In Illinois law 625 ILCS 5/11-709 subsection? b there is text that states the following:

(b) Upon a roadway which is divided into 3 lanes and provides for two-way movement of traffic, a vehicle shall not be driven in the center lane except when overtaking and passing another vehicle traveling in the same direction when such center lane is clear of traffic within a safe distance, or in preparation for making a left turn or where such center lane is at the time allocated exclusively to traffic moving in the same direction that the vehicle is proceeding and such allocation is designated by official traffic control devices. http://www.ilga.gov/legislation/ilcs/ilcs4.asp?DocName=062500050HCh%2E+11&ActID=1815&ChapterID=49&SeqStart=111500000&SeqEnd=136400000

What I'm trying to determine is what type of roadway is being referred to when it's stated "3 lanes and provides for two-way movement of traffic". This initially sounds like a two-way left turn lane, but there is also text stating that:

a vehicle shall not be driven in the center lane except when overtaking and passing another vehicle traveling in the same direction when such center lane is clear of traffic within a safe distance

Which to me would mean 625 ILCS 5/11-709 subsection b mustn't be referring to a two-way left turn lane because using those to pass is strictly prohibited by 625 ILCS 5/11-801.b.2:

A vehicle shall not be driven in the lane except when preparing for or making a left turn from or into the roadway or when preparing for or making a U turn when otherwise permitted by law.

So what type of 3 lane two-way roadway is 625 ILCS 5/11-709.b talking about?

5 Answers 5


I believe the law refers to a three lane configuration that is no longer in common use in the United States. It was common in some locations in the 1950s, I have been told, and I think I found it in rural Virginia in the mid-1990s, but I wonder whether my memory is playing tricks on me, because such a configuration was clearly already deprecated in the 1978 Manual on Uniform Traffic Control Devices (source: http://www.trafficsign.us/oldmutcd.html).

The outer lanes are for traffic moving in opposing directions, while the center lane is for traffic passing in either direction. The center lane cannot be used unless there's an adequate line of sight, of course, just as with passing on a two-lane road. No-passing zones must therefore be marked on curves and at the crests of hills. Earlier editions of the MUTCD make some mention of this.


Some 3-lane roads, in large municipalities, only go one direction (a.k.a one-way street): (b) doesn't refer to them. In the remainder, the outer lanes go opposite directions, and the center lane could be a two way left-turn lane, or an additional lane for turning or passing for traffic going one direction. In those three cases, the law prohibits using the center lane for travel without special permission. That means you may use the center lane only for passing, for left turns, or for travel only in case there is signage that allows using the center lane for travel. This description would also include two-way turn lanes, but the allowance "except when overtaking...or in preparation for making a left turn" is overridden by the more specific exclusion spelled out in 625 ILCS 5/11-801.b.2 that specifically only allows left turns from two-way turn lanes. In other words, the first clause does refer to two-way turn lanes, but a later more specific law further restricts use of two-way turn lanes.


The law sounds like it is strongly focused on reversible lane roads. Refer to this image for the different types of three-lane roads:

three lane roads

Reversible lane roads oftentimes have green arrows and red exes above them every so many feet to indicate which lanes are currently allowed for the direction you are travelling. Oftentimes with a three lane version, the center lane displays a red X for both directions during off hours, with a green arrow for a particular direction during rush hours that see a lot of traffic in one direction. These kinds of signals are what the law is referring to as far as "allocation" goes.

  • There is, or at least was, another type of three-lane road in addition to those shown in your diagram, in which the center lane is available for passing traffic in either direction.
    – phoog
    Aug 26, 2017 at 21:00

I've seen this around our town in a few places. There are 3 "lanes" all unmarked and I believe the intent is to allow side street parking on one side while allowing traffic to safely move in both directions when such side street parking is used.

Imagine a north and south bound road with 3 "potential" lanes. The north bound traffic allows for side street parking; the southbound does not. When no parking exists the "middle lane" is removed as both north and south bound move away from the curbs and each take a portion of the middle lane. When parking exists on the north bound lane, the southbound lane hugs the curb, while the north bound drives down the "Middle" of the road.

A friend recently had an accident involving such a 3 lane while driving south, turning left into a private drive; while a vehicle traveling in the same direction passed them on their left.


Mountain roads often have three lane sections for limited stretches of road to allow intermittent passing by traffic going in one of two directions. It would typically look like the image below, but without the orange cones.

enter image description here

The side of the road that the third lane is on is fixed at any given point, but changes with the terrain. I suspect that this is the kind of road that is primarily referred to in this law.

  • I think the law refers to three lane roads in which the center lane admits traffic in both directions, either because the downhill traffic has a dashed yellow line to allow passing (I don't know if these exist in the US anymore, but I passed someone recently on such a road in Bosnia), or because the center lane is set off from both outer lanes by dashed yellow lines.
    – phoog
    Aug 26, 2017 at 20:59

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