Tapers and diagrammatic signage

[Chris]

I was wondering how common a "taper" is in the United States. I thought we Dutchies copied it from the Americans, but when I look at the numerous freeway videos available on Youtube, I don't see any at all.

A taper is a second lane from an entrance to a freeway which has to merge immediately, unlike the regular merging lanes which allows for traffic to pick up speed before merging to the left. If you're into a taper, you have to find a gap between traffic on the right lane of the upcoming freeway, and then merge between it.

A lot of people are scared of it, frightened that they can't find a spot to merge into, and get "squashed" between the traffic. The following photo was shot in my city, and shows a taper. It was closed at the time, because traffic had stalled because of a truck breakdown further downstream. Leaving the taper open would exacerbate the traffic congestion, because traffic has to stop to merge.



There are also tapers that split off the freeway, adding an additional exit lane, increasing capacity. Unfortunately, their usage is usually low, and until recently, signage in the Netherlands didn't support this type of road configuration.

Old signage, you don't see the exiting taper unless you're already at the spot.


New signage, the taper is signed, and comes with additional signage showing the taper on the signs.

[froggie]

Cases of the "taper" on on-ramps do exist within the U.S (there's a few in the DC area if you know where to look, and also at I-94/494/694 in Maple Grove, MN), but are fairly rare.  And they're also frowned upon by FHWA.

Having the "taper" on exit ramps (I've heard the term "Decision Lane" used before) is much more common in the states.

[Bryant5493]

I've encountered a few, and didn't know I had to merge until the last minute, because it wasn't signed well.

Here's an example of one that I encountered. The taper is about 1:00.

http://www.youtube.com/watch?v=yR8j3yNdjWY


Be well,

Bryant

[Mergingtraffic]

I've seem them in Boston quite a bit.

For example:  Where you merge onto I-90 WB from Route 128 NB.

Quite dangerous in my opinion.

[realjd]

Here's one from Fort Wayne, which may be gone now because of the construction. The corresponding SB exit on I-69 also seems to fit, although exit configurations like that are not uncommon:
http://maps.google.com/?ie=UTF8&ll=41.140288,-85.129897&spn=0.001501,0.003433&t=k&z=19

Most places I've seen do the "taper" before the actual merge onto the freeway. A 2 lane on-ramp will merge to 1 lane before it gets close enough to the freeway to merge, as seen here along I-95:
http://maps.google.com/?ie=UTF8&ll=27.999567,-80.63069&spn=0.00176,0.003433&t=k&z=19

[SSOWorld]

http://maps.google.com/?ie=UTF8&hq=&hnear=790+N+4th+St,+Platteville,+Grant,+Wisconsin+53818&ll=43.035905,-89.451467&spn=0.004988,0.009645&t=k&z=17

This one in Madison has a four lane ramp caused by a two lane left turn from NB connecting with a two lane right turn - it tapers to 2 lanes almost immediately, then to one as it merges onto the mainline.

[WillWeaverRVA]

There are at least two in Richmond: at the point that I-64 east merges onto I-95 south, and at the end of the onramp from VA 161 to I-95 south. The latter tends to create major traffic problems during rush hour.

[SSOWorld]

Minnesota is full of them.  Don't get me started.

[Mergingtraffic]

CT has one on the 4-lane C&D  road off Exit 23 on I-84 EB in Waterbury.  2-lanes from each side merging into one another.  However, there isn't much traffic, so it isn't much of an issue.

[UptownRoadGeek]

Mississippi used to have them on the northern stretch if I-55 in Jackson, but they were removed during when the highway was resurfaced.

[Mr_Northside]

The only one I'm personally aware of in PA (which by no means makes it the only one), is where the 2 lane ramp coming from the borough of Millvale meets PA-28 (southbound) right before the 40th St. bridge.

http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=15212&sll=43.035905,-89.451467&sspn=0.005583,0.009645&ie=UTF8&hq=&hnear=Pittsburgh,+Allegheny,+Pennsylvania+15212&ll=40.47577,-79.970799&spn=0.001453,0.003433&t=k&z=19

This situation should be changed in a couple of years when they redo Rt. 28 between here and I-279.


(The reverse "taper", where it is an exiting ramp, is found pretty often.)

[Brandon]

I was wondering how common a "taper" is in the United States. I thought we Dutchies copied it from the Americans, but when I look at the numerous freeway videos available on Youtube, I don't see any at all.

Chicagoland is chock full of them in the suburban areas.  They're more common for exits than entrances, but there's a fair number of entrances that have them.

[J N Winkler]

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.

In the US lane drops with optional lanes are used quite extensively, but are considered difficult to sign.  As others have noted, inside lane merges are deprecated but are still used by a number of agencies, including in new construction (Illinois portion of Borman Expressway comes to mind).

[froggie]

Minnesota is full of them.  Don't get me started.

Do tell.  The only one I recall is at 94/494/694 in Maple Grove (as I already mentioned).

[mightyace]

Tennessee seems to uses them often both on exits and entrances.

For example, on I-65 south of Nashville,
The SB exit and NB entrances of Exit 53, Saturn Pkwy.; Exit 59, TN 840; and Exit 65, TN 96 among many others.

[Riverside Frwy]

To me, these so called "tapers" look like a design flaw or problem in the highway plan.I mean, the lane is practically getting smashed.I wouldn't use that lane anyway.

[Duke87]

I-95 southbound merging onto the Cross Bronx has a situation like that (street view).

The New Jersey Turnpike at the end of the quad-carriageway system also sort of does (seen here). That one gives you a significant amount of space to merge, although it does still fly in the face of the typical convention that you make the right or left lane end before or after the merge point rather than having two lanes in the middle forced together. Usually it's safer that way, hence the convention.

As for diverging/exiting, "optional lanes" are all over the place.

[Scott5114]

In Oklahoma, there are several situations where a taper *could* exist, but generally how it is handled is to have the left-hand lane end before the ramp reaches the mainline. Kansas generally handles the situation by simply adding two lanes then having one or both end after a reasonable period.

The exit taper situation generally presents itself not in the way that is shown, but more like the second-to-right lane merely bifurcating itself at the exit point. This is often signed like so:



In the new MUTCD, this will be disallowed, and the new signs will be more like the Canadian ones in the same situation. These signs in Milwaukee illustrate the future of diagrammatic signing in the U.S.

[Chris]

^^ That first sign is hard to comprehend at 60 - 65 mph. The second one is better, also more like international standards (though that's not really an important issue in the U.S.)

[froggie]

In Oklahoma, there are several situations where a taper *could* exist, but generally how it is handled is to have the left-hand lane end before the ramp reaches the mainline. Kansas generally handles the situation by simply adding two lanes then having one or both end after a reasonable period.

Agreed, and I wonder if people are perhaps getting confused.  What you described is what I see *FAR MORE OFTEN* than a true "taper"...

[realjd]

In the new MUTCD, this will be disallowed, and the new signs will be more like the Canadian ones in the same situation. These signs in Milwaukee illustrate the future of diagrammatic signing in the U.S.

Up arrows instead of down now for through lanes?

[J N Winkler]

In the new MUTCD, this [stippled-arrow diagrammatics] will be disallowed, and the new signs [one-arrow-per-lane diagrammatics] will be more like the Canadian ones in the same situation. These signs in Milwaukee illustrate the future of diagrammatic signing in the U.S.

At the moment that change is only a proposal.  I am aware a number of agencies, including MoDOT, have been going for one-arrow-per-lane diagrammatics in a big way, but FHWA tried to make this change in the last major revision (2002) and failed.  I would guess that stippled-arrow diagrammatics would be retained as an option (they are useful in indicating left exits and exits on sharp curves) and diagrammatics will not be limited to situations where there is an optional lane, as is also currently proposed.

[haljackey]

Here in Canada Tapers are only used for off-ramps. 

Here's a quick example:

Approaching the off-ramp:


At the off-ramp:


I would get scared if they were on-ramps because there is very little room for the inside lane to merge with traffic.  In an off-ramp, the opposite of merging occurs, so its fine.

[J N Winkler]

The stippled-arrow versus one-arrow-per-lane diagrammatic issue was the subject of my comments to FHWA during the 2008 MUTCD rulemaking process.  My submission can be found here:

http://www.regulations.gov/search/Regs/contentStreamer?objectId=09000064806a56a4&disposition=attachment&contentType=pdf

[florida]

We have those down here.