wayfinding maps, electronic message displays, and bench seating. Each station features unique artwork reflecting local culture and/or the function of transit in society. Stations are unstaffed during regular hours. Call boxes are available at stations to allow employees at the Metro Rail Operations Control Center to assist passengers with concerns. Metro Rail uses a proof-of-payment fare system, with Metro's fare inspectors randomly inspecting trains and stations to ensure passengers have a valid fare product on their Transit Access Pass (TAP) electronic fare card. When passengers enter a station, they encounter TAP card validators which collect fares when a customer places their card on top. Additionally, fare gates (turnstiles) connected to TAP card validators are at all underground stations, all elevated stations and some surface stations. Once passengers pass these validators or board a train, they have entered the "fare paid zone," where fare inspectors may check their TAP card to ensure they have a valid fare. Underground stations are typically large in size with a mezzanine level for fare sales and collection above a platform level where passengers board trains. Street-level stations are typically simpler with platforms designed with shade canopies, separated from nearby roads and sidewalks, where passengers can purchase fares and board a train. Subway stations and tunnels are designed to resist ground shaking that could occur at a specific location, but there is no general magnitude of earthquake that the entire system is expected to withstand. The Metro Rail system has not suffered any damage due to earthquakes since its opening in 1993. Some suburban stations have free or paid park and ride lots available and most have bike storage available. Rolling stock Metro Rail maintains two distinct systems of rail: a light rail system and a subway system, which use incompatible technologies, even though they both use . Metro's subway lines are powered by third rail, whereas its light rail lines are powered by overhead catenary. Also, the two separate systems have different loading gauge, and platforms are designed to match the separate car widths. Hours of operation Between the system's opening in 1990 and February 2020, Metro Rail lines ran regularly between 5:00 am and midnight, seven days a week. Limited service on particular segments was provided after midnight and before 5:00 am. On Friday and Saturday evenings, service operated until approximately 2:00 am. There was no rail service between 2:00 am and 3:30 am,