4-lane through freeways near metro areas (and an interesting metric)

[michravera]

What is the closest to the "downtown" or "central" interchange that your major through freeway becomes 4 (or 3 or 2) lanes? Now, divide this distance into the population of the city to obtain what I think is an interesting metric (something about how isolated the metro area is or how abruptly urban development ends).

Rules:
1) The freeway need not be an interstate
2) The freeway (not necessarily continuing as freeway, especially if it drops to two lanes) must eventually connect to a city at least half the size of the city in question, so I suspect that San Juan and Anchorage freeways are not to be counted.
3) Brief sections of 4 lanes engendered by an exit lane that either continues under or over or restarts as part of the merge lane such that the freeway is "for practical purposes" 5 or more lanes don't count as "ending".
4) A few poor access controls do not disqualify the route
5) Constructed, but as yet unopened lanes count as continuing. Lanes that are "permanently" closed and blocked off or partially destroyed do not count as continuing. Temporarily closed lanes (due to recent events) that are expected to reopen do not count as ending.
6) If the road doesn't, at some point before the next city that qualifies it, get a speed limit of at least 80 km/h, this isn't the road that counts.

I will give you some candidates, but I am sure that you can do better:
1) CASR-1 (which reaches both San Luis Obispo and San Francisco) drops to 4 lanes almost immediately south of the CASR-68 interchange in Monterey (but is 6 or more lanes for about 10 km to the north).
2) US-101 is only 6 lanes for a short distance through San Luis Obispo, and for that matter, through Salinas and Santa Maria.
3) I-580/US-395 barely stays 6 lanes very far north of the I-80 interchange in Reno (but I think that they are widening it), but I am not sure that Susanville is large enough to make my definition work. I-80 stays 6+ lanes for several km on both sides of I-580/US-395.

But none of these get much above 20K/km.

I know that Lincoln and Omaha are widening I-80, but I am not sure how far the widening has gotten.

[Eth]

Atlanta:

The central interchange involves I-20 and I-75/85. I'm counting I-20 and I-75 as the through routes (I-85 exits from I-75 at both ends of the overlap). Both eventually reach larger cities (Dallas 1.34M, Detroit 673k, Atlanta 486k).

I-75 south of Atlanta narrows to 4 lanes at the I-475 split, 70 miles away.
I-75 north of Atlanta narrows to 4 lanes just past the US 11/64 exit north of Chattanooga, about 118 miles away.
I-20 west of Atlanta narrows to 4 lanes at the GA 61/101 exit, 33 miles away, though construction is ongoing for widening west of there.
I-20 east of Atlanta narrows to 4 lanes at the GA 142 exit, 36 miles away.

It sounds like you're looking for one specific freeway to call the "major" one, in which case it's most likely I-75, so dividing the distance (70 mi/113 km) into the city's population (486k) gives us a value of roughly 4300/km.

[michravera]

Atlanta:

The central interchange involves I-20 and I-75/85. I'm counting I-20 and I-75 as the through routes (I-85 exits from I-75 at both ends of the overlap). Both eventually reach larger cities (Dallas 1.34M, Detroit 673k, Atlanta 486k).

I-75 south of Atlanta narrows to 4 lanes at the I-475 split, 70 miles away.
I-75 north of Atlanta narrows to 4 lanes just past the US 11/64 exit north of Chattanooga, about 118 miles away.
I-20 west of Atlanta narrows to 4 lanes at the GA 61/101 exit, 33 miles away, though construction is ongoing for widening west of there.
I-20 east of Atlanta narrows to 4 lanes at the GA 142 exit, 36 miles away.

It sounds like you're looking for one specific freeway to call the "major" one, in which case it's most likely I-75, so dividing the distance (70 mi/113 km) into the city's population (486k) gives us a value of roughly 4300/km.

You could have picked either. It sounds like I-75 goes to 4 or fewer lanes the quickest. I haven't been far enough *OUTSIDE* of Atlanta to appreciate how abruptly the city drops off, but, if your numbers are accurate (and I trust you), Atlanta goes on forever or sprawls a great distance by comparison to any of the California cities that I mentioned.

[TheStranger]

- US 101 in the Bay Area is an interesting case:

in SF (population about 826K), the ramps that carry 101 between the Bayshore Freeway and Central Freeway (where I-80 splits off as Exit 433B) are a combined 4 lanes, with the Bayshore being primarily 8 lanes from there to Route 85 in San Jose (excepting a brief segment in SF between the long I-280 ramps and the Alemany Boulevard interchange) and the Central Freeway being six lanes west of the ramp merge.  (San Jose has 1 million people at present)

To get to the next 4-lane segment southbound, one has to drive all the way through the recently widened Morgan Hill and Gilroy portions of 101 to get to the junction with Monterey Street/Business US 101 in the south part of Gilroy, Exit 355.  So that's a segment of 78 miles between 4-lane sections!

The next 4-lane segment north of the Central/Bayshore switchoff for US 101 used to be Petaluma, but with the recent narrowing of Van Ness Avenue to accomodate MUNI's bus rapid transit lanes, Van Ness between Mission Street and Lombard Street is now 4-lanes as well, while the Petaluma Narrows is being widened recently.

- 80 starts out as a six-lane freeway from that spot and towards the western reaches of Oakland (about 410K), becomes eight lanes up until parts of Contra Costa County, then is mostly 6 lanes (excepting 8 lane portions in Vallejo and Fairfield)  before finally going down 4 lanes briefly at the US 50 split in West Sacramento via ramps that connect it to the beltline freeway going towards Natomas in Sacramento - a distance of about 80 miles from US 101.  Then 80 has a stretch of about 48 miles of at least 6 lanes, ending in Applegate.

- Interstate 280 never goes below 6 lanes at any point and is primarily 8 lanes between the two US 101 junctions, even though it goes through a more rural portion of San Mateo County.


===

Oakland

If we think of the MacArthur Maze as the main interchange of the East Bay (even though it is not in downtown Oakland) -

- with the widening of the Richmond Bridge (reopening of the third through lane in each direction, really), I-580 reverts to 2 lanes in each direction at the western approach, 2 miles from its terminus with US 101 in San Rafael and about 17 miles from the Maze.  On the east end, the next 4-lane segment is after the I-205 split (approximately around Exit 65), 36 miles from the Maze.

- I-880 through its entire length is at least 6 lanes, primarily 8 in most spots.

===

Sacramento:

If the "central" interchange of downtown Sacramento is the I-5/US 50 junction (I-5 exit 518, US 50 exit 4A/4B), which also involves Route 99:

- I-5 narrows down to 4 lanes on the south side at Elk Grove Boulevard (exit 506), only 12 miles south of US 50.  On the north end, the next 4-lane segment is just west of the northern Route 99 split in the Natomas area of Sacramento, exit 525B (only 7 miles north of US 50).  This is also where Route 99 narrows down to 4 lanes on the north end.

- Route 99 south of downtown Sacramento goes to 4 lanes just south of the Grant Line Road (Exit 284) junction in Elk Grove.   This is about 15 miles southwest of the I-5/US 50 interchange.

- US 50 never goes below 6 lanes in the final West Sacramento portion of the route (former US 40/99W/I-80) before ending at I-80.  East of I-5, the nearest 4 lane segment is at Exit 35 in Cameron Park, about 29 miles east.

[Roadsguy]

Philadelphia, Schuylkill Expressway (I-76). The closest it gets to City Hall is one mile away, and this section is already four lanes (under 30th Street Station). Depending on whether the I-76/676 or I-95/676 interchange is considered the "central" interchange, the answer is either two miles (I-95/676) or immediately (I-76/676). The Schuylkill is six lanes running northwest from this interchange, but narrows back to four lanes just four miles away at US 1/Roosevelt Expressway and I-76 remains four lanes until Harrisburg after joining the Turnpike. To the southeast, I-76 doesn't get narrower than six lanes before it ends at I-295, though the expressway continues and ultimately narrows to four lanes where NJ 42 diverges and the Atlantic City Expressway begins.

I-95 to the northeast narrows to four lanes at the partial interchange with the Turnpike 18.5 miles from the I-676 interchange. The flyovers, considered Interstate mainline, are two lanes each way, and I-95/semi-unsigned PA Turnpike is four lanes east of the interchange, with one eastbound auxiliary lane until US 13. To the southwest of the I-676 interchange, it drops to four lanes through the I-476/Blue Route interchange 15 miles away, becomes six lanes again, and doesn't drop to four lanes until I-495 at the DE state line 22 miles from the I-676 interchange.

By I-76 being four lanes just one mile from City Hall, Philly's ratio is just the population: 1,580,863. With I-95 to the Blue Route interchange, the ratio is 105,390.

[ipeters61]

I'll cover Delaware's two largest cities: Wilmington and Dover.

Wilmington (I-95, population 71,106): Between the final stretch of 4-lane I-95 in Delaware (and for a long time - Exit 8, DE/US-202) and the downtown exit (Exit 6, 4th Street) is 2.2 miles (3.5 km), giving Wilmington a figure of 20316/km.

Dover (DE-1, population 37,538): Dover is an odd case, we're not big enough to have anything more than a four lane expressway (outside of summer weekends, with all the beach traffic, it's plenty sufficient), so I'll just do the terminus of the DE-1 expressway at the Barkers Landing Bridge (St. Jones River), which is 8.1 miles south of the southbound downtown interchange (Exit 98, DE-8) and 6.3 miles south of the northbound downtown interchange (Exit 95, DE-10).  Averaging these together for 7.2 miles (11.6 km), Dover has a figure of 3236/km.

[webny99]

Excluding segments through interchanges, and what's left of the Inner Loop, I-490 between exits 25 and 27 is by far the busiest and closest to downtown.

It needs to be six-laned badly, as I have quite frequently grumbled about elsewhere on the forum.

[US 89]

For Salt Lake City:

I-80 drops to four lanes about 6 miles west of downtown. While that sounds pretty close, 56th West is about the western limit for any sort of development north of SR-201, due to the area's low elevation and risk of flooding by the Great Salt Lake. I can't imagine the soil out there is very good (too salty), so no farms either.

I-215 is also only four lanes between Redwood Rd and I-15 north of Salt Lake. That's about 5 miles north of downtown by direct distance, but that segment is really more of a glorified exit ramp from I-15.

Legacy Parkway (SR-67) is four lanes for its entire distance, which starts about 6 miles north of downtown SLC. It's worth noting that this was originally to be a 6-lane, 65mph freeway, but environmentalists nearly shut down the entire project. The compromise worked out between UDOT and the environmentalists watered the project down to a 55mph 4-lane parkway, though apparently this has a sunset date of 2020.

To the east, I-80 doesn't narrow to 4 lanes until the US-40 exit, 25 miles to the east. I-15 doesn't narrow to 4 lanes for 50 miles to the north (US-91), and for 60 miles to the south (Payson).

[Tom958]

I-75 south of Atlanta narrows to 4 lanes at the I-475 split, 70 miles away.
I-75 north of Atlanta narrows to 4 lanes just past the US 11/64 exit north of Chattanooga, about 118 miles away.
I-20 west of Atlanta narrows to 4 lanes at the GA 61/101 exit, 33 miles away, though construction is ongoing for widening west of there.
I-20 east of Atlanta narrows to 4 lanes at the GA 142 exit, 36 miles away.

You could have picked either. It sounds like I-75 goes to 4 or fewer lanes the quickest.

I-20 isn't being widened west of Atlanta. The ongoing construction is for pavement replacement only. Hard to believe, but it's true.

michravera: 108 and 70 are a lot farther than 33 and 36. That said, the I-75 south corridor, via I-475 around Macon, actually extends all the way to Tampa save for a half mile of four lanes at the northern end of 475. Obviously, where it drops to four lanes has nothing to do with how much Atlanta sprawls.

[djsekani]

Well, I guess I could run the six freeways spiraling out of the East L.A. Interchange. Los Angeles has a population of about 4 million.

I-5 North is eight or more lanes all the way up to the CA-99 interchange in Wheeler Ridge, a distance of 142 km. It drops to four lanes after the interchange. (28,169/km)
I-5 South is eight or more lanes through San Diego to the Mexican border, and from there traffic is distributed along several six-lane boulevards through Tijuana. Not really sure where to stop counting mileage in this case, but it's 214 km to the border. (18,692/km)

I-10 West ends in Santa Monica where it turns into Pacific Coast Highway, which is six lanes until the intersection with Temescal Canyon Road. This is a distance of 34 km. (117,647/km)
I-10 East is six to eight lanes out to the interchange with CA-86 in Coachella, 210 km away, where it drops to four lanes on its desert run to Phoenix. (19,048/km)

CA-60 East is ten lanes out to the split with I-215 in Riverside, drops to six through Moreno Valley, and drops again to four lanes at the Redlands Blvd interchange. The six-lane portion ends 105 km away from downtown L.A. (38,095/km)

US-101 North doesn't shrink to four lanes until the Bailard Avenue interchange in Carpenteria, which is 138 km away. (28,986/km)

[michravera]

Well, I guess I could run the six freeways spiraling out of the East L.A. Interchange. Los Angeles has a population of about 4 million.

I-5 North is eight or more lanes all the way up to the CA-99 interchange in Wheeler Ridge, a distance of 142 km. It drops to four lanes after the interchange. (28,169/km)
I-5 South is eight or more lanes through San Diego to the Mexican border, and from there traffic is distributed along several six-lane boulevards through Tijuana. Not really sure where to stop counting mileage in this case, but it's 214 km to the border. (18,692/km)

I-10 West ends in Santa Monica where it turns into Pacific Coast Highway, which is six lanes until the intersection with Temescal Canyon Road. This is a distance of 34 km. (117,647/km)
I-10 East is six to eight lanes out to the interchange with CA-86 in Coachella, 210 km away, where it drops to four lanes on it's desert run to Phoenix. (19,048/km)

CA-60 East is ten lanes out to the split with I-215 in Riverside, drops to six through Moreno Valley, and drops again to four lanes at the Redlands Blvd interchange. The six-lane portion ends 105 km away from downtown L.A. (38,095/km)

US-101 North doesn't shrink to four lanes until the Bailard Avenue interchange in Carpenteria, which is 138 km away. (28,986/km)

The west end of I-10 shouldn't count as ending. It only misses the ocean by what?  A couple hundred meters? You could argue that it picks up as I-H1 4000km away on Oahu. I suspect that you could drive a car into San Pedro or Long Beach, hop on a ship, get dropped off at Pearl Harbor (or the cruise ship terminal) and never travel on a road of less than 5 lanes until well outside of Honolulu (or for that matter Tokyo or Jakarta).

[ilpt4u]

I'll try Chicago. I will count the Jane Byrne Circle Interchange as the Central Interchange, but since the I-55 junction is not far from the Circle, I will add it in also, but count Mileage as South on the Dan Ryan from the Circle exiting onto I-55/Stevenson to the Southwest

I-90 to the Northwest: 93 Miles to the IL/WI border near Beloit
I-94 to the North: 23 Miles, following US 41 onto Skokie Highway to the Clavey Rd Exit, since the Edens Spur Tollway/I-94 drops to only 4 Lanes. If the Edens Spur was at least 6 Lane, I believe this would be past Milwaukee before I-94 drops to 4 Lane. Or if I-94 were routed Kennedy->Tri-State->Wisconsin, it would also be well beyond Milwaukee
I-290 to the West: The whole route, to Lake Cook Rd (continuing as the IL 53 Freeway)/37 Miles. If the "Next City"  rule applies, then it needs to continue along Parent I-90 instead of IL 53, to the IL/WI border, 98 Miles. Or, using the idea that I-290->I-88 is the "Main"  route (even IDOT gives I-290 Outbound a Control of Aurora, at the Circle), then we have 40 miles, to the IL 56/Sugar Grove Exit. To satisfy the "Next City"  Rule, I-88 continues onto I-80 at the Quad Cities to Points West
I-90 to the Southeast: 18 Miles, to the Indiana Toll Road/IN 912/Cline Ave Exit
I-94 to the South, then East, then North: 105 Miles, to the I-196 Exit in Michigan
I-55 to the Southwest: 45 Miles, to the I-80 Cloverleaf

[hotdogPi]

NYC has about 75k per km for both I-95 (into CT) and I-87, but it is disqualified by Rule 2.

[TheHighwayMan3561]

St. Paul has a four-lane through freeway at its central interchange, that being I-35E south of I-94.

I-94 to the west becomes four through lanes at St. Michael, 24/35 miles from the downtowns. To the east it's at Exit 4 in Wisconsin, 19/30 miles from the downtowns.

[webny99]

NYC has about 75k per km for both I-95 (into CT) and I-87, but it is disqualified by Rule 2.

Rule 2 should be re-worded; I think it was meant to exclude "freeways to nowhere", not actual large metros like Albany and Boston.

[michravera]

NYC has about 75k per km for both I-95 (into CT) and I-87, but it is disqualified by Rule 2.

Rule 2 should be re-worded; I think it was meant to exclude "freeways to nowhere", not actual large metros like Albany and Boston.

I will reword Rule #2 as "at least 250K people or half the size of the city in question". The point is that the road has to go somewhere and not just serve the local area. I am specifically not interested in roads that stop due to geographical impossibility -- at least not in the direction of geographical impossibility. If one can only really go North, South, and West from a city, I am not interested in 4-lane roads to the east. Similarly on the West Coast, and on islands. 

[jdb1234]

I-75 south of Atlanta narrows to 4 lanes at the I-475 split, 70 miles away.
I-75 north of Atlanta narrows to 4 lanes just past the US 11/64 exit north of Chattanooga, about 118 miles away.
I-20 west of Atlanta narrows to 4 lanes at the GA 61/101 exit, 33 miles away, though construction is ongoing for widening west of there.
I-20 east of Atlanta narrows to 4 lanes at the GA 142 exit, 36 miles away.

You could have picked either. It sounds like I-75 goes to 4 or fewer lanes the quickest.

I-20 isn't being widened west of Atlanta. The ongoing construction is for pavement replacement only. Hard to believe, but it's true.

michravera: 108 and 70 are a lot farther than 33 and 36. That said, the I-75 south corridor, via I-475 around Macon, actually extends all the way to Tampa save for a half mile of four lanes at the northern end of 475. Obviously, where it drops to four lanes has nothing to do with how much Atlanta sprawls.

Actually I-75 is 6 lanes all the way to Naples.

[SkyPesos]

Old thread, but interesting



Cincinnati (distance will be from the I-71/I-75/US 50 interchange for I-71 and I-75, and I-74/I-75 interchange for I-74):

I-74 West: becomes 4 lanes at the N Bend Rd interchange (exit 15), 4 miles west of it's terminus at I-75. It's 6 lanes again at its concurrency with I-275, but after the concurrency, it's 4 lanes all the way to I-465.

I-71 North: becomes 4 lanes at the OH 48 interchange (exit 28), about 28 miles north.
I-71 South: becomes 4 lanes at the I-75 split (exit 173), about 20 miles south.

I-75 North: becomes 4 lanes north of the OH 41 interchange (exit 74), about 74 miles north.
I-75 South: oh god, I don't know how far KY has 6 laned its section of I-75; has the 6 lane section been continuous to London, KY yet?



Columbus (distance will be from I-70/I-71/OH 315 interchange):

I-70 West: becomes 4 lanes at the OH 48 interchange (exit 29), about 70 miles west
I-70 East: becomes 4 lanes a mile east of exit 112, about 13 miles east

I-71 South: becomes 4 lanes south of the OH 665 interchange (exit 97), about 10 miles south
I-71 North: no remaining 4 lane sections



St. Louis (distance will be from I-44/I-55/I-64/US 40 interchange for the 3 interstates in it, and the I-44/I-70/Tucker interchange for I-70):

I-44 West: becomes 4 lanes at the MO 100 interchange (exit 251), about 40 miles west

I-64 West: becomes 4 lanes at the MO K interchange (exit 9), about 31 miles west
I-64 East: becomes 4 lanes at exit 16, about 16 miles east

I-70 West: becomes 4 lanes at the US 40/US 61 interchange (exit 210), about 39 miles west
I-70 East: becomes 4 lanes at the IL 157 interchange (exit 11), about 11 miles east

I-55 South: becomes 4 lanes at the MO Z interchange (exit 180), about 29 miles south
I-55 North: becomes 4 lanes at the IL 157 interchange (exit 11), about 11 miles north

[Bruce]

WA 99 under Downtown Seattle is only 4 lanes.

[Great Lakes Roads]

Indianapolis:

I-65 South- 21.3 miles (starting from the South Split Interchange to south of the Franklin exit)
I-65 North*- 10 miles (starting from the North Split Interchange to I-465)

I-70 West- 14.2 miles (starting from the South Split Interchange to west of the Plainfield exit)
I-70 East- 12.9 miles (starting from the North Split Interchange to Mt. Comfort exit)

I-69 North- 26.8 miles (starting from the I-465 interchange to east (north) of the SR 9 exit in Anderson)

*Although there is a 4-lane section on I-65 northwest of Indy, it expands back to six lanes after the 865 interchange, and it goes northward until you hit Lebanon where it goes back down to 4 lanes.

[NWI_Irish96]

In Louisville, I-64 EB and I-71 NB are both 4 lanes immediately after splitting from each other at the I-65 interchange

[achilles765]

Interstate 45 is between 3 to 5 lanes each direction all the way from Galveston at exit 1 to outside Conroe at exit 97.
Interstate 10 is anywhere from 6 to 26 overall lanes from exit 720 something in the far west almost all the way to Beaumont now, aside from a stretch between Beaumont and Winnie which looked like it was being widened this weekend. Before long I see I 10 being six lanes all the way from San Antonio to the state line
Interstate 69 is six lanes or more for about 80 miles.
So if we divided by population it would be
(Doing metro area)
5 million/97 for Ih 45=51,546.39
5 million/ 110 for IH 10= 45454.54

[Flint1979]

I-75 is four lanes north of Bay City, then becomes eight lanes at MM 164, goes back down to six lanes at MM 155 to cross the Zilwaukee Bridge and I-675 is four lanes as a bypass in the area, once MDOT is done with the construction between MM 150 and 148 it'll be eight lanes all the way to MM 125 right now it's six lanes to MM 148 it's being widened to eight and will be finished next year. Then after MM 125 it goes down to six lanes until MM 115 where it goes down to four lanes then back to six lanes at MM 111. After that it goes up to eight lanes at MM 82. Then back down to six lanes at MM 75. Then back up to eight lanes at MM 59. This information is all off the top of my head I can't remember where it drops back down south of Detroit.

[webny99]

What about Pittsburgh? It's really unbelievable we made it this far without mentioning Pittsburgh.
Really no other major US city can touch it in terms of their through freeways being only four lanes.

PA 28, 2 miles northeast of downtown
I-376, 4 miles east of downtown
I-376, 5 miles southwest of downtown
PA 65, 4 miles northwest of downtown.

[webny99]

Speaking of PA, here is an example in the Philadelphia area that blows my mind: this section of I-476.
And of course, this section of I-76, also crazy but at least self-explanatory given the ROW.