They're made of a polyethylene, a plastic prized for its flexibility. Some states require impact testing. A 129-page section of a Federal Highway Administration manual lays out standards for orange barrels, but they vary by state. An ultraviolet-ray inhibitor is added to delay fading. Federal rules say they must be at least 3 feet tall and 18 inches around.
Warning lights are optional.
Michigan, for example, requires four reflective stripes on the barrels for night-time visibility. That boosts the price. One minute to a dozen years or more, depending on use and luck. Three decades ago, black steel barrels, some with white stripes, were filled with dirt, concrete or other materials. And they detach from their weighted bases on impact.