A few thoughts to digest... The old MILW line from Ellensburg, thru Cle Elum to Easton IS nearly level; I have pedaled my fat butt on it as recently as this past summer. It's the westbound grade from the Columbia River @ Beverly to Boylston that will kill you; 17 miles of 2.2% grade & the so-called " Heartbreak Curves " near Cohasset... Also consider the cost of renewing the bridge over the Columbia, as well as the missing bridge @ Lake Easton State Park. Then there's the wet side of the line; sure you can move pipelines & power lines, but what about the bridges?? The Milwaukee was not known for high maintenance budgets on their Lines West. The bridge @ Garcia is missing 2 original spans; these have been replaced with 1 loooong span for John Wayne trail use only.( The missing bridge @ Lake Easton has likewise been replaced with a "trail use" span; although it does meet the clearance profile of a 1980 Chevy pickup !! )
Now we've made it West to Cedar Falls, oops, I mean Rattlesnake Lake State Park. Ya think the Greenies would mind sharing the trail with a train or two ??? And how about the underpass @ Interstate 405 in Renton; its been replaced with a new LOWER highway span since the line was abandoned by BN in 1987. I think the reuse of the Milwaukee line will happen right after the re-opening of the NWP!!! ( Oops - now I've done it ... )
Just so you NP guys don't feel left out, consider the current condition of Stampede Tunnel. The roof is still mostly 100 year old brick; and according to a BNSF track maintainer who hirails the line weekly, is crumbling just from the few trains currently using the line. So it will have to be renewed anyways. But what about that 2.2% grade; it tops out near the middle of the tunnel. We're talking lots of trapped smoke & hot gasses !!! ( Kind'o like me...). Then there is the Omnipotent Dictatorship of Tacoma Water. They own vast amounts of watershed ( i.e. - land ) on the west side of the pass; from Lester to almost Palmer Jct. And they are VERY ANAL about "their" ( former NP - owned ) land. I've read where they nixed a proposed garbage train thru " their " land due to concerns of derailed cars polluting " their" watershed. Imagine how big their eyes will get from seeing Placarded ( i.e.- hazardous materials ) containers traveling thru " their" land. I guess they aren't looking when Placarded tank cars & "empty" Sulpher cars returning to B.C. go thru there currently.
Oh well, I'll shut up now...