To save energy, a county in the United States changed street lights and road signs to LED.

According to foreign media reports, Washtenaw County, Michigan, plans to replace 30 intersections with street lights and road signs for energy-efficient LED bulbs, the project is planned for six to eight months.

Signal Engineer Jeff Young said the aim of the county is to reduce energy and cost as much as possible. At present, 400 watt metal halide bulbs are used at the intersections, and the service life is about 15000 hours. It needs to be replaced at least once a year.

"Modified LEDs can use the same lamps and lanterns for 50,000 hours, consuming only 120 watts of electricity." "We'll save energy immediately.

Each LED costs $197, but is expected to last about 11 years, saving the county about $500,000.

He said converting road signs to LED would be "the biggest savings".

He said that one of the reasons for upgrading is capital. The cost of retrofit comes from the Michigan transport fund rather than directly from the citizens. The department needs to spend 1% of its national transportation funds on non motorized projects.