Guide to Renting Steel Road Plates

By Glen McCord
Maintaining safety is job one when performing underground utility work. To temporarily bridge trenches and other excavations dug for installing or repairing underground utilities, utility contractors often rely on steel road plates. These large plates keep disturbed roads and walkways open to vehicles and pedestrians while work is underway, minimizing disruptions to the worksite or community and protecting workers and the public from the hazard of an open pit or uneven surface.
Choosing and using steel road plates may seem entirely straightforward, yet contractors often make mistakes without realizing it when sizing or securing them. These mistakes can subject the contractor to fines for failing to comply with federal or municipal regulations. More important, they can create safety hazards that put workers and the public at risk.
Here are seven tips to keep in mind on your next project that requires road plates.
Determinate the anticipated loads
One of the first steps in choosing road plates for an underground utility project is understanding the loads that will pass over them and determining the load rating needed. For excavations on roads with vehicle traffic, it’s critical to take into account the weight of the vehicles and also the speed at which they travel.
Refer to the engineer’s tabulated data to understand the load-bearing capacity of the plates you’re considering.
Size the plate properly for the span
Rental road plates range in size from 4-by-4-feet to 8-by-20-feet. Sizing a road plate isn’t complicated—or is it? Contractors may think that as long as the plate covers the hole, it works. But there’s more to it.
A plate can’t be used on spans greater than those indicated in the engineer’s tabulated data. A 1-inch-thick A36 steel plate has a maximum allowable span of 4.5 feet, for example.
Plates must cover the excavation with sufficient overlap on each side for safety. Too often, contractors fail to choose a plate size that provides sufficient overlap, and that oversight can lead to accidents and fines.
On a road with vehicle speeds less than 45 mph, a minimum overlap of 12 inches on each side is required, assuming you’re using a 1-inch-thick steel plate. At higher speeds, at least 24 inches of overlap on each side is required.
One way to cover more span with the same plate is to decrease the speed traffic passing over the plate. Allowable spans increase by 20% when vehicle speeds are less than 10 mph.
Choose the right plate thickness for the load and span
The thickness of a plate influences the loads it can bear and the size of the hole it can safely cover. Standard road plates come in thicknesses of 1 inch, 1.25 inches and 1.5 inches, with 1-inch plates being the most common. Thicker plates can support heavier loads and cover wider spans.
A 1-inch A36 steel plate is rated for HS-20-44 loading. In other words, it can support moving vehicles with a per-axle load of up to 32,000 pounds. If you need to cover a span larger than 4.5 feet, you’ll need a thicker plate. Commonly, a 1.25-inch plate has a maximum allowable span of 7 feet, and a 1.5-inch plate has a maximum allowable span of 10 feet.
A span is defined as edge of asphalt to edge of asphalt or edge of trench to edge of trench plus 6 inches each side.
Properly secure the road plates
In some cases, road plates should be secured to the ground so they don’t rock, lift under the weight of passing vehicles or “walk” and create an uneven surface or expose a hole. Vehicle speeds and how the plate is positioned relative to the hole can affect whether you need to anchor the plate. Consult the tabulated data.
There are several effective ways to secure plates. Anchoring systems include railroad spikes driven in around plate edges, drilled-in bolts, and plate locks that go around the edges of the plate. For major streets, recessing the plate into the road surface is another option.
Tapered ramps can be installed on both sides of the plate to taper the bump, smoothing the transition between the plate edge and the road for safety and comfort of motorists and bicyclists. Check with your state for the required taper lengths.
Look for anti-skid coatings
“Slippery when wet” applies to steel road plates. To reduce slip hazards, look for road plates that feature an anti-skid coating for improved traction. Your local municipality and/or project owner may require a skid-resistant road plate surface with a coefficient of friction of at least 0.35 percent. Wet steel has a lower coefficient of friction than dry steel.
Designate a competent person
To help ensure you’re choosing and installing road plates correctly, it’s important to designate a competent person to oversee plate usage. The competent person is someone who is capable of identifying existing and predictable hazards in the surroundings and working conditions that are unsanitary, hazardous or dangerous to employees, and who has authorization to take prompt corrective measures to eliminate them.
This person should see to it that the tabulated data is interpreted correctly and that plates are used according to the tabulated data requirements. They should also ensure that daily inspections of the plates are conducted throughout the project.
Work with a knowledgeable supplier
The ability to determine the right road plate for the project and install it correctly isn’t necessarily a core skill of most utility contractors, who are focused on and trained in performing top-quality utility work. An equipment vendor with deep knowledge of steel road plates and a team of in-house engineers can help customers select and install plates based on the application, tabulated data and site conditions.
Glen McCord is a Regional Product Development Manager for United Rental Trench Safety with 16 years in the Trench Safety business. Tags: United Rentals