Tapers and diagrammatic signage

[myosh_tino]

I saw 3 California diagrammatic signs this weekend:
15/215 north split
10/60 west split
end of 62 splitting into 10 east/west

Just got back from Las Vegas and there is a diagrammatic sign at the I-15/I-40 interchange in Barstow.

BTW, citrus, don't copy my avatar! 

[Truvelo]

Inside lane merges are used quite extensively on the British motorway network, but with a special striping arrangement (called "tiger tails") which is designed to establish lateral separation between the merges for ramp lane 2 and ramp lane 1.  Tiger tails are also used for lane drops with optional lanes, which is the reverse of the merging situation.

The traditional British design had two lanes on entry and exit ramps but without the "tiger tail" treatment. These are no longer being applied due to safety problems where two vehicles could be side by side on the entry ramp at the point of merge. Newer ramps have just a single lane and many existing ones are being restriped into a single lane. Where traffic levels are high they are being tiger tailed where space allows.

Below is a typical example of the traditional design. As far as I'm aware the UK is the only country to have two lane on-ramps without any separation where there are no lane gains at the merge - unless anyone can tell me different.

[Brandon]

Below is a typical example of the traditional design. As far as I'm aware the UK is the only country to have two lane on-ramps without any separation where there are no lane gains at the merge - unless anyone can tell me different.

I've seen a similar design in Illinois (and a few other places) where there are two lanes on the ramp, one lane drops just before the merge, and there is no lane gain at the merge.  It is commonly used where there are two left turn lanes onto the entrance ramp.

Example: Roosevelt and I-355, northbound:
http://maps.google.com/maps?hl=en&ie=UTF8&ll=41.859557,-88.038297&spn=0,359.964209&z=16&layer=c&cbll=41.859628,-88.040554&panoid=lSBrAD09bo7KvwyPrc9GdQ&cbp=12,12.12,,0,5
Two lane ramp looses a lane before the merge, and no lane is added to I-355 after the merge.

[codyg1985]

The largest diagrammatic sign I have seen is in Birmingham, AL along I-65 approaching the I-20/59 interchange:

Street View

[thenetwork]

The more I thought of it, there are several merging tapers that were never used on the west side of Cleveland -- they only allow traffic on one of the lanes, then stripe off the other.

-  SB I-71 to SB SR 176/Jennings freeway (actually its the ramp coming from I-90 East to I-71 South which includes a crossover ramp to SR-176.

-  WB I-480 to SR-237 South (Airport Exit)

-  NB I-71/SR 176 to I-490 East.

-  (I think) NB I-77 to East 55th Street (Unsigned I-490 East)

And based on the way people drive in Cleveland, it's no wonder why despite the laneage being there for over 30 years, it was never implemented.

[vdeane]

There are also some two-lane on-ramps in the Rochester area where there are no lane gains on the freeway.  The second lane is usually very short though, and I can't think of a case where it shouldn't be removed altogether.

[roadfro]

Below is a typical example of the traditional design. As far as I'm aware the UK is the only country to have two lane on-ramps without any separation where there are no lane gains at the merge - unless anyone can tell me different.

These situations are probably a lot more common than you'd think...

I can think of a few examples in Nevada. Most come from having two left turn lanes from the cross street onto the ramp, which must merge into a single lane before making the merge onto the freeway mainline.  I-80 EB onramp at McCarran Blvd West in Reno (Google Map) or US 95 SB onramp at Craig Road in Las Vegas (Google Map) are two that come to mind.

The difference between these examples and the photo above is that the two lanes on the onramp merge into one further upstream from the gore, which greatly reduces the likelihood of having two vehicles next to each other at the end of the ramp.

[jdb1234]

The largest diagrammatic sign I have seen is in Birmingham, AL along I-65 approaching the I-20/59 interchange:

Street View

Like This:

[citrus]

I saw 3 California diagrammatic signs this weekend:
15/215 north split
10/60 west split
end of 62 splitting into 10 east/west

Just got back from Las Vegas and there is a diagrammatic sign at the I-15/I-40 interchange in Barstow.

BTW, citrus, don't copy my avatar! 

Heh....sorry about that...but I can see "the 5" when I walk out my apartment door...

[myosh_tino]

Heh....sorry about that...but I can see "the 5" when I walk out my apartment door...

No problem but the "5" on your interstate shield is too big for California standards.

BTW, when you say "the 5", is it safe to assume you're living in southern California?  When people use the word "the" in front of a route number (like "the 5" or "the 101" or "the 405") it makes us northerners shudder. 

[Chris]

Like This:
http://s761.photobucket.com/albums/xx260/jdbarnes1234/100_0370.jpg

What's that, a Christmas tree? 

Never seen such signs in Europe, although fork-signs are common.

[citrus]

Heh....sorry about that...but I can see "the 5" when I walk out my apartment door...

No problem but the "5" on your interstate shield is too big for California standards.

BTW, when you say "the 5", is it safe to assume you're living in southern California?  When people use the word "the" in front of a route number (like "the 5" or "the 101" or "the 405") it makes us northerners shudder. 

Yes, I live in San Diego (unfortunately). It does feel natural to use the definite article when I'm down there though....but it sounds weird when people refer to highways elsewhere though.

Back on topic, here's a diagrammatic sign that I absolutely hate. The "tail" is way too long. This sign is relatively new (replaced sometime in the early 2000's), and I thought the old one looked a lot better.

[Bryant5493]

^^ Yeah, I agree the tail is too long. It could be shortened at least a 1/4.


Be well,

Bryant

[Duke87]

In NYSDOT's rather slow but ongoing effort to modernize the signage on the Cross Bronx, a shiny diagrammatic has shown up eastbound for a junction that at this point is actually three exits away:


Brand new sign bridge, too. This isn't a replacement, there previously was no signage in that particular location of any sort (as the street view demonstrates).

It's a nice addition, considering how many out of state truckers may not be aware of the necessity to stay left to follow I-95 there - especially since the configuration of lane pickups and drops over the following couple miles is such that a car in the left lane at exit 6B will have to shift left twice to end up in the right lane at exit 8B!

I think most drivers know what state New Haven is in, though.

[agentsteel53]

I think most drivers know what state New Haven is in, though.

one can never have too little faith in the dolts that are churned out by the American public school mill.

[rawmustard]

I saw a taper on an I-75 entrance ramp to eastbound I-69 on my way here for Thanksgiving. I'm thinking it'll probably be gone whenever the interchange gets rebuilt.