4 things you need to know about rumble stripes
Rumble strips, also called alert strips, are grooved or raised road safety accessories located on roads to alert drowsy or inattentive drivers when they move from their traffic lane.
Even if they have all different names, they are all rumble devices.
Rumble strips exist in a variety of shapes and dimensions; as a result, they produce different amounts of vibrations and sounds when motor vehicles pass over them. This vibration and sound travels through the tires and reaches the driver’s compartment to alert him.
You can divide rumble strips into different types based on their size, shape, and position on the road.
Here, we have explained the four main types of strips that vary from each other based on their size, shape, the amount of sound and vibration they produce, and how they are applied on the pavement.
We also have an article introducing more about speed bump types.
Types of rumble stripes
1. Milled rumble strips
Milled rumble strips are made with the help of a milling machine that creates uniform grooves and depressions in the asphalt pavement. Studies indicate that different dimensions of the milled rumble stripes exist.
They all produce a different amount of vehicle vibration and sound in the vehicle. It happens when the tires of the motor vehicle go into the grooves of the strips. It is believed that if the strips are deeper and wider, the car experiences more noise and vibration and vice versa.
It is also believed that, out of all the types of rumble strips, milled rumble stripes produce the most vibration and sound in the passenger compartment.
Milled rumble strips usually have 5 to 7 inches in length and 0.5 inches in depth. They usually have 10-inch spacing. They are produced on the existing concrete roads.
Even though these strips are very effective for most automobiles, it does not produce much noise in large trucks to awaken a drowsy driver.
2. Rolled rumble strips
Rolled rumble strips are either round or V in shape. They are made during road construction when a shaped groove is pressed into the asphalt pavement or shoulder.
Unlike the milled-in strips, rolled-in strips are made on the newly laid asphalt pavement when it is moldable. Rolled rumble stripes produce a different amount of vibration as well as sound, depending on their dimensions.
Still, no matter what their size is, they produce less noise and vibration in the vehicles compared to the milled rumble strips, which makes them less effective.
3. Raised rumble strips
As the name indicates, this kind of rumble stripe has a raised surface compared to the above-mentioned two types. They can be round or rectangular in shape. And people can apply them to the existing as well as new pavements.
People use raised markers and sometimes raised buttons to create this kind of rumble stripe. They usually come in fluorescent, yellow, and white colours.
They can be 6 to 13 mm in height. Raised rumble strips are commonly applied in warmer areas where snow does not cover the roads.
4. Formed rumble strips
Formed rumble stripes resemble the rolled rumble strips in many ways. However, their key difference lies in the application process.
Formed rumble strips are formed by applying forms on the concrete shoulders when they are warm, fresh, and constructed.
On the other hand, rolled rumble strips are applied on existing, hard asphalt pavement.
Formed rumble stripes can be rounded and V-shaped. Most of the formed rumble strips are 44 mm wide and 32 mm deep. These dimensions are not limited but also vary depending on different factors.
Common names of rumble strip device
As the main role of rumble strips is to wake up sleepy drivers and prevent serious road accidents, people have given them many names based on their function.
These names include:
- Growlers (as they produce sound)
- Drift lines
- Audible lines
- Wake up calls
- Sleepy bumps
- Drunk bumps
Irrespective of the type of the rumble strips, these names are used by people randomly. These names are assigned to the strips because of their role in awakening the sleepy driver by producing audible sounds and vibrations.
You can call rumble strips any of these names based on your preferences.
Rumble strips device dimensions
Rumble strips have varying dimensions. You should know the following terms in order to understand their dimensions properly.
- Width: It tells how wide the strip is. It is measured parallel to the travel lane of the roadway.
- Length: It is also called transverse width. It is the length that is measured or checked lateral to the travel lane.
- Depth: It tells how deep the depression or groove is on the pavement. It is measured as the distance between the pavement surface and the bottom of the groove.
- Offset: This measurement tells the distance between the travel lane and rumble strips. It is measured from the inside edge of the strip to the outside edge of the travel lane.
- Spacing: It shows the distance between the adjacent rumble strips.
Rumble strips placement
Rumble strips are mostly placed in three different places on the roads.
Based on this factor, they are divided into three types: shoulder rumble strips, transverse rumble strips, and centerline rumble strips.
Shoulder rumble strips are applied on the shoulders of the roads, which are situated on the outer sides of the travel lane. It means they are found on the outside of the wheel paths.
They are applied to reduce SVROR-type crashes. If the highways are divided, shoulder strips can be either on the left or the right side.
Transverse rumble strips are applied on the travel line where they warn the drivers about the approaching highway traffic intersections and toll booths.
Centerline rumble strips are on the centerline of the roadway, where their main role is to reduce the risk of SVROR-to-the-left crashes and head-on-crashes.
Benefits of rumble strips device
Rumble strips are applied on the roads for the safety of drivers and the reduction of road accidents.
It has many benefits, including the ones described below.
- These strips make the edges, as well as the centre of the road, more visible even when there are no traffic lights.
- Rumble strips give warning to sleepy drivers about the coming hazards and dangers.
- They are also known to reduce the speed of vehicles when they approach intersections on high-speed roads.
- These sleepy bumps alert the drivers having distracted driving and prevent different types of crashes that commonly occur on high-speed roads.
- They give the drivers time to reduce their speed and the severity of a crash.
Rumble strips are road traffic safety equipment like speed bumps, speed humps, traffic signals, traffic signs, pavement markings, road markings, traffic control signs, and speed signs or signals that improve the safety of pedestrians as well as drivers.
They collectively slow down traffic flow in different places, such as:
- Bike paths,
- Railroad crossings,
- Sidewalks, crosswalks,
- Protected bike lanes,
- Bicycle lanes,
- Upstream of Traffic roundabouts,
- City streets in the urban areas, etc.
Rumble strips prevent collisions between vehicles and reduce the risk of unsafe circumstances and serious injuries by alerting drowsy drivers.
They are applied in different shapes and sizes on road pavement. Some are applied when the asphalt or concrete road is still fresh and warm, while others are applied to the existing road surface.
To learn more, we advise you to refer to the following pages: