1. Work Zone Traffic Control

2. 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

3. - contains standards and principles for design, installation, and maintenance of traffic control devices in work zones. Direct link to pdf version:
Key resources …
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

4. Maintenance of Traffic Plans (MOT) or Traffic Control Plans (TCP)
A plan directed to the safe and expeditious movement of traffic through construction and to the safety of the work force performing those operations
How/when traffic is maintained during construction
Typically required … always needed
Often not given proper time or attention – switching time most dangerous

5. Plan Components 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
Cost estimate must include labor, signs, cones, etc.
Include the following (if needed):
Diversion/detour alignments
Tapers and lane drops (see MUTCD)
Pedestrian accommodations
Traffic control (signals, sign type, sign location)

6. This page includes links to databases and web sites of standards, specifications, and practices that are related to work zone safety.   Work Zone Safety Standards and Practices Database   Manual on Uniform Traffic Control Devices (MUTCD)   Visibility and Retroreflectivity Related   OSHA Regulations   Best Practices on Work Zone Safety   FHWA's National Highway Specifications   FHWA's Work Zone Mobility and Safety Fact Sheets   Work Zone Traffic Control Inspection Forms

7. Special conditions in TCP
High volume or high speed traffic.
Rush hour or seasonal traffic patterns.
Heavy use by pedestrians.
Changing work conditions or other conditions that would be confusing to the traveling public.
Hazards due to nighttime operations.
Complex detours or traffic patterns.
Closely spaced intersections, interchanges, or other decision points.

8. Checklist of factors
Estimated traffic volumes, vehicle types, and direction of travel.
Traffic speeds.
Required number of travel lanes.
Traffic control layouts including signing, markings, channelization devices, traffic signals, traffic
delineators, barriers, and detour schemes.
Restrictions on work periods such as rush hours, holidays, special events, nights, weekends.
Characteristics of adjacent highway segments.
Requirements for partial completion and opening sections to traffic.
Maneuvering space available for traffic.
Requirements for installing, maintaining, moving, or removing traffic control devices.
Turns or cross movements required by traffic.

9. Additional Considerations (but not in contract)
The need for public relations, such as notifications to the local news media.
Any special agreements reached with other agencies relating to traffic control or traffic management.
Accident reporting requirements.
Any special guidance on traffic management for the project engineer.

10. 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

11. Work Zone Safety Facts Late 90s … ~700 deaths/year … 1074 in 2005!
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??)

12. Work Zone Safety Facts
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.

13. Number of Work Zone Fatalities - 2002

15. 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

16. Temp. Traffic Control Devices & Signs

27. Temporary barriers - Portable Concrete Barrier (PCB)
TTI study of portable concrete barrier design

40. 617. 1. 5 Temporary Glare Screens
Temporary Glare Screens. Temporary glare screens in work zones consist of modular units installed on top of temporary concrete traffic barrier. Temporary glare screens prevent headlight glare. Glare screens may also be used to block the driver’s view of construction activities. Glare screens are not used where they could restrict driver visibility and sight distance. Use of these units are limited due to installation and maintenance concerns to areas where work zone activities could impact the flow of traffic, or geometrics could create a blinding effect on drivers. When specified, quantities are calculated and shown on the plans. - MODOT
Glare screen should not be installed in medians wider than 6.1 m. -CalTrans
Transpo Industries web site

41. BMW Takes On Glare Screen
                              
WSDOT's IRT member Don Harris said the weekend accident on westbound SR 520 near 92nd Avenue was one of the more unusual situations to which he’d responded.  The driver of a BMW lost control and drove for 780 feet on the jersey barrier, taking out 640 feet of glare screens.  The screens are on top of the jersey barrier to prevent the headlights of opposing traffic from blinding or distracting drivers. Harris’s job was to pick up all those glare screens while WSP Troopers took custody of the driver. Traffic was up and running again shortly after the 8:15 a.m. accident.

42. Detour considerations
Speed
Capacity
Distance
Safety

43. 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.)

46. 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

47. 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)

48. 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)

49. 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)

50. 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

51. 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

52. 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)

57. 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)

58. 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

59. When conditions are more complex, use …
A. Additional devices:
1. Signs
2. Arrow panels
3. More channelizing devices at closer spacing (see Section 6F.68 for information regarding detectable
edging for pedestrians)
4. Temporary raised pavement markers
5. High-level warning devices
6. Portable changeable message signs
7. Temporary traffic control signals (including pedestrian signals and accessible pedestrian signals).
8. Temporary traffic barriers
9. Crash cushions
10. Screens
11. Rumble strips
12. More delineation
B. Upgrading of devices:
1. A full complement of standard pavement markings
2. Brighter and/or wider pavement markings
3. Larger and/or brighter signs
4. Channelizing devices with greater conspicuity
5. Temporary traffic barriers in place of channelizing devices
C. Improved geometrics at detours or crossovers
D. Increased distances:
1. Longer advance warning area
2. Longer tapers
E. Lighting:
1. Temporary roadway lighting
2. Steady-burn lights used with channelizing devices
3. Flashing lights for isolated hazards
4. Illuminated signs
5. Floodlights

66. Research comparisons on Control Devices
Cones, signs and barricades more effective in conjunction with a flagger
Barricades, panels, and drums lead to earlier transition time at night than did cones and tubes
Size and visible area of control device had more impact than shape
Only arrows and chevrons successfully conveyed the message of direction (not stripes)
Generally, devices of equal visibility had equal value
Motorists respond to the channelization path, but not to a single device

67. OECD Research comparisons on devices
Cones and tubes advantages
provide less impediment to traffic flow
Cause less damage to vehicles and workers
Easier to store, transport and set up?
Smaller “projectile” than drums
Don’t blow over as easily
Disadvantages
easy to penetrate/displace
don’t command respect as drums

72. Edge drops in Construction Zones

76. Edge drop mitigation in construction zones
Place a 45 degree wedge at drop-off site
What are the potential problems?
Place channelizing devices near drop-off using a 3 foot buffer
Install portable concrete barriers (or other barrier type)
What factors affect the wisdom of doing this?