Change existing lines for google map

I have a google map on my website which shows a rout from A to B via 1 or 2 other defined points. All points are defined by geocoordinates. Currently lines between two points are always polylines, however, depending on the case I need a certain line between two points to be a train route, or a route by car. You will be provided by the current working map and need to deliver a version with all lines to be train connections, all lines to be public transport lines and all lines to be a connection by car. A piece of cake if you know about google maps.