You say it is in the turntable area? fire the truck up and rotate the boom a few times. Might grind them up! Just make sure you wear your suit. A smoker at the entrance would bee (get it
) good for directing their attention elsewhere. (masks the attack pheromones.)
If you seal it up, they will find another way in and out. you could be sealing many holes in it for a long time. And if the queen dies, but you don't get all the rest of the bees, there is a posiblity that the hive will go into an emergancy queen replacement. If there are less than 3 day old larva in the hive, (and there probably is) they can be converted to queens. Then the first queen to be born will kill all the other unborn queens and the hive carries on. (I'm planning on keeping bees next year and have been shadowing a local beekeeper and reading alot)
My beekeeping friends recommendation- if you can't get in there to fight them, get some kind of small tube (like you tried to do) and spray a chemical in there to kill them. He said flood it with it, get as much in there as you can. They build a lot of small cracks in hives. He said he has had mixed results with the foam, in your case he said it depends on how far up in there the hive is set up.
Or step two- a local beekeeper could get them all out alive, if he knows what he is doing. he can set up a hive box near the area, and put some open honey frames in it. The bees will smell the already made honey and swarm out to 'rob' the other hive. if the other hive is set up better, they will just move in there instead of carrying all that honey back to their hive.
hope that helps.