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MD-295, The Baltimore - Washington Parkway

Started by bing101, March 09, 2019, 08:31:16 PM

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cpzilliacus

#50
Quote from: froggie on July 30, 2019, 08:45:19 AM
A few things:

- The 4-laning and limited access on Route 4 predates the Beltway.  It was considered a more important route than Suitland Parkway, especially considering there were long-range plans at the time for a freeway upgrade of Route 4 from what is now the Beltway to Upper Marlborough.

Correct.  The four lane MD-4 came to a halt at what is now the signals at Dower House Road in 1964 (many crashes here over the years - this needs to be an interchange).  For reasons not clear, in 1964 the four lanes resumed at the old half interchange at Ritchie Marlboro Road (former MD-221).

Also, the Suitland Parkway was onlu widened to four lane divided from MD-4 to MD-458 (Silver Hill Road) in the early 1990's.  Before that, it was two lanes undivided using what are now the outbound lanes.  The grading work for the inbound lanes was done when the parkway was built, but there was no subgrade or anything else.

Quote
- Route 4 is too close to Suitland Parkway to have interchanges at both.  Route 4 was deemed more important.

Correct. Also consider that prior to the NMSL in 1973, the posted limit here on I-495 was 70 MPH.

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- More important than having a Suitland Parkway interchange at the Beltway would be a Suitland interchange at Forestville Rd.

Also remember that the primary reason for building the Suitland Parkway was to provide federal road access to and from D.C. to what was then Andrews AFB. not the Capital Beltway.
Opinions expressed here on AAROADS are strictly personal and mine alone, and do not reflect policies or positions of MWCOG, NCRTPB or their member federal, state, county and municipal governments or any other agency.


sprjus4

Quote from: cpzilliacus on July 31, 2019, 09:05:32 PMto the NMSL in 1973, the posted limit here on I-495 was 70 MPH.
And even today most people still do 65-75 mph on it. I'd argue it should be at least 60 mph, or even 65 mph. 70 mph might be acceptable if some of the interchanges were better designed and farther spread out.

froggie

Quote from: sprjus470 mph might be acceptable if some of the interchanges were better designed and farther spread out.

(emphasis mine)

...which runs counter to the idea of having a Suitland Pkwy interchange given its proximity to Route 4.

sprjus4

Quote from: froggie on August 01, 2019, 07:27:40 AM
Quote from: sprjus470 mph might be acceptable if some of the interchanges were better designed and farther spread out.

(emphasis mine)

...which runs counter to the idea of having a Suitland Pkwy interchange given its proximity to Route 4.
Nowadays an interchange with Suitland Pkwy would be problematic due to close proximity and high traffic volumes, but in a time where I-495 was considered as a rural highway with lighter volumes, it could have been acceptable in a 60s design.

Braided ramps could also be used to eliminate the weaving issues.

Alps

Quote from: sprjus4 on August 01, 2019, 07:36:43 AM
Quote from: froggie on August 01, 2019, 07:27:40 AM
Quote from: sprjus470 mph might be acceptable if some of the interchanges were better designed and farther spread out.

(emphasis mine)

...which runs counter to the idea of having a Suitland Pkwy interchange given its proximity to Route 4.
Nowadays an interchange with Suitland Pkwy would be problematic due to close proximity and high traffic volumes, but in a time where I-495 was considered as a rural highway with lighter volumes, it could have been acceptable in a 60s design.

Braided ramps could also be used to eliminate the weaving issues.
That design was never acceptable, even less so on a rural highway where interchanges should be spaced farther. A C-D road might have helped. Braided ramps are a more modern concept.



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