Here's a shot of a BNSF business train in Cajon pass last year in the midst of the triple-tracking at the summit.  Sorry, I don't have any details about the train, just the project. 

Construction technology 100 years ago said "tunnel through".  Nowdays, instead of multiple bores, they just cut the top off the mountain.  The tunnel had a thin concrete liner, but once the mountain was removed from around it, the concrete started crumbling whenever a train rolled through, so they cut off the top half of the liner.  The photo was taken by Warren Smith.

Another reason they are cutting back some of the mountains where tunnels went through is because Southern California has had so many earth quakes in the past 60 years that many of the tunnels are shifting and cracking and they have found in many cases it's cheaper to tear down the mountain than rebuild or enlarge these Tunnels especially when the tunnel is very short through a smaller mountain and the fact they are re-routing and adding to the number of tracks through the Sierras. My fathers company has a number of contracts to build new and widen older railroad right-of-way. My father said they want to put the super fast comutter trains running up and down the coast and they have to run on some new kind of round top rails with concave wheels on the trains. Has anybody ever heard of this kind of track? It's new to me!!

There are some photos of BNSF business cars on the Peavine line (Phoenix sub) in Arizona on Aeromoe's Guide to Railfanning the BNSF Peavine. Just scroll down a bit.

It would beat the track maintenance headache within the tunnel.  If anyone's truly interested, I'll scounge up a few more photos.  

edit:  Started a separate thread showing tunnel daylighting:    

 http://model-railroad-hobbyist.com/node/1872

Can't help you with your questions, but I took some pictures of a BNSF business train in Seattle back in 2007.  You can see more of the pictures here.

http://s257.photobucket.com/albums/hh230/pwkrueger/2007%20BNSF%20busines...

I've never seen it with either a big dome or high level cars before.  I had thought that all of Santa Fe's big domes and El Capitan high level cars had been turned over to Amtrak.  Learn something new everyday I guess.

Didn't Great Northern (and Milwaukee) have "Great Dome" cars as well?

Did the Great Northern have high level coaches too?  Those high level cars do look a bit different from El Capitan equipment, but I'm not sure what the difference is.

Those don't appear to be high level - they may have 2 floors but the doors between the cars appears to be on the first level.  On the El Capitan/Superliner equipment they're on the second level.

I took the train from Baltimore MD to NY City last year and we rode in a car that looked just like the one in your photo and when you enter the car from the Dinner car there was a stair way that spiraled up to the left and you end up maybe 4 feet higher than we started and you can sit anywhere un-occupied and look out the Dome windows you can also Eat dinner there or have drinks. Also as you enter the car on the right of the spiral stairway is a door that's says "No entry unless with porter Baggage stowage " We had two bags in there and there was a set of 3 steps down then turn left and down 3 more steps and walk into a cor-adore with what looked like 10 rooms and our bags were in the 3rd room. I don't know if this is the same type car but it does look like it.

Dan