Work Zone Traffic Control
CE 453 Lecture 35
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Objectives
Describe a maintenance of traffic plan for
a roadway project
Define work zone problems and reasons
for same
Identify work zone traffic control devices
Present details of work zone traffic control
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Key resources …
http://mutcd.fhwa.dot.gov/ - contains
standards and principles for design,
installation, and maintenance of traffic
control devices in work zones
http://wzsafety.tamu.edu/
AASHTO Roadside Design Guide: Chapter 9 discusses:
Traffic Barriers, Traffic Control Devices and Other
Features in Work Zones. Should be used with Traffic
Control Devices Handbook – Part VI
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http://safety.fhwa.dot.gov/fourthlevel/pdf/bestprac.pdf
Maintenance of Traffic Plans
 How/when traffic is maintained during
construction
 Typically required/not always – really needed
 Include the following (if needed):
Diversion/detour alignments
Tapers and lane drops (see MUTCD)
Pedestrian accommodations
Traffic control (signals, sign type, sign location)
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http://www.fhwa.dot.gov/tfhrc/safety/pubs/89035/89035.pdf
Maintenance of Traffic Plans
Pavement marking, cones, barriers for
channelization
Illumination and warning lights (steady for
path, flashing for single points)
Policies for removal of signs, etc.
Staging of Traffic (how it flows)
Need for flaggers, etc.
Notes (e.g, move or sign all equipment when
not in operation in the work zone)
No parking of employee cars in work zone
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Maintenance of Traffic Plans
Cost estimate must include labor, signs,
cones, etc.
Often not given proper time or attention –
switching time most dangerous
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Why are Work Zones more Prone to
Crashes?
Why are work zones difficult for drivers
and subsequently dangerous for workers?
Violate – Expectancy
Increased – Workload
Combine – Both
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Work Zone Safety Facts
 Late 90s … ~700 deaths/year … now, ~1000!
 Tractor/trailer involvement in work zones
crashes are high (26% of fatalities)
 Work Zone crashes generally more severe
(more injuries/fatalities than national average)Fixed object impacts result in more
injuries/fatalities than vehicle to vehicle impacts
 ½ of work zone fixed object impacts occur at
night (impact on staging??)
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Work Zone Safety Facts
 1994-98 Average was that 16% of work
zone fatalities were peds/bicyclists
 Fatal work zone crashes are twice as
high as non-work zone fatals on urban
interstates (14% are FATAL!)
 The majority of fatal work zone crashes
occur on 55 mph or greater speed limits
(No need for slow speed MOT?
Ped/bike/ car fatalities? – increase over
35 mph but occur much lower)
 29% of fatals on weekends! (most in
summer and fall)
 ~150 workers killed each year (who are
the workers???)
Utility work in bike lanes can
often be accomplished without
blocking the entire lane.
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http://safety.fhwa.dot.gov/ped_bike/univcourse/swless12.htm
Number of Work Zone Fatalities - 2002
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http://www.dot.state.ia.us/workzone/index.htm
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Work Zone Traffic Control Devices
 Cones/Tubular Markers
 Vertical Panels
 Drums (watch breakaway lamps –
ballast at bottom and no greater than
25 kg)
 Barricades Type I, II, and III
 Shadow Trucks, etc. for moving
construction or maintenance
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Work Zone Traffic Control Devices
 Temporary barriers (Portable Concrete Barrier (PCB)
used by many states - uses: bridge widening,
shielding roadside structures, roadway widening, and
the separation of two-way traffic on a normally
divided roadway)
 Glare Screens (block view of construction, for design
consider separation distance, vertical curvature,
horizontal curvature)
 Signs and Supports – meet normal specifications –
breakaway within clear zone, etc. (MUTCD)
 Warning lights (minimum height 3 ft. or 900 mm –
securely fasten and battery on ground – why?)
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Detour considerations
Speed
Capacity
Distance
Safety
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How to increase detour
capacity
(e.g., during I-235 reconstructions – Univ. Ave., etc.)
 eliminate some turns
 reroute some trucks and buses
 ban parking
 ban loading/unloading during peak
 eliminate some bus stops
 coordinate signals
 widen the traffic way
 implement one-way
 ITS??? (incident management, esp.)
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http://www.dot.state.ia.us/design/e00_toc.htm#Chapter_9
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Specifics for Work Zones
Fundamental principles of work zone
traffic control design
Four work zone areas and their
components
Taper lengths and types
Advance signing applications and
factors that impact setup
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Work Zone Traffic Control Design –
10 Fundamental Principles (MUTCD Part 6)
Why? worker/motor vehicle safety in temporary
traffic control areas
 Traffic safety must be integral and high-priority
during project development (from planning to
construction) and rehab/ maintenance or utility
activities
 Follow same principles of normal permanent
roadside/roadway designs (goal is use
comparable geometrics/traffic control if
possible)
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Fundamental Principles (cont.)
 Produce a traffic control plan (TCP)
(understand before field work)
 Traffic should be inhibited as little as practicable
Avoid frequent and abrupt geometry changes
Provide for incident management vehicles
Minimize work time and do off-peak if possible
 Guide drivers/peds in a clear and positive
manner approaching and through zone
(adequate traffic control, proper action with
permanent control, flagging)
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Fundamental Principles (cont.)
 Routinely inspect your traffic control elements
 Maintain the roadside during construction (for
safety)
 Train all levels of workers in temporary traffic
control zone safety
 Provide statutes that allow work zone traffic
control (no real engineer control???)
 Maintain good public relations (media)
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Activity Area
Storage
(not shown)
Work
Buffer
Traffic
4. Termination
Area – returns
traffic to normal
3. Activity Area –
where the work
happens
2. Transition
Area – channels
the traffic
1. Advance Warning
- what to expect
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Older AASHTO
New MUTCD
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Tapers – Important Safety Element of
Work Zones (Why?)
 Used in transition and possibly termination
areas of work zone
 Use a series of channelizing devices and/or
pavement markings
 Observe after implementation (adjust as
appropriate)
 Channelizing device spacing (in feet)
approximately equal to the roadway speed in
MPH
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Taper Lengths (See Table next page)
40 mph or less L = WS2/60
45 mph or greater L = WS
L = taper length in feet
W = width of offset in feet
S = Posted speed, off-peak 85th percentile
speed before work, or anticipated
operating speed in MPH
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Taper Types
 Merging – longest because it requires drivers to merge
with other traffic (use L minimum)
 Shifting – merging not required, but a lateral shift is (use
½ L minimum)
 Shoulder – used where shoulder may be mistaken for
driving lane (use 1/3 minimum, but L is traveled on)
 Downstream – provide visual cue that original lane is
now accessible (optional – if used 100 feet/lane
minimum, 20-foot device spacing)
 One-lane, Two-way – used when one lane closed and
used by both directions (use 100-foot maximum and typ.
flagger)
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Warning Signing for Typical Applications
 Place warning signs in advance of work areas
at spacing indicated
 Distances measured from transition or point of
restriction start
 Table 6C-1 suggests spacing for warning signs
on different roadway types
• “A” is distance from transition/point of restriction to first
sign
• “B” is distance to from first to second sign, and
• “C” is distance from second sign to initial sign
encountered by driver (in a three-sign series)
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Selecting a Typical Sign Setup
Consider:
 Duration of Work (long-term stationary,
intermediate-term stationary, short-term
stationary, short duration, and mobile)
 Location of Work (e.g., outside shoulder,
near/on shoulder, median, on roadway)
 Roadway Type (e.g., rural two-lane, urban
arterials, other urban arterials, rural or urban
divided/undivided, intersections, and freeways)
• MUTCD has 44 typical applications split by these
categories
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I65 Work Zone, North of Louisville
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