Traffic Control, Mobile Equipment & Work Zones

Learn traffic control, mobile equipment, backing, spotter, visibility, and work-zone safety principles for water and wastewater operators working near vehicles and public roads.

Water and wastewater operators often work in streets, rights-of-way, plant yards, loading areas, excavation sites, and other locations where moving vehicles and heavy equipment create serious struck-by and caught-between hazards. A worker may be exposed to public traffic, dump trucks, backhoes, loaders, service vehicles, cranes, forklifts, or other equipment during the same job.

Safe work-zone operation depends on planning vehicle movement, controlling traffic, maintaining visibility, separating workers from equipment, communicating clearly, and recognizing that drivers and equipment operators may have large blind areas.

Traffic and Mobile Equipment Hazards

Common hazards include:

workers struck by public vehicles;
workers struck by backing trucks or equipment;
workers caught between equipment and fixed objects;
equipment entering an excavation;
workers struck by swinging equipment or loads;
poor visibility at night or during bad weather;
drivers entering a work area unexpectedly;
equipment operators losing sight of ground workers;
congestion caused by several vehicles moving in the same work area.

These hazards should be considered before work begins rather than managed only after vehicles arrive.

Establish the Work Zone Before Starting Work

A work zone should clearly communicate where drivers can travel and where workers are expected to be.

Depending on the job, temporary traffic control may include:

advance warning signs;
cones or channelizing devices;
barricades;
flaggers;
temporary lane closures;
work vehicles with warning lights;
pedestrian controls;
barriers or positive protection where appropriate.

Traffic-control devices should be positioned and maintained according to the applicable traffic-control plan and requirements.

Use Appropriate Traffic Control Devices

Construction areas at points of hazard must be protected with appropriate traffic-control signs and devices.

Temporary traffic control should guide drivers before they reach the immediate work area and continue through the work zone until normal traffic operation resumes.

Signs or cones placed too close to the hazard may not give drivers enough time to recognize the condition and react safely.

High-Visibility Apparel

Workers exposed to public traffic or moving construction equipment should be highly visible to drivers and equipment operators.

High-visibility apparel is especially important:

during roadway work;
during low-light or nighttime work;
around backing equipment;
when serving as a flagger or spotter;
around excavations near traffic;
when workers may enter vehicle travel paths.

High-visibility clothing improves recognition, but it does not replace traffic separation, barriers, safe equipment operation, or other controls.

Blind Spots

Large vehicles and construction equipment can have substantial blind areas in front, behind, and beside the machine.

An operator may be unable to see a worker who is only a few feet away.

Ground workers should avoid standing:

directly behind equipment;
between equipment and a fixed object;
near the swing radius of excavators or similar machines;
in areas where the operator cannot clearly see them.

A good rule is: if you cannot see the operator, do not assume the operator can see you.

Backing Hazards

Backing is one of the most dangerous vehicle movements on construction and utility sites.

Where a vehicle has an obstructed view to the rear, appropriate measures are required, such as an audible reverse alarm or backing only when an observer signals that it is safe.

Reverse alarms help warn workers, but alarms should not be treated as the only protection. Busy work sites may contain several alarms, high noise levels, or workers whose attention is directed elsewhere.

Use Spotters Correctly

A spotter can help the equipment operator move safely when visibility is limited.

Before movement begins, the operator and spotter should agree on:

the signals that will be used;
the intended movement;
the safe position of the spotter;
what the operator will do if visual contact is lost.

The operator should stop immediately if the spotter disappears from view or communication becomes unclear.

Spotter Safety

The spotter must also be protected from the vehicle being guided.

Spotters should:

remain visible to the operator;
stay out of the direct path of the vehicle;
avoid standing between the vehicle and another object;
wear high-visibility apparel;
remain focused on spotting duties;
avoid distractions such as phones or headphones.

A spotter should not be given another task that prevents continuous attention to vehicle movement.

Establish Internal Traffic Flow

Work sites are safer when vehicle routes are planned rather than improvised.

An internal traffic-control plan can address:

vehicle entry and exit points;
one-way routes;
backing areas;
material delivery locations;
pedestrian routes;
equipment staging;
parking areas;
restricted zones around excavations or lifting operations.

Reducing unnecessary backing is one of the most effective ways to reduce backing risk.

Separate Workers and Equipment

Whenever practical, use physical distance, barriers, designated routes, or scheduling to keep workers away from moving vehicles.

Workers should not routinely walk through active loading or backing areas simply because they know the equipment operators.

Likewise, equipment operators should not drive through established pedestrian areas unless the movement is specifically controlled.

Vehicle Inspections

Vehicles used on a work site should be maintained in safe operating condition.

Important items may include:

service brakes;
parking brakes;
emergency brakes where applicable;
horns;
reverse alarms;
lights;
windshields and mirrors;
seat belts;
tires;
steering;
warning lights.

Defects that affect safe operation should be corrected before the vehicle is used.

Seat Belts

Seat belts should be used where provided and required.

Construction equipment can overturn, strike obstacles, or stop suddenly. A rollover protective structure is most effective when the operator remains within the protected zone.

An operator who is thrown from the seat can be crushed by the same equipment the protective structure was designed to withstand.

Parking Mobile Equipment

Before leaving mobile equipment unattended:

place controls in the appropriate neutral or safe position;
set the parking brake;
lower buckets, blades, forks, or attachments where appropriate;
secure the equipment against unintended movement;
follow the manufacturer and facility procedure.

Equipment parked on a slope may require additional precautions.

Lower Raised Equipment Before Working Around It

Raised buckets, blades, booms, attachments, or equipment components can fall if hydraulic pressure is lost or controls move unexpectedly.

Employees should not work beneath raised equipment unless it is properly supported, blocked, or otherwise secured against movement.

Hydraulic pressure alone should not be relied upon to hold heavy equipment safely above a worker.

Swing Radius Hazards

Excavators, cranes, backhoes, and similar equipment can rotate and create a dangerous area around the machine.

A worker caught between the counterweight and a fixed object can be crushed even at relatively low machine speed.

Keep personnel out of swing areas and use barricades, markings, spotters, or other controls where appropriate.

Suspended Loads

Workers should stay clear of loads being lifted or moved overhead.

Loads can shift, rigging can fail, or equipment can move unexpectedly.

Do not stand beneath suspended pipe, pumps, trench boxes, equipment components, or other materials.

Lifting operations should use suitable equipment and rigging and should be performed by personnel with the appropriate training and responsibilities.

Working Near Excavations

Mobile equipment near an excavation can create several hazards:

equipment can fall into the excavation;
equipment weight can affect excavation stability;
workers can be pinned between the equipment and trench;
operators may have difficulty seeing the excavation edge;
vibration can contribute to soil instability.

Where the operator cannot clearly see the edge, warning systems or observers may be necessary.

Excavation and trench protection are covered in detail in the separate excavation safety article.

Public Traffic Near Excavations

Utility excavations in streets can expose workers to both cave-in hazards and passing vehicles.

Traffic control must prevent vehicles from entering the excavation and reduce the risk of drivers striking workers.

Barriers, channelizing devices, warning signs, flaggers, or other controls may be required depending on the location and traffic conditions.

Flaggers

Flaggers control vehicle movement when normal traffic flow cannot safely continue through the work zone.

A flagger should:

be positioned where drivers can see the signal in time to respond;
have an escape path;
avoid standing directly in the path of approaching traffic;
use the approved signaling method;
remain focused on traffic;
wear appropriate high-visibility apparel.

Flaggers should not perform unrelated tasks that distract them from traffic control.

Night Work and Low Visibility

Night work can increase risk because drivers and equipment operators have less time to recognize people and hazards.

Lighting should allow work to be performed safely without creating disabling glare for drivers.

Reflective or high-visibility apparel, equipment lighting, illuminated traffic-control devices, and clean reflective surfaces become especially important in low-light conditions.

Weather Conditions

Rain, fog, snow, dust, and glare can reduce visibility and increase stopping distance.

Operators should reassess traffic-control arrangements when weather changes.

A traffic setup that was adequate in daylight and dry weather may be inadequate during heavy rain or darkness.

Communication Between Workers and Operators

Clear communication prevents assumptions.

Before a worker approaches mobile equipment:

make sure the operator sees you;
establish communication;
wait for acknowledgement;
approach only when it is safe.

Do not assume the equipment operator knows that you are nearby simply because you can see the cab.

Entering and Exiting Equipment

Operators should use steps, ladders, handholds, and access points provided by the manufacturer.

Good practices include:

maintaining three points of contact where appropriate;
keeping steps free of mud, grease, and ice;
not jumping from equipment;
not climbing while carrying objects that prevent a secure grip.

Many equipment injuries occur during entry and exit rather than while the machine is moving.

Do Not Carry Unauthorized Riders

Mobile equipment should not carry passengers unless a safe seat or riding position is specifically provided.

Standing on steps, buckets, fenders, forks, or other equipment surfaces can result in falls or crushing injuries.

Phones and Distraction

Vehicle operators, spotters, flaggers, and workers near moving equipment should avoid distractions that reduce situational awareness.

Phones, headphones, and unrelated conversations can prevent a worker from hearing alarms, recognizing movement, or maintaining communication with an operator.

Work Vehicles as Temporary Protection

Work vehicles may sometimes form part of a temporary work-zone setup, but a parked truck should not automatically be treated as a protective barrier.

The vehicle must be positioned according to the applicable traffic-control plan and should not create new visibility, access, or struck-by hazards.

Unattended Equipment Near Traffic

Equipment left unattended near a roadway or active work area should be clearly identifiable to approaching traffic when required.

Appropriate lights, reflectors, barricades, or other measures may be needed, particularly at night or in low visibility.

Emergency Vehicles and Changing Traffic

Work zones should account for unusual traffic conditions when practical, including emergency vehicles, school traffic, deliveries, or peak travel periods.

If traffic begins behaving differently than expected, workers should reassess the traffic-control setup rather than continuing to rely on a plan that is no longer effective.

Common Traffic and Mobile Equipment Mistakes

Standing behind equipment because a reverse alarm is sounding.
Assuming the operator can see every worker around the machine.
Continuing to back after visual contact with the spotter is lost.
Allowing the spotter to perform unrelated duties.
Walking through active backing or loading zones.
Standing between mobile equipment and a fixed object.
Working beneath raised equipment supported only by hydraulics.
Standing beneath suspended loads.
Removing high-visibility apparel because traffic is moving slowly.
Using too few traffic-control devices to give drivers adequate warning.
Leaving equipment or materials where they block driver sight lines.
Ignoring reduced visibility caused by darkness or weather.
Allowing phones or headphones to distract workers near moving equipment.

A Practical Work-Zone Safety Sequence

Identify public traffic, equipment, pedestrian, and excavation hazards.
Establish the temporary traffic-control setup before exposing workers.
Plan vehicle entry, exit, backing, staging, and pedestrian routes.
Use high-visibility apparel where workers are exposed to vehicle hazards.
Inspect vehicles and equipment before operation.
Keep workers out of blind spots, swing areas, and backing paths.
Use reverse alarms, spotters, or other required controls.
Stop equipment immediately if communication with a spotter is lost.
Keep workers clear of suspended or unsupported raised loads.
Maintain signs, cones, barricades, lighting, and other control devices throughout the job.
Reassess the work zone when traffic, weather, lighting, or job conditions change.

What to Remember for the Exam

Work zones can expose operators to both public traffic and construction equipment.
Traffic-control signs and devices must be placed and used according to applicable requirements.
High-visibility apparel helps drivers and equipment operators recognize exposed workers.
Large mobile equipment can have major blind spots.
If you cannot see the operator, do not assume the operator can see you.
Vehicles with obstructed rear visibility require appropriate backing protection, such as a reverse alarm or observer where the applicable rule requires it.
Operators should stop backing if they lose sight of the spotter.
Spotters must stay visible, focused, and outside the vehicle path.
Separating pedestrian and equipment routes reduces struck-by hazards.
Inspect brakes, alarms, lights, horns, mirrors, and other safety equipment.
Use seat belts where provided and required.
Do not work beneath raised equipment unless it is properly supported.
Stay outside equipment swing areas and clear of suspended loads.
Mobile equipment near excavations can affect both worker safety and soil stability.
Night work and bad weather require additional attention to visibility.
Workers approaching equipment should establish communication with the operator before entering the hazard area.
Changing traffic or work conditions require reassessment of the work-zone controls.