In some cities in the US, other methods of pedestrian detection are being or have been tested, including infrared and microwave technology, as well as weight sensors built in at curbside. A 2000 study of these detectors in Los Angeles, Phoenix, and Rochester found that the infrared and microwave technologies both helped reduce conflicts between pedestrians and turning vehicles, as well as pedestrians starting during the "don't walk" phase. Subsequent studies found that the efficacy of these sensors varied based on pedestrian traffic at the location where they were installed.