Construction zones and traffic control

• Objective Review extent of problem

Identify contractor responsibilitesIdentify control plan components

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National Data - fatalities

WZ crashes by type (Maine)

Contributing factors (Maine)

National summary data resource

• See http://safety.fhwa.dot.gov/wz/wz_facts.htm

• 2003 data indicate over 40,000 injuries per year, 85% of this to drivers and passengers.

• http://safety.fhwa.dot.gov/wz/wz_facts.htm

Traffic Control Plan

• A plan directed to the safe and expeditious movement of traffic through construction and to the safety of the work force performing those operations is defined as a Traffic Control Plan (TCP).

Iowa requirements to contractors

The Contractor shall perform the following quality control work associated with monitoring and documenting traffic control conditions daily as the project is constructed:

• 1. Review all traffic control operations for compliance with contract documents and maintain a project traffic control daily diary, which shall be submitted to the Engineer and will become a part of the Contracting Authority's project records. The diary shall include:

Iowa requirements to contractors – Diary components:

a) All reviews of traffic control devices and operations,

b) approved changes to traffic control,c) incidentals affecting the efficiency and

safety of traffic, d) a list of trained flaggers used on the

project

Iowa TCP responsibilities (continued)

• 2. Monitor traffic operations and submit proposed Traffic Control Plan changes to the Engineer for approval.

• 3. Coordinate all changes to the Traffic Control Plan.

• 4. Coordinate all traffic control operations, including those of subcontractors and suppliers.

Iowa TCP responsibilities (continued)

• The Contractor shall have an ATSSA Certified Traffic Control Technician on staff, even though the Traffic Control portion of the contract may be subcontracted. This Certified Traffic Control Technician shall be responsible for the overall management of the contractor's quality control program for traffic control."

Special considerations 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.

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.

Factors – cont’d

• 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.

Add’l – but may not be 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.

Principles of Work Zone Control

• 1 - integral part of overall process in design and construction

• 2) - traffic movement is to be unaltered as much as possible

• 3) - related to 2 , speed changes greater than 10 mph should be avoided, if possible

Principles of Work Zone Control

• 4 - construction vehicles and moving traffic should have their separate space

• 5 - traffic control plans to be developed by those who understand the nature of construction and traffic control

• 6 - construction markings to provide adequate warning time to users is critical

Principles of Work Zone Control

• 7 – principles of Positive Guidance under varying conditions (More will be discussed on Positive Guidance later )

• 8 - markings and signs should only be present if they are applicable – not too early, not too late.

• 9 - flaggers used only when needed, and with appropriate training (entire sections and workshops)

Principles of Work Zone Control

• 10 - inspection of work zone layouts need constant review under varying roadway and lighting conditions

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Research Comparisons of Control Devices

Cones, signs, and barriers more effective with flagger

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)

Research comparisons on devices – cont’d

• Generally, devices of equal visibility had equal value

• Motorists respond to the channelization path, but not to a single device

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 (EJK questions last

point)

OECD Research comparisons on devices

Reservations: (Disadvantages)

Cones and tubes: easy to penetrate/displace don’t command respect as drums

Drums: The large size that makes them more visible and commands respect also can be large projectiles into construction worker area.

Edge drops in Construction Zones

Edge drop mitigation in construction zones

• Place a 45 degree wedge at dropoff site• (What are the potential problems?)• Place channelizing devices near dropoff using a 3

foot buffer • Install portable concrete barriers (or other barrier

type)• ( What factors affect the wisdom of doing

this?)• OTHER