This site answers connection your question Shows Bachmann EZ Track connected to Peco Setrack, but ATLAS track connects in same way.
http://www.hobbiesplus.com.au/tracklaying.htm
Bachmann makes pier (riser) sets:
http://shop.bachmanntrains.com/index.php?main_page=index&cPath=258_366_368
but you don't need them. Some other methods that are more flexible: You can make your own risers, lay track on inclines made of plywood, or use Woodland Scenic foam inclines
http://woodlandscenics.woodlandscenics.com/Show/category/SubTerrainSystem/page/4
I tried to sell my two cents worth, but no one would give me a plug nickel for it.
I don't have a leg to stand on.
Nk,
FWIW, it would be helpful if you could elaborate a little more in your subject line about your inquiry or need. "Bachmann to Atlas track transition" is much more descript than "Help?" and most members will be much less apt to pass over your post or open it up.
Just a suggestion...
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.