Dropping a lane, but not from either edge

[vtk]

But I thought this thread was intended to be about just losing a lane, not at a merge.

Ditto.

In many ways, a merge is worse than a lane just ending because neither lane has clear priority. While the Green Book includes standards for such a setup, it is explicitly stated that such a situation is less than ideal and should be avoided.

Yes but if an interior lane ends by merging into another interior lane, or (almost equivalently) two interior lanes merge into one – the situation this thread is looking for – it's just about as hazardous as the common "inside lanes merge" situation where two distinct traveled ways converge.

[myosh_tino]

Found another one similar to the San Tomas Expressway one I posted earlier.

It's located on northbound Wolfe Road in Cupertino approaching the I-280 interchange.  In this case, the far right lane is an exit only lane to southbound I-280 and the next lane to the right ends and has to merge with the lane to its left because the Wolfe Road overpass is only 4 lanes wide (2 in each direction).

https://goo.gl/maps/iu2K7jzbpM82

It's kind of hard to see the lane-drop because the pavement markings have worn off in the street view image.

[Jardine]

Hey, no problem with all the variations noted above.  It turned out to be a very interesting topic, and the diversity of the replies was fun.

Some of the examples would scare the poo out of me if I happened upon them unawares at rush hour.

[jeffe]

Eastbound Interstate 80 in Emeryville, California has this type of situation.  The left two lanes are HOV lanes and the right lane is dropped.

https://goo.gl/maps/wfeg3basWaT2

[mrsman]

Eastbound Interstate 80 in Emeryville, California has this type of situation.  The left two lanes are HOV lanes and the right lane is dropped.

https://goo.gl/maps/wfeg3basWaT2

The configuration would be safer if there was a passing restriction between main lanes and HOV lanes in the area of the lane drop.  I know that generally Bay area HOV lanes allow people to change lanes at any time (unlike So Cal) but there should be an exception for at least 1/4 mile in the area of this interchange so that those from the right HOV lane can merge to the left without worrying about somebody from the lane on their right merging in as well.  IT can be signified with 4 yellow lines, the same way SoCal signifies no passing zones between HOV and general purpose lanes.

[mrsman]

Found another one similar to the San Tomas Expressway one I posted earlier.

It's located on northbound Wolfe Road in Cupertino approaching the I-280 interchange.  In this case, the far right lane is an exit only lane to southbound I-280 and the next lane to the right ends and has to merge with the lane to its left because the Wolfe Road overpass is only 4 lanes wide (2 in each direction).

https://goo.gl/maps/iu2K7jzbpM82

It's kind of hard to see the lane-drop because the pavement markings have worn off in the street view image.

This makes no sense at all.  If I interpret this correctly, Wolfe Rd has 3 lanes of traffic northbound approaching Vallco Pkwy.  It then widens to 4, but the 3rd lane merges into the 2nd lane, so that the 4th lane can lead directly to I-280.  At the I-280 ramp, the left 2 lanes continue on Wolfe Rd and the right lane exits onto the interstate.

Why even widen to 4 lanes at all?  Simply force the third lane onto the I-280 ramp.  There is no need for this complicated setup.

[mrsman]

Better than the original end of the Truck and Bus Lanes at Exit 9 where all three lanes dropped completely before the extension to 8A took place.  At least the truck lanes afterwards had continuous lanes as I am sure they do now.

However, I think that the NJTA should have done at Exit 6 what they did at the Eastern and Western Spur split just north of 14.  Have the three lanes split into 2 for the 6 ramp and 2 through on both carriageways then the the 2 through lanes merge into the 3 continuing lanes, as well as the 2 ramp lanes merge into the 3 Penn Extension lanes.

You figure that set up is working at the transition of the dual carriageways from the Inner and outer to the two spurs, that the engineers would have copied that design instead of making the Exit 6 like any other interchange along the dual configuration.

I remember attending a meeting before the project first started.  They said numerous studies showed that what they did at Exit 6, both for the merge and diverge, was the optimal way to go.

As I have not driven by exit 6 since the extension of the dual-dual setup from exit 8A, can someone please tell me in detail how the lanes are now set up?  There is no updated GSV as far as I can tell.

[mrsman]

One more comment:  When two highways merge so that the left lane of one highway and the right lane of the other are forced into one, it is known as an inside lane merge.

[jeffandnicole]

Better than the original end of the Truck and Bus Lanes at Exit 9 where all three lanes dropped completely before the extension to 8A took place.  At least the truck lanes afterwards had continuous lanes as I am sure they do now.

However, I think that the NJTA should have done at Exit 6 what they did at the Eastern and Western Spur split just north of 14.  Have the three lanes split into 2 for the 6 ramp and 2 through on both carriageways then the the 2 through lanes merge into the 3 continuing lanes, as well as the 2 ramp lanes merge into the 3 Penn Extension lanes.

You figure that set up is working at the transition of the dual carriageways from the Inner and outer to the two spurs, that the engineers would have copied that design instead of making the Exit 6 like any other interchange along the dual configuration.

I remember attending a meeting before the project first started.  They said numerous studies showed that what they did at Exit 6, both for the merge and diverge, was the optimal way to go.

As I have not driven by exit 6 since the extension of the dual-dual setup from exit 8A, can someone please tell me in detail how the lanes are now set up?  There is no updated GSV as far as I can tell.

As the inner/outer roadways merge, forming 6 lanes. We'll number them from left to right 1,2,3,4,5,6, with the car lanes being 1,2,3 & the truck lanes being 4,5,6.

Lane 1 ends, merging right into lane 2.

Lanes 3 & 4 merge.

Lane 6 ends, merging left into lane 5.



First, the left lane ends, merging into the

[Tom958]

Southbound San Tomas Expressway in Santa Clara... https://goo.gl/maps/r29KxSh1ihL2

In this case, there are 4 lanes and the two middle lanes merge into a single lane.  The reason why is because the far right lane is an HOV lane (typical for Santa Clara county's expressways).

Well, son of a gun, it does exist!  I have to wonder, though, is this really the best way to end a lane there?  I can think of three alternatives: (1) end the left lane and then shift the remaining three lanes to the left; (2) exchange the width of the right shoulder for a hard barrier between the HOV lane and the left three lanes, and run the barrier from a point before the lane termination to a point after the lane has fully terminated; or (3) drop the far-left lane as a left-turn-only lane at the preceding intersection (this is probably the least desirable option in terms of maximizing traffic capacity within the available space).  But maybe the present configuration works just fine and drivers handle it in a safe and efficient manner.  Notice the odd signs informing motorists of the merge, though!

I probably would have opted for (1) to avoid this unusual situation.  (2) might make some sense but having a hard barrier does present some safety issues and would require the placement of sand barrels at the start of the barrier to prevent cars from hitting it head-on.  (3) wouldn't work given the amount of traffic San Tomas handles on a daily basis at that intersection.

I seem to recall that the county wants to add another lane to San Tomas south of El Camino but funding is an issue.

Why not paint a solid white line or, better, a double solid white line between the HOV lane and the regular lane through the merge area? Oh, maybe because the HOV lane is 3-7pm only. Not a very good reason.