And the good thing is also:
The offroad tracks are part of the set, I am develloping at the moment. As you see, the track is labelled 'concrete'.
First, I have to do some 'cosmetics' on the vehicles and still (sic!) on the catenary (the intercatenary distance is not exactly matching).
After this, I will continue on the following variations:
1. Citytram Cobblestone (tram is directly put in the road with cobblestone inlay), Intro year 1880, Max-Speed 40 km/h
2. Citytram Asphalt (tram is directly put in the road with asphalt inlay), Intro year 1938, Max-Speed 50 km/h
3. Concrete Citytram (tram rides on concrete panels), Intro year 1976, Max-Speed 60 km/h (see this Beta-Version)
4. Grass-panel Citytram (tram rides on off-road green stripe), Intro year 1988, Max-Speed 75 km/h
5. Welded gravelbed citytram (tram rides off-road, welded tracks with gravel topping), Intro-year 2002, Max-Speed 90 km/h
A part of this is already in progress, but I first want to finish the first one with a good quality
Now, the textures of the concrete panels are already different from the road textures (they are more light, as in reality). For your other ideas, ave616, it could be a bit difficult.
As this system is for the moment only a 'graphical issue', the tracks have to be shared between tram and road vehicles. The only solution could be the definition of a new waytype. As this system is half-way shifted from the boardwalks, such a waytype would only make sense, if the road vehicles would have also an off-set, more close to the boardwalk.
(This would actually mean to shift all present road vehicles, I guess).