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"Congestion-Proof" Freeways

Started by webny99, December 13, 2022, 10:26:44 AM

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webny99

Some discussion in another thread got me thinking about cases where a new lane opens up on a freeway and there are no new entrances for a considerable distance (or where any new entrances also contribute through lanes, providing an "extra" lane).

Most often, this would be where there are two lanes in one direction and it expands to three lanes. Using that as an example, the section with two lanes restricts the amount of traffic that can reach the 3 lane section. So, even if the two lanes are at full capacity, it's still not enough to fill the full three lanes. This effectively guarantees that there will not be congestion on that 3 lane section. Obviously, there can be an incident that causes a backup, or downstream congestion, but under normal circumstances, congestion will not occur there because only 2 cars can reach that section at once and there's 3 lanes to use.

The example that comes to mind in my area is this section of I-490 where a third lane opens south of NY 153 and the on ramp from the next pair of exits is almost 2 miles away. So both sides of this segment often get congested but you're pretty much guaranteed to keep moving on this 2 mile segment.

I'm curious what other examples exist and what is the longest example we can find of a built-in congestion-proof freeway segment (not counting ramp meters or anything related to a specific incident or construction project).


Max Rockatansky

#1
I don't recall ever running into a traffic jam on the Glendale Freeway segment of CA 2.  The traffic always seemed to be on the south end of the freeway as CA 2 transitioned into Glendale Boulevard.  I think the phenomenon I used to see was that the Glendale Freeway simply wasn't utilized by many despite being close to downtown Los Angeles.

Dirt Roads

We just had a discussion about the short section of I-85 [westbound] just west of Hillsborough that widens to three lanes in approach to the merge with I-40 to become "The Spine of North Carolina".  This section opened in the early 1990s as part of widening The Spine to eight lanes.  The [eastbound] lanes of I-85 needed to be 3 lanes to improve truck flow at The Split headed up the short distance to the top of Occoneechee Mountain, and I highly suspect that the [westbound] lanes were widened in anticipation that the entire stretch of I-85 between The Split and Durham would need to widened soonafter.  Still ain't started, but they did survey for that widening project about 7 or 8 years ago.

RobbieL2415

Are you sure the intent by the added lane there is as you say it is?
It does appear to be provisioned for an extension with a few hundred feet of wider shoulder.

Dirt Roads

Quote from: RobbieL2415 on December 13, 2022, 07:44:06 PM
Are you sure the intent by the added lane there is as you say it is?
It does appear to be provisioned for an extension with a few hundred feet of wider shoulder.

The [eastbound] lanes are fairly steep and need a truck climbing lane after The Split.  Without it, traffic would back up significantly in the left two lanes before The Split.  But the current arrangement causes problems as well.  Truckers that get into either of the left two lanes before The Split cause I-85 traffic to pass on the right side (interfering with I-40 traffic).  Truckers that stay in the second lane from the right hit the upgrade before The Split and slow down the "fast lane" heading to I-40.  But even with two miles of advance notice with overhead diagrammatics, everyday you see traffic headed for I-40 get caught in the two left lanes and slash across the lanes and split the gore (the one I saw today had to stop in the gore and wait to pull into the fast lane later).

webny99

Quote from: Dirt Roads on December 13, 2022, 07:40:09 PM
We just had a discussion about the short section of I-85 [westbound] just west of Hillsborough that widens to three lanes in approach to the merge with I-40 to become "The Spine of North Carolina".  This section opened in the early 1990s as part of widening The Spine to eight lanes.  The [eastbound] lanes of I-85 needed to be 3 lanes to improve truck flow at The Split headed up the short distance to the top of Occoneechee Mountain, and I highly suspect that the [westbound] lanes were widened in anticipation that the entire stretch of I-85 between The Split and Durham would need to widened soonafter.  Still ain't started, but they did survey for that widening project about 7 or 8 years ago.

Yep, that was exactly the discussion that inspired this thread, along with the example on I-490 that I mentioned in the OP.


Quote from: Dirt Roads on December 13, 2022, 08:36:39 PM
Quote from: RobbieL2415 on December 13, 2022, 07:44:06 PM
Are you sure the intent by the added lane there is as you say it is?
It does appear to be provisioned for an extension with a few hundred feet of wider shoulder.

The [eastbound] lanes are fairly steep and need a truck climbing lane after The Split.  Without it, traffic would back up significantly in the left two lanes before The Split.  But the current arrangement causes problems as well.  Truckers that get into either of the left two lanes before The Split cause I-85 traffic to pass on the right side (interfering with I-40 traffic).  Truckers that stay in the second lane from the right hit the upgrade before The Split and slow down the "fast lane" heading to I-40.  But even with two miles of advance notice with overhead diagrammatics, everyday you see traffic headed for I-40 get caught in the two left lanes and slash across the lanes and split the gore (the one I saw today had to stop in the gore and wait to pull into the fast lane later).

That seems like a no-win situation for trucks trying to keep right. Isn't I-40 the busier movement here? In that case it would make more sense to have three lanes going to I-40 and two to I-85. The ideal setup would probably be to add a fifth lane from Exit 161 and have three lanes for both I-40 and I-85 (at least when the I-40 widening is complete).


Dirt Roads

There's also one in my old backyard, but it doesn't always seem congestion proof.  I-64 westbound currently widens from two lanes to three lanes just west of Rock Stepp Road (near MM 41) and runs great until the lane drop at Exit 39 for Teays Valley.  Since a significant portion of the westbound traffic is heading for US-35 or the Teays Valley exit, this has all the making of a congestion-proof freeway.  But alas, there are those moments where Exit 39 backs up onto the right lane exit only (sheer volume), or on occasion, I-64 chokes down from three lanes to two lanes heading westward towards Hurricane -and- Huntington.

It's going to take a while, but the four-lane section of I-64 between MM 41 and MM 45 is currently being widened, including the new twin-bridge replacement over the Kanawha River.

Alex4897

I-95 southbound picks up a 4th lane coming out of Philadelphia just after the Schuykill River. The right lane ducks into a CD ramp for PA 291 and the Philly Airport not long after, but it's about 1.75 miles before traffic from the next on-ramp meets the main lanes and loses the lane it came with.

Quote from: Dirt Roads on December 13, 2022, 07:40:09 PM
We just had a discussion about the short section of I-85 [westbound] just west of Hillsborough that widens to three lanes in approach to the merge with I-40 to become "The Spine of North Carolina".  This section opened in the early 1990s as part of widening The Spine to eight lanes.  The [eastbound] lanes of I-85 needed to be 3 lanes to improve truck flow at The Split headed up the short distance to the top of Occoneechee Mountain, and I highly suspect that the [westbound] lanes were widened in anticipation that the entire stretch of I-85 between The Split and Durham would need to widened soonafter.  Still ain't started, but they did survey for that widening project about 7 or 8 years ago.

The north/eastbound approach into Durham's a good example too, it's about 2.5 miles between the third lane opening up and the onramps from Cole Mile Road and US 15 / 501. The whole of I-85 through Durham seems to behave this way in either direction, at least in my experience.
👉😎👉

webny99

A bit of a bump here as I thought of another good one.

The *entirety* of I-290 westbound, which has three lanes throughout, is essentially "congestion-proof" because of the bottleneck created by the two-lane ramp from I-90 Eastbound. Factor in that I-90 Westbound has just two lanes total approaching the I-290 interchange, and through traffic on I-90 is the dominant movement, so it's basically never contributing a full lane of traffic exiting to I-290 at any point in time, and then you have roughly equal traffic exiting and entering at Exits 7 and 6, quite a bit more exiting traffic at Exit 5, 10 lanes west of Exit 4 and another net loss at Exit 3, so there's not really any point along the route at which enough traffic could all hit at once to cause congestion.

I-290 Eastbound, meanwhile, is a different story, thanks to the same bottleneck at I-90 affecting it in reverse.

pderocco

Quote from: webny99 on November 02, 2024, 09:50:42 PMA bit of a bump here as I thought of another good one.

The *entirety* of I-290 westbound, which has three lanes throughout, is essentially "congestion-proof" because of the bottleneck created by the two-lane ramp from I-90 Eastbound. Factor in that I-90 Westbound has just two lanes total approaching the I-290 interchange, and through traffic on I-90 is the dominant movement, so it's basically never contributing a full lane of traffic exiting to I-290 at any point in time, and then you have roughly equal traffic exiting and entering at Exits 7 and 6, quite a bit more exiting traffic at Exit 5, 10 lanes west of Exit 4 and another net loss at Exit 3, so there's not really any point along the route at which enough traffic could all hit at once to cause congestion.

I-290 Eastbound, meanwhile, is a different story, thanks to the same bottleneck at I-90 affecting it in reverse.
Which I-290?

Bobby5280

I'm going to beat the dead horse on this a few more whacks, but in order to make a freeway more congestion proof serious improvements need to happen at the interface between the freeway and surface streets. That's often where the freeway traffic jams usually begin.

Freeways that carry increasingly large volumes of traffic obviously need more lanes to improve traffic flow. There is no disputing that. But freeways are more than just their main travel lanes. The design of the exits and surface streets in the immediate area of the freeway matter too. A high capacity freeway must have high capacity exits. That means exits that are more free-flowing rather than ones with a traffic light at the end of a straight, standard ramp.

Additionally, traffic that is exiting the freeway and merging onto a surface arterial street must be able to travel some distance before hitting a traffic signal. The main surface arterials near freeway exits need their own access restrictions. Intersections with side streets and driveways into businesses have to be very limited.

Within our own bodies we don't have tiny capillaries going right off the main aorta. There is an order of different branches going from larger to smaller. I'm sure traffic engineers understand that. The damned politicians and business people screw up all of that with their own demands of city planning. That's how you get a 10-lane freeway with a standard diamond exit to a busy surface street pigged with traffic lights, driveways and all sorts of other crap to choke the flow of traffic.

TheStranger

I don't know if Route 73 in Orange County is "congestion-proof" but the combination of toll and most of the business centers being situated closer to the El Toro Y probably helps keep it from being as busy as 405 and 5 in that area.

(But how much of that is just because 73 is tolled, I am not sure)

To that extent I wonder if all of the Orange County toll freeways are "congestion-proof" due to the cost.  Further south, that probably applies to the toll portion of Route 125 in Chula Vista...which bankrupted its private operator as a result.

---

Since I don't have too much experience with these sorts of roads, would bypass freeways of small/medium cities (i.e. I-470 Wheeling, I-210 Lake Charles, I-474 Peoria, I-469 Fort Wayne, I-475 Macon) fit tihs category too?  Things like these really don't exist im California at all due to the scope of urban/suburban development here as well as the extensive pre-Interstate history of freeway construction - i.e. Route 99 doesn't go through Fresno's downtown so it's not like there's an obvious need to bypass it, and while Victorville has grown massively in the last couple of decades, I-15 there has never been a candidate to have a bypass.
Chris Sampang

mgk920

Although not intended to be 'congestion proof', The US 10 freeway west of Appleton, WI (opened in late 2003) was built with no interchanges between WI 76 and US 45 (Winchester interchange) solely to prevent premature development of the farmland area that it passes through.

Mike

webny99

Quote from: pderocco on November 03, 2024, 03:16:14 AM
Quote from: webny99 on November 02, 2024, 09:50:42 PMA bit of a bump here as I thought of another good one.

The *entirety* of I-290 westbound, which has three lanes throughout, is essentially "congestion-proof" because of the bottleneck created by the two-lane ramp from I-90 Eastbound. Factor in that I-90 Westbound has just two lanes total approaching the I-290 interchange, and through traffic on I-90 is the dominant movement, so it's basically never contributing a full lane of traffic exiting to I-290 at any point in time, and then you have roughly equal traffic exiting and entering at Exits 7 and 6, quite a bit more exiting traffic at Exit 5, 10 lanes west of Exit 4 and another net loss at Exit 3, so there's not really any point along the route at which enough traffic could all hit at once to cause congestion.

I-290 Eastbound, meanwhile, is a different story, thanks to the same bottleneck at I-90 affecting it in reverse.
Which I-290?

Whoops, I somehow managed to not specify while failing to provide context clues. I-290 (NY) outside Buffalo, NY.

vdeane

Quote from: Bobby5280 on November 03, 2024, 10:16:55 AMA high capacity freeway must have high capacity exits. That means exits that are more free-flowing rather than ones with a traffic light at the end of a straight, standard ramp.

Additionally, traffic that is exiting the freeway and merging onto a surface arterial street must be able to travel some distance before hitting a traffic signal. The main surface arterials near freeway exits need their own access restrictions. Intersections with side streets and driveways into businesses have to be very limited.
In my experience, far more congestion is caused by large volumes of entering traffic having to merge in than by exiting traffic getting backed up onto the freeway.
Please note: All comments here represent my own personal opinion and do not reflect the official position of NYSDOT or its affiliates.

pderocco

Quote from: TheStranger on November 03, 2024, 12:18:57 PMI don't know if Route 73 in Orange County is "congestion-proof" but the combination of toll and most of the business centers being situated closer to the El Toro Y probably helps keep it from being as busy as 405 and 5 in that area.

(But how much of that is just because 73 is tolled, I am not sure)

To that extent I wonder if all of the Orange County toll freeways are "congestion-proof" due to the cost.  Further south, that probably applies to the toll portion of Route 125 in Chula Vista...which bankrupted its private operator as a result.
I've noticed the tolls in SoCal vary all over the map, probably based on county. CA-73, last I checked, is fairly expensive even in the middle of the night, so I rarely choose it, while CA-125 is cheap when I drive it on weekends. The latter is SANDAG, which also handles I-15 express lanes in SD county, whose minimums are dirt cheap. I haven't checked the other OC toll road prices because I rarely drive them. But I think tolls have a lot to do with congestion, because most people aren't willing to pay them. Since I usually drive at off-peak times, and can afford the tolls, this makes me happy.

webny99

Quote from: vdeane on November 03, 2024, 02:28:58 PM
Quote from: Bobby5280 on November 03, 2024, 10:16:55 AMA high capacity freeway must have high capacity exits. That means exits that are more free-flowing rather than ones with a traffic light at the end of a straight, standard ramp.

Additionally, traffic that is exiting the freeway and merging onto a surface arterial street must be able to travel some distance before hitting a traffic signal. The main surface arterials near freeway exits need their own access restrictions. Intersections with side streets and driveways into businesses have to be very limited.
In my experience, far more congestion is caused by large volumes of entering traffic having to merge in than by exiting traffic getting backed up onto the freeway.

And in the case of freeway-freeway ramps, the two are pretty much inseparable. I-290 EB merging onto I-90 WB is a great example. Could you say traffic exiting I-290 is causing congestion? Sure, but the ramp isn't really the problem. It's more accurate to say the congestion is caused by traffic entering I-90, since that's where the bottleneck occurs.


Bobby5280

Quote from: vdeaneIn my experience, far more congestion is caused by large volumes of entering traffic having to merge in than by exiting traffic getting backed up onto the freeway.

I've seen it go the other way (traffic clogging an exit ramp and backing into the freeway main lanes) quite a lot. Traffic entering a freeway and being unable to merge into the main lanes is a symptom of a larger overall back-up.

Quote from: webny99And in the case of freeway-freeway ramps, the two are pretty much inseparable. I-290 EB merging onto I-90 WB is a great example. Could you say traffic exiting I-290 is causing congestion? Sure, but the ramp isn't really the problem. It's more accurate to say the congestion is caused by traffic entering I-90, since that's where the bottleneck occurs.

Plenty of freeway to freeway interchange ramps are inadequate. They'll have a single lane when they need to be two or even three lanes wide.

RZF

Quote from: Bobby5280 on November 03, 2024, 10:16:55 AMI'm going to beat the dead horse on this a few more whacks, but in order to make a freeway more congestion proof serious improvements need to happen at the interface between the freeway and surface streets. That's often where the freeway traffic jams usually begin.

Freeways that carry increasingly large volumes of traffic obviously need more lanes to improve traffic flow. There is no disputing that. But freeways are more than just their main travel lanes. The design of the exits and surface streets in the immediate area of the freeway matter too. A high capacity freeway must have high capacity exits. That means exits that are more free-flowing rather than ones with a traffic light at the end of a straight, standard ramp.

Additionally, traffic that is exiting the freeway and merging onto a surface arterial street must be able to travel some distance before hitting a traffic signal. The main surface arterials near freeway exits need their own access restrictions. Intersections with side streets and driveways into businesses have to be very limited.

Within our own bodies we don't have tiny capillaries going right off the main aorta. There is an order of different branches going from larger to smaller. I'm sure traffic engineers understand that. The damned politicians and business people screw up all of that with their own demands of city planning. That's how you get a 10-lane freeway with a standard diamond exit to a busy surface street pigged with traffic lights, driveways and all sorts of other crap to choke the flow of traffic.
Sounds a lot to me like US 101 in the San Fernando Valley in Los Angeles. It's a 10-lane freeway that can barely support 10 lanes (no middle shoulder in many spots, narrow lanes), and many of the exits are either diamond interchanges or small stubs that flow onto side streets. It's almost always congested during non-sleep hours.

vdeane

Quote from: Bobby5280 on November 03, 2024, 11:30:10 PMI've seen it go the other way (traffic clogging an exit ramp and backing into the freeway main lanes) quite a lot. Traffic entering a freeway and being unable to merge into the main lanes is a symptom of a larger overall back-up.
That's actually fairly uncommon where I live, and almost always involved freeway ramps, not surface streets (and just slowdowns rather than full stops).  If a surface street ramp backs up onto a freeway here, it's a one-off occurrence due to a crash nearly all of the time.  The exceptions?  That one time there was traffic signal malfunctions at the newly opened exit 3/4 ramps on I-87, and the first couple days after Sonic opened their first store in the Capital District and the line was so long that it wrapped around the local roads and down the ramp onto the Northway (thank God the first non-airport CFAs opened concurrently in Clifton Park and North Greenbush and not Latham!).

Meanwhile, I-87 is a total cluster due to traffic getting on.  Southbound in the morning rush, the continuously large volumes without added lanes at exits 9, 8A, and 8 are a problem.  Northbound in the evening rush, the same issues happen at exits 4-7.  The fact of the matter is, if there's a continuous string of cars trying to merge onto a mainline that doesn't have the lane space to accommodate them, traffic is going to back up.  There's a similar issue on I-90 west at exits 4, 3, and 2.

Rochester might be closer to what you describe, but still, it's slowdowns from traffic approaching freeway/freeway interchanges, not exiting traffic backing up to the mainline due to inadequate signal capacity (outside of traffic downtown if there's an event at Frontier Field or Blue Cross Arena).  Perhaps ODOT just sucks at traffic signal management as much as they do at signage?
Please note: All comments here represent my own personal opinion and do not reflect the official position of NYSDOT or its affiliates.

webny99

Quote from: Bobby5280 on November 03, 2024, 11:30:10 PMTraffic entering a freeway and being unable to merge into the main lanes is a symptom of a larger overall back-up.

Yes, but the larger overall backup isn't always an exit ramp backup. It is also quite common for the mainline itself to be the bottleneck and traffic to back up from there.


Quote from: Bobby5280 on November 03, 2024, 11:30:10 PMPlenty of freeway to freeway interchange ramps are inadequate. They'll have a single lane when they need to be two or even three lanes wide.

This is also true, but the question is how much congestion is caused by ramp constraints vs. mainline constraints. I find that a fascinating and seemingly very under-studied/under-discussed question, so I'm going to do a bit of a deep dive for my area (upstate NY) - be interesting to see how it tracks with other areas.


webny99

#21
Quote from: vdeane on November 04, 2024, 12:09:00 PMRochester might be closer to what you describe, but still, it's slowdowns from traffic approaching freeway/freeway interchanges, not exiting traffic backing up to the mainline due to inadequate signal capacity (outside of traffic downtown if there's an event at Frontier Field or Blue Cross Arena).

Agreed with this - there are plenty of freeway-freeway ramps that one could argue cause issues, but signals backing onto the mainline are a non-issue or at least non-recurring issue in the Rochester area. I-490 WB at Culver and Goodman can both back up at times, but it's basically never enough to slow traffic on the I-490 mainline thanks to the auxiliary lanes.

I have seen the NY 104 EB service Rd at Holt Rd back up nearly onto the mainline during holiday shopping season - which is a nearly 3/4 mile long backup. That definitely fits the category of poor traffic signal management, made even worse by one of the most awful lane configurations you'll ever see, but it's still only an issue during peak shopping season.

TheStranger

#22
Quote from: RZF on November 04, 2024, 01:28:44 AMSounds a lot to me like US 101 in the San Fernando Valley in Los Angeles. It's a 10-lane freeway that can barely support 10 lanes (no middle shoulder in many spots, narrow lanes), and many of the exits are either diamond interchanges or small stubs that flow onto side streets. It's almost always congested during non-sleep hours.

Further southeast, the Hollywood Freeway portion also fits this concept of not being congestion-proof:  from Highland Avenue (former Route 170) to the Four-Level, there are so many interchanges spaced generally 1/4 mile apart or less, that the end result is a never-ending series of bottlenecks due to folks getting on or off at such short intervals, even though the freeway itself is decently wide.


---

One thought that just came to mind is the concept of 'congestion-proof" being more a function of either:

1. Road capacity being perfect or larger than needed for a corridor
1A. Road bypasses a nearby choke point, but itself does not provide service there (where the choke point is an important destination in of itself)
2. (tied to the earlier concepts in thread) decent exit spacing to reduce merge situations

I thought of this looking at Google Maps's feature where you can measure typical traffic for a particular day in time; the section of state route 210 east of 215 to Redlands (which formerly was the isolated Route 30 freeway) seems to qualify for this for several reasons:

- the vast majority of drivers use 215 and 10, which both existed decades before what was then 30 finally opened
- Colton, where 215/10 meet, has been an important logistics site dating back to when rail was more prominent
- 210 in that area is away from the population centers of San Bernardino

The next freeway that came to mind is MO 370 west of St. Louis, which has ample capacity while serving an area that already has nearby freeway routes (I-270 and I-70).

For comparison, Route 85 up in Cupertino is not congestion-proof at all even though it is a modern regional bypass:
- only freeway serving the southwest suburbs of San Jose, despite the fact exit spacing is very much up to modern standards
- capacity is only 6 lanes in spots, even 30 years after the road opened
- 85 itself took over the primary arterial role from previously busy Blossom Hill Road
- Equally related, the 1960s/1970s proposal Santa Clara County had of turning their expressways into full freeways never went through; this means that Lawrence Expressway and San Tomas Expressway (while important) are not north-south substitutes for the freeway, and Camden Avenue/Hillsdale Avenue doesn't really provide relief to the east-west segment of 85.
Chris Sampang

webny99

Quote from: TheStranger on November 04, 2024, 01:22:20 PM1. Road capacity being perfect or larger than needed for a corridor
1A. Road bypasses a nearby choke point, but itself does not provide service there (where the choke point is an important destination in of itself)
2. (tied to the earlier concepts in thread) decent exit spacing to reduce merge situations

Great points, I hadn't even really thought about 1A.

For 2, I would add that while greater spacing between exits is ideal, it still comes down to the traffic density approaching a particular point. As one example, Ontario's QEW between Niagara and Burlington is very congestion-prone despite having what I would consider decent exit spacing: that's because heading east from Burlington, you have 7 lanes squeezing into 3 at the Red Hill Valley, so those three lanes become so full that basically any degree of entering traffic at downstream exits can cause congestion, and similarly heading west out of St. Catharines, you have 6 lanes squeezing into 3 at 406/Seventh St, so those three lanes become so full by the time you reach Grimsby that basically any degree of entering traffic can cause congestion. I suppose at a certain point that means that road capacity is less than what it should be, but by the same token, using a series of "choke points" to reduce the rate at which entering traffic can reach these segments - for example, reducing the on-ramps to a single lane before joining the mainline instead of all collapsing into the mainline at once - would go a long way towards mitigating the issues further downstream.

TheStranger

I mentioned Missouri's Route 370 in my previous post, but suddenly thought of this photo of Route 364, the Page Avenue Extension:

(from AARoads wiki)


Is most of 364 congestion-proof?  (factoring in both width and that it is a fourth parallel corridor after US 40/I-64, I-70, and MO 370)  Google Maps does show a little bit of a slow spot in the afternoon rush at MO 94.

---

Since ramp merges have been a big part of this discussion, I immediately thought of the mess that is the San Francisco Skyway portion of I-80, originally built as US 40/50, as the total example of a freeway that inherently generates congestion due to how it is laid out. (As I write this at 11:26 AM local time, Google Maps is already showing severe congestion still)

Because it predates the Interstate system by about 3-4 years (and to some degree was adapted from 1936-era ramps from the Bay Bridge), the lane drops here are not nearly as intuitive as roads built a decade later.

Essentially:

Coming from US 101 north, the lane configuration is as follows:

Leftmost lane: US 101 north only to Central Freeway
lane 2: either Us 101 or I-80
lane 3: I-80
Lane 4: eventual Exit Only lane to 7th Street

So functionally there are already only TWO through lanes from the Bayshore Freeway portion of 101 to I-80 east.

Once one gets a half mile down, the leftmost lane has a blind merge with traffic coming on from US 101 south/Central Freeway eastbound.  (Note that that ramp originally was to have carried I-80 coming in from the west, before the controversial Western Freway project spanning the Panhandle district was canceled) 

At that point the configuration is now:
Lane 1 (originally from the Central Freeway) - I-80 from southbound 101
Lane 2: awkward merge between traffic from southbound 101 and traffic from northbound 101
Lane 3: I-80...but more on that later.
Lane 4: the exit-only ramp to 7th Street
https://www.google.com/maps/@37.7709661,-122.4058326,3a,75y,132.49h,90.51t/data=!3m7!1e1!3m5!1sSN1wtDG7EI9rQABgtiaIQw!2e0!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fcb_client%3Dmaps_sv.tactile%26w%3D900%26h%3D600%26pitch%3D-0.5058414376752438%26panoid%3DSN1wtDG7EI9rQABgtiaIQw%26yaw%3D132.49013300459427!7i16384!8i8192!5m1!1e1?coh=205410&entry=ttu&g_ep=EgoyMDI0MTAyOS4wIKXMDSoASAFQAw%3D%3D

At 7th street, Lane 3 is also an option lane for the exit:
https://www.google.com/maps/@37.7726695,-122.4066198,3a,42.9y,4.37h,83.7t/data=!3m7!1e1!3m5!1sundvP2ubCSxSz8KZcTj2UQ!2e0!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fcb_client%3Dmaps_sv.tactile%26w%3D900%26h%3D600%26pitch%3D6.299895355188298%26panoid%3DundvP2ubCSxSz8KZcTj2UQ%26yaw%3D4.369932951770588!7i16384!8i8192!5m1!1e1?coh=205410&entry=ttu&g_ep=EgoyMDI0MTAyOS4wIKXMDSoASAFQAw%3D%3D

However...

At 8th Street, a left onramp comes in and becomes the new leftmost through lane.
There:

8th Street onramp is new Lane 1 (as noted)
Old lane 1 (which originally came in from the Central Freeway) is now Lane 2
Old lane 2 (which was originally the Lane 1 from the south 101/80 ramp set) is now lane 3!
What had been Lane 3 after the Central Freeway...

...eventually becomes an exit only ramp for 4th Street.
https://www.google.com/maps/@37.7782897,-122.4006528,3a,75y,55.35h,89.77t/data=!3m8!1e1!3m6!1sAF1QipPF3fSjxcflhmXFN43NYkL3f6OunE2nTkxk6xiD!2e10!3e11!6s%2F%2Flh5.ggpht.com%2Fp%2FAF1QipPF3fSjxcflhmXFN43NYkL3f6OunE2nTkxk6xiD%3Dw900-h600-k-no-pi0.2338862275259288-ya5.061562647133947-ro0-fo100!7i5504!8i2752?coh=205410&entry=ttu&g_ep=EgoyMDI0MTAyOS4wIKXMDSoASAFQAw%3D%3D

Essentially, the ONLY lane from the south 101/80 ramp complex that guarantees you will stay on I-80 without any lane changes as you approach the Bay Bridge...is what had been Lane 2 on the Bayshore Freeway, the one that forces you into a blind merge from the Central Freeway.  Otherwise, every driver heading to Oakland from the Bayshore Freeway has to make a lane change on I-80 at some point in the slightly under 2 miles to 4th Street. 
Chris Sampang



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