I really think the 495 is off the table because there are too many homes that would need to be demolished. There are far fewer obstacles on the 270, so if you play politics, you can get the widening that would be very helpful.
It is true that the right-of-way is constrained across most of Montgomery County (originally I-495 in Maryland was six lanes from the Potomac River to the Potomac River (some early sections, including between MD-193 (Exit 29) and MD-97 (Exit 31) were opened as four lanes but widened to six by the time that the entire road was opened in 1964).
But as I think I have mentioned here before - the parkland along the way and not the homes was and is the bigger impediment to widening. Between MD-650 (Exit 28) and I-270 (Exit 35), the I-495 corridor crosses several parks that belong to the bicounty Maryland-National Capital Park and Planning Commission (anyplace else these would be county parks). They are: Northwest Branch stream valley (crossed by a high and massive steel arch that is not visible to I-495 drivers); Sligo Creek stream valley (crossed by a modest concrete culvert where the freeway crosses the stream valley on a large filled-in dirt embankment) and Rock Creek stream valley (crossed near the Mormon Temple over the creek and adjacent Stoneybrook Drive). From Stoneybrook Drive almost to MD-355 (Exit 34), I-495 runs hard by the bed of the creek. In addition to having the same ownership, all of these parks have something else in common - the purchase of the lands were financed in whole or in part by the federal Capper-Cramton Act (originally passed 1930 and amended later). The significance of Capper-Cramton cannot be understated - long before the USDOT Act was passed in 1966 (with its Section 4(f) that limited taking of parkland for federally-financed transportation projects), lands purchased under Capper-Cramton had protection in federal law against conversion to non-park uses.
in the late 1950's, the Maryland State Roads Commission was able to take enough parkland to build the six-lane I-495 but not really more, and even when I-495 was widened to 8 lanes (between I-295 near the Wilson Bridge and MD-97 in the early 1970's and not for many more years between MD-97 and the American Legion Bridge in the late 1980's and early 1990's), the state was not able to take much additional right-of-way from the Capper-Cramton parks. I suspect that if MDOT today were to try and take enough land for four at-grade managed lanes, it would be challenged in court, and the state would lose - because of Capper-Cramton and Section 4(f).
So if there were to be managed lanes in the "top" part of I-495, they would presumably need to go up to an elevated structure (perhaps similar to I-110 (Harbor Freeway) in Los Angeles County, California) or down to some sort of bored tunnel.
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Topic: I-495 and I-270 P3 Program (Read 66049 times)