Jump to content

The Transportation and Mass Transit Megathread


TopTenn

Recommended Posts

57 minutes ago, PruneTracy said:

Note also Bos2Nash this is not incompatible at all with a freeway cap, aside from having it bordered by two one-way four-lane roads. Sorry, it's one lane bigger, but it should improve traffic considerably.

Apologies, I didn't mean to say a collector would kill a cap, but rather I did not want more roadway ROW. In all honesty, we already have 3-lane wide roads without any people (aka hippie stuff lol) infrastructure along the edge. So if we are talking about 1 additional lane, but somehow integrating better access management (please no flyover ramps lol) it really isn't that bad and honestly a somewhat reasonable trade off.

1 hour ago, PruneTracy said:

(it would work better if it skipped 12th and started at Division but that's my interpretation of it)

Agreed, but if this would allow for a larger cap, I am not totally against it. Seems like going all the way to 12th could create merge nightmare for folks wanting to be on I-40 and not I-65. Could this be because of a potential height issue at the 12th Ave bridge if things terminated at Division?

1 hour ago, PruneTracy said:

The typical section shows retaining walls between the Interstate and C-D roads and if this were the case it could also be built on a smaller footprint than existing ROW, opening that space for development or other uses.

So are you saying the collector road could also be down in the ROW and could ultimately be capped? Would that not then replace 13th Ave S/George L Davis Blvd and 14th Ave N – or at least allow for possible road diets?

Link to comment
Share on other sites


I recall when I was doing an internship in Dallas back in the mid 1990s, central expwy was being completely rebuilt with cantelever access roads along both sides (a Texas thing that works very well) because they could not go any wider with the ROW. The main express lanes  are below grade. Seems that a redo of the loop would need to do that while reducing the merges at the key junctions. I could even see dedicated lanes/ramps from some downtown streets to interstate lanes outside the loop such as demonbreun/division to i-40 east to the airport. That wouldn’t be any good though as things are now along that stretch from the silliman evans bridge to the i24/40 split. Too narrow and too many merges and crossing lanes are done now. 

  • Like 1
Link to comment
Share on other sites

32 minutes ago, Bos2Nash said:

Apologies, I didn't mean to say a collector would kill a cap, but rather I did not want more roadway ROW. In all honesty, we already have 3-lane wide roads without any people (aka hippie stuff lol) infrastructure along the edge. So if we are talking about 1 additional lane, but somehow integrating better access management (please no flyover ramps lol) it really isn't that bad and honestly a somewhat reasonable trade off.

I think the flyovers are all but necessary at the interchanges given the plan shown. On the north side, for example, it has dedicated ramps to/from both Interstate 40 and Interstate 65. The problem with this is that means one more conflict point in each direction that can't be accommodated in the existing interchange layout, so it will have to go over (or under). The existing overpass for Jefferson Street further complicates things; is the intent for the C-D ramps to overpass Jefferson Street? They should be able to land before they reach Charlotte but would be difficult to get in before the Rosa Parks Boulevard interchange on I-65 or the proposed cap at D. B. Todd on Interstate 40. These issues are also all present on the south side with the additional problem of the 2nd/4th interchange being so close. You could continue the C-D roads to include 2nd/4th and add access to I-65 here but at that point you're just recreating the inner loop traffic patterns on a separate roadway.

32 minutes ago, Bos2Nash said:

Agreed, but if this would allow for a larger cap, I am not totally against it. Seems like going all the way to 12th could create merge nightmare for folks wanting to be on I-40 and not I-65. Could this be because of a potential height issue at the 12th Ave bridge if things terminated at Division?

I meant to say started at Demonbreun. The problem with 12th and Division is mostly on the I-40 westbound / I-65 northbound side; the two overpasses are too close to get a C-D road up or down between them, but are also too close to have two high-capacity signalized intersections. So you can't really start in between them but also don't really want to include both either. It could be done in the eastbound/southbound direction more easily but that would be partial access which the FHWA frowns upon. I'm not sure they would provide that much benefit from the perspective of collecting or distributing traffic relative to the other streets anyway and would probably hack off all the rich yuppies in the Gulch.

32 minutes ago, Bos2Nash said:

So are you saying the collector road could also be down in the ROW and could ultimately be capped? Would that not then replace 13th Ave S/George L Davis Blvd and 14th Ave N – or at least allow for possible road diets?

The C-D roads really need to be surface streets to work effectively. If you're including ramps or similar to move between them and the surface streets, it's similar to what I said before, you're just recreating the inner loop traffic patterns on a separate roadway. That's not to say that they couldn't change grade between intersections, especially with Nashville's topography. But the intent with the bike lanes and sidewalks seems to be to present these as surface streets with frontage for developments in which case they definitely do replace 13th and 14th. It's really not that different than what we have now but would be much cleaner and without the internal weaving/signals from the ramps.

16 minutes ago, MLBrumby said:

I recall when I was doing an internship in Dallas back in the mid 1990s, central expwy was being completely rebuilt with cantelever access roads along both sides (a Texas thing that works very well) because they could not go any wider with the ROW. The main express lanes  are below grade. Seems that a redo of the loop would need to do that while reducing the merges at the key junctions. I could even see dedicated lanes/ramps from some downtown streets to interstate lanes outside the loop such as demonbreun/division to i-40 east to the airport. That wouldn’t be any good though as things are now along that stretch from the silliman evans bridge to the i24/40 split. Too narrow and too many merges and crossing lanes are done now. 

They could do that here and cut the ROW down even further (at the expense of any potential cap) but the main issue (as well as the issue with retaining walls) is maintenance. Much easier and cheaper to work on a series of roads at the ground surface with slopes between them than walls or bridge elements. So if the ROW is existing then I say use it. This is however a potential solution for the east side of the inner loop minus Ellington Parkway which needs to be a full interchange with I-24. Honestly if we nuked the 2nd/4th interchange it would make fixing the problems everywhere else on the inner loop much easier.

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

2 hours ago, PruneTracy said:

It's not desirable to extend all the way to the ramp diverge for traffic engineering nerd reasons but your description of the improvements are correct and should help simply from being marked (and having new pavement, as it was people were dodging potholes on the shoulder). Here is a layout of the proposed conditions.

Thanks for all your insights!! And thanks for linking to the actual-to-critical crash rate data visualization. The exit 207-216 stretch with ratio >2.0 is not surprising ... I've started taking Briley the long way around to get to the airport to avoid most of that mess. Presumably the critical crash threshold accounts for volume of traffic, etc. but it would be nice to see the crash numbers in the table normalized to traffic volume or at least to the length of the segment in question. I guess the latter can be approximated by the exit mile markers.

 

Link to comment
Share on other sites

36 minutes ago, AsianintheNations said:

Thanks for all your insights!! And thanks for linking to the actual-to-critical crash rate data visualization. The exit 207-216 stretch with ratio >2.0 is not surprising ... I've started taking Briley the long way around to get to the airport to avoid most of that mess. Presumably the critical crash threshold accounts for volume of traffic, etc. but it would be nice to see the crash numbers in the table normalized to traffic volume or at least to the length of the segment in question. I guess the latter can be approximated by the exit mile markers.

 

The crash rate is expressed in crashes per million vehicle-miles traveled, so it accounts for both traffic volume and length of segment, setting aside the normal issues that pop up when quantifying anything in that manner (e.g., arbitrarily short segments can have crash rates approaching infinity). The critical crash rate is more of a statistical function than something that is actually tied to a specific roadway's characteristics; its only inputs are the statewide average crash rate and the segment's exposure rate (the million vehicle-miles traveled number). I forget the statistics terminology but you're just calculating the upper limit of a confidence interval where you can say to a certain p (95%, 99%, etc.) that a segment's crash rate is not attributable to random variation if it is above that limit, i.e., that it has a characteristic that is causing crashes. Of course, if we were being fair, we would calculate the lower limit too and hand out awards to roadway designers if the calculated crash rates were below it, but that approach doesn't get federal funding nor does it cause Phil Williams to come barging into the TDOT commissioner's office.

  • Thanks 1
Link to comment
Share on other sites

Looking at the right of ways available through the downtown loop, TDOT still has room to play with as far as expanding the roadway and I would not be a bit surprised if the made more use of flyovers. I suspect the bridges at Division, Broadway, Church, and maybe 12th will have to be replaced at some point too.

I am not sure when those are due to be replaced either and there needs to be a more efficient system of getting cars on and off the interstate.

  • Like 1
Link to comment
Share on other sites

  • 2 weeks later...

On 1/6/2022 at 3:10 PM, markhollin said:

Metro Nashville has put LAZ Parking Georgia LLC — the same firm once at the center of a controversial parking privatization proposal — in charge of its upstart smart parking program.

NDOT Spokesperson Cortnye Stone told the Post that several key details of the contract are still being negotiated but reassured that LAZ was chosen for their approach, experience and qualifications.

"The contract has not yet been negotiated and a contract amount has not yet been set," Stone said. "The values for various components such as capital, operations and management will be determined in the contract negotiation process."

Then-Mayor David Briley sought to give the same company control of Nashville’s parking spaces with the authority to issue tickets and collect fines as well as issue permits for loading zones, street parking and valet parking. The firm’s management of on-street parking came with 2,000 new metered parking spaces at the time.

"Bottom line," Press Secretary Andrea Fanta said, "this is the better deal Mayor Cooper insisted on for taxpayers. We’ll finally modernize our coin-based parking meters and stop leaving millions of dollars on the table. But we won’t sell off the city’s meters, or the public curbside, to do it. The difference here is that Metro, and not a private company, is in control of its own smart parking — and Nashvillians will benefit."


More behind the Nashville Post paywall here:

https://www.nashvillepost.com/politics/metro/metro-awards-smart-parking-contract/article_4403686e-6cd7-11ec-bea5-db1966d0957f.html

Someone smarter than me can chime in, but I struggle with to balance passing the cost of parking on to the end user (an undisputed good idea) with creating a stronger revenue stream that will ultimately make it harder to kill street parking in the future - whether for bike lanes or transit or wider sidewalks.

Link to comment
Share on other sites

I am sure if you look at the list, if it were available, most of the cities that rank low are in the south and the west, and the cities ranking high are in the north and east.  Sort of a no brainer. The exception to the list in the south will probably be New Orleans, with cities like Portland ranking higher on the list in the west.

We have to change attitudes towards mass transit and that takes a generation or two to do unfortunately to change a city to a less car dependent city. The other thing that works against Nashville is the fact that this is a city county govt., and the numbers are skewed even worse against it due to its size.

  • Like 3
Link to comment
Share on other sites

9 hours ago, smeagolsfree said:

I am sure if you look at the list, if it were available, most of the cities that rank low are in the south and the west, and the cities ranking high are in the north and east.  Sort of a no brainer. The exception to the list in the south will probably be New Orleans, with cities like Portland ranking higher on the list in the west.

We have to change attitudes towards mass transit and that takes a generation or two to do unfortunately to change a city to a less car dependent city. The other thing that works against Nashville is the fact that this is a city county govt., and the numbers are skewed even worse against it due to its size.

If we can get a few neighborhoods with high scores, like East Nashville and Downtown, they will attract the residents that want a higher walk and bike score.  I think the city versus city comparison is silly.  By this measurement, no one lives in the entire city: they live at an address and want to know if they can walk and bike to places.

Link to comment
Share on other sites


57 minutes ago, smeagolsfree said:

The problem with walking and biking is that it has to be safe! From my experience in the downtown area walking & biking, it is not a safe experience, especially the biking part. I used to bring my bike in and ride downtown but no longer. It's OK on the Greenway I suppose, but to get on regular street and bike is putting your life at risk. I do a lot of walking as you know downtown, and I have to be extremely vigilant as I have almost been hit several times by drivers who run stop signs, red lights, make illegal turns on red, speed, talk on their phones, don't pay attention, or are distracted by the many crazy thing going on downtown. 

As a driver downtown, I have found myself distracted by other things and have almost hit pedestrians because of all the distractions of scooters, trashportaniment, etc., blocking my view. I tend to try and limit my drives and walks now to Sunday mornings.

Spot on, Smeags.  It's so easy to be distracted by all the activity.  About three years ago, I almost pressed the gas to turn on to an interstate on ramp and happened to glance up just in time to see two tourists walking in front of my car.  I'll never make that mistake again.  @markhollin, is safety addressed in the study?

Link to comment
Share on other sites

8 minutes ago, Mr_Bond said:

Spot on, Smeags.  It's so easy to be distracted by all the activity.  About three years ago, I almost pressed the gas to turn on to an interstate on ramp and happened to glance up just in time to see two tourists walking in front of my car.  I'll never make that mistake again.  @markhollin, is safety addressed in the study?

All I know about the study is what I posted from NASHtoday.  So I don't think safety was really addressed.  

  • Thanks 1
Link to comment
Share on other sites

Looks like a plan ! I also daydream a lot about what the future of Nashville can look like. How about using your map and instead of waiting on the impossible with CSX , they just go ahead and build light rail or monorail lines. I really believe that building commuter lines needed to start long ago, and waiting is really not a option. We all know what’s coming down the pike as far as development goes, as long as there’s no major disruption insight it’s just going to keep building. If nothing gets done soon , expect 2-3 hour commute times in the near future. 
PS .. you forgot to assign a color for the one and only existing commuter rail line.. the WEGO STAR , from Lebanon to Downtown. 

  • Like 3
Link to comment
Share on other sites

Well said. Ever since the transit referendum vote it seems like there's been zero dialogue about where to go from here.

And the WeGo STAR omission was halfway on purpose - as far as I can tell, that line ties in with the rest of them down near Radnor Yards at the 65/440 interchange, and it would require a new turning track onto the northbound line. I couldn't think of a great way to go about it so I just left it off.

  • Like 2
Link to comment
Share on other sites

23 minutes ago, bnacincy said:

I don't understand CSX's reluctance when it comes to commuter rail in Nashville-it would be a win win for everyone and the trains would only travel on CSX's tracks a couple of times a day-Amtrak runs on CSX tracks in other cities at least that much if not more.

Frustrating.

Agreed!

CSX is asshoe

  • Like 2
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

By using this site you agree to our Terms of Use and Privacy Policy. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.