A bus operating regularly along a set route and stops (transit/fixed-route bus), used for city or regional public transport.
路線バスで駅まで行けば、そこから電車に乗り換えられる。
If you take the route bus to the station, you can transfer to a train from there.
都心では路線バスの運賃支払いにICカードが使えることが多い。
In city centers it's common to be able to pay route-bus fares with IC cards.
あの路線バスは観光地を回るので、乗客が多い。
That route bus goes around tourist spots, so there are many passengers.