1. What Are Those Road Markings?
During my lessons, I am often quite surprised by the total
lack of knowledge from both Driver Ed class grads, and
from those who already HAVE a license (we also do
defensive and court-mandated classes for drivers),
regarding roadway markings and their meanings. So,
here’s a primer on those yellow, white, red and green
paint marks on the road. We’ll take them by color.
(for more detailed info, please go to:
http://mutcd.fhwa.dot.gov/ )
YELLOW – most commonly used to separate traffic going in opposite directions, and in the
USA, should ALWAYS be on your left. If a yellow line is on your RIGHT, you are A) going the
wrong way on a one-way road, B) going ON an EXIT ramp, C) INSIDE of a “shared left turn”
lane, D) using a reversible (rush-hour) lane.
Copyright, GAM Consulting, 2013

2. Symbolically, in Traffic Engineering, the color YELLOW is used to indicate a warning.
Yellow road markings are used to alert a driver of a potential danger, such as oncoming
traffic, obstacles, and left-edge of lanes and roadways (one-way streets and ramps).
In the picture to the left, the yellow lines indicate a
“shared left-turn” lane, where traffic from either
direction may enter, and wait for a break in traffic,
before making a left turn. The SOLID yellow lines on the
outside of the lane indicate traffic in opposite directions,
while the BROKEN yellow lines inside the lane indicate
permission to exit for a left turn.
In many states, drivers may also enter this lane from a
side road intersection to await a break in traffic for
merging RIGHT into traffic. This helps traffic flow by
allowing a driver to enter the roadway without needing
to wait for a break in traffic in BOTH directions at the
same time.
Copyright, GAM Consulting, 2013

3. Notice that, in the picture above, there are FOUR solid yellow lines. This formation is
called a “double-double” yellow, and is used to represent a wall or divider, without the
needed cost of a physical barrier. It is forbidden to cross these double-double lines for any
reason. The optional diagonal “zebra-stripe” markings indicate a “safety zone”, which is
also forbidden for a motorist to enter or cross.
Similarly, the double-double and zebra-striping are often used in
the middle of the roadway to indicate an obstacle, usually
permanent, with a safety zone surrounding it. This warns motorists
early, to avoid passing or driving left-of-center.
Copyright, GAM Consulting, 2013

4. Double yellow lines, and double-double ones, may or may not, converge near an
intersection and a “left-turn-only” lane. If they converge it is called a closed-throat
design, if not, it is called an open-throat design. The differences are important to a
motorist.
The picture to the left shows an OPEN THROAT design, where a motorist
MAY enter the shared-left-turn lane and continue to the turn-only lane,
often seen being done during heavy traffic flow situations.
The picture below shows a CLOSED THROAT design, which forbids traffic
from going over it. Again, during high-volume traffic, many motorists are
seen violating this, with traffic backing up into the shared-left-turn lane.
Copyright, GAM Consulting, 2013

5. Occasionally, you may see one or more sets of dashed, yellow lines. These are used to
indicate “REVERSIBLE” lanes (often called “rush-hour” lanes), where traffic flow direction
varies with the amount of traffic anticipated. These are also often seen at toll-gate plazas.
This is an exception to the “yellow on left” rule, if you are in the reversible lane, going with
the general traffic flow.
Copyright, GAM Consulting, 2013

6. Traffic engineers will also used a dashed yellow line to
indicate and “extended center-line” through a multi-lane
turn. HINT: If you see one of these during a drive test or
evaluation, DO NOT TOUCH the yellow line, or you may fail
the test/evaluation.
REMEMBER: In Traffic Safety, YELLOW always means a potential hazard is
nearby. Whether it is a sign, a road marking, or a curb, the color yellow
should put the prudent driver on alert.
Copyright, GAM Consulting, 2013