Adding and Dropping Lanes over Distance

[CtrlAltDel]

Here's something I've long wondered about:

Take I-10, heading eastbound from its western terminus in Santa Monica, right as it crosses Ocean Avenue. Here, the road has two lanes, which we can number according to the standard California convention, 1 for the left lane and 2 for the right. Let's call this configuration (1 2). As the highway crosses the Pacific Coast Highway, it picks up another lane on the right. This would be lane 3, leading to (1 2 3). Near Cloverfield Boulevard, it picks up another, again on the right, making (1 2 3 4).

Now, imagine that the left lane ends, leaving three lanes. But instead of renumbering all the lanes, simply retire the 1, giving you (2 3 4). Similarly, if three more lanes were to be added to the left, we could give them the next lowest numbers in sequence, making for (−1 0 1 2 3 4).

And so, my question is if you did this for the entire length of the highway, what would the lane numbers be when you get to the three lanes at the end of the line in Jacksonville?

Has anyone else wondered this? Has anyone bothered to figure it out? Does anyone even have an idea of how to figure this out without having to trace the entire route.

It would be interesting to see if things stay pretty close to (1 2 3), or if they veer off a bit, leading to (6 7 8) or perhaps even (−4 −3 −2). Or maybe there's a middle lane that ends somewhere, leading to something like (1 3 4), for example.

[Rothman]

Egads.  I'd hate to do this for I-84 from NY to Hartford in CT.  Last I went through there, there were all these climbing lanes and other lane adds/subtractions that cause traffic problems when cars had to merge back in.

[pianocello]

I'm pretty sure we've done this before, but I don't feel like digging it up.

Anyway, I-74 eastbound starts as (1 2) from Davenport to Bloomington (except the two TOTSO ramps where it funnels into lane 3 and the 3+ lane segments in Peoria), has a (1 0 -1) segment along the west side of Bloomington, and then continues as (0 -1) to Indianapolis. At the beginning of its concurrency with I-465, it's (-5 -4 -3 -2 -1), and the segment between Indy and Cincinnati is (-4 -3). Inside I-275 in Cincinnati, it's (-3 -2), and at the end it's (-3 -2 -1).

It's interesting what a couple concurrencies can do to this count. It'd be cool to see the numbers for I-64.

[froggie]

I'm pretty sure we've done this before, but I don't feel like digging it up.

We did a few years ago, yes, but I couldn't find it after a cursory search.

[Duke87]

Let's for fun see what happens with a shorter route, but one in an urban area. Here's I-678.

Begins in JFK with (1 2 3). Belt interchange makes it leave with just (1 2). At the next ramp we go back to (1 2 3), followed by a new lane to the left making (0 1 2 3). A lane drop to the C/D road gives us (0 1 2), and the right lane ending then gives us (0 1). When the C/D road ends, another lane adds... but it's continuous with the lane that dropped when it began. So, we're now at (0 1 2), but we've performed some voodoo and transformed what was the number 3 lane into the number 2 lane. So that's funky.

Continuing north, a left exit at Kew Gardens gives us (1 2) heading up the ramp. The added lane afterwards is to the right so we are back to (1 2 3) where we began. A lane drop at Northern Blvd gives us (1 2), two added lanes to the left then gives us (-1 0 1 2). But those lanes exit at the Cross Island so we're back to (1 2) through that interchange, and since the lane adds back to the right we're once again at (1 2 3) going over the Whitestone Bridge.

Then the toll plaza makes this difficult, but if we follow the striping as best as possible...
1 becomes two toll lanes, call 'em 0 and 1.
2 fans out into three toll lanes, call 'em 1.5, 2, and 2.5.
3 becomes 3, 4, 5, 6, and 7.

Coming out of the toll plaza, 0 and 1 go back together so that's just 1 again. 1.5 and 2 merge together, so that's 2. 2.5 and 3 merge, so we'll say that's 3. 4 merges into 5, and 7 merges into 6. 5 and 6 merge together with neither obviously favored but 6 is wider at the merge so we'll say 6 continues. That means we now have (1 2 3 6) heading north!

And then that's how the route ends. (1 2) continues to the Hutch, (2 3 6) goes to various places in the Bruckner Interchange, with 2 being an option lane.

[CtrlAltDel]

I'm pretty sure we've done this before, but I don't feel like digging it up.

We did a few years ago, yes, but I couldn't find it after a cursory search.

At least I'm not crazy. Or, crazier than anyone else here.

[mrsman]

Here's something I've long wondered about:

Take I-10, heading eastbound from its western terminus in Santa Monica, right as it crosses Ocean Avenue. Here, the road has two lanes, which we can number according to the standard California convention, 1 for the left lane and 2 for the right. Let's call this configuration (1 2). As the highway crosses the Pacific Coast Highway, it picks up another lane on the right. This would be lane 3, leading to (1 2 3). Near Cloverfield Boulevard, it picks up another, again on the right, making (1 2 3 4).

I wish that the entire forum would adopt the convention of numbering the lanes.  It would make it so much easier to refer to technical stuff on the highways.

Nothing outs me as a native Californian more than this.  I don't refer to the local (Washington DC area) highways with "the" anymore, but I do say stuff like, "be sure that you're in the number 3 lane of 270 as you approach the Beltway so that you can merge over and exit at Georgia Ave."  And the response is "What's the number 3 lane?"

But I-5 will ALWAYS be "the 5" and US 101 will ALWAYS be "the 101". 

[hotdogPi]

I usually say:

Two lanes:
Left lane, right lane

Three lanes:
Left lane, middle lane, right lane

Four lanes:
Left lane, second left lane, second right lane, right lane

Five lanes:
Left lane, second left lane, middle lane, second right lane, right lane

"Right lane" can be substituted with "exit lane" (or "breakdown lane" on I-93*) when appropriate. Also, "one lane to the left" and "one lane to the right" can be used relative to the current lane.

*Driving in the breakdown lane is allowed at certain times of day between exits 41 and 47 on I-93 in Massachusetts.

[mrsman]

And now for a comment relevant to your topic:

I-405 in the LA area does not have any left entrance or exits.  One can drive in the left two regular (non-HOV) lanes all the way from Sylmar to El Toro without being forced to merge ever.

CA-134 on the other hand has a terrible interchange with I-5 with lanes coming in from the left.  And the HOV lane does not simplify the setup.  When I drove this road, I feel as though I'm constantly changing lanes just to stay on the freeway!

Eastbound 134:  Lanes 12 of US 101 become lanes 12 of CA-134 at the NoHo interchange.  Then, lanes from the 170 come in from the left, so we have -1 0 1 2.  An HOV lane is then added on the left for: -2 -1 0 1 2.  This is consistent through Toluca Lake and Burbank until you approach the 5.

Lanes 1 and 2 force an exit to I-5.  Lane -2 loses its HOV restriction, so three lanes through the interchange.  Then, two lanes come in from southbound I-5 on the left:  -4 -3 -2 -1 0.  Lane 0 ends.  A new HOV lane, -5 is added on the left.  From I-5 northbound a new lane 0 is added to the right, but it quickly exits at San Fernando Road.  So at this point, in Glendale, we have -5 -4 -3 -2 -1.  Occasionally, lane 0 is added for a quick entrance quick exit situation.  But for this entire stretch in Glendale and Eagle Rock -5 -4 -3 -2 -1 is consistent. 

In Pasadena, Lane 0 comes in from San Rafael and is forced out as an exit to I-210 west and 710.  Another lane 0 is added at Orange Grove and forces an exit at Fair Oaks.  Lane 0 is added in from I-710 and lane 1 and 2 is added in from I-210.  Lane 2 ends.  And now the whole freeway continues as I-210.

No time to do westbound now.

[Duke87]

I wish that the entire forum would adopt the convention of numbering the lanes.  It would make it so much easier to refer to technical stuff on the highways.

Nothing outs me as a native Californian more than this.  I don't refer to the local (Washington DC area) highways with "the" anymore, but I do say stuff like, "be sure that you're in the number 3 lane of 270 as you approach the Beltway so that you can merge over and exit at Georgia Ave."  And the response is "What's the number 3 lane?"

In the northeast, as least, it's quite unusual to have more than four lanes in one roadway. The convention of "left lane", "right lane", and then as needed "center lane" or "center-left lane" and "center-right lane" works just fine up until that point. It's only when you have five or more lanes that numbering them is the only clear way to identify a specific one.

California has a decent number of freeways with more than four lanes in one roadway, so they have developed this convention out of necessity. Elsewhere in the country, freeways for the most part aren't built that way, so the need isn't there.

It's also worth noting that while "right", "left", and "center" have clear meanings understood perfectly by any English speaker, understanding numbered lanes requires knowing the convention of how they are numbered. This adds difficulty and therefore means that such a convention isn't going to be adopted if it isn't needed.

[vdeane]

NYSDOT uses the numbered lane system internally but I don't know of anyone outside of DOT that uses anything other than "left", "center", and "right".  Even having a fourth lane is rare outside of exit-only lanes etc.

[MASTERNC]

I'll also go over a shorter route, the PA Turnpike going west.

East of the Blue Mountain tunnel, you mainly have lanes 1 & 2 being continuous (there are 3-lane sections east of there, but the same lane adds and drops).  Near Sideling Hill, you add a third lane on the right (1 2 3).  However, at the top of the hill, the left lane ends (so you are down to 2 3).  Before the Allegheny Tunnel, the same thing happens (right lane added, left lane drops), so you are left with (3 4).  Between the tunnel and Somerset, there is another climbing lane on the right, but the left lane ends at the top of the hill.  The result is none of the original lanes west of Harrisburg remains by the time you reach Somerset.

[Super Mateo]

Four lanes:
Left lane, second left lane, second right lane, right lane

Five lanes:
Left lane, second left lane, middle lane, second right lane, right lane

I tend to use "left center lane" and "right center lane" instead of second.  ISTHA numbers them, at least when driving through an open road toll.

[Sykotyk]

Or as my Grandfather called them: the Hammer, Sandwich, and Granny lanes.

I brought this topic up sometime in the past few years. Mostly because some states had the bad habit of adding a right line for slow vehicles (or extended on-ramps) and then ending the left lane. Ohio did this east of Columbus on I-70. Originally the right lane ended, but now the left lane ends. This is better for traffic, but because the right lane was just added, it meant the left lane number went up by one.

[DeaconG]

Or as my Grandfather called them: the Hammer, Sandwich, and Granny lanes.

I'm going to use this from now on!

[bzakharin]

I-76 from its Eastern terminus in NJ to the approach to the PA Turnpike is -4, -3 due to the left merges and right exits

[Kacie Jane]

And now for a comment relevant to your topic:

I-405 in the LA area does not have any left entrance or exits.  One can drive in the left two regular (non-HOV) lanes all the way from Sylmar to El Toro without being forced to merge ever.

Coincidentally, it's the same for the other 405 as well. At either end, once all the ramps from I-5 merge together, you have an HOV lanes and two GP lanes that all continue to the other I-5 interchange. (However, at the south end, the ramp from I-5 north becomes lane #4, which becomes exit only at SR 167.)

But if you include the state highway extensions, it's a little different. At the south end, if you're coming from SR 518, you become lane #3, and have to merge left to continue onto SR 525 instead of I-5. Southbound, if you're coming from SR 525, you're in either 1 or 2, and you have to be in either 2 or 3 to continue onto SR 518, so no merge required in that case, unless you're an HOV.

[ET21]

Or as my Grandfather called them: the Hammer, Sandwich, and Granny lanes.

I'm going to use this from now on!

I'm a sandwich person lol, occasionally going for the hammer

[bzakharin]

I-295 in DE/NJ is also interesting due mainly to the 42/76 interchange mess.
It starts as 2 lanes as it breaks off from I-95 in Delaware
A left lane is added from South 495, 95, etc, while a right lane is added from US 13 (0 1 2 3)
On the other side of the bridge, the left 3 lanes form the NJ Turnpike, while  I-295 gets a new right lane (3 4)
When US 130 joins I-295 it adds another lane from the right (3 4 5)
Exit 26 to I-76 takes away the left lane (4 5)
Entrance from I-76 adds a lane on the right (4 5 6)
The remaining 40 miles or so maintain this configuration

Going Southbound into Exit 26 with 3 lanes
The left lane exits to I-76 (2 3)
Replaced by one entering from 76 (1 2 3)
The right lane ends right after US exits 130 (1 2)
The NJ Turnpike merges in from the left (-1 0 1 2)
After the toll plaza in Delaware, 6 lanes emerge. It's hard to keep track, but looks like (-1 0 0.5 1 2 3)
The left and right lane exit (0 0.5 1 2)
The right two lanes exit to US 13 (0 0.5)
Two lanes enter, one from the left and one from the right (-1 0 0.5 1)
The right two lanes exit to I-95/495 North (-1 0)
And 295 ends at I-95

[Alex4897]

Here's I-95 within Delaware:

Maryland -> Pennsylvania

I-95 start with 3 lanes at the Maryland state line: (1, 2, 3)
The road enters the the toll plaza gains a lane between lanes 1 and 2 for the EZPass express lanes: (1, 1.5, 2, 3)
This configuration continues until DE 1 / 7, where it gains a lane on the left: (0, 1, 1.5, 2, 3)
The right lane peels off for I-295 and the Delaware Memorial Bridge: (0, 1, 1.5, 2)
A left lane is added from DE 141: (-1, 0, 1, 1.5, 2)
The two right lanes split off for I-495: (-1, 0, 1)
A left lane is added from I-295 while the right lane ends: (-2, -1, 0)
The right lane exits off for DE 4: (-2, -1)
A right lane is added from 10th St: (-2, -1, 0)
A right lane is added for the exit at US 202, then the two right lanes exit off: (-2, -1)
This continues until I-495 where two right lanes are added, then the highway crosses the state line: (-2, -1, 0, 1)

Pennsylvania -> Maryland

I-95 starts off with 2 lanes at the state lane (I-495 appears to split off prior to the line in Pennsylvania): (1, 2)
A right lane is added from US 202: (1, 2, 3)
The right lane splits off for Adams St: (1, 2)
A left lane is added from MLK Blvd: (0, 1, 2)
A left lane is added from I-495: (-1, 0, 1, 2)
The right lane splits off for DE 141: (-1, 0, 1)
Two lanes are added from I-295: (-3, -2, -1, 0, 1)
The right lane splits off for DE 1 / 7: (-3, -2, -1, 0)
The right lane ends after the toll plaza: (-3, -2, -1)

I hadn't realized that southbound was worse than northbound in this aspect.