CE 342
Transportation Engineering-II
BLOCK_5A
Traffic Engineering
Traffic Control Devices
Dr. Sarfraz Ahmed
Military College of Engineering
National University of Sciences & Technology
Traffic Control Devices
◼ Traffic control devices are the media by which
traffic engineers communicate with drivers
◼ Virtually
every traffic law, regulation, or
operation instructionD must be communicated
through the use of devices that fall into three
broad categories:
◼
◼
◼
Traffic markings
Traffic signs
Traffic signals
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Traffic Control Devices
◼ Signs
◼ Portable Changeable Message Signs (PCMS)
◼ Arrow boards
◼ Traffic control signals
◼ Markings
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◼Temporary raised pavement markers
◼ Rumble strips
◼ Channelizing devices
◼ Delineation Markers (small posts)
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Manual on Uniform Traffic Control
Devices (MUTCD)
◼ Uniformity in Design and Application
◼ Available on the Internet at
http://mutcd.fhwa.dot.gov/
◼ http://mutcd.fhwa.dot.gov/pdfs/2009/pdf_index.htm
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◼ http://www.urbanunit.gov.pk/
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General Principle of the TCD
◼ Purpose of Traffic Control Devices (TCD)
is to “promote highway safety and efficiency
by providing for orderly movement of all road
users on streets and highways, throughout
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the Nation”.
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Requirements for TCD
◼ Fulfill a need
◼
Superfluous (Unessential) devices should be
avoided
◼ Command Attention of Road Users
◼
Proper visibility and design attracts attention
◼ Convey a Clear, Simple Message
◼ Command the Respect of Road Users
◼
Overuse/ misuse promotes non-adherence
◼ Give Adequate Time For Proper Response
◼
Placement of devices - STOP/Guide signs
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Communicating with the Driver
◼ Messages are conveyed through the use of:
◼ Color
◼
◼
◼
◼
Color is the most easily visible characteristic of a
device.
Color is recognizable long before a general shape
may be perceived and considerably before a specific
legend can be read and understood.
The principal color used in traffic control devices
are red, yellow, green, black, blue, and brown.
These are used to code certain types of devices and
to reinforce specific messages whenever possible.
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Communicating with the Driver
◼ Shape
◼
After color, the shape of the device is the next
element to be discerned by the driver
◼
Particularly in signing, shape is an important
element of the message, either identifying a
particular type of information that the sign is
conveying a unique message of its own.
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Communicating with the Driver
◼ Pattern
◼
◼
◼
Pattern is used in the application of traffic
marking. In general, double solid, solid, and
broken lines are used.
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Each conveys a type
of meaning with which
drivers become familiar.
The frequent and consistent use of similar
patterns in similar applications contributes
greatly to their effectiveness and to the instant
recognition of their meaning.
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Communicating with the Driver
◼ Legend
◼ The last element of a device that the driver
comprehends is its specific legend.
◼
Signals and marking, for example, convey their
entire message through use of color, shape, and
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pattern.
◼
Signs, however, often use specific legend to
transmitted.
Legend must be kept simple and short, so that
drivers do not divert their attention from the driving
task, yet are able to see and understand the
specific message being given.
◼
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Traffic Signals (normal traffic light)
RED
◼ Come to complete stop at stop line or before
crosswalk or intersection.
◼ After stopping, you may turn left on red
at most all intersections if the way is clear.
◼ Some intersections display “NO TURN ON
RED,” which you must obey (for, Western
Countries like US).
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Traffic Signals (normal traffic light)
YELLOW
◼ Stop if you can do so safely.
◼ The light will soon be red.
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GREEN
◼ Go, but only if intersection is clear.
◼ If turning right, wait for gap in oncoming
traffic to complete turn.
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Traffic Signals (lighted arrows)
RED ARROW
◼ Come to a complete stop at marked stop line or before
crosswalk or intersection.
YELLOW ARROW
◼ Stop if you can do so safely.
◼ The light will soon be red. D
◼ Means the same as yellow light, but applies only to movement
in the direction of arrow.
GREEN ARROW
◼ A green arrow, pointing right or left, means you may make a
turn in the direction of the arrow if you are in the proper lane for
the turn, after yielding the right-of-way to vehicles and
pedestrians, even if a red light is showing at the same time.
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Traffic Signals (lane signals)
Lane signals are used:
◼ When the direction of the flow of traffic changes.
◼ To show that a tollbooth is open or closed.
◼ To show which lanes areDopened or closed.
◼ You must never drive in a lane under a red X.
◼ A yellow X means that your lane signal is going to
change to red. Prepare to leave the lane safely.
◼ You may drive in lanes beneath a green arrow, but
you must also obey all other signs and signals.
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Traffic Signs
◼ Categories
◼
Regulatory Signs / Regulatory Signs
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Warning Signs
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Inform User of Regulation
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Inform Users of Hazards
Guide Signs/ Informatory Signs
◼
Navigation Information
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Traffic Signs………..
◼ Traffic Signs Should be
◼
Retro-reflected (Signs which must be capable
of being seen at night)
◼
Letter sizes should commensurate the visual
acuity and perception reaction distance
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Traffic Signs-Standard Colors & Shapes
There are eight shapes and eight colors of traffic
signs. Each shape and each color has an exact
meaning, so you must acquaint yourself with all of
them.
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Traffic CONTROL Signs- Standard Colors
GREEN: Guide, directional information
RED: Stop, yield, do not enter, or wrong way
BLUE: Motorist services guidance. Also used to identify
parking spaces for drivers with disabilities
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ORANGE: Construction and maintenance warning
BROWN: Public recreation areas and scenic guidance
YELLOW: General warning
WHITE: Regulatory
BLACK: Regulatory
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Traffic Signs-Standard Shapes
VERTICAL RECTANGLE: Generally for regulatory signs
PENTAGON: School advance warning and school crossing signs
OCTAGON: Exclusively for stop signs
HORIZONTAL RECTANGLE: Generally for guide signs
TRIANGLE: Exclusively for yield signs
PENNANT: Advance warning of no passing zones
DIAMOND: Exclusively to warn of existing or possible
hazards
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Traffic Signs-Standard Shapes
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Traffic Signs- WARNINGs
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Warning Signs
Narrow Bridge. The bridge is wide enough to accommodate two
lanes of traffic, but with very little clearance.
One lane bridge. The bridge is wide enough for only one vehicle
at a time. Make sure the bridge is clear of oncoming traffic before
you cross.
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Soft shoulder. The dirt on the side of the road is soft. Don’t
leave the pavement except in an emergency.
Dip. There is a low place in the road. Go slowly and be ready to
stop if the dip is filled with water.
Pavement ends. Road surface ahead changes from a hard
surfaced pavement to a low-type surface or earth road.
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Warning Signs
Slippery when wet. In wet weather, drive slowly. Do not speed up or brake
quickly. Make sharp turns at a very slow speed.
Divided Highway Ahead. The highway ahead is divided into two one-way
roadways. Keep to the right.
Divided highway ends. The divided highway on which you were traveling ends
350 to 500 feet ahead. You will then be on a roadway with two-way traffic. Keep
to the left (right in US).
Low clearance. Do not enter ifDyour vehicle is taller than the height listed on the
sign.
Bicycle crossing. Warns you in advance that a bikeway crosses the roadway
ahead.
Merging traffic. You are coming to a point where another traffic lane joins the
one you are on. Watch for other traffic and be ready to yield the right-of-way
when necessary.
Pedestrian crossing. Watch for people crossing the street. Slow down and
proceed with caution. Pedestrians always have the right-of-way.
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Warning Signs
Stop sign ahead. When you come to this sign, slow down to be ready to stop at
the stop sign.
Right curve. Slow your speed and keep well to the left. The road will curve to
the right.
Double curve. The road will curve to the right, then to the left. Slow your speed,
keep to the right, and do not pass.
Winding Road. There are several curves ahead. Drive slowly and carefully.
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Truck Crossing. Watch for trucks entering or crossing the highway.
Side Road. Another road enters the highway from the direction shown. Watch
for traffic from that direction.
Right Turn. The road will make a sharp turn to the right. Slow your speed, keep
to the right, and do not pass other vehicles.
Reduction of lanes. There will be fewer lanes ahead. Traffic must merge left.
Drivers in the left lane should allow others to merge smoothly. Right lane ends.
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Warning Signs
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Toronto Transit Commission
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Construction and Maintenance
Traffic Control Signs
Various traffic control devices are used in road construction and
maintenance work areas to direct drivers and pedestrians safely
through the work site and to provide for the safety of highway
workers.
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Be prepared to reduce your speed and use caution when directed
to do so by a sign, flagger, and/or police officer.
Construction and maintenance signs are used to notify drivers of
unusual or potentially dangerous conditions in or near work areas.
Most signs used in highway and street work areas are diamond
shaped.
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Warning Signs
Cross road. A road crosses the main highway ahead. Look to
the left and right for other traffic.
Hill/downgrade. Slow down and be ready to shift to lower gear
to control speed and save brakes.
Yield Ahead. Warning of yield sign ahead. Slow down and be
prepared to stop at yield sign or adjust speed to traffic.
Traffic signal ahead. Warning of traffic signals at intersection
ahead. Slow down; poor visibility is likely.
Two-way traffic ahead. The one-way street or roadway ahead
ends. You will then be facing oncoming traffic.
Animal crossing. The animal pictured on the sign is common in
this area. Watch for this species crossing the road, particularly
during twilight and nighttime hours.
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Regulatory Signs
(NHA Term: Mandatory Signs)
Inform User of Regulation & Legal Requirements
You cannot make a complete turn to go in the opposite
direction where this sign is displayed.
You must not make a right turn at this intersection.
50 miles per hour is the top speed you can travel in this area.
Rain or other conditions may require you to go slower.
You cannot go straight ahead. You must turn either to the
right or left.
You are going the wrong way on an expressway exit ramp. Do
not drive past this sign. Turn around immediately.
This sign lists the maximum recommended safe speed for an
entrance or exit on an expressway. Slow down to no more
than whatever speed is shown
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Regulatory Signs
You may not turn right or left during the red light. You
must wait for the signal to turn green.
A diamond-shaped marking shows that a lane is reserved
for certain purposes or certain vehicles. The lanes are
usually reserved for HOV (buses or car-pool vehicles)
during rush hour traffic. Other diamond signs are used to
designate bicycle lanes.
The center lane is shared for left turns in both directions of
travel. You may not travel a significant distance in this
lane.
A divided highway is ahead. Stay on the right side of the
divider.
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Regulatory Signs
Parking only for vehicles displaying an official permit and transporting
a person with disabilities.
You must not pass any other vehicles going in the same direction,
while you are in this area.
When you have passed this sign, you are reminded to pass other
vehicles with care.
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Traffic in left lane must turn left at the intersection ahead.
Stopping permitted only for emergencies.
You are approaching an area where a reduced speed zone has been
established.
At the intersection ahead, traffic in left lane must turn left and traffic in
adjoining lane may turn left or continue straight ahead.
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Regulatory Signs
This marks a one-way roadway with traffic coming
toward you. You must not enter the one-way
roadway at this point.
You must not turn either to the right or to the left at
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If you park, you must always park off the pavement
of the highway.
When entering a right turn lane, motorists may
conflict with bicycles. Always yield.
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Guide Signs
NHA Term: Informatory Signs
Navigation Information
◼ Rectangular in shape
◼ White messages on green/ blue background
◼ Different colors and shapes for special purposes
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Traffic control devices for toll plazas,
managed lanes, and preferential lanes
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Guide Signs
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NHA Term: Informatory Signs
◼ Route markers
◼ Route turn arrows and directional arrows
◼ Familiar destination
◼ Mileage signs
◼ Recreation areas
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◼ Service signs
◼ Locations of airports, bus
stations, and train stations
Guide Signs,
NHA Term: Informatory Signs
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Enhanced Conspicuity for signs
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Letter Heights on Street Name Signs
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Horizontal Alignment Sign Selection
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ARROW BOARDS
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Roadway Markings
◼ Purpose
◼
Indicate Regulations
◼
Supplement OtherD Devices
◼
Guide Road Users
◼
Warn Road Users
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Lane Drop Arrows MARKING
◼ Alert driver in
advance of lane
closure
◼ Encourage drivers to
reduce speed and
move to the open
lane
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Raised Pavement Markers - Cat’s Eye
◼ Clearly define traffic lanes by night and by day and signal
a driver staying out of a lane with a gentle tire thump as the
line of markers is hit/ crossed.
◼ Applications: Prime road applications include:
◼ Centre-line marking
◼ Lane marking
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◼ Highway edge marking
◼ Limited access highway ramps
◼ Entrances - acceleration lanes
◼ Exits - deceleration lanes
◼ Service - low speed lanes
◼ Wall mounted bridge and tunnel marking
◼ Construction zones
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Temporary Raised Pavement Markers
◼ Retroreflective or internally illuminated raised
pavement markers
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Removable Orange Rumble Strips
◼ Alert motorists of a work
zone
◼ Benefits:
◼
◼
◼
◼
◼
Highly visible
Repeating rumble soundD
Vibration of the steering
wheel
Easy to install and
remove
Reduce approach speed
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Roadway Marking…..
◼ Colors
◼
Yellow: Separate traffic traveling in opposite
directions
◼
White : Separate traffic traveling in the same
direction
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Red: Restricted roadway
◼
Blue: Parking space for persons with disability
◼
Black: for contrast
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Roadway Marking…..
◼ Patterns
◼
Solid Line: Prohibits or discourages crossing
◼
Double Solid Line: Maximum or special
restrictions
◼
Broken Line: Crossing is Permissible
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Roadway Marking…..
◼ Categories
◼
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◼
Longitudinal Marking
◼
Centerline
◼
Lane Markings
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Transverse Markings
◼
Stop Line
◼
Crosswalk
◼
Parking Space Marking
Object Markers and Delineators
Roadway Markings……
◼ Crosswalk Markings
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◼ Delineators
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White
Yellow
Red
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Channelizing Devices
◼ Traffic safety cones are the most common devices used
◼
◼
◼
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to separate and guide traffic past a work area.
Cones must be a minimum of 18 inches tall.
For high speed, high volume, or nighttime operations,
devices must be a minimum of 28 inches tall, and retroreflectorized.
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Traffic safety drums must be 36 inches tall and are
recommended for use in the tapers on high-speed
roadways due to their greater visibility and imposing size.
Tall Channelizing devices are a minimum of 42 inches tall,
using a tapered cone type shape and are recommended
for use on high speed roadways in lieu of 28 inch cones
due to their greater visibility.
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Channelizing Devices
◼ Channelizing devices provide for smooth and
gradual vehicular traffic flow from one lane to
another, onto a bypass or detour, or into a
narrower traveled way.
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◼ They are also used to channelize vehicular
traffic away from the work space, pavement
drop-offs, pedestrian or shared-use paths, or
opposing directions of vehicular traffic
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Channelizing Devices
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Delineators
◼ Delineators may be used in work zones to indicate
the alignment of the roadway and to outline the
required vehicle path through the work zone
◼ Lighting devices may be used to supplement
retroreflectorized signs, barriers, and channelizing
devices.
◼ During normal daytime maintenance operations,
the functions of flashing warning beacons may be
provided by high-intensity rotating, flashing,
oscillating, or strobe lights on a maintenance
vehicle.
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Delineators
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Portable Signal Systems
◼ Portable traffic control signals are trailer mounted
traffic signals used in work zones to control traffic
instead of using a flagger.
◼ These versatile, portable units allow for alternative
power sources such as solar power, generator, and
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deep cycle marine batteries
in addition to AC power.
◼ Temporary traffic control signals are typically used in
work zones such as temporary haul road crossings;
temporary one-way operations along a one-lane,
two-way highway; temporary one-way operations on
bridges, reversible lanes, and intersections
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Portable Signal Systems
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