How can I build a bridge like branch or overcross?
As the graph.
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All of this is a flyover (US=overpass) system.
(first screenshot) Here I used raised ground sections and elevated ways for the cross-track.
(second screenshot) If your pak does not have elevated ways, you will have to start a bridge on a sloped tile on one side (the other side can terminate at a "block" raised ground square).
with elevated ways, you can also build on an angle.
(http://i199.photobucket.com/albums/aa131/AEObikes/simutrans/th_simscr70.png) (http://i199.photobucket.com/albums/aa131/AEObikes/simutrans/simscr70.png)
(http://i199.photobucket.com/albums/aa131/AEObikes/simutrans/th_simscr71.png) (http://i199.photobucket.com/albums/aa131/AEObikes/simutrans/simscr71.png)
Excellent, AEO, that is even better. Note, though, that bridge supports have a single graphic and if your tracks run the "wrong" way, trains run right through the bricks!
AEO, that's brilliant, i never realised i could have a completely diagonal elevated way.