Reversible highway lanes

[Duncan MacGregor]

Early on, many pictures of people leaving New Orleans
showed six-lane highways with three empty inbound lanes
and three packed outbound lanes.

It seems sad, that in a matter of life and death, that some of
the empty inbound lanes could not also be used for outbound traffic.
This would leave, say, one inbound lane, and five outbound lanes.

Where are there highways or road systems that allow this?

How do these systems work?
How are the lanes switched over?

[Mark Brader]

Post by Duncan MacGregor
It seems sad, that in a matter of life and death, that some of
the empty inbound lanes could not also be used for outbound traffic.
This would leave, say, one inbound lane, and five outbound lanes.

I suggest that this topic belongs in misc.transport.road, but I'll
respond here.

With a divided highway there would need to be special ramps in order
for the lanes to be used the wrong way. It would be easier to declare
all six lanes outbound, with all ramps reversed, than leaving one lane
in the normal direction, but the motoring public probably couldn't
deal with it, and there would be accidents.

Post by Duncan MacGregor
Where are there highways or road systems that allow this?

If I recall correctly, I-5 in Seattle has (or used to have) a section
of center express road with ramps both ways; it's only opened in rush
hours and then runs in the direction of the primary traffic. That's
the only place I've seen that sort of thing done on a divided highway.
The ramps currently going the wrong way are closed off by movable barriers.

On non-divided roads one sometimes sees one or more center lanes with
overhead signals every so often, telling whether you can use the lane
(green) or not (red X symbol). Three examples that come to mind
immediately are Jarvis Street in Toronto (5 lanes in no-parking hours),
the Lions Gate Bridge in Vancouver (3 lanes), and the Golden Gate
Bridge in San Francisco (6 lanes, 2 reversible). I know I've seen
this in other places, mostly on bridges.

I've also seen streets with signs like "ONE WAY -> (3-6 PM MON-FRI)",
particularly in Washington DC. I remember seeing a street there
that was one-way one way in the morning rush hour, the other way in
the evening rush, and two-way at other times. This was years ago and
I don't know if they still do it.

[James Robinson]

Post by Duncan MacGregor
Early on, many pictures of people leaving New Orleans
showed six-lane highways with three empty inbound lanes
and three packed outbound lanes.
It seems sad, that in a matter of life and death, that some of
the empty inbound lanes could not also be used for outbound traffic.
This would leave, say, one inbound lane, and five outbound lanes.

They did use the inbound highway lanes for evacuation. They implemented a
plan that posted police at all the on-ramps to prevent cars from getting on
the highway, then set up contraflow. It takes a lot of police to block all
the necessary access to the highway, but the plan did work as they hoped.

[Michael G. Koerner]

Post by Duncan MacGregor
Early on, many pictures of people leaving New Orleans
showed six-lane highways with three empty inbound lanes
and three packed outbound lanes.
It seems sad, that in a matter of life and death, that some of
the empty inbound lanes could not also be used for outbound traffic.
This would leave, say, one inbound lane, and five outbound lanes.
Where are there highways or road systems that allow this?
How do these systems work?
How are the lanes switched over?

Several interstates in southeast Louisiana and southwest Mississippi were set
up for such 'contraflow'. The six and more-lane urban freeways were not set
up that way as there would have been severe backups where all of those lanes
mush down to the four lanes on the rural interstates.

They use permanently paved crossovers with gates and reverse-reading signs for
traffic control.

MANY places in the southeast coastal regions are set up to allow contraflow
use for such mass evacuations.