Clipper card, the card must be "tagged" (read) by the Clipper card reader installed at the front of the bus near the farebox. The reader checks for a SamTrans monthly pass and local-fare credits from other agencies, computes the remaining fare and (if there is one) collects it in Clipper Cash. Note that northbound passengers on route KX to San Francisco must "tag" their Clipper card twice: once when boarding within San Mateo County (which collects a local fare or equivalent) and once before exiting in San Francisco (which collects any remaining fare). Caltrain monthly passes (with two or more zones) and VTA monthly passes (that have been tagged on VTA in the last two hours) are honored on SamTrans as a local-fare credit. To use a local-fare credit from a monthly pass loaded onto a Clipper card on higher-cost routes, the remaining fare must be collected in Clipper Cash. New fareboxes were installed in June 2011. The fareboxes collect fares, issue new magnetic striped tickets (e.g., day passes, change cards) and process previously issued magnetic striped tickets (e.g., day passes, youth summer passes, change cards). When a patron does not have exact change, a change card is issued with a cash value that can be redeemed at a future farebox transaction for up to a year. Up to three kids under 5 with fare-paying rider can board for free. Fleet SamTrans currently has a fleet of 296 buses of various sizes for its fixed-route service. Fifty-five are articulated buses made by New Flyer Industries with the 10 m (35 ft) and 12 m (40 ft) buses with low flooring, are made by the Gillig Corporation. Each bus is equipped with GPS tracking providing both visual and voice next-stop announcements, and are accessible to passengers in wheelchairs and those with limited mobility. In 2009, SamTrans added 135 custom made Gillig low floor buses to their fleet, numbered 400-490, 500-539 & 2900-2903, replacing 137 older Gillig Phantom buses in their fleet. In 2018, SamTrans placed an order for 10 Proterra 40-foot Catalyst BE40s buses as a first step towards the goal to have an all-electric fleet by 2033. The battery electric buses are expected to enter revenue service in early 2019, and a charging station will be installed at each SamTrans maintenance facility. See also AC Transit Bay Area Rapid Transit Caltrain Clipper card List of SamTrans bus lines Muni Metro