The GRF can be found here: http://www.tt-forums.net/viewtopic.php? ... 3#p1037463
With the kind permission to use the graphics of Red*Star (the platform inside the tunnel), Born Acorn (the UK road) and the developers of the Japan Set (the tunnel itself), I have made a new traintunnel with UK-roads on top to make tunnels blend in more in city environments. I don't like grass inside my cities

Please note that the road is pure eyecandy, vehicles will not drive over that!
This GRF will change all traintunnels to this tunnel, but it also looks good in rural environments when roads are placed next to it.
I chose the UK road to be on top, because I only use that roadset in my games, if anyone wants to make tunnels with different roadset graphics on top, they are very welcome to alter these graphics and post new GRF's or graphics here (please do check if those roadset graphics are GPL-licensed or ask permission of the original artist).
A special request however to railtrack-developers. As this GRF will change all traintunnels, it would be better if these graphics are used in a seperate railtrack-GRF with no speed limitations, that can be used alongside other railtrack-GRF's. So a player can build this tunnel in places where it would fit in best and it won't be built everywhere. I sadly don't have the knowledge to create that myself, so any help will be very welcome.
EDIT: Beul has been so nice to code these graphics into a railtype!

The sprites:
Looks like this:
The GRF: