Work Zone - 4.03 Work Zone Considerations

4.03 Work Zone Considerations

Work zones should be planned and designed to consider work operations and address safety impacts for workers, traffic regulators, motorists, and nonmotorized users.

4.03.01 Work Zone Hazards

Each work zone should be assessed for hazards. The following provides a list of example conflicts for drivers, workers, and traffic regulators that designers should consider when developing the TTCP:

• Congestion related crashes
• Work zone crashes & crash patterns
• Roadway configuration, merging tapers and lane drops
• Unexpected queues
• Unstable traffic flow
• Lane widths
• Pavement markings
• Clear zone safety issues
• Drainage
• Lane departures
• Barrier wall and attenuation
• Roadway geometrics
• Vertical hazards, drop offs
• Emergency vehicle access
• Disabled vehicle refuges
• Night work visibility
• Confusing or conflicting signs, markings and features

Designers should also consider the following conditions for workers and traffic regulators when developing a work zone TTCP:

• Work zone protection
• Impaired or distracted drivers
• Errant vehicles
• Narrow work zones
• Equipment and materials storage
• Escape routes for workers
• Exposure to moving equipment
• Aggressive drivers
• Speeding drivers
• Vehicle crashes and crash patterns
• Work zone access (ingress / egress)
• Pedestrians/Non-motorized Traffic
• Shared use trails and paths

4.03.02 Workers

(Updated 12/3/2020)

Drivers experiencing long delays become impatient and can act unpredictably increasing worker exposure. Other driver conditions to consider include:

• Impaired drivers
• Drowsy drivers
• Distracted drivers
• Aggressive drivers

Designers should also take into account the position of the workers behind barrier walls. Unless the wall is secured to the pavement or has limited deflection, consideration should be given to improving or creating a lateral buffer space.

Barrier protected work zones should be considered on a project-by-project basis and not just for long term stationary projects.

In addition to the location of the workers and their proximity to traffic, the type of work taking place should be factored into the design of the TTCP.

Active work should not take place with traffic on both sides of the workers, on the same roadbed, unless there is positive protection. Traffic can be on both sides of a lane closure for concrete curing when no workers are present.

A. Traffic Regulators and Spotters

Traffic regulators are typically used to stop and direct traffic for work activities such as:

• One lane alternating traffic control
• Intersection control
• Road closures (Parades, Special Events, etc.)
• Short durations
• Spot locations
• Ingress and egress Locations

A spotter may be used to watch traffic and alert workers of an approaching errant vehicle.

The following are some TTCP considerations:

• Evaluate the necessity of using traffic regulators at night. If determined that traffic regulating is the most effective option for the TTCP, the engineer should review and approve the lighting plan and layout prior to the start of construction. Balloon Lighting is required for traffic regulator stations.
• Traffic regulators must not be utilized on freeways at any time. Haul road crossing may require a traffic regulator and should be reviewed and approved by the project office.
• The traffic regulator’s location, escape route, protection and other safety related issues should be incorporated into the traffic regulator station.
• Law enforcement may be used for some traffic regulator operations. See Section 4.05 Work Zone Law Enforcement, for information on how to include enforcement in projects.
• Spotters may be used to decrease worker exposure when applicable. Intended spotter locations should be shown on the TTCP.

Detailed information on traffic regulator procedures and conduct is available through the resources included in Appendix G (Resources).

4.03.03 Road Users

(Updated 12/3/2020)

The message conveyed to the user through signing, pavement markings, and devices must be concise and consistent.

A. Drivers

Drivers and their passengers account for a large portion of work zone fatalities. It is important to provide a TTCP that effectively guides and protects drivers while traveling through the work zone. Effective planning and design of work zones should be considered from the driver’s perspective.

To provide adequate time to react and make rational decisions to navigate safely, the work zone impact mitigation strategies should be easily understood by motorists.

Temporary channelization and alignment should be modified to the work zone conditions. MDOT work zone guidelines and typicals should be followed; however modifications that improve the safety and operations of the work zone should be made according to field conditions. Changes should be documented in the Inspector’s Daily Report (IDR).

The riding surface is important for the safety of motorcycle riders. Whenever possible, construction operations should be avoided that place motorcycles on grooved pavement, pavement lane edge drops from milled surfaces, rumble strips and unpaved surfaces. If these conditions cannot be avoided, the TTCP should include adequate warning signs for these conditions to alert the motorcycle riders. Consideration should also be made for ingress/egress points, where designs should include the capability of a motorcyclist accessing the roadway perpendicular to differentials in pavement elevations.

B. Non-Motorized Users

Adequate facilities should be provided to allow non-motorized users to travel through or around the work zone. Requirements and guidance on maintaining non-motorized user traffic in work zones are found in Chapter 5: Non-Motorized Work Zone Safety and Mobility.

C. Oversized Vehicles

If the TTCP for the proposed work zone does not allow vehicles that exceed the legal width, height or weight limits, notify the region/TSC transport permit agent. Warning signs notifying vehicles of the restriction must be provided. On some projects, it may be necessary to designate a detour route for oversized vehicles.

4.03.04 Work Zone Crash Reduction Strategies and Mitigations

(Updated 1/20/2020)

According to the MDOT Trunkline Crashes in Work Zones Report (2012), the five primary crash types in work zones are:

• Rear-end straight (RE-ST)
• Sideswipe-same direction (SS-SM)
• Fixed object (FXOBJ)
• Other object (O-OBJ)
• Angle-straight (AN-ST)

The five primary crash types have accounted for approximately 80% of trunkline work zone crashes from 2002 to 2014. Each type may be related to several work zone factors. Potential crash reduction strategies for the TTCP design and during construction are shown in the tables below. Please contact the WZDE for additional methods or option details.

Table 4-1: Work Zone Crash Reduction Strategies and Tools: Rear End Crashes

Work Zone Crash Factors	Crash Reduction Strategy	Crash Reduction Tools
Speed	Review Work Zone Speeds	Single, Double, or Triple speed limit step downs
	Additional devices	Temporary rumble strips Flashing speed limit signs
	Uniformed Law Enforcement Presence	Use law enforcement to alert motorists of work zone queue
Geometry	Review Work Zone Lane Closure / Shift Tapers	Work Zone Audit Report (Form 0397) Drive thru work zone after initial setup and stage changes Verify work zone taper lengths
	Review sight distance and operation at intersections and driveways within the work zone	Turn restrictions Decrease device spacing Gap for approaches Worker Vehicle Equipment Location
Access	Review ingress and egress of work zone vehicles	Internal Work Zone Traffic Control Plan Add signing (Truck Entrance / Exit Ahead, Truck Crossing) Add acceleration / deceleration area for trucks
	Signing for work zone ingress and egress locations	Turn restrictions at driveways and access points
Capacity / Congestion	Additional warning for motorists	Dynamic Message Signs PCMS Queue Detection Systems Dynamic Lane Merge System Rumble Strips (transverse prior to work zone) Additional Global Signing Travel time information signs
	Accelerated construction techniques: working / lane closure time restrictions	Night work Off-Peak work Switch to full closure Use lane / ramp rental or liquidated damages special provisions
	Minimized number of stops / delay improvement	Temporary signal timing coordination Adjust signal phasing and splits Add turn lanes and/or passing flares Close crossovers or alternate intersections Close on / off Ramps
	Alternate Route	Alternate Route Signing Plans Traffic signal optimization along alternate route
	Review MOT staging, look at ways to add lanes (capacity)	Moveable barrier One-way detour Temporary Widening Split Merge
Delineation and Signs	Additional warning signs for approaches and high traffic volume driveways	Add temporary signing for approaches i.e., W2-1, W2-2, W2-3
	Review work zone devices at intersections and driveways within the work zone	Decrease device spacing Gap for approaches Review barricade locations – do not interfere with intersection sight distance

Table 4-2: Work Zone Crash Reduction Strategies and Tools: Sideswipe-Same Direction Crashes

Work Zone Crash Factors	Crash Reduction Strategy	Crash Reduction Tools
Speed	Review work zone speeds	Single, Double, or Triple speed limit step downs
	Intelligent Transportation System (ITS) speed warning signs	Flashing speed limit signs Increase law enforcement
Geometry	Increase lanes and/or shoulders widths, where possible	Separate truck lane Parking restrictions
	Review Traffic Shift and Lane Closure Taper Lengths	Work Zone Audit Report (Form 0397) Verify taper lengths Verify proper sight distance to closure
Delineation and Signs	Review configurations for Yield, Merge, or Acceleration Lanes	Temporary application of Geometric Design Guide, if possible Remove when work is complete
	Review travel path delineations	Temporary rumble strips
	Additional signs for traffic merge / shift locations	Add warning signs (i.e., W11-24) Dynamic Lane Merge System Add R4-9 Signs (Stay in Lane)
	Add delineations	Channelizing devices and/or temporary barriers Temporary delineators
	Pavement markings	Solid temporary pavement markings (no temporary skips) Increase pavement marking reflectivity Temporary raised pavement markings Increase width of pavement markings Use contrast markings

Table 4-3: Work Zone Crash Reduction Strategies and Tools: Fixed-Object Crashes

Work Zone Crash Factors	Crash Reduction Strategy	Crash Reduction Tools
Work Zone Speed	Review work zone speeds	Single, Double, or Triple speed limit step downs
	ITS speed warning signs	Flashing speed limit signs
Delineation and Signs	Place object markers at fixed object locations near travel path	Temporary reflector Temporary attenuator
	Add delineation	Channelizing devices Temporary delineators Safety Edge
Fixed Object Location	Remove, relocate, or protect fixed object	Temporary guardrail Temporary concrete barrier

Table 4-4: Work Zone Crash Reduction Strategies and Tools: Other Object

Header text	Header text	Header text
Delineation and Signs	Frequent inspection and review location and placement of temporary devices (signs, drums, barricades, channelizing devices, etc.)	Work Zone Audit Report (Form 0397)
	Delineate travel path from objects and devices	Ensure Lighting for Night Work requirements. See the section titles "Lighing for Night Work" in section 812 in the specbook Review pavement marking Temporary delineators
Speed	ITS speed warning signs	Flashing speed limit signs
	Review work zone speeds	Single, Double, or Triple speed limit step downs