Work Zone Traffic Control

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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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http//mutcd.fhwa.dot.gov/ - contains standards
and principles for design, installation, and
maintenance of traffic control devices in work
zones
Key resources
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
http//safety.fhwa.dot.gov/fourthlevel/pdf/bestpra
c.pdf
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Maintenance of Traffic Plans

• How/when traffic is maintained during
  construction
• Typically required 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)

http//www.fhwa.dot.gov/tfhrc/safety/pubs/89035/89
035.pdf
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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
• Physical standards Lower

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Work Zone Safety Facts

• Late 90s 700 deaths/year 2007 - 835!
• 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)
• 31 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.
http//safety.fhwa.dot.gov/ped_bike/univcourse/swl
ess12.htm
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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

• eliminate some turns
• reroute some trucks and buses
• ban parking
• ban loading/unloading during peak
• eliminate some bus stops

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How to increase detour capacity

• 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.htmChap
ter_9
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Source Ill DOT
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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 impeded 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)
4. Termination Area returns traffic to normal
Work
3. Activity Area where the work happens
Buffer
2. Transition Area channels the traffic
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 third sign
  (first one 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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I-65 Work Zone, North of Louisville
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