Down to the knitty-gritty: The practicalities of GA 400 MARTA expansion (Atlanta: real estate, transfer)

[bryantm3]

Okay, so we all know that expanding MARTA up GA 400 is definitely in the cards, the question isn't if, but when. MARTA has started the process of examining the corridor and holding sessions under the Connect 400 banner, but no final or working plans have been released.

First, I want to address why this project is going to have some major challenges.
Look at the topography north of the north springs station:

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See all those lines? Each line denotes a 10' difference in elevation, once you get north of North Springs, it goes all over the place, especially around the Chattahoochee. Which is the second challenge. MARTA hasn't ever built over water. If MARTA is going to go up 400, it's inevitable that a big bridge building project is going to have to take place or the project dead ends at Northridge.

Another challenge is the environment— 400 south of Mansell Road and north of Holcomb Bridge is a swamp, literally, on both sides of 400. Much of the area around the Chattahoochee is nature preserves, city parks, national parks and state parks. The last challenge is probably historic and culturally significant properties, specifically around the Roswell area.

Another discussion I really think needs to happen is, what kind of a line is this going to be? Are they just going to build the line up 400 and basically put a series of stations with huge parking lots, à la North Springs, essentially building a commuter rail line? Or is the line going to take a long-term approach by building where dense development is likely to increase, and going to where people live?

I think so far the idea has been to build a commuter rail type extension up 400 to relieve the traffic situation by targetting commuters only, when I think the approach needs to be to build transit into the existing fabric so that people can get around without a car at all, if they choose to do so. I think that this would require stations in both downtown Roswell and downtown Alpharetta, in addition to major commercial sites like North Point Mall and Windward Parkway, and possibly the new Avalon development.

This will be more expensive, especially getting transit into downtown Roswell— it will have to be entirely underground, from after it crosses the Chattahoochee up to around Holcomb Bridge. Alpharetta is a lot more flexible, there is a swath of industrial land directly south of the city centre along Maxwell road, which is conveniently at a lower elevation, that leads to 400. This could potentially serve at-grade or above grade tracks, with the only underground portion of the line being in the downtown area.

There's a lot of stuff to think about but I've outlined some of these ideas in a map, with a potential idea for a line that would serve multiple purposes.

https://maps.google.com/maps/ms?msid...a51ea8aa&msa=0

[cqholt]

I know that 2 weeks ago MARTA was conducting a survey at the Sandy Springs Station about the GA 400 extension.
I think HRT should be continued north of North Springs. Makes no sense to run LRT and have people transfer, when HRT has higher speeds and that corridor will be all about commuters. Extending the HRT north will allow MARTA to focus buses on moving people to/from the office parks and residential areas.
The issue with building through a swamp isn't big, as concrete posts can be set in the swamp to bedrock, as a foundation, and then a large concrete pad can be built on top to support the piers. They do this a lot in Florida.
I think that running a line underground will be hard for the current residents to approve. The best bet MARTA has is to follow the GA 400 ROW. Roswell and Alpharetta could always implement streetcars, in the future, to move people between the historic cores and stations. I do think that having a station in close proximity to Northpoint Mall is ideal, much like Perimeter Mall. It will allow the mall to be in reach to more people.
Also, great map bryant!

[testa50]

Agreed 400 ROW is probably the best approach. There just isn't the residential or office density around DT Roswell to make MARTA feasible. The best approach with transit-friendly development is to make development follow the transit, rather than vice versa.

One side note: if you were to extend north of North Springs, you'll end up with a huge oversupply of parking at that station. Seems like an ideal opportunity to develop a large office complex on the adjacent piece of land, taking advantage of the existing parking and transit infrastructure.

[cqholt]

One side note: if you were to extend north of North Springs, you'll end up with a huge oversupply of parking at that station. Seems like an ideal opportunity to develop a large office complex on the adjacent piece of land, taking advantage of the existing parking and transit infrastructure.

Great idea. A way for MARTA to get income from real estate holdings. I was at North Ave and Midtown Stations Friday and thought, why don't they build a mixed-use tower on-top of the station and make the ground level the station entrance with retail?

[waronxmas]

I don't think there is any question that the extension of rail transit in to Alpharetta/Roswell will be anything other than HRT. While it hasn't fully reached it's potential yet, MARTA was designed to be a hybrid commuter/subway system the same as in DC and San Francisco. The Red Line from Buckhead north already functions that way and quite well. There is no doubt that expanding the line further north would greatly reduce congestion along GA400.

You do however make a good point about just how it can be done. From where the spur ends until the Chattahoochee river, it should be fairly simple to build an elevated line that straddles GA400. I think it would make sense to build commuter stations here near Pitts Road, here at Northridge. While the three station model in this area may seem like overkill, there is a population of 218,000 people within a 5 mile radius of Pitts Road (got that number using this tool: CAPS10C - Missouri Census Data Center).

Once it hits the river, it does become quite interesting on what to do. Tunneling under the Chattahoochee would be prohibitively expensive, while building a bridge will require quite a large amount of logistical maneuvering since it also happens to be one of the most clogged sections of GA400. Your point on the quality of the land is a valid one. MARTA already had problems with this in the past while constructing Doraville station.

Moving past the engineering considerations I think stations at Holcomb Bridge, Mansell Road, Haynes Bridge, and Windward Parkway would serve the area well.

[cqholt]

Defiantly got to have a station at the North Point Mall area.

[Columbuskidd92]

Is the MATRA round trip fee still $2.00?

[JoeTarheel]

Originally Posted by Columbuskidd92

Is the MATRA round trip fee still $2.00?

I don't know, is it 1986?

MARTA fare is $2.50 one way.

[waronxmas]

Originally Posted by JoeTarheel

I don't know, is it 1986?

I wish. A one way fare in 1986 on MARTA was $0.60, or a $1.18 adjusted for inflation.

Atlanta

[MattCW]

I agree with most of the commenters here that say going right up GA-400 is the best route. In fact, it looks like there is enough room between the highway and the various dwellings on the east side that the rail line could be placed in. In most places, there looks to be enough room that the line could be laid at-grade which would save tremendously over the cost of a continuous viaduct. Crossing the Chattahoochee doesn't look to hold any great challenges, there's a small boat launch or park or something on the north of the river, but just bend the route 100 feet east and things should be fine.

An issue I see however is the Northpoint routing. The simple and obvious solution is to keep the route right next to 400 with a station at Encore parkway for the mall itself, or a station at Mansell Rd and Haynes Bridge. However, I could also see merit to running the route along the east side of the Northpoint "complex" before rejoining north of where Encore re-joins Northpoint Parkway then cutting over maybe at Kimball Bridge road.

Continuing North, I don't see any reason to divert from GA-400 at all before terminating at Windward at the existing park and ride across from the ATT data center. I'd add a glass, or open pedestrian bridge to the West side of Windward parkway however to give more convenient access to all the businesses over there.

For stations, I personally would place stations at Northridge, Holcomb Bridge, some around Northpoint (discussed above), then Windward. So about 4 or 5 stations. I don't think a Pitts Road station is necessary, because just about anyone that would use it, would either be "caught" by the Northridge road station, or they would save all of 3 minutes versus driving to North Springs and I just don't see that the advantage of a station here outweighs the disadvantage of the trains slowing and stopping for another station. I don't think Kimball Bridge Road or Old Milton deserve stations for the same reason, people going to those are either caught by stations to the north already, or would only add a few minutes to their travel time going to the next station to the south.