Grounding the McGrath

cubbe8 said:

New project website. There is a meeting on March 25.

Construction now scheduled to begin in 2027.

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Where are you seeing 2027?
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This is tangential to the thread, but I couldn't find a better place to ask something I've long wondered: why does the elevated northbound side briefly return to grade for a signalized intersection at Somerville Av/Poplar St, while the southbound side remains elevated entirely? Was is always this way? Because it seems counterintuitive to 1950's highway planning.
 
Camberville said:
This is tangential to the thread, but I couldn't find a better place to ask something I've long wondered: why does the elevated northbound side briefly return to grade for a signalized intersection at Somerville Av/Poplar St, while the southbound side remains elevated entirely? Was is always this way? Because it seems counterintuitive to 1950's highway planning.
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Best guess:
There was only width for one ramp between the Medford & Washington St intersections.

The (mercifully) closed SB offramp is ~26’ wide; assuming the same width, the retaining wall of NB ramp would be about to the present NB frontage Rd bike lane.


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If the NB barrel remained elevated, NB traffic on Medford St would have to continue via the frontage road and intersect Washington St at grade. As this segment of McGrath hijacked the Medford St ROW, it would kinda defeat the point of elevating Medford St over Washington St… only to have all NB traffic on Medford St still sit at the Washington St light.


Why NB instead of SB at grade?

Without burrowing too deep into the signal phasing rabbit hole, tying McGrath NB into the Somerville/Medford intersection is immeasurably preferable to bringing the SB direction down to grade.
But in so many words, elevating the SB direction buys a free left turn (a traffic engineer’s favorite currency); elevating the NB direction just grade separates a right turn. Which is silly.
 
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Camberville said:
This is tangential to the thread, but I couldn't find a better place to ask something I've long wondered: why does the elevated northbound side briefly return to grade for a signalized intersection at Somerville Av/Poplar St, while the southbound side remains elevated entirely? Was is always this way? Because it seems counterintuitive to 1950's highway planning.
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The NB didn't need to be elevated because up until relatively recently there was no traffic light on the NB direction of McGrath Hwy. This was the case for several decades after the elevated SB highway was built in the 1950s. Traffic heading NB from Medford St went into a roadway that ran underneath the SB elevated McGrath roadway from Somerville Ave all the way to Washington St, then that traffic joined McGrath Hwy NB morth of that intersection.
 
Charlie_mta said:
The NB didn't need to be elevated because up until relatively recently there was no traffic light on the NB direction of McGrath Hwy. This was the case for several decades after the elevated SB highway was built in the 1950s. Traffic heading NB from Medford St went into a roadway that ran underneath the SB elevated McGrath roadway from Somerville Ave all the way to Washington St, then that traffic joined McGrath Hwy NB morth of that intersection.
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Oh, this actually makes sense. It took me a while to understand what you were describing, but I think I understand after looking at old mapjunction images. Thanks!
 
Camberville said:
Oh, this actually makes sense. It took me a while to understand what you were describing, but I think I understand after looking at old mapjunction images. Thanks!
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Yes, on this 2007 Google streetview you can see the roadway (now gone) that ran underneath the SB overpass. It took NB Medford Street traffic to Washington Street, then to the NB McGrath Hwy.
 
Longfellow said:
Work with a developer to use 1/2 the footprint to build apartments, 1/2 for a surface boulevard? Then we can get it for free.
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This would be amazing! Doubt we would see it done this way, but I like the way you're thinking. I do like that there's enough room for the current design to have a fully-protected intersection at least, but that's more of a silver lining imo.
 
Charlie_mta said:
The NB didn't need to be elevated because up until relatively recently there was no traffic light on the NB direction of McGrath Hwy. This was the case for several decades after the elevated SB highway was built in the 1950s. Traffic heading NB from Medford St went into a roadway that ran underneath the SB elevated McGrath roadway from Somerville Ave all the way to Washington St, then that traffic joined McGrath Hwy NB morth of that intersection.
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Thanks Charlie!

Before the new signal, the weave from where the NB frontage road ends at Cross St to the left turn lanes at (the Northern) Medford St intersection must have been a complete mess; absolute sterling example of myopic 1950’s era highway design!

In that case, the original designers probably realized space limitations precluded NB Medford St traffic from entering NB McGrath until Cross St. In that case, displacing where NB Medford crossed under NB McGrath would allow an at grade NB McGrath to still operate conflict free. So why not save a few bucks on steel and make it easier to tie in Poplar St? (There are/were 101 other reasons to not do any of this, but the infinitely wise 1950’s highway engineers didn’t consider those).
 
Highwayguy said:
Thanks Charlie!

Before the new signal, the weave from where the NB frontage road ends at Cross St to the left turn lanes at (the Northern) Medford St intersection must have been a complete mess; absolute sterling example of myopic 1950’s era highway design!

In that case, the original designers probably realized space limitations precluded NB Medford St traffic from entering NB McGrath until Cross St. In that case, displacing where NB Medford crossed under NB McGrath would allow an at grade NB McGrath to still operate conflict free. So why not save a few bucks on steel and make it easier to tie in Poplar St? (There are/were 101 other reasons to not do any of this, but the infinitely wise 1950’s highway engineers didn’t consider those).
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I (was) a highway designer, and also have followed expressway planning and design since I was a kid.
In the 1950s, city planning and highway design were completely car-centric, ignoring the micro-transit connectivity provided by small streets and pathways in favor of pushing through expressways and creating barriers and super blocks, forcing people to drive in cars to get around. In the wake of the chaos and destruction of WW II, the 1950s were a traumatized time in which history and tradition were being obliterated in a headlong rush into a supposedly bright and exciting future. Human scale was swept aside in favor of wide streets, super blocks, and expressways on sweeping alignments plowing through the old city walkable street grid. That's why Poplar Street is not connected across McGrath Hwy to Somerville Ave, and the McGrath overpass and highway form a wall separating Somerville.
Hopefully the Grounding McGrath project will actually happen, and this part of Somerville can become connected and walkable.
 
Massive improvement. The comparison to the casey overpass/casey arborway is an apt one. Its nice that the city has a finished example to point to, to show how successful and absolutely transformative a project like this can and will be.
 
So I never noticed this in the presentation but it was pointed out in the GSNC meeting yesterday, the barrier in the median is not something we’ve seen before. The neighborhood council could not get confirmation from MassDOT or Rep Connolly as to the nature of the barrier. Could be an 8ft chain link fence or a highway median crash barrier. Either option is counterproductive to the mission of connecting the community.
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Badusername said:
So I never noticed this in the presentation but it was pointed out in the GSNC meeting yesterday, the barrier in the median is not something we’ve seen before. The neighborhood council could not get confirmation from MassDOT or Rep Connolly as to the nature of the barrier. Could be an 8ft chain link fence or a highway median crash barrier. Either option is counterproductive to the mission of connecting the community.View attachment 61713
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That’s a guardrail by the looks of it and it’s only on the stretch where there is another road next to McGrath. Probably a safety feature to protect the small roads.
 
cubbe8 said:
That’s a guardrail by the looks of it and it’s only on the stretch where there is another road next to McGrath. Probably a safety feature to protect the small roads.
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If planned vehicle speeds are high enough to require a guard rail for feeder streets, we are leaving a lot to be desired with this design. It doesn’t seem logical to protect the frontage road while leaving only the curb for the cycle lane on the other side. The impression from the neighborhood meeting was that it is potentially a fence to prevent jaywalking.

I should also note there is no guardrail there now. So it wouldn’t make much sense to add protection to the frontage road when there are fewer lanes than there are now. The fear is they want to put the existing median fence there.
 

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