The Transportation and Mass Transit Megathread

[Mr_Bond]

When mudslides took out all major roads up and down the coast south of Santa Barbara in January 2018, the state paid whale watching ships to run passengers from Ventura harbor to Santa Barbara.  My nephew had to move his wedding venue and my family members who flew into SB, had to take the ferry down to Ventura and back up again because the airlines would not allow them to move their tickets to an L.A. airport.

[rookzie]

Fatigue and fracture behavior in steel bridges has led to a much increased understanding over the last 50-60 years of the phenomena which shorten the life of these structures.  PHofKS and PruneTracy know this more than I and most others.

Much has been gleaned that has led to guidelines for modern practice for minimizing deformation-induced cracks, as with the glaring failure in that fabricated box beam on the de Soto Bridge.  Older designs of steel bridges also continue to serve as ongoing case studies of the effects that variable-amplitude loading have on metal fatigue.   Internal *static* loading always is incorporated by design.  Bridges incur external forces which dynamically impose deformation stresses throughout, every time a wheel passes along a bridge’s deck.  We realize this, whenever we walk or stand on a bridge with traffic passing beside us because that bridge very often will shake noticeably, particularly when a loaded vehicle suspension passes over uneven surfaces in the pavement or across expansion joints.  For the most part, these “deformations” are “elastic”, but over time the surges in tension and compression distributed among all those bridge structural members becomes infinitesimally IN-elastic.  Then, even with that member essentially at mostly a state short of complete failure, the transmission impulses throughout depends of the redundancy of remaining members.

Trapped moisture also takes toll with deleterious effects on mating surfaces between structural members themselves and fasteners (bolts and rivets).  Surface defects may develop from external factors or from hidden internal metallurgical molecular grain structure, many of which cannot be seen, such as those within an enclosed continuous box beam or girder.  Moisture only exacerbates the issue with corrosion.  That’s the reason for the need of periodic close inspections, some of which might require the use of devices for humanly inaccessible portions of a bridge.   Then there are the lateral forces from wind gusts and the effects of non-ending thermal changes.  During a period of engineering standards and practices for highway construction during the 1960s and ‘70s, the enormity of interstate highway construction during those decades has translated 50-60 years later into a significantly higher number of incidences of critically reduced structural integrity.  We all have been made aware of this.  In the area of fracture, tougher and more ductile modern steels, adopted by ASTM (American Society for Testing and Materials) specifications during the 1990s, have since replaced the use of conventional high-strength low-alloy steels of the 1960s.  But this has taken time to understand and to develop.

On the other hand, many railroad bridges still in heavy use were constructed between just before the turn of the 20th Century, while some were built as realignments during the 1930s and '40s.  In general, specifications for most of those were much different from those for highway use ─ even for more recent railroad bridges with longer fixed or moveable spans over waterways.  They don't have the same requirements for distribution of rolling-equipment dynamic forces and for decking support and materials, as those used for highway vehicles.   Also these "beefy" older railroad steel bridges were built with a much higher rate of material redundancy when alloy construction steels were not available.  The Harahan Bridge, just south of the de Soto Bridge, is one such example.  These bridges usually have massive end portals and top chords attached to deep-girder decks.  Then too, some bridges ─ through-truss bridges in particular ─ carry both railroad and highway traffic, such as the Huey P. Long Bridge in Jefferson Parish, LA, and the Fort Madison Toll Bridge (IA-IL).  Another significant factor is that the longest span of the de Soto Bridge is significantly greater than those of most railway bridges (900 feet vs 790-800 feet).  That 100-foot difference has a big added effect on imposed compression and tension load demand from a paved deck full of bumper-to-bumper traffic ─ from Smart cars to low-boys hauling excavators.

 

Edited May 18, 2021 by rookzie

[PruneTracy]

For those of you who are often wondering what TDOT is up to around the state, or what is going on near you, or when TDOT is finally going to etc., etc., they've released a new GIS tool called iTRIP that shows all projects in the TDOT pipeline.

https://www.arcgis.com/apps/dashboards/e14888bce2954050a10df5e949a1bc1d

[smeagolsfree]

Sure cant get that piss poor website to work for me.

18 minutes ago, PruneTracy said:

For those of you who are often wondering what TDOT is up to around the state, or what is going on near you, or when TDOT is finally going to etc., etc., they've released a new GIS tool called iTRIP that shows all projects in the TDOT pipeline.

https://www.arcgis.com/apps/dashboards/e14888bce2954050a10df5e949a1bc1d

Not user friendly, let me know if it works for you.

[smeagolsfree]

The map works, but there is a whole lot of useless information on there. I am sort of a just the facts mam kind of guy and I really don’t care who the state rep or senator in the district is.

The tables still do not work on my desk top. The older system worked a lot better..My old adage is, If it ain’t broke don’t fix it.

[nashscan]

I couldn't glean anything useful. 

[Hushpuppy321]

Anymore Mass Transit Initiatives on the drawing board for the Greater Nashville Metro Area?

[PaulChinetti]

https://twitter.com/jbouie/status/1397542517755846661

I like this. 

People live here!

[rookzie]

17 hours ago, PaulChinetti said:

https://twitter.com/jbouie/status/1397542517755846661

I like this. 

People live here!

 

To the guy who tweeted from Detroit:

Quote

matt @billikenhawk·May 26
"This is literally Detroit’s policy. More than half of downtown is parking, and highways are optimized to get suburban folks in and out of downtown as quickly as possible."

I don't know what planet he landed from, but even long before Detroit lost its big-city status and still offered a sizable streetcar network (until the mid 1950s), Detroit never was a urban district expected to be anything other than car-centric.

Besides the usual I-75/94/96 urban expressway network, the old arterials haven't changed which convey the multitudes into and out of the center city:

Woodward Ave, (M1)
Gratiot Ave. (M3)
Grand Ave (M5)
Michigan Ave. (US-12)

Since the 2013 city bankruptcy, Quicken Loans' Dan Guilbert has infused a half dozen or so $billion into realty and redevelopment of the city's central core, just to restore it into some state of viability, after decades of being a "lights-out" district.  So Detroit is NOT a good example for comparison IMO ─ not at this point, anyway.
 

[Nashvillain]

6 hours ago, rookzie said:

 

To the guy who tweeted from Detroit:

 

I don't know what planet he landed from, but even long before Detroit lost its big-city status and still offered a sizable streetcar network (until the mid 1950s), Detroit never was a urban district expected to be anything other than car-centric.

Besides the usual I-75/94/96 urban expressway network, the old arterials haven't changed which convey the multitudes into and out of the center city:

Woodward Ave, (M1)
Gratiot Ave. (M3)
Grand Ave (M5)
Michigan Ave. (US-12)

Since the 2013 city bankruptcy, Quicken Loans' Dan Guilbert has infused a half dozen or so $billion into realty and redevelopment of the city's central core, just to restore it into some state of viability, after decades of being a "lights-out" district.  So Detroit is NOT a good example for comparison IMO ─ not at this point, anyway.
 

Detroit was Motor City after all

[Nicholson]

Motown's love for the automobile...

   

 Where Did Our Love Go?

 

^ from dailydetroit.com - 'Detroit's Modern Day Parking-Lot-A-Palooza'

^^ from Oklahoma University, Institute for Quality Communities Institute for Quality Communities Institute for Quality Communities

[markhollin]

3 hours ago, Nicholson said:

 

These bottom two are actually aerial views of Cincinnati.ute

[PaulChinetti]

Good lord those interstates destroyed half the city! 

[Nicholson]

5 hours ago, markhollin said:

These bottom two are actually aerial views of Cincinnati.ute

Whoops - good catch.

Here's Detroit from the same site.

[PaulChinetti]

Nashville.

One thing that I notice in these too is the density that we lost as the years progressed. In the older images it seems like there are building everywhere!

 

[MLBrumby]

On 5/28/2021 at 2:28 PM, PaulChinetti said:

Nashville.

One thing that I notice in these too is the density that we lost as the years progressed. In the older images it seems like there are building everywhere!

 

I believe if you look closely you can see the NES and Cordell Hull bldgs under construction. 

Edited June 4, 2021 by MLBrumby

[MontanaGuy]

On 5/28/2021 at 1:28 PM, PaulChinetti said:

One thing that I notice in these too is the density that we lost as the years progressed. In the older images it seems like there are building everywhere!

Yeah that's very noticeable.  I wonder if that's because so much of it was residential back in the old days before the suburbs had grown and today a lot of that property is a whole lot of parking lots as well as quite a bit of industrial areas as you move out from downtown where there used to be houses packed together.

[PaulChinetti]

33 minutes ago, MontanaGuy said:

Yeah that's very noticeable.  I wonder if that's because so much of it was residential back in the old days before the suburbs had grown and today a lot of that property is a whole lot of parking lots as well as quite a bit of industrial areas as you move out from downtown where there used to be houses packed together.

Probably a lot more mixed use, store/shop/etc on the ground floor, live up top. 

[AsianintheNations]

On 5/28/2021 at 1:28 PM, PaulChinetti said:

Nashville.

One thing that I notice in these too is the density that we lost as the years progressed. In the older images it seems like there are building everywhere!

 

Same area today, courtesy of Google Earth. The 2014 comparison image is particularly unflattering with Capitol View, Ascend Amphitheater, and much of SoBro, Rolling Mill Hill sitting as empty lots (plus Lake Palmer). And minimal shadows so you can't appreciate height.

Glad the blight of block-sized surface parking lots is slowly receding. Will be exciting to see how the other side of the river will develop, as it looks like there was never much going on there even in the 1951 photo.

[Nashvillain]

2 hours ago, AsianintheNations said:

Glad the blight of block-sized surface parking lots is slowly receding. Will be exciting to see how the other side of the river will develop, as it looks like there was never much going on there even in the 1951 photo.

Apparently we understood the flood plain and that the East Bank wasn't a good spot for intensive development. But nowadays ... YOLO! (Is YOLO still a thing?)

[AsianintheNations]

24 minutes ago, Nashvillain said:

Apparently we understood the flood plain and that the East Bank wasn't a good spot for intensive development. But nowadays ... YOLO! (Is YOLO still a thing?)

YOLO is still a thing, at least for WallStreetBets investors. (Made a little bit myself on AMC, but it's scary that some people seem to think meme day trading is a viable financial strategy ... but I digress)

I am sure Oracle and the others will put a lot of thought into flood/stormwater management given the absurd sums paid for very recently catastrophically flooded land. Admittedly, the early renderings of the Oracle campus don't show much effort to elevate the land above the river, but the major buildings are set farther from the river and a lot of currently impervious surfaces look to be replaced by vegetation. The current new residential construction flood management guidelines are pretty extensive, so I hope and am pretty sure there will be attention to this for such huge projects on the East Bank.

[rookzie]

On 5/28/2021 at 1:28 PM, PaulChinetti said:

Nashville.

One thing that I notice in these too is the density that we lost as the years progressed. In the older images it seems like there are building everywhere!

 

 That's in part what the urban expressways did to density within the deep inner cores of urban stock built mostly after WW-I.

While much of the old residential stock shown in the 1951 aerial view (the year my parents moved from DE to TN and I was born) was pre-20th C. built and had been considered sub-standard (left [west] of the railroad "Wye", just left of upper center), instead of being replaced, essentially it became "dis"-placed and over time rezoned.  Typically, dwellings of the low income occupied the inner-urban core near downtown and within close vicinity to railroad rights-of-way.  The 1951 photo also includes a portion of the blighted residential sub-district mentioned in previous years ─ "Hell's Half Acre".  it also includes other old but more substantial housing close to Capitol Hill, much of which was razed to make way for structures such as the Cordell Hull State Office Bldg.

The area occupied between 10th Ave and the railroad and between Charlotte and Broadway (just north of Union Station) has undergone three (3) major transformations since around 1900.  The 1951 photo shows the gigantic railroad freight depot, still in full use, and extending from Broadway to Charlotte.  That began to change around 1959 and into the 1980s.  Currently, it is undergoing its 3rd "renewal" (as it were).  Basically, with a high-rise vengeance, that strip is "catching" up with  the ongoing redev to the west and south of the railroad (Gulch).  That area as a whole had been commercial and light industrial.

These photos illustrate the dramatic and wholesale scale of repurposed property and escalation of land values, a commonly occurred (and occurring) condition of circumstances  or plight (based on relative viewpoints) in nearly every U.S. city medium-sized and larger.  The disruption of the traditional surface-street grid is highly noticeable in the more recent photo.

[Sean blackdog]

Today this morning from Facebook Sky5. 
Briley Parkway at I-40
Is that guitar shaped...or just me?

[PaulChinetti]

Pretty cool.

Also, wowza, big intersections like that are so much wasted space.

[PruneTracy]

6 hours ago, Sean blackdog said:

Today this morning from Facebook Sky5. 
Briley Parkway at I-40
Is that guitar shaped...or just me?

6 hours ago, PaulChinetti said:

Pretty cool.

Also, wowza, big intersections like that are so much wasted space.

TDOT relocated two of the ramps (Briley SB to I-40 EB and I-40 WB to Briley SB) in design as a stack interchange violated FAA height restrictions and the original design took the ramps in tunnels under the Interstate. It was featured for a long time on TDOT's website as an example of value engineering (possibly because for a long time it was TDOT's only example of value engineering).