When Should Rumble Strips Be Installed on Roadways?

Rumble strips are one of the most effective and low-cost safety features used on highways and rural roads. They serve a simple but critical purpose: to alert drivers when vehicles drift out of the travel lane, helping to prevent run off the road crashes, head on collisions, and other common highway incidents. Knowing when should rumble strips be installed on roadways is essential for transportation officials, paving contractors, and highway maintenance agencies who aim to improve safety for all roadway users.

At Capitol Barricade, we provide rumble strips for rent or sale and guide clients on proper installation to meet safety standards. In this article, we will explore installation guidelines, types of rumble strips, location considerations, and operational needs for maximum safety benefits.

Why Install Rumble Strips?

Rumble strips provide both tactile vibration and audible rumbling when vehicles drift out of their lane. This alert can warn drivers who are inattentive, fatigued, or distracted, reducing the risk of cross over crashes, run off the road crashes, and other crash types. Edge line rumble strips along the shoulder and centerline rumble strips between lanes of oncoming traffic are both widely used to improve safety on two lane and rural freeways.

These strips are especially effective on rural two lane roads where high speed and narrow shoulders increase the likelihood of vehicles leaving the traveled way. Studies conducted by the federal highway administration show that properly installed rumble strips can significantly reduce run off the road and head on collisions.

Types Of Rumble Strips

There are two main methods for installing rumble strips:

1. Mill rumble strips
   This method involves cutting grooves into the existing hardened asphalt pavement using specialized paving equipment. Mill rumble strips provide durable and long-lasting tactile vibration and audible rumbling. They are often installed with pavement rolling machines and can be modified for width and depth based on operational needs.
2. Roll Out Rumble Strips

   Roll out rumble strips are specifically designed commercially and applied during new paving operations. They are created using modified rollers that form grooves or sleeper lines into hot asphalt. This method is commonly used on freshly paved shoulders and provides immediate safety benefits. Roll out rumble strips help alert drivers and improve safety from the moment the pavement is open to traffic, making them a reliable choice for new construction and resurfacing projects.

Both methods produce tactile vibration and audible lines that help alert inattentive drivers. The choice between mill rumble strips and rolled in rumble strips depends on whether the roadway is new or existing, traffic volumes, and project budget.

Where Should Rumble Strips Be Installed?

Rumble strips can be installed along the edge line of the traveled way, the shoulder area, or as centerline rumble strips to separate lanes of oncoming traffic. Location is determined based on several factors:

• Minimum shoulder width: Shoulder rumble strips require sufficient space to avoid creating potential hazards for bicyclists or parked vehicles. The federal highway administration recommends a minimum shoulder width of four feet for edge line strips. Narrow shoulder areas may still benefit from rumble stripes, but additional pavement markings or safety barriers may be needed.
• Travel lane proximity: Centerline rumble strips are installed to warn drivers when they drift into oncoming traffic. This is particularly important on rural two lane roads with a history of cross over crashes.
• Road type: Rural freeways and two lane state highways are common locations due to higher vehicle speeds, limited shoulder area, and the increased likelihood of run off the road crashes.
• Traffic volume and speed: Rumble strips are most effective on highways where speeds exceed 35 miles per hour and on roads with consistent traffic flow. They alert drivers early enough to adjust before leaving the traveled way.
• Crash history: Transportation officials often use crash data to determine where to install rumble strips. Areas with frequent head on collisions, cross over crashes, or vehicles leaving the lane are high priority.
• Pavement type: Both existing hardened asphalt pavement and newly paved shoulders can accommodate rumble strips. Mill rumble strips are ideal for hardened pavement, while rolled in rumble strips work best with new asphalt.

Shoulder Rumble Strip Installation Guidelines

When installing shoulder rumble strips, paving contractors must consider:

• Entire shoulder area: Strips should extend across the full width of the shoulder to maximize safety.
• Noise levels: Audible rumbling should be noticeable to the driver inside the vehicle without creating excessive noise for nearby residents.
• Tactile vibration: The vibration transmitted through the vehicle alerts drivers without causing loss of control.
• Pavement markings: White line or edge line markings are often paired with shoulder rumble strips for visual guidance, creating what some call “singing shoulders” or sleeper lines.
• Operational needs: Installation may require temporary traffic control, lane closures, and coordination with highway maintenance agencies.

Proper shoulder rumble strip installation helps alert inattentive drivers and reduces the potential danger of run off the road crashes, flat tires, and vehicles leaving the roadway.

Safety Benefits Of Rumble Strips

The safety benefits of rumble strips are clear:

• They warn drivers who are drifting, fatigued, or distracted.
• They reduce run off the road crashes and cross over crashes.
• They help drivers maintain proper lane position, especially on narrow shoulders or high speed roads.
• They provide early alerts for bicyclists, pedestrians, and motorists.
• When combined with pavement markings and variable message signs, rumble strips integrate into a complete traffic management strategy.

By installing rumble strips strategically, transportation officials can significantly improve safety and reduce accidents on rural and urban roadways.

Considerations For Installing Rumble Strips

Before installing rumble strips, agencies and contractors should evaluate:

• Crash types and historical data for the project site.
• Width and type of shoulders and lanes.
• Existing pavement condition and whether milling or rolled in methods are more appropriate.
• Potential impact on noise levels for nearby communities.
• Operational needs during installation to minimize risk to workers and drivers.

Following guidelines from the federal highway administration and state DOTs ensures that rumble strip installation aligns with safety standards and provides long-term benefits.

Ensuring Roadway Safety With Rumble Strips

Knowing when should rumble strips be installed on roadways is essential for any road safety initiative. Whether as mill or rolled-in rumble strips, these devices provide vibration and rumbling to alert drivers.

They help reduce the risk of run-off-road and crossover crashes. Proper placement along the edge, shoulder, or centerline maximizes safety for vehicles, bicyclists, pedestrians, and workers.

At Capitol Barricade, we offer rumble strips available for rent or sale, along with guidance for proper installation to meet federal highway administration standards and state DOT requirements. Check out our options today to improve safety on your next roadway project.