对开

对开	duì kāi	running in opposite direction (buses, trains, ferries etc)
对	duì	right; correct / towards; at; for / concerning; regarding / to treat (sb a certain way) / to face / (bound form) opposite; facing; matching / to match together; to adjust / to fit; to suit / to answer; to reply / to add; to pour in (a fluid) / to check; to compare / classifier: couple; pair
开	kāi	to open (transitive or intransitive) / (of ships, vehicles, troops etc) to start / to turn on; to put in operation; to operate; to run / to boil / to write out (a prescription, check, invoice etc) / (directional complement) away; off / carat (gold) / abbr. for Kelvin, 开尔文 / abbr. for 开本, book format