I don't remember posting a road magnet before

In December 1945, the Virginia Department of Highways debuted its newest piece of equipment on U.S. Route 1 between Richmond and Ashland. The road magnet, moving at about 15 mph, picked up nails, spikes, tacks and other metallic objects on roads that might lead to flat tires.

https://richmond.com/news/local/history/from-the-archives-250-photos-of-richmond-in-the-1940s/collection_3a97b2d3-eb3c-575b-8ba5-f6ddfa4de67f.html