by shuttle or by shuttle bus

I think there is no need for bus because in this sentence shuttle gives the meanig of a vehicle.

You can omit it unless it's really important to let someone know the type of transport provided.

But what is a shuttle anyway??

It's a vehicle that does a routine journey between two points, backwards and forwards all day. For example, a hotel near an airport (with most of its guests being people who are going to catch a flight) might run a shuttle service to the local airport. Hotels near Disneyland often have a shuttle service between the hotel and Disneyland.

Now I got it!
thanks nona!

I would like to make some remark here. In general, a shuttle is a vehicle that travels between two points without stops inbetween. But in my city, a shuttle also makes several stops on it route. This seems to make the concepts of bus and shuttle a little confusing, as you know, any bus must travel between two points with stops inbetween. So I guess we'd better understand shuttle like this: a shutt

No comments! It was very detailed thanks Osee!

When we were in university we used to call it just 'shuttle' .

OseeAny comment about it? Thanks.

You my friend, are utterly correct.
You somehow gave us an uncommonly clarification, which I owe to you my deepest expression of gratitude.