The Transportation and Mass Transit Megathread

[smeagolsfree]

21 hours ago, Bos2Nash said:

They would also be better for cyclists as well.  The grade at this intersection presents an interesting "challenge" as I cannot say I have seen many roundabouts on a slope. I would presume it is possible, but who knows.

Would love to see some dutch inspired roundabouts built in the next few years.

Just as long as people know which way to go around the loop. I watched in horror one day a stupid driver going the wrong way around the Music Row round about.  For the life of me I do not know how people get a license.

[BnaBreaker]

4 hours ago, smeagolsfree said:

Just as long as people know which way to go around the loop. I watched in horror one day a stupid driver going the wrong way around the Music Row round about.  For the life of me I do not know how people get a license.

As my grandad would say... "That'll learn em!"  

[PruneTracy]

On 9/13/2023 at 5:23 PM, PaulChinetti said:

Is there a good reason that this intersection isn’t a large roundabout? There is actually tons of space for the roundabout and then space could actually be given back for housing or a park.

Wedgewood, Magnolia, 16th, and 17th.

On 9/13/2023 at 6:57 PM, BnaBreaker said:

Good call, that is a perfect location for a roundabout.  Actually the entire street grid is a bit of a cluster there thanks to whoever thought it was a good idea to make Magnolia into a pseudo expressway, and a roundabout would probably help to de-clutter things.  

On 9/14/2023 at 7:31 AM, CenterHill said:

Totally.   I raised the same question on here a couple years ago.  The double stoplights take a while to get through.  When you’re sitting there waiting and look around it’s just so obviously screaming out for a roundabout.   

The biggest issue is the distance between 16th and 17th Avenues (and, to a lesser extent, the "median" width of Magnolia Boulevard). If you constrain the roundabout diameter to typical for a multilane roadway, it will easily fit within existing right-of-way, but realigning 16th and 17th Avenues to meet it at appropriate angles becomes difficult. If you expand the roundabout diameter to try to help these approaches, it cuts into Belmont and other adjacent properties, and circulating speeds within the roundabout become unacceptably high.

For reference I was able to fit a 350' diameter circle in the intersection without getting into existing structures, if Belmont will donate a little land (the yellow circle). The maximum recommended diameter for a roundabout is 200', which is the orange circle. But you can see even with the larger circle that the 16th Avenue exit is poorly aligned without much room to fix it. The positioning is also troublesome as pushing the roundabout to the east (right) improves the 16th Avenue exit but makes the 17th Avenue entrance much worse, and in either case there is a lot of unused space. On the other hand both Wedgewood Avenue and Magnolia Boulevard are well-aligned for roundabout approaches (it's desirable to have the centerline hit a little to the left of the center of the roundabout as it allows for more deflection and speed reduction on entrances).

A second issue, mostly for the larger diameters, is the grades within the site. It's about a fifteen-foot change in elevation from the top of Wedgewood to 17th Avenue. Roundabouts generally need no more than a 2% cross-slope on the circulating roadway and max 4% grade longitudinally (circumferentially?); if you go higher drivers start to have a harder time navigating the traffic conflict points while turning and trying to maintain speed across varying grades. On the other hand, if we are thumbing our nose at the FHWA and AASHTO by building a big-ass roundabout we can probably do the same by making it go up and down hills.

There are also several properties that only have access to streets within this area which would be cut off by a roundabout. Maybe not an issue since they all seem to have alley access.

All said maybe we can take a lunch break one day to fix it.

[markhollin]

North Nashville Transit Center update.

Looking south from Clarksville Highway, 1/2 block east of 26th Ave. North:

Looking east from 26th Ave. North, 1/4 block south of Clarksville Highway:

Looking west from Clarksville Highway, at 25th Ave. North:

[GregH]

On 9/16/2023 at 7:40 AM, smeagolsfree said:

Just as long as people know which way to go around the loop. I watched in horror one day a stupid driver going the wrong way around the Music Row round about.  For the life of me I do not know how people get a license.

A friend told me that he had a former coworker that would do that intentionally to freak out his passengers/ as a some kind of protest because he didn't like roundabouts.

I guess that's even stupider than doing it by accident.

[markhollin]

Broadway Viaduct (700 feet) update.

Looking NE from 11th Ave. North, 1/8 block south of Broadway:

Looking west from underneath viaduct:

Looking SE from 11th Ave. North, 1/8 block north of Broadway:




Looking west from intersection of Broadway and 10th Ave:

Looking west from Viaduct, 1/2 block west of 10th Ave:

[Deepdish53]

On 9/16/2023 at 3:40 PM, PruneTracy said:

The biggest issue is the distance between 16th and 17th Avenues (and, to a lesser extent, the "median" width of Magnolia Boulevard). If you constrain the roundabout diameter to typical for a multilane roadway, it will easily fit within existing right-of-way, but realigning 16th and 17th Avenues to meet it at appropriate angles becomes difficult. If you expand the roundabout diameter to try to help these approaches, it cuts into Belmont and other adjacent properties, and circulating speeds within the roundabout become unacceptably high.

For reference I was able to fit a 350' diameter circle in the intersection without getting into existing structures, if Belmont will donate a little land (the yellow circle). The maximum recommended diameter for a roundabout is 200', which is the orange circle. But you can see even with the larger circle that the 16th Avenue exit is poorly aligned without much room to fix it. The positioning is also troublesome as pushing the roundabout to the east (right) improves the 16th Avenue exit but makes the 17th Avenue entrance much worse, and in either case there is a lot of unused space. On the other hand both Wedgewood Avenue and Magnolia Boulevard are well-aligned for roundabout approaches (it's desirable to have the centerline hit a little to the left of the center of the roundabout as it allows for more deflection and speed reduction on entrances).

A second issue, mostly for the larger diameters, is the grades within the site. It's about a fifteen-foot change in elevation from the top of Wedgewood to 17th Avenue. Roundabouts generally need no more than a 2% cross-slope on the circulating roadway and max 4% grade longitudinally (circumferentially?); if you go higher drivers start to have a harder time navigating the traffic conflict points while turning and trying to maintain speed across varying grades. On the other hand, if we are thumbing our nose at the FHWA and AASHTO by building a big-ass roundabout we can probably do the same by making it go up and down hills.

There are also several properties that only have access to streets within this area which would be cut off by a roundabout. Maybe not an issue since they all seem to have alley access.

All said maybe we can take a lunch break one day to fix it.

A traditional roundabout would certainly have numerous problems keeping it from being a realistic option (as you've laid out), but I do wonder if a dumbbell roundabout design (typically used with highway interchanges) would be possible. I haven't worked with them enough to know the ideal distance between the connecting roundabouts, but it seems like this could be a good candidate to have two smaller diameter roundabouts that would help with the offsets for deflection without having to alter the approaches too much.

Ultimately I think grade would still be the constraint keeping it from being a feasible option, but it seems like a more reasonable option geometrically and could be worth exploring.

[Bos2Nash]

1 hour ago, Deepdish53 said:

A traditional roundabout would certainly have numerous problems keeping it from being a realistic option (as you've laid out), but I do wonder if a dumbbell roundabout design (typically used with highway interchanges) would be possible. I haven't worked with them enough to know the ideal distance between the connecting roundabouts, but it seems like this could be a good candidate to have two smaller diameter roundabouts that would help with the offsets for deflection without having to alter the approaches too much.

Ultimately I think grade would still be the constraint keeping it from being a feasible option, but it seems like a more reasonable option geometrically and could be worth exploring.

I have little experience interacting with the dumbell-esqe roundabouts, but they are intriguing. An intersection that I grew up driving through - Kelley Square in Worcester, MA - used to be terrifying and they designed a peanut shaped rotary to help with conflicts and alignments. 

Before:

After:

I still think the grades could be an issue though, but I'm not sure if this approach would allow for additional storm drainage to be integrated.

[Archibum]

Maybe an ovalabout...

[andywildman]

On 9/16/2023 at 12:38 AM, rookzie said:

Nashville's growth evolved more as "outward" than "upward" (vertical), so it's no wonder its has had major bottlenecks, given that it has sizable surrounding suburbs and exurbs.

This has to be the foundation for any conversation on transit in Nashville. The demand for living in downtown/midtown/east Nashville is sky high, as evidenced by high rise apartments and sky-high rents. Successful transit requires a high density of jobs and people to be worthwhile, which means that we'd need meaningful upzoning around any light rail (and around BRT stations) to further build a ridership base. That's part of why I think the Metro plans for Hickory Hollow are so underwhelming, if we want the Crossings to be a regional center with a transit hub.

[PaulChinetti]

On 9/16/2023 at 3:40 PM, PruneTracy said:

The biggest issue is the distance between 16th and 17th Avenues (and, to a lesser extent, the "median" width of Magnolia Boulevard). If you constrain the roundabout diameter to typical for a multilane roadway, it will easily fit within existing right-of-way, but realigning 16th and 17th Avenues to meet it at appropriate angles becomes difficult. If you expand the roundabout diameter to try to help these approaches, it cuts into Belmont and other adjacent properties, and circulating speeds within the roundabout become unacceptably high.

For reference I was able to fit a 350' diameter circle in the intersection without getting into existing structures, if Belmont will donate a little land (the yellow circle). The maximum recommended diameter for a roundabout is 200', which is the orange circle. But you can see even with the larger circle that the 16th Avenue exit is poorly aligned without much room to fix it. The positioning is also troublesome as pushing the roundabout to the east (right) improves the 16th Avenue exit but makes the 17th Avenue entrance much worse, and in either case there is a lot of unused space. On the other hand both Wedgewood Avenue and Magnolia Boulevard are well-aligned for roundabout approaches (it's desirable to have the centerline hit a little to the left of the center of the roundabout as it allows for more deflection and speed reduction on entrances).

A second issue, mostly for the larger diameters, is the grades within the site. It's about a fifteen-foot change in elevation from the top of Wedgewood to 17th Avenue. Roundabouts generally need no more than a 2% cross-slope on the circulating roadway and max 4% grade longitudinally (circumferentially?); if you go higher drivers start to have a harder time navigating the traffic conflict points while turning and trying to maintain speed across varying grades. On the other hand, if we are thumbing our nose at the FHWA and AASHTO by building a big-ass roundabout we can probably do the same by making it go up and down hills.

There are also several properties that only have access to streets within this area which would be cut off by a roundabout. Maybe not an issue since they all seem to have alley access.

All said maybe we can take a lunch break one day to fix it.

Thanks for the breakdown @PruneTracy 

[PaulChinetti]

Unrelated, this thread popped up on my feed this weekend. 

By 1920, the network of interurbans in the US was so dense that a determined commuter could hop interlinked streetcars from Waterville, Maine, to Sheboygan, Wisconsin—a journey of 1,000 miles—exclusively by electric trolley.

https://urbanists.social/@straphanger/111059691532896415

[Bos2Nash]

4 minutes ago, PaulChinetti said:

Unrelated, this thread popped up on my feed this weekend. 

By 1920, the network of interurbans in the US was so dense that a determined commuter could hop interlinked streetcars from Waterville, Maine, to Sheboygan, Wisconsin—a journey of 1,000 miles—exclusively by electric trolley.

https://urbanists.social/@straphanger/111059691532896415

I'd be curious to see that map. Must be a very detirmined person. I wouldn't really call it a commuter at that point though haha

[MidTenn1]

On 9/16/2023 at 4:40 PM, PruneTracy said:

The biggest issue is the distance between 16th and 17th Avenues (and, to a lesser extent, the "median" width of Magnolia Boulevard). If you constrain the roundabout diameter to typical for a multilane roadway, it will easily fit within existing right-of-way, but realigning 16th and 17th Avenues to meet it at appropriate angles becomes difficult. If you expand the roundabout diameter to try to help these approaches, it cuts into Belmont and other adjacent properties, and circulating speeds within the roundabout become unacceptably high.

For reference I was able to fit a 350' diameter circle in the intersection without getting into existing structures, if Belmont will donate a little land (the yellow circle). The maximum recommended diameter for a roundabout is 200', which is the orange circle. But you can see even with the larger circle that the 16th Avenue exit is poorly aligned without much room to fix it. The positioning is also troublesome as pushing the roundabout to the east (right) improves the 16th Avenue exit but makes the 17th Avenue entrance much worse, and in either case there is a lot of unused space. On the other hand both Wedgewood Avenue and Magnolia Boulevard are well-aligned for roundabout approaches (it's desirable to have the centerline hit a little to the left of the center of the roundabout as it allows for more deflection and speed reduction on entrances).

A second issue, mostly for the larger diameters, is the grades within the site. It's about a fifteen-foot change in elevation from the top of Wedgewood to 17th Avenue. Roundabouts generally need no more than a 2% cross-slope on the circulating roadway and max 4% grade longitudinally (circumferentially?); if you go higher drivers start to have a harder time navigating the traffic conflict points while turning and trying to maintain speed across varying grades. On the other hand, if we are thumbing our nose at the FHWA and AASHTO by building a big-ass roundabout we can probably do the same by making it go up and down hills.

There are also several properties that only have access to streets within this area which would be cut off by a roundabout. Maybe not an issue since they all seem to have alley access.

All said maybe we can take a lunch break one day to fix it.

Thanks, P T. That's pretty much how I saw it also. I might have seen it as necessary to close the westmost 16th Avenue entrance and opted to signalize the east 16th Ave entrance which would have created a mess, also.

[PaulChinetti]

https://www.fastcompany.com/90952175/this-spanish-city-has-been-restricting-cars-for-24-years-heres-what-we-can-learn-from-it

Slowly, and consistently get rid of cars. 

Let's start with Broadway.

[Bos2Nash]

Interesting article about choosing what kind of transit is right for the city. 

I know everyone wants trains/light rail/subway, but if our density isn't approaching that, then it would really be silly to go after that. Hey @UTgrad09, can you help with comparing the numbers below to recent census information?

Quote

For subways, a minimum population density of 47 people per acre is required, while for light rail a minimum population density of 28-60 people per acre is required. [Editor's note: other transportation professionals may suggest different ratios.] To put it in perspective, Baltimore City has approximately 650,000 people on 58,800 acres, or less than 12 people per acre — far below the minimum population density requirements for either option. While it may not seem that way, the reality is that Baltimore City is simply not dense from a residential or commercial perspective, at least outside of a few pockets.

True BRT may be the best bet for the next 15-20 years. Hell, the 30 acre master development around the Titans Stadium is slated for final completion in 2034 (11 to 12 years from now). I may behoove our new mayoral administration to work through a BRT transit referendum with a vision plan for how things grow and possibly evolve into a train heavy system in 20 years. 

While we work on BRT for the airport along Murfreesboro Pike, here is a thought for downtown BRT.

BLUE = BRT buses without protected lanes, share full road with traffic

ORANGE = BRT dedicated bus lane in a single direction with one-way traffic going opposite direction. buses would share the road with vehicles going the opposite direction and the protected lane could switch directions depending on which time of day (and commute direction)

RED = Two-way, BRT only traffic. No private cars.

[go_outside]

15 minutes ago, Bos2Nash said:

Interesting article about choosing what kind of transit is right for the city. 

I know everyone wants trains/light rail/subway, but if our density isn't approaching that, then it would really be silly to go after that. Hey @UTgrad09, can you help with comparing the numbers below to recent census information?

True BRT may be the best bet for the next 15-20 years. Hell, the 30 acre master development around the Titans Stadium is slated for final completion in 2034 (11 to 12 years from now). I may behoove our new mayoral administration to work through a BRT transit referendum with a vision plan for how things grow and possibly evolve into a train heavy system in 20 years. 

In a recent interview, Mayor O'Connell seems to agree with this BRT-centric approach.

[Luvemtall]

I tend to agree with BRT as a starting point. But it somehow needs to be separated from normal traffic, otherwise the “R” will stand for ridiculous. 
there’s no way anyone would resolve to taking a bus , if it doesn’t get them to their destinations any quicker then they can drive themselves. The objective is to get people to park their cars and find alternative ways to get somewhere, in a mass transit environment. Plus the buses will need to be clean, modern, and tech friendly so people can feel comfortable and able to use internet connections. Also IMHO , this has to be a collaboration with all the Counties within the MSA to make a difference, getting commuters to leave their cars in the city they live and getting a bus into a hub downtown to make connections to intercity destinations. And there definitely needs to be a real incentive to make the WEGO ( Music City) STAR a true commuter rail service, it’s there let’s use it to its fullest. 

[go_outside]

51 minutes ago, Luvemtall said:

I tend to agree with BRT as a starting point. But it somehow needs to be separated from normal traffic, otherwise the “R” will stand for ridiculous. 
there’s no way anyone would resolve to taking a bus , if it doesn’t get them to their destinations any quicker then they can drive themselves. The objective is to get people to park their cars and find alternative ways to get somewhere, in a mass transit environment. Plus the buses will need to be clean, modern, and tech friendly so people can feel comfortable and able to use internet connections. Also IMHO , this has to be a collaboration with all the Counties within the MSA to make a difference, getting commuters to leave their cars in the city they live and getting a bus into a hub downtown to make connections to intercity destinations. And there definitely needs to be a real incentive to make the WEGO ( Music City) STAR a true commuter rail service, it’s there let’s use it to its fullest. 

Agreed. The question isn’t whether it runs on rails or rubber. The question is whether it has dedicated right of way.

This will be challenging downtown, and I’m curious to see how the eventual transit proposal handles that.

Edited September 19, 2023 by go_outside

[PaulChinetti]

Road diets would give plenty of dedicated right of way, and give people reasons to ride buses. 

[Luvemtall]

31 minutes ago, PaulChinetti said:

Road diets would give plenty of dedicated right of way, and give people reasons to ride buses. 

With you on that! Start with the HOV lanes, since you rarely see them properly used anyway. Oh so many times I see that one person vehicle, makes me just laugh out loud. What a failure and farce, supposed to be High Occupancy Vehicles for the purpose of car pooling to reduce the amount of cars. 

[Bos2Nash]

2 hours ago, go_outside said:

In a recent interview, Mayor O'Connell seems to agree with this BRT-centric approach.

This is the way forwards. We have seen how badly train based plans have failed and we need to start somewhere. Bus routing and neighborhood transit hubs are part of that.

2 hours ago, Luvemtall said:

I tend to agree with BRT as a starting point. But it somehow needs to be separated from normal traffic, otherwise the “R” will stand for ridiculous. 
there’s no way anyone would resolve to taking a bus , if it doesn’t get them to their destinations any quicker then they can drive themselves. The objective is to get people to park their cars and find alternative ways to get somewhere, in a mass transit environment. Plus the buses will need to be clean, modern, and tech friendly so people can feel comfortable and able to use internet connections.

Dedicated ROW is desirable,, but difficult. That's why in the sketch above - as a basic starting point - showed true dedication in downtown, but phase down as we moved outside the core. 3rd Ave was chosen because it is the only road that is uninterrupted north to south through the inner loop. While separated lanes are easy to implement on a new road such as the East Bank Boulevard, getting them in places like Germantown, Salemtown, MetroCenter, WeHo/Chestnut Hill may be harder due to the vast amount of single family housing. Doable yes, but I don't think it would prevail if it was proposed as dedicated lanes everywhere out of the gate. Maybe a Vision plan that shows a roll out of lanes, similar to a vision plan that would convert certain buses into trains. 

The WeGo buses are typically very clean and not really sure how more "tech-savy" they can be when they announce every stop and have the typical bus technology of signaling you need to stop. I'm not sure of any bus system in the country that would have WiFi on the buses seeing as they are typically in hubs and have great access to cellular data. Sure we have some homeless people or some would even say "less than desirable characters", but that would also happen on a train system too. Every time I get on the bus, I have been very comfortable. The only time I had an "odd" encounter was when the bus driver told me I needed headphones so that she wasn't distracted my phone audio haha.

2 hours ago, Luvemtall said:

Also IMHO , this has to be a collaboration with all the Counties within the MSA to make a difference, getting commuters to leave their cars in the city they live and getting a bus into a hub downtown to make connections to intercity destinations. And there definitely needs to be a real incentive to make the WEGO ( Music City) STAR a true commuter rail service, it’s there let’s use it to its fullest. 

For real transit to occur it will take a state level cooperation. Getting other counties onboard will help maneuver the state, but working county by county I don't think is a long term solution. I am a huge advocate for the Star (just see my earlier proposals for upgrading way up thread here), but they just celebrated their 17th year and are still touting the fact that they are the cheapest implemented CR line in the country. Not really something to hang a hat on seeing they don't have a great level of service. I've been attending meetings and participating in surveys and trying to have conversations, but I don't know how much funding they are wanting to throw at the train in the short term (especially seeing as PTC is still a "long-term" goal)

[go_outside]

TDOT has provided some Transportation Modernization Act updates. From NewsChannel 5:

TDOT staff are currently studying which corridors across the state to recommend building choice lanes. They will run alongside normal lanes of traffic, and drivers can access them with a fee. Transit operators like buses will be allowed to use the lanes free of charge . . . . TDOT Commissioner Butch Eley says the choice lanes will all be new construction, and no current lanes will be converted to their purpose . . ."We've got wide right-of-ways if you think about it from here (Nashville) to Murfreesboro or here to Franklin, there's still a lot of room in many of our locations," he said. "And when you think about even downtown you can build up (over the current roadway). So there's a way to engineer a solution to be able to do these choice lanes just as other states have" [Emphasis added].

Per the article, TDOT will present the full plan on December 1.

[PaulChinetti]

9 minutes ago, go_outside said:

"And when you think about even downtown you can build up (over the current roadway).

No, stop it TDOT, bad TDOT!

[Luvemtall]

I would rather see stacked lanes, then more sprawling spread out lanes. This is similar to Dallas, or Atlanta with their express lanes.