Stacks - Biggest and/or most interesting

[Stephane Dumas]

I spotted 2 stack interchanges in the Detroit area on I-696
one with I-75
http://maps.google.com/maps?t=k&q=42.281389,-83.748333&ie=UTF8&ll=42.476418,-83.110693&spn=0.021365,0.038452&z=15
the other with Mount Road, planned for a (aborted?) extension of M-53 freeway
http://maps.google.com/maps?t=k&q=42.281389,-83.748333&ie=UTF8&ll=42.487289,-83.044024&spn=0.021362,0.038452&z=15

[larryao]

The longest flyover I been on is the one in Riverside, CA from NB I-215 to WB SR91 which is just over a mile long.

[mightyace]

The longest flyover I been on is the one in Riverside, CA from NB I-215 to WB SR91 which is just over a mile long.

Nashville has some fairly long ones as we've finished a round of upgrading.

At I-40 Exit 204 (TN 155 Briley Parkway), the ramp from I-40 West to TN 155 North and the one from TN 155 South to I-40 East extend for around a mile.

At I-65 Exit 90 (TN 155 Briley Parkway/US 31E Ellington Parkway), there are flyovers that connect I-65 South to US 31E South and US 31E North to I-65 North that are fairly long.  Those ramps are there to provide a direct connection between US 31E and I-65 without going onto Briley Parkway for about a half mile.  Ellington Pkwy. is often used as a "relief" route when traffic is bad on I-24/I-65 between East Nashville and the north side of town.

[BigMattFromTexas]

The biggest inter change in my town (San Angelo, Tx) is like 3 levels

[mightyace]

Here is a link to the Google Maps Streetview of the I-65/I-440 four level stack in Nashville

http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=nashville,+tn&sll=40.450654,-80.301175&sspn=0.011136,0.022209&ie=UTF8&ll=36.114615,-86.773109&spn=0.022812,0.044417&t=h&z=15&layer=c&cbll=36.114783,-86.773155&panoid=ygQsLznG_nM-921h6D3xFg&cbp=12,354.3971758951517,,0,0.3043478260869564

The view is looking NB on I-65.  On the left, is US 31 aka Franklin Road which also uses the bottom level of the stack.

The second level are the I-65 to I-440 ramps.  The third level has the I-440 to I-65 ramps and the top level is I-440.

[Revive 755]

Ellington Parkway would probably be even better used if the southern end had direct connections to I-24.

For stack-like interchanges, I find the I-40/I-275 interchange in Knoxville interesting:
http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=&ie=UTF8&ll=35.967917,-83.93044&spn=0,359.978027&z=16&layer=c&cbll=35.968529,-83.929084&panoid=bt8Hlkgufaeqn2ewRKvNbg&cbp=12,202.83290835631198,,0,0.9570312500000014

[mightyace]

Yes, Revive 755, Ellington Parkway would be much handier if it connected with I-24 at the south end.  If you've ever driven it or looked at it on a map, you'll see that the southern end is kinda weird.  It's almost as if something more was planned but never built.

[jgb191]

Houston's newest stack completed last year....I-10 West freeway at Sam Houston Tollway/Beltway 8

[shoptb1]

Here are a couple of photos of the Houston area stacks....

This is a shot of the five-level interchange at the US 290 and Beltway 8 built over twenty years ago.



This is the a shot of the five-level interchange at I-45 and Beltway 8 built in 2001.

I was driving back from Arkansas to Ohio yesterday and was thinking about certain stacks, and it occurred to me that Ohio really doesn't seem to have any substantial elevated fly-overs or stacks.  But in comparison with other states (Texas always comes to mind)...they build their stacks to be like 100-120 feet tall (or more) in some cases.  (I-45 and Beltway 8, US-75 and George H Bush Turnpike as examples). 

Questions: Why do some states build these monster elevated fly-overs in their stacks, and why do others seem to avoid elevation?  Thoughts?

[agentsteel53]

everything's bigger in Texas 

[shoptb1]

everything's bigger in Texas 

Somehow, I knew to expect that response from you 

Honestly though...I wonder how much that plays into it.  Is there any real functional need to have the stacks reaching colossal proportions other than it just looks cool? 

[agentsteel53]

Somehow, I knew to expect that response from you  

Honestly though...I wonder how much that plays into it.  Is there any real functional need to have the stacks reaching colossal proportions other than it just looks cool?  

are the vertical separations between lanes bigger too, or just the horizontal lead-ups?  If it's just the horizontal, then scaling outwards diminishes the grades, which is an important consideration for heavy trucks.  

if it's both horizontal and vertical separation, I'd surmise it *allows* larger and larger trucks to use the ramp, though for vehicles over about 16 feet tall, there are so many other overpasses along the route that they'd never get to a freeway stack - those vehicles have their own infrastructure, mainly consisting of older back roads without grade separation.  I know in Massachusetts, route 62 (old old old Boston Post Road) is the preferred alternate to the Pike for tall vehicles.  It's slow as dirt but generally not too curved and ... nearly all intersections are at grade, and the ones that aren't are easily bypassed.

A 120 foot tall five-level stack implies about 25 feet between separations, if the decks themselves are 5 feet thick, which seems to me to be a bit of overkill.

speaking of large stacks: I-110 and I-105 in the Los Angeles area.  I believe that's a six-level stack with the addition of separate HOV flyover lanes.  I know people that are terrified of that lane because it's narrow (one lane only) and the highest level. 

[Mergingtraffic]

Also, in Connecticut, this one's a partial stack.

What makes it interesting is that it's an interchange with the Merritt Parkway (Exit 52). This, and exit 49 with CT 25 are quite anomalous. You're driving along a quite little scenic old parkway and then all of a sudden you're going through this huge freeway junction.

As you might imagine, the design of these interchanges was quite controversial and, decades later (just a couple years ago), CONNDOT's plans to construct a similar huge interchange at US 7 got shot down in court over similar concerns. The current plan is now for a lower key, lower capacity, but still complete interchange. Some residents who would be right near one of the new ramps are making noise now, though, so we'll have to wait and see what becomes of that plan.

Actually, you forgot to mention that the Merritt Parkway interchange with CT-8 is a true 3-level stack.  It comes right after the CT-25 interchange.  The CT-25 interchange isn't a stack as the ramps are so long they are side by side to each other.

3-Level Stacks in CT:
CT-20 & I-91 Windsor Locks
I-84 & I-291 Manchester (although the center point is off on the ramps)
CT-15 & CT-8 Trumbull
I-84 & Exit 11 in Newtown

4-Level Stacks in CT:
CT-9 & I-84 (half unused thanks to NIMBYs who killed I-291)

Proposed 4-Level Stacks in CT:
CT-8 & I-84 in Waterbury  (preliminary study will be complete in 2010)
See page 19 of the pdf link:
http://www.i84wins.com/AC%20meeting%204%20presentation-Final.pdf

[hbelkins]

y 8, US-75 and George H Bush Turnpike as examples). 

Questions: Why do some states build these monster elevated fly-overs in their stacks, and why do others seem to avoid elevation?  Thoughts?

Weather-related conditions, perhaps? It's my understanding that some of the flyovers in the Atlanta area can get pretty hairy when they have the occasional ice- or snowstorm. I can see this being a problem in, say, Ohio or New York, but much less of a problem in Florida or southern Texas.

[xcellntbuy]

There are two large stack-type interchanges in Broward County, Florida:

Interstate 595/Interstate 75/FL 869 where Interstate 75 bends 90-degrees east-west and north-south, Interstate 595 comes in from the east and FL 869 (Sawgrass Expressway) comes down from the north.  All ramps are at least two lanes, some are three lanes, and the driving speed can be comfortably kept at a steady 70 mph through all the ramps, irrespective of direction.  The stack is on the municipal corner of Sunrise and Weston and the canal boundary of the eastern Everglades.  It is an interchange found in the movie The Fast and the Furious.

Interstate 595/Interstate 95, 11 miles to the east of the previously mentioned stack, is the famous "rainbow interchange" with the multiple pastel-colored flyover ramps on the south side of Fort Lauderdale, next to Fort Lauderdale-Hollywood International Airport and one mile east of Port Everglades.  There are much longer collector/distributor ramps on the northern side of this ramp system since there are major cross streets impacted with ramps to access Davie Blvd. (FL 736), Broward Blvd. (FL 842) and the rarely named Everglades Blvd./SW 24 Street (FL 84).

[shoptb1]

y 8, US-75 and George H Bush Turnpike as examples).  

Questions: Why do some states build these monster elevated fly-overs in their stacks, and why do others seem to avoid elevation?  Thoughts?

Weather-related conditions, perhaps? It's my understanding that some of the flyovers in the Atlanta area can get pretty hairy when they have the occasional ice- or snowstorm. I can see this being a problem in, say, Ohio or New York, but much less of a problem in Florida or southern Texas.

That's an interesting supposition...I wonder if the tighter stack is done to avoid higher elevations due to weather.  Of course, it could also be due to cost of land...maybe it's easier to acquire additional land to make the stacks larger in Texas than in the NE.

[J N Winkler]

Questions: Why do some states build these monster elevated fly-overs in their stacks, and why do others seem to avoid elevation?  Thoughts?

Weather-related conditions, perhaps? It's my understanding that some of the flyovers in the Atlanta area can get pretty hairy when they have the occasional ice- or snowstorm. I can see this being a problem in, say, Ohio or New York, but much less of a problem in Florida or southern Texas.

There are many factors which influence stack form, and I tend not to think weather is prominent among them.

There are some states which have built stacks over a period of many years, and others which have built stacks within a relatively short period of time.  In California, for example, the first stack was built in 1949 and the last stack was probably built in 1992 (as part of the Century Freeway).  The first stack is compact, while the Century Freeway stacks are sprawling with high-elevation ramps.  I-10/I-405 near Santa Monica was built in the early 1960's, possibly as California's first stack after the Four Level, and is much less compact than the earlier interchange.  In Texas there is a similar pattern--the smaller stacks tend to be older (cases in point include the I-610 stacks, and I-10/I-610 counts since it was effectively reconstructed in place although the direct connectors are on slightly different alignments because this was required to facilitate traffic management), while the really large and tall stacks (High Five, I-35E/PGBT, etc.) tend to be much newer--High Five was finished around 2006, while the I-35E/PGBT interchange was finished around 2004.

Meanwhile, states like Alabama, Ohio, and Michigan built their stacks during a relatively short period of time in the 1960's and 1970's, and they are all relatively small.  On the other hand, Arizona built its first stack in the late 1980's, and has just finished its third.  They are all sprawling interchanges.  Georgia built its first and only stack in the 1980's, and it too sprawls.

As a generalization, the taller and more sprawling a stack is, the higher the chances that it was built recently in a given state.

Another factor is drainage.  Many newer stacks which sprawl and have high ramps are built in flat terrain susceptible to flooding, often with a creek or other minor drainage running within the interchange complex which makes it impractical to put ramps or one of the intersecting freeways in tunnel or retained cut.  The Dallas High Five in Texas and the SuperRedTan TI near Phoenix are both examples of this.  Up to a certain point, it is worthwhile to trade off added bridge square footage against the initial cost of the added earthwork and the running cost of a pump station which would otherwise be necessary to handle the design storm event.

It is difficult to prove that weather is not a consideration in determining the layout of stacks, especially in cold-weather states.  Dating is not helpful because all of the cold-weather states, with the exception of Maryland, have built their stacks within a relatively short period of time before 1980.  (Maryland's latest stack, which is currently under construction, does have a sprawling design.)  However, I tend not to think icing is a factor in choosing compact layouts, for the simple reason that a compact layout is not necessarily advantageous over a more sprawling one in terms of icing.  It is true that compact interchanges tend to have less bridge square footage and bridges are typically the first to ice in cold weather, especially if they are high enough to receive maximum exposure to freezing rain.  However, the left-turning direct connectors in compact interchanges also have tighter curve radii at the points where they cross the intersecting freeways.  This means that, in comparison to left-turning direct connectors in sprawling interchanges, more superelevation has to be provided and the side friction demand is also greater at the design speed.  This, in turn, narrows the range of speeds at which a vehicle can negotiate an iced-up DC without skidding into the bridge rail on either side.

Put simply, if icy weather were a controlling consideration for design of stacks in icy-weather states like Ohio and Michigan, the preference would be for sprawling stacks over compact ones, rather than the reverse.

[agentsteel53]

I've always wondered why the four-level was finished in 1949, and only opened in 1953.  Were the freeways leading up to it unbuilt for four years?

[J N Winkler]

The HAER report on the Arroyo Seco Parkway has more details, but I recall that the entire Four Level had to be built in 1949 because it was impractical to leave intermediate levels unbuilt, but the Arroyo Seco and Harbor Parkways (which run on the second level; US 101 runs on the top level, and the other levels are occupied by direct connectors) were not actually extended to the Four Level until 1953.

The reason it was impractical to leave intermediate levels unbuilt is that the Four Level is actually a single bridge structure, with a single National Bridge Inventory number.  It simply has three decks, each of which has its own set of support columns.  In fact, the left-turning direct connectors on the third level are carried on a common deck, which is an extremely odd-shaped piece of concrete because one DC is on a rising grade while the other is on a falling grade.

[Bickendan]

I-5/I-405/US 30/N Greeley Ave in Portland, Oregon: http://maps.google.com/?ie=UTF8&ll=45.54381,-122.675657&spn=0.008776,0.016329&t=k&z=16 Movements to/from the Kirby St ramps were never built, but the ghost ramps are evident.

I-5/I-705/WA 7 in Tacoma: http://maps.google.com/?ie=UTF8&ll=45.54381,-122.675657&spn=0.008776,0.016329&t=k&z=16 If not a true stack, definitely an odd interchange.

I-5/Seattle Freeway in Seattle: http://maps.google.com/?ie=UTF8&ll=47.572067,-122.320189&spn=0.008454,0.016329&t=k&z=16

I-5/I-90 in Seattle: http://maps.google.com/?ie=UTF8&ll=47.593734,-122.320833&spn=0.008451,0.016329&t=k&z=16

I-90/I-405: http://maps.google.com/?ie=UTF8&ll=47.580347,-122.174406&spn=0.016906,0.032659&t=k&z=15

[TheStranger]

JN Winkler: Kinda a tangential question, but obviously the Harbor and Arroyo Seco (Pasadena) were built separately and ultimately linked to the interchange.  Was the Hollywood/Santa Ana linked to the Four-Level from the get-go as one through route, or were they physically two separate freeways built entirely apart (as were the two segments of then-Route 11 mentioned earlier) and joined by the interchange?

[Truvelo]

I-5/I-405/US 30/N Greeley Ave in Portland, Oregon: http://maps.google.com/?ie=UTF8&ll=45.54381,-122.675657&spn=0.008776,0.016329&t=k&z=16 Movements to/from the Kirby St ramps were never built, but the ghost ramps are evident.

Ah yes, I remember driving through this last year. It was jammed solid. I wonder if the missing freeway to the NE had been built it would have relieved I-5 somewhat?

You can see a ghost ramp behind the tree.

Click to enlarge

[architect77]

Can't talk about massive stack interchanges without mentioning Spaghetti Junction in the greater Atlanta Metro Area (I think it's technically Doraville, GA, in DeKalb County) where I-85, US 23 and I-285 meet.

I spent several years in Atlanta and LA, and Spaghetti Junction is perfect and elegant in every way. I just hate the eventual fading and discoloration of the concrete. The flyovers were a stunning white when first built.

You're correct, Spaghetti Junction is technically in Doraville, just north of Downtown Atlanta.


Here's some leftover footage that I had from driving the other day.

Spaghetti Junction (a.k.a. Tom Moreland Interchange):

http://www.youtube.com/watch?v=6PckvluLDQg


Be well,

Bryant

[hm insulators]

The then partially finished I-5/CA 14 interchange suffered damage in the 1971 San Fernando quake when a flyover ramp collapsed onto the Golden State Freeway, and then again in the 1994 Northridge quake.

I remember that. I went through both those earthquakes.

[Bickendan]

I-5/I-405/US 30/N Greeley Ave in Portland, Oregon: http://maps.google.com/?ie=UTF8&ll=45.54381,-122.675657&spn=0.008776,0.016329&t=k&z=16 Movements to/from the Kirby St ramps were never built, but the ghost ramps are evident.

Ah yes, I remember driving through this last year. It was jammed solid. I wonder if the missing freeway to the NE had been built it would have relieved I-5 somewhat?

You can see a ghost ramp behind the tree.

Click to enlarge

No, it would have been a relief of sorts for I-84/US30 (to the south) or Bypass US 30 (to the north).
The Rose City Freeway was to run northeast from the Fremont/Minnesota Stack to NE Prescott St, then due east to I-205, ending at about the current I-205/Bypass US 30 interchange. All in all, this would have been a very, very superfluous freeway, though in my opinion, the stack should be finished to give access to/from Legacy Emanuel Hospital and I-5.

Now, if PDOT or ODOT were smart, they'd upgrade Lombard St and Columbia Blvd between I-5 and I-205 to a full freeway, but NIMBYs would still wield a nice poisonous dagger to the project. Essentially, between I-5 and NE MLK Jr Blvd (OR 99E), Columbia Blvd would be the freeway; from there east, Lombard would be the eastbound carriageway, Columbia would be the westbound, leaving the rail lines in between intact.