keep left except to pass?

[zachary_amaryllis]

at one time, i remember seeing a 'keep left except to pass' sign, in ne colorado on I-76.. what would be the reason for this?

my best uneducated guess.. low traffic counts mean the right lane wears out before the left does, so they want to wear out the left lane before repaving it?

am i close?

[GaryV]

So you don't camp in the left lane, blocking faster traffic.

[hotdogPi]

So you don't camp in the left lane, blocking faster traffic.

That would be the purpose of a keep right except to pass sign. This is the exact opposite.

[jeffandnicole]

So you don't camp in the left lane, blocking faster traffic.

Reread what was written.

[I-55]

It could be that they want traffic to stay in the left lanes due to closely grouped interchanges (near Brush and Ft Morgan, 8 exits in 17 miles) and traffic merging on/off from the right. I-70 through Zanesville, OH has signs saying "Thru Traffic Keep Left", so maybe its something like that

[jakeroot]

Most analogous example I can think of would be the "thru traffic use left [xx] lanes" signs seen in areas such as I-5 in Olympia, WA.

[Ned Weasel]

This would make sense in situations where you have multiple successive left exits and entrances, but such situations are rare.

[kphoger]

The closest I've seen is signs telling truckers to use the left lane through a construction zone.

[zachary_amaryllis]

It could be that they want traffic to stay in the left lanes due to closely grouped interchanges (near Brush and Ft Morgan, 8 exits in 17 miles) and traffic merging on/off from the right. I-70 through Zanesville, OH has signs saying "Thru Traffic Keep Left", so maybe its something like that

this is (or was) much further northeast, i want to say from the state line down towards sterling.

[kendancy66]

In the OP the location CO was mentioned as location for this signage.  But no one has mentioned that this signage might exist in right hand driving countries like Great Britain or Japan

[jakeroot]

In the OP the location CO was mentioned as location for this signage.  But no one has mentioned that this signage might exist in right hand driving countries like Great Britain or Japan

Probably Australia or New Zealand, since they use MUTCD-inspired signage. But also not the point since they are RHD and keeping left is the law. Keeping right (in one form or another) is the law in the US; regulatory signs as described in the OP just don't make any sense, and direct traffic to not only (A) drive in the left lane regardless of what's in the right lane (generally illegal), but then (B) pass in the right lane, which is itself illegal in some places too. Just one big "WTF" kind of situation.

[mrsman]

The only thing that I could think of is perhaps there is some obstruction (like a low clearance overpass or tunnel) in the right lane so larger traffic (including trucks) are encouraged to drive in the left lane, instead of the right lane.  In that case, the usual rules would be reversed: drive left, pass right.

[doorknob60]

This is not quite the same, but there's a few places in Idaho on Interstates with signage "Thru Traffic Keep Left". This is due to short onramp merges onto 80 MPH freeways in semi-rural areas. Here's one near Burley, but I think there's a couple more in the state (I think there's one near Jerome, maybe near US-93, and possibly up on I-90 in Coeur d'Alene).


GSV Link: https://www.google.com/maps/@42.5689641,-113.7189791,3a,75y,268.78h,83.6t/data=!3m6!1e1!3m4!1scHMX28PSPRwAb7X2ow2ctw!2e0!7i13312!8i6656

[mrsman]

This is not quite the same, but there's a few places in Idaho on Interstates with signage "Thru Traffic Keep Left". This is due to short onramp merges onto 80 MPH freeways in semi-rural areas. Here's one near Burley, but I think there's a couple more in the state (I think there's one near Jerome, maybe near US-93, and possibly up on I-90 in Coeur d'Alene).


GSV Link: https://www.google.com/maps/@42.5689641,-113.7189791,3a,75y,268.78h,83.6t/data=!3m6!1e1!3m4!1scHMX28PSPRwAb7X2ow2ctw!2e0!7i13312!8i6656

Thanks.  That was helpful.

But it begs the question, if 80 MPH traffic parks itself in the left lane, does that mean that speeding traffic going even faster than 80 MPH will ride in the right lane in order to pass the traffic.  It would seem to be even more dangerous for entering traffic to encourage faster traffic in the right lane.

[sprjus4]

The percentage of traffic exceeding a speed limit such as 80 mph by more than 5 mph would be very minimal.

[Bitmapped]

I seem to recall signs on I-90 in South Dakota telling trucks to stay in the left lane when I drove across the state in 2005. It wasn't in a construction zone. I think it might have been because of crosswinds or to distribute wear across both lanes.

[Truvelo]

There's a keep left sign here

https://goo.gl/maps/k9MuoocMYJh3issd8

[webny99]

The closest I've seen is signs telling truckers to use the left lane through a construction zone.

That was my first thought as well.

[sprjus4]

The closest I've seen is signs telling truckers to use the left lane through a construction zone.

That was my first thought as well.

Which tends to result in some truckers following the signage, others ignoring it, and on major corridors sometimes results in trucks riding alongside other trucks in both lanes and never passing.

Drivers can then get frustrated with trucks blocking the left lane and not staying right, unaware of any signage that nobody actually pays attention to anyway.

[StogieGuy7]

I've seen signs asking trucks to use the left lane in places where there's an issue with the pavement or underlayment in the right lane (some interstates in PA come to mind where semis wore ruts into the right lane over time).  But that's different than "Keep Left Except to Pass" which sounds like something you'd see on a British motorway.