Inside Lanes Merging

[kphoger]

not being from illinois i was unaware ... that I had ROW in that situation.

You didn't.  See what I posted right before you.  Both drivers are required to accommodate each other.  Neither one is granted the "right of way" at merge situations in Illinois.

[Occidental Tourist]

The East LA interchange and Golden State/San Bernardino interchange have a couple of inside lanes merge at the transitions.  The 60 east has one and the 5 south at the 5/10 merge has another.

The Bellflower Blvd on ramp to the 405 north in Long Beach has two lanes entering the freeway where the inside lane merges with the mainline and the outside lane continues on as an auxiliary lane for the upcoming Lakewood Blvd exit.

[jeffandnicole]

The NJ Turnpike example could also be noted for its use of lane striping.  They don't maintain a full passing zone between all lanes as the roadways merge, but rather use a single line to encourage traffic to stay in their group.  But, by not using the double white line, it's not technically illegal to merge out of the 2 lanes that are merging. 

It's also notable that this merging area is a mile south of Interchange 6.  Quite a bit of traffic will exit at Exit 6, and that leaves traffic time to adjust to lighter traffic conditions before needing to merge.  The Turnpike maintains its 65 mph speed limit thru this area.  Traffic can be noticeably heavier in the 3 lane area just south of the 6 lane area, but rarely does traffic slow down below the speed limit, much less congest, except on the busiest of travel days.

The New Jersey Turnpike is a special case though. Their arrangement is an attempt to compromise among 3 possibilities: both roadways open, left roadway closed, or right roadway closed. A configuration that avoids inside merging would result in some amount of thru traffic having to change lanes twice.

It's minor, but generally speaking there may always be traffic on the outer roadway at this point.  There is only 1 ramp from the NJ/PA Turnpike Extension East (technically I-95 North) onto the NJ Turnpike South, which takes traffic to the outer roadway. 

(I think that instead of such a merge, one lane could be dropped from each of the roadways at Exit 6 so that only 4 lanes instead of 6 lanes reach the merge point)

I believe this was considered, but the NJ Turnpike prefers to keep the mainline traffic flowing in continuous lanes, rather than use an 'Exit Only' lane setup.  At Exit 4 SB where the Turnpike goes from 3 lanes to 2, and Exit 13 NB where the turnpike goes from 4 lanes to 3, the right lane ends just after the gore point of the ramp, rather than forcing traffic off via 'Exit Only' signage.

In the cases of a merge between different roads, having "thru traffic" from the minor route (i.e. not thru traffic from the perspective of the dominant route) change lanes twice would be safer than inside lane traffic not having any escape room if unable to merge.

And what's a little peculiar about all of this:  The NJ Turnpike is noted for their calm merging pattern south of Interchange 6.  Yet, if you're coming from PA on the Extension and continue North on 95 & the Turnpike, the 2 lane ramps from the extension immediately ends and both lanes must quickly merge over into the mainline travel lanes.  There's about an 800 foot distance for this to occur

As my reply from 10 years ago was noted in #20, at the time I clearly remember at a public open-house meeting that longer acceleration lanes were going to be used.  800 feet would barely acceptable for a single ramp lane; we have 2 lanes ending in that distance here!

[jakeroot]

In the cases of a merge between different roads, having "thru traffic" from the minor route (i.e. not thru traffic from the perspective of the dominant route) change lanes twice would be safer than inside lane traffic not having any escape room if unable to merge.

I believe this was considered, but the NJ Turnpike prefers to keep the mainline traffic flowing in continuous lanes, rather than use an 'Exit Only' lane setup.  At Exit 4 SB where the Turnpike goes from 3 lanes to 2, and Exit 13 NB where the turnpike goes from 4 lanes to 3, the right lane ends just after the gore point of the ramp, rather than forcing traffic off via 'Exit Only' signage.

I've noticed this preference also exists in Washington State. Seems to be better for capacity (in some situations) and safety (again, in some situations). Unless an exit is tremendously busy, you'll have higher capacity with all lanes continuing, as you don't have through traffic avoiding the exit-only lane needlessly early, as can sometimes be the case. It can also be safer, as traffic merging into the through lanes can use the defined merge point at the end, rather than trying to find a place randomly along the length of the lane (especially dangerous if the through traffic is moving slower than the exit-only lane).

Places with heavy usage of auxiliary lanes between exits must have a lot of free-for-all situations when traffic is heavy; where do drivers merge? This is one of the few situations where I see people drive through shoulders, to pass someone who had to stop to merge because there is no defined merge point.

[ran4sh]

In the cases of a merge between different roads, having "thru traffic" from the minor route (i.e. not thru traffic from the perspective of the dominant route) change lanes twice would be safer than inside lane traffic not having any escape room if unable to merge.

I believe this was considered, but the NJ Turnpike prefers to keep the mainline traffic flowing in continuous lanes, rather than use an 'Exit Only' lane setup.  At Exit 4 SB where the Turnpike goes from 3 lanes to 2, and Exit 13 NB where the turnpike goes from 4 lanes to 3, the right lane ends just after the gore point of the ramp, rather than forcing traffic off via 'Exit Only' signage.

I've noticed this preference also exists in Washington State. Seems to be better for capacity (in some situations) and safety (again, in some situations). Unless an exit is tremendously busy, you'll have higher capacity with all lanes continuing, as you don't have through traffic avoiding the exit-only lane needlessly early, as can sometimes be the case. It can also be safer, as traffic merging into the through lanes can use the defined merge point at the end, rather than trying to find a place randomly along the length of the lane (especially dangerous if the through traffic is moving slower than the exit-only lane).

Places with heavy usage of auxiliary lanes between exits must have a lot of free-for-all situations when traffic is heavy; where do drivers merge? This is one of the few situations where I see people drive through shoulders, to pass someone who had to stop to merge because there is no defined merge point.

"Places with heavy usage of auxiliary lanes between exits must have a lot of free-for-all situations when traffic is heavy; where do drivers merge?"

Drivers merge when they have accelerated to the speed of the mainline. Exiting drivers change to the auxiliary lane early on and then slow to exit speed only after getting out of the thru lane.

Or at least that is the safest way to do it, based on my experience when driving Atlanta-area freeways that have 8, 10, or 12 lanes often with auxiliary lanes between exits.

[jakeroot]

In the cases of a merge between different roads, having "thru traffic" from the minor route (i.e. not thru traffic from the perspective of the dominant route) change lanes twice would be safer than inside lane traffic not having any escape room if unable to merge.

I believe this was considered, but the NJ Turnpike prefers to keep the mainline traffic flowing in continuous lanes, rather than use an 'Exit Only' lane setup.  At Exit 4 SB where the Turnpike goes from 3 lanes to 2, and Exit 13 NB where the turnpike goes from 4 lanes to 3, the right lane ends just after the gore point of the ramp, rather than forcing traffic off via 'Exit Only' signage.

I've noticed this preference also exists in Washington State. Seems to be better for capacity (in some situations) and safety (again, in some situations). Unless an exit is tremendously busy, you'll have higher capacity with all lanes continuing, as you don't have through traffic avoiding the exit-only lane needlessly early, as can sometimes be the case. It can also be safer, as traffic merging into the through lanes can use the defined merge point at the end, rather than trying to find a place randomly along the length of the lane (especially dangerous if the through traffic is moving slower than the exit-only lane).

Places with heavy usage of auxiliary lanes between exits must have a lot of free-for-all situations when traffic is heavy; where do drivers merge? This is one of the few situations where I see people drive through shoulders, to pass someone who had to stop to merge because there is no defined merge point.

"Places with heavy usage of auxiliary lanes between exits must have a lot of free-for-all situations when traffic is heavy; where do drivers merge?"

Drivers merge when they have accelerated to the speed of the mainline. Exiting drivers change to the auxiliary lane early on and then slow to exit speed only after getting out of the thru lane.

Or at least that is the safest way to do it, based on my experience when driving Atlanta-area freeways that have 8, 10, or 12 lanes often with auxiliary lanes between exits.

But what about when mainline traffic is flowing slower than the auxiliary lane (example here)? Where do you merge?

Obviously the answer is "wherever you find a gap", but what about those cars not looking to enter the mainline? Or those cars behind you who left the mainline who you are now blocking? That's when you start getting shoulder-driving and annoyed drivers.

This was my point when I said "when traffic is heavy". Somehow you quoted this verbatim yet seemed to miss my point.

[ran4sh]

The auxiliary lane is not a thru lane, so anyone that is using it to pass slow mainline traffic is an asshole.

The auxiliary lane is for both entering and exiting traffic, so although an entering vehicle that is using a long length of the lane to enter the mainline may annoy exiting traffic behind, there's nothing exiting traffic can do about it.

[jakeroot]

The auxiliary lane is not a thru lane, so anyone that is using it to pass slow mainline traffic is an asshole.

The auxiliary lane is for both entering and exiting traffic, so although an entering vehicle that is using a long length of the lane to enter the mainline may annoy exiting traffic behind, there's nothing exiting traffic can do about it.

The fact that it isn't a through lane is what I'm getting at: by forcing the lane off at the next exit, you're not providing a clear point for traffic to merge at. This is a serious problem if the auxiliary lanes are moving faster than mainline traffic, and you block traffic using the auxiliary lane trying to exit. There's clearly a safety issue by requiring drivers to come to a near-stop just to merge, while their tail end is still parked in the auxiliary lane. You may not see this much in Georgia, but it's something I see here in WA often enough. Primarily along that stretch I linked to before.

What can be done about it is: not forcing the lane off at the next exit. Instead, have it continue past the exit for a few hundred feet, and then merge in.

[ran4sh]

That doesn't really work if the next exit has more than one lane. (Or even just 1 exit-only lane [the auxiliary lane] and 1 option lane [right mainline lane has the option to exit or stay on].)

[jakeroot]

That doesn't really work if the next exit has more than one lane. (Or even just 1 exit-only lane [the auxiliary lane] and 1 option lane [right mainline lane has the option to exit or stay on].)

In those situations, yes, there's not much that can be done. I find the issue is most prevalent between two "quieter" ramps with just a single lane coming in, and a single lane departing.

[I-55]

US-35 in Ohio is pretty good at this:

- Both ends of the US-23 concurrency

- Westbound entering the state at OH-735 the lanes basically feed right into 735's alignment.

[kphoger]

The auxiliary lane is not a thru lane, so anyone that is using it to pass slow mainline traffic is an asshole.

The auxiliary lane is for both entering and exiting traffic, so although an entering vehicle that is using a long length of the lane to enter the mainline may annoy exiting traffic behind, there's nothing exiting traffic can do about it.

The fact that it isn't a through lane is what I'm getting at: by forcing the lane off at the next exit, you're not providing a clear point for traffic to merge at. This is a serious problem if the auxiliary lanes are moving faster than mainline traffic, and you block traffic using the auxiliary lane trying to exit. There's clearly a safety issue by requiring drivers to come to a near-stop just to merge, while their tail end is still parked in the auxiliary lane. You may not see this much in Georgia, but it's something I see here in WA often enough. Primarily along that stretch I linked to before.

What can be done about it is: not forcing the lane off at the next exit. Instead, have it continue past the exit for a few hundred feet, and then merge in.

And then have to reconstruct this bridge, while you're at it.  Seriously, the afternoon rush-hour traffic jam here could be improved so much, if only the K-254 exit-only ramp continued and became an I-235 exit-only ramp instead.

Wait a minute, though, isn't this interchange finally on the books to be redone?

[jakeroot]

The auxiliary lane is not a thru lane, so anyone that is using it to pass slow mainline traffic is an asshole.

The auxiliary lane is for both entering and exiting traffic, so although an entering vehicle that is using a long length of the lane to enter the mainline may annoy exiting traffic behind, there's nothing exiting traffic can do about it.

The fact that it isn't a through lane is what I'm getting at: by forcing the lane off at the next exit, you're not providing a clear point for traffic to merge at. This is a serious problem if the auxiliary lanes are moving faster than mainline traffic, and you block traffic using the auxiliary lane trying to exit. There's clearly a safety issue by requiring drivers to come to a near-stop just to merge, while their tail end is still parked in the auxiliary lane. You may not see this much in Georgia, but it's something I see here in WA often enough. Primarily along that stretch I linked to before.

What can be done about it is: not forcing the lane off at the next exit. Instead, have it continue past the exit for a few hundred feet, and then merge in.

And then have to reconstruct this bridge, while you're at it.  Seriously, the afternoon rush-hour traffic jam here could be improved so much, if only the K-254 exit-only ramp continued and became an I-235 exit-only ramp instead.

Wait a minute, though, isn't this interchange finally on the books to be redone?

At that interchange, yes, I think it would make much more sense for the exit-only to continue past the first exit. It would require replacing the bridge, clearly. But I don't think continuing that lane past the second exit would be necessary.

Continuing the auxiliary lane past the exit ramp is clearly not something that needs to be done under all circumstances. Especially when the exit is either nearly as busy, or as busy, as the mainline maneuver. But I can appreciate them in high-traffic areas. I suspect the I-135/I-235/K-254 interchange isn't a place where it would be necessary.

[Hot Rod Hootenanny]

ODOT loved doing inside lane merges.
Signs like this below were common around Columbus:
http://www.roadfan.com/sqdia.jpg
(I-71 SB - I-670 EB merge near Broad St. exit, back in 2000)

I-76/77 in Akron had a sign similar to what Skypesos showed for Cincy


One of the few inside merges still existing in Columbus, I-270 NB between US 40 & Oh 16
https://goo.gl/maps/HeaMCYUt9mqyyFHJA

[roadfro]

What is the best way to sign an inside lane merge?

I think that sign could be too easily mistaken as a triple added-lane with no merging necessary. This is my idea:

You'd need to show both of the outside arrows with curved stems, to make it more clear that is a merge. I also like the first example that shows the lane lines (similar to the added lane sign) to make it even more obvious

[GaryA]

Here's an inside-merge sign in use (Pasadena, CA):
https://goo.gl/maps/moY9a9E1UwRhskeB6

It replaced a normal merge-from-right between 2011 and 2014, according to the GSV dating.

Note that this is actually at a merge of two surface streets (NB Sierra Madre Blvd and NB San Gabriel Blvd), and the intersection is signal-controlled so that (I believe) there are no times when traffic from both streets actually needs to merge.  It's actually somewhat of an interesting intersection, with a WB I-210 frontage road making it a five-way.

[CtrlAltDel]

What is the best way to sign an inside lane merge?

I think that sign could be too easily mistaken as a triple added-lane with no merging necessary. This is my idea:

Maybe something like this?

[jakeroot]

I might argue that anything left of the merge lane may not be necessary. This is my concept:

[SkyPesos]

I might argue that anything left of the merge lane may not be necessary. This is my concept:

That looks similar to what was posted above for Akron (image didn't show for some reason, here's the link for it).

[CtrlAltDel]

It's a question, I think, of whether you add in the third arrow or the lane lines. The design I borrowed seems a bit less busy than yours, but that might also give rise to a lack of clarity. Also, for the record, the arrows in my attempt are yours. I took them from one of your APL designs.

[jakeroot]

I might argue that anything left of the merge lane may not be necessary. This is my concept:

https://live.staticflickr.com/65535/51001658041_058427e77d_o.png

That looks similar to what was posted above for Akron (image didn't show for some reason, here's the link for it).

Ahhh, because it's damn near the same. The image also didn't show for me, which may be why I missed it.

It's a question, I think, of whether you add in the third arrow or the lane lines. The design I borrowed seems a bit less busy than yours, but that might also give rise to a lack of clarity. Also, for the record, the arrows in my attempt are yours. I took them from one of your APL designs.

Glad my arrows are getting use! The arrowheads themselves I installed myself into the arrowheads library in Illustrator.

I added the lane lines but I suppose those are fairly dispensable.

[Revive 755]

I might argue that anything left of the merge lane may not be necessary. This is my concept:

Iowa has a similar sign


Then's there this version in Chicagoland

[webny99]

I might argue that anything left of the merge lane may not be necessary. This is my concept:

I like this a lot. If there has to be an inside lane merge, this is what I'd go with out of everything posted so far.

[interstatefan990]

I would also add that it would be important to keep the "Center Lanes Merge" plaque along with the sign. It's better to have symbol/word ambiguity for redundancy, since the sign might confuse drivers.

[kphoger]

I added the lane lines but I suppose those are fairly dispensable.