Collection,” Bismarck Tribune, 6-2-1942
“State's Magnetic Nail Picker Even Collects Iron Pennies,” Bismarck Tribune, 8-14-1947
“Magnet Sweeper Saves Car Tires,” Fredricksburg VA The Free Lance-Star - Jun 16, 1948