i am running the newer lionel dockside switcher and lionel USRA 0-8-0 switcher. both are really powerful and have traction tires with momentum flywheel. i usually will have them pulling about 4-8 cars. my question is(and i am sure it has been asked several times), what is the steepest grade these guys can handle (i am not asking if it will look realistic, i know it won't be anything close to what a real train could do). i want to run a line connecting two areas of the layout. i need to get over a line but only have about 7ft to get up 6 inches and another 7 feet to get back down. i realize this causes about a 7% grade, which is realy steep. i thought about the lionel tressel set they sell that makes 5% grade and my older trains handled that pretty well in the past. i specified what trains i will run on the grade because it seems these newer guys can handle a lot more. these newer steam engines seem as powerful or more than my 20yr old hudson's and berkshire's with magnetraction! looking for someone with experience in these steep grade. thanks for all the help.