Why aren't reversible lanes more popular?

[404inthe404]

The vast majority of urbanized areas have a dense core surrounded by ring(s) of suburbs. Predictably this causes traffic congestion going to the dense core in the morning and leaving the dense core in the afternoon.

It seems natural to "resize" a freeway with reversible lanes to help meet capacity demand. This idea is not new and already exists in several places, such as Chicago and LA. My question is why this is not more common in the US. It seems like a no-brainer to me.

I am blessed with a reverse commute in Atlanta. Every day, I leave midtown Atlanta along I-85 (via the Buford-Spring) and every afternoon I return on I-85 southbound. On both trips, I see a sea of cars on the opposite side, rolling at a snails pace, advancing in feet per minute, while traffic on my side could easily be accommodated by 3 or 4 lanes of traffic rather than the 6 or 7 available. Obviously converting lanes to reversible lanes would incur construction costs, but I imagine these costs are nowhere near the cost of a large-scale infrastructure expansion.

[hotdogPi]

I have seen reversible lanes in Atlanta, although it's 1 lane on one side and 2 lanes on the other, and it's a surface road, not a freeway.

It has a lane with an electronic "X" or "√" on it (a check, not a square root), and the fact that it's electronic (unlike the outside lanes) makes me think it's reversible.

[DaBigE]

Reason: High-speed, head-on crash risk.

Directional separation, whether by barrier wall or wide median is a necessity at freeway speeds. Occasionally, you'll see movable barriers in construction zones, but they are far from standard (at least around here) and they don't come cheap.

[Indyroads]

Reason: High-speed, head-on crash risk.

Directional separation, whether by barrier wall or wide median is a necessity at freeway speeds. Occasionally, you'll see movable barriers in construction zones, but they are far from standard (at least around here) and they don't come cheap.

That can be resolved by the moveable concrete/metal median barriers.

[jeffandnicole]

Reason: High-speed, head-on crash risk.

Directional separation, whether by barrier wall or wide median is a necessity at freeway speeds. Occasionally, you'll see movable barriers in construction zones, but they are far from standard (at least around here) and they don't come cheap.

That can be resolved by the moveable concrete/metal median barriers.

That's what he said.

It's a slow moving truck.  And yes, they don't come cheap, and on occasion, the vehicle moving that barrier will break down.  And there are employee costs to look at as well.

The zipper barrier mover is used on the Walt Whitman & Ben Franklin Bridges every day, both of which are 7 lane bridges between Philly & South Jersey.  It takes, I believe, 45 minutes to go about 1 1/2 miles.

[31E]

I've long wondered why reversible lanes aren't used more often on busy arterials in suburban environments, particularly the denser areas where NIMBYs are dominant or where physical constraints preclude widening. Reversible lanes can be a simple and easy way to relieve congestion but for some strange reason most places resist the concept. Reversible lanes on freeways are tougher to implement, and on most freeways widening the roadway would probably be easier. However, urban freeways that are physically constrained (read: we'd have to demolish a mile-long row of buildings to widen it) and feature asymmetric traffic congestion (read: every morning westbound is crawling but eastbound is free-flowing) would be great candidates for reversible configurations. Movable barriers are expensive, but in the situation I outlined widening the road would probably be even more expensive.

My guess for why solutions like these aren't more popular is the same reason divided 2+1 roads remain very rare in the U.S. - lack of funding and commitment to transportation, which is rooted in political laziness on the part of state legislatures (Congress has the same affliction but states are responsible for most roads).

[deathtopumpkins]

There's precedent for doing this with a movable barrier.

On I-93 south of Boston, for example, during afternoon rush hour MassDOT uses a movable barrier to cordon off one of the northbound lanes to carry southbound traffic. This is done with the existing permanent jersey barrier in place, using nothing more than two (slow speed) crossovers, a barrier truck, and a few message boards, which demonstrates that it doesn't even need to be a significant, long-term investment. If it doesn't work out you still have the road just like it was before.

I also think full reversible carriageways like the I-95 and I-64 ones in Virginia) would be a nice idea in more places.

[SignBridge]

A very interesting set of reversible lanes exists on I-395 just outside Washington D.C. in Arlington/Fairfax Counties, Virginia. It's a separated set of 2 lanes between the north and southbound lanes, with separate entrance and exit ramps. The whole thing is remotely controlled by a dispatcher. Multiple sets of gates and lights are used at all entrance ramps. This was built about 40 years ago, extended further south more recently. A very sophisticated set-up for its time and still is even today.  A very interesting highway to drive. 

[JREwing78]

I'm seeing the construction-zone variant of this much more frequently, when one lane of traffic crosses over and uses the opposite-direction carriageway with a barrier in between.

I would imagine in most places that could use a movable barrier, the bridge piers in the median make executing such a plan impossible. It also requires considerable manpower to monitor and execute the lane reversal transition. Also, in places like Chicago, the traffic is often equally heavy in both directions, basically turning your decision into which direction of traffic to sacrifice to speed up the other one.

[realjd]

Tampa's Selmon Expressway has something like this. They built elevated express toll lanes above the medians that reverse direction depending on the time of day. I remember Norfolk also having reversible HOV lanes in the median.

Melbourne, Australia has an entire reversible freeway.

[Alps]

Reason: High-speed, head-on crash risk.

Directional separation, whether by barrier wall or wide median is a necessity at freeway speeds. Occasionally, you'll see movable barriers in construction zones, but they are far from standard (at least around here) and they don't come cheap.

That can be resolved by the moveable concrete/metal median barriers.

That's what he said.

It's a slow moving truck.  And yes, they don't come cheap, and on occasion, the vehicle moving that barrier will break down.  And there are employee costs to look at as well.

The zipper barrier mover is used on the Walt Whitman & Ben Franklin Bridges every day, both of which are 7 lane bridges between Philly & South Jersey.  It takes, I believe, 45 minutes to go about 1 1/2 miles.

The machine can move at 7 mph during operation, certainly at least 5, so it should only take half that to traverse the bridge. Disabled machines can be towed through the remaining barrier run. Only one employee is required to run the machine (two are preferable), but there's a second one required to retrieve the first one from the far end of the run.

[1995hoo]

The Theodore Roosevelt Bridge (I-66 and US-50) in Washington, DC, has a single center reversible lane that is switched via a zipper barrier of the sort described above. I don't believe I've ever actually seen the machine operating, though I've certainly noticed when the barrier has been moved.

Poster "SignBridge" mentions the reversible center carriageway on I-395 and I-95 here. There's another much newer similar reversible center carriageway in the Tidewater area of Virginia on I-64. "SignBridge" is mistaken on one thing, though, when he says the I-395/95 setup is remotely controlled by a dispatcher. It's not. They actually have a guy in a truck driving through the lanes making sure it's clear and then opening/closing the gates as appropriate. VDOT is extremely cautious about the process for reversing the lanes due to their understandable fear that if they mess up, they might have vehicles closing on each other at 150 mph or more (i.e., if I'm going south at 75 mph and you're coming north in the same lane at 75 mph, our closing speed is 150 mph). They haven't been willing to rely solely on cameras and computers for fear of equipment failure.

[2Co5_14]

There is a reversible lane project proposed for I-75 & I-575 northwest of I-285 in suburban Atlanta.  It will be a design-build-operate project, and it is currently in the stage of reviewing consultants' proposals to select the winner.  It will have 2 reversible lanes, partly elevated and partly at grade, operating southbound in the morning and northbound in the afternoon.

http://www.nwcproject.com/

I'm hoping this project will be coming soon, since it would directly benefit my daily commute on the express bus.

[SteveG1988]

Reason: High-speed, head-on crash risk.

Directional separation, whether by barrier wall or wide median is a necessity at freeway speeds. Occasionally, you'll see movable barriers in construction zones, but they are far from standard (at least around here) and they don't come cheap.

That can be resolved by the moveable concrete/metal median barriers.

That's what he said.

It's a slow moving truck.  And yes, they don't come cheap, and on occasion, the vehicle moving that barrier will break down.  And there are employee costs to look at as well.

The zipper barrier mover is used on the Walt Whitman & Ben Franklin Bridges every day, both of which are 7 lane bridges between Philly & South Jersey.  It takes, I believe, 45 minutes to go about 1 1/2 miles.

The machine can move at 7 mph during operation, certainly at least 5, so it should only take half that to traverse the bridge. Disabled machines can be towed through the remaining barrier run. Only one employee is required to run the machine (two are preferable), but there's a second one required to retrieve the first one from the far end of the run.

The walt whitman is getting a lighter movable steel barrier, perhaps that is to help with the switchover time?

RE: STeel shell movable barrier  http://www.drpa.org/deckthewalt/

[SignBridge]

1995hoo; my apologies if I made an error re: the control of the I-395 reversible lanes. But I don't understand. If the gates are manually operated, then who controls the messages on the overhead signs saying that the lanes are open or closed? I just always assumed that the whole operation must be remotely controlled from a central point.

[1995hoo]

1995hoo; my apologies if I made an error re: the control of the I-395 reversible lanes. But I don't understand. If the gates are manually operated, then who controls the messages on the overhead signs saying that the lanes are open or closed? I just always assumed that the whole operation must be remotely controlled from a central point.

Oh, believe me, it's a valid assumption and it's been a matter for some debate among at least some local roadgeeks as they extend the reversible carriageway further south. As far as I know, the guy driving the truck doesn't control the signs. But I don't know who does. "cpzilliacus" or "mtantillo" may know.

[lordsutch]

There is a reversible lane project proposed for I-75 & I-575 northwest of I-285 in suburban Atlanta.  It will be a design-build-operate project, and it is currently in the stage of reviewing consultants' proposals to select the winner.  It will have 2 reversible lanes, partly elevated and partly at grade, operating southbound in the morning and northbound in the afternoon.

http://www.nwcproject.com/

I'm hoping this project will be coming soon, since it would directly benefit my daily commute on the express bus.

There's also a similar toll reversible lanes project on I-75 south from I-675 to McDonough, and should be finished before the Northwest Corridor (75/575) is done. Details at http://www.dot.ga.gov/travelingingeorgia/expresslanes/I75expresslanes/Pages/default.aspx

[jeffandnicole]

Reason: High-speed, head-on crash risk.

Directional separation, whether by barrier wall or wide median is a necessity at freeway speeds. Occasionally, you'll see movable barriers in construction zones, but they are far from standard (at least around here) and they don't come cheap.

That can be resolved by the moveable concrete/metal median barriers.

That's what he said.

It's a slow moving truck.  And yes, they don't come cheap, and on occasion, the vehicle moving that barrier will break down.  And there are employee costs to look at as well.

The zipper barrier mover is used on the Walt Whitman & Ben Franklin Bridges every day, both of which are 7 lane bridges between Philly & South Jersey.  It takes, I believe, 45 minutes to go about 1 1/2 miles.

The machine can move at 7 mph during operation, certainly at least 5, so it should only take half that to traverse the bridge. Disabled machines can be towed through the remaining barrier run. Only one employee is required to run the machine (two are preferable), but there's a second one required to retrieve the first one from the far end of the run.

The walt whitman is getting a lighter movable steel barrier, perhaps that is to help with the switchover time?

RE: STeel shell movable barrier  http://www.drpa.org/deckthewalt/

Maybe the time included time to start up/shut down the machinery. This site, which includes pics for those that haven't seen the truck in use, says it takes about 30 minutes. http://www.barriersystemsinc.com/stuff/contentmgr/files/0/c0a0053d6a03f88d12ab6702fd439dc7/files/ben_franklin_bridge_case_study.pdf


The steel zipper barrier was installed prior to the redecking project.  The width was 6" more narrow than the concrete barrier they had (and still have on the other bridges).  The reasoning was, per the DRPA, they needed every inch available. During the redecking, they redecked one lane at a time.  That required two jersey construction barriers on either side of the lane, and the zipper barrier to separate the flow of traffic.  Normal lane width is only about 11 feet wide, so the 3 barriers narrowed down the remaining 6 lanes nearly another foot or so each.

[Alps]

The walt whitman is getting a lighter movable steel barrier, perhaps that is to help with the switchover time?

RE: STeel shell movable barrier  http://www.drpa.org/deckthewalt/

The actual reason for the steel barrier, at least here, is because it costs more to constantly replace sections of concrete barrier. The steel barrier costs a lot more upfront but hardly ever is damaged enough to require replacement.

[jeffandnicole]

Or could be for both reasons, as both are referred to on page 1 of this: http://www.drpa.org/publish/library/november%202010%20ceo%20report.pdf

[cpzilliacus]

1995hoo; my apologies if I made an error re: the control of the I-395 reversible lanes. But I don't understand. If the gates are manually operated, then who controls the messages on the overhead signs saying that the lanes are open or closed? I just always assumed that the whole operation must be remotely controlled from a central point.

Oh, believe me, it's a valid assumption and it's been a matter for some debate among at least some local roadgeeks as they extend the reversible carriageway further south. As far as I know, the guy driving the truck doesn't control the signs. But I don't know who does. "cpzilliacus" or "mtantillo" may know.

I believe the guy who drives the truck checks for vehicles that have been abandoned on the shoulders as part of his journey prior to reversing the facility, and arranges to have them towed and stored (I have never seen an abandoned vehicle left from when the facility was running in the opposite direction).

The truck used to be a VDOT truck, now it belongs to the third-party contractor that has the maintenance contract for I-95 between Va. 234 (Dumfries Road) and I-495 and for all of I-395.

As I understand it, the truck starts from the south when the lanes are to be flipped from northbound to southbound operation, after they are closed to all traffic.   Once the trip is complete, the truck radios in that the lanes can be opened for southbound operation.  If they are to be flipped from soutbound operation to northbound operation, the truck starts from the Pentagon and drives south, repeating the process.

It will be interesting to see what the arrangements are once Transurban starts HOV/Toll lane operation on the I-95 segment (being extended to Garrisonville in Stafford County now) and on the short I-395 segment from I-495 north to the Turkeycock Run ramps between Va. 648 (Edsall Road) and Va. 236 (Duke Street). From Turkeycock Run north to the Pentagon, they will remain conventional HOV lanes.