According to reports, 50 to 60% of guardrail accidents lead to injuries or fatalities. But the truth is, many crashes were not reported. And, when these are included, only 6% of all guardrail impacts actually result in injury or death.
The dimensions of guardrail actually decide how well this structure can protect vehicles and people during a collision. Hence, you can reduce the risk of serious injury with right size guardrail installation. We have written all standard sizes of guardrail in this article.
Standard Guardrail Dimensions
Guardrail size is an important component of road safety. With the correct size of these devices, you can provide the maximum protection for drivers and pedestrians. Below you can read the required dimensions for a standard guardrail system.
Minimum Guardrail Length
The minimum recommended length for a standard road guardrail is mostly 175 to 200 feet (around 53-60 meters). This length also includes the end treatments.
However, professionals test some systems which allow a minimum of 75 feet (23 meters) long guardrail. In general, at least 50 feet (15 meters) of guardrail is required before and after the hazard.
Height of Guardrail
According to OSHA regulations, you must install guardrails which have a top edge height of 42 inches (107 cm) above the surface. An allowance of plus or minus 3 inches (8 cm) is also permitted.
You should follow this rule for maximum fall protection systems. If we talk about the minimum height for guardrail you can place, it is 36 inches.
Guardrail Thickness & Guardrail Width
You should place a guardrail that is 2.67 mm (12 gauge) or 3.43 mm (10 gauge) thick. This size provides maximum strength and durability. For general industry, the guardrail top rails and midrails should be at least 0.25 inches (6.35 mm) in thickness.
The standard width of the safety guardrail is 12 to 15 inches (310 to 506 mm). But the exact width is changed based on its application.
Guardrail End Terminal
This is the part you will find at the start or end of a guardrail section. Its major job is to reduce the force of impact if a vehicle hits the end. The terminals of guardrail are generally 12 to 16 feet long. Other common parts such as fish tail end caps are 700-800 mm in length and 310 to 506 mm wide.
Standard Highway Guardrail Dimensions
Thrie Beam Guardrail Dimensions
A thrie beam is a special type of guardrail with a “W” shape. You will see these structures on high speed roads. They are 510 mm (20 inches) wide. Each rail is around 4.32 meters (14 ft) long.
You should mount thrie guardrail rail 31 inches high from the ground. It has a three wave design which gives extra strength and handles vehicle impact better.
W Beam Guardrail Dimensions
This is the most common guardrail type which you will observe on highways. Due to its wavy “W” design, it can easily absorb the impact of vehicles. This safety tool is available in two lengths, which is 14 ft (4.32 m) and 12.5 ft (3.81 m). Its height above the ground is between 29.5 and 32 inches (750 to 810 mm).
If we talk about its thickness, you should use 12 gauge (2.67 mm) or 10 gauge (3.43 mm) thick rails. Standard W beam guardrail posts are 6 feet (1828.8 mm) tall. You can spaced its posts 6 ft 3 in (1905 mm) apart.
Box Beam Guardrail
This guardrail is not common as a W beam or thrie beam guardrail. But it is your go to choice where you want strong roadside prevention. Basically, it has a hollow rectangular shape, which makes it very stable.
Its rail height is 36 inches or 914 mm. Plus, the width of box beam guardrail is around 6 inches. We suggest you place this structure in areas like bridges or sharp curves roads.
Size of Polymer Guardrail
Well, these guardrails are made from strong plastic which is light but very durable. They are manufactured in various sizes and customized designs. On average, the height of the polymer guardrail is between 500 mm, 750 mm or 1000 mm. They are approximately 600 mm to 1800 mm wide.
Cable Guardrail Design
These guardrails actually use steel cables instead of solid metal beams. For commercial use, you should install cable guardrails which are at least 36 inches high (42 inches).
The vertical cable gaps no more than 4 inches to meet safety rules. The cables are mostly 1/8 to 1/4 inch thick. You can place its posts 3 to 4 feet apart.
Wood Guardrail Size
Deck wood guardrails are 36 to 42 inches tall. The post you use for the wood guardrail never exceeds 6 feet gap to meet safety standards.
However, the width of this guardrail is not fixed. It varies based on where you want to install it. The minimum thickness range for rail and its post is 2 inches by 4 inches.
Pedestrian Guardrail Dimensions
You have to place these structures to keep people safe along roads and walkways. Pedestrian guardrails are shorter and lighter as compared to vehicle guardrails. Standard pedestrian guardrails are 2 m long and 1 to 1.1 m in height.
You will find them designed with 50×30 mm steel hollow sections with vertical bars. These bars are 12 mm or 16 mm thick which spaced 110 mm apart.
Guardrail Post Dimensions
Guardrail posts are the vertical supports which you should use to hold the guardrails in place. These posts keep the rails stable so they can guide or stop vehicles safely. Following are the standard specifications of guardrail posts which are commonly used.
Guardrail Post Height: 1.8 to 2.16 m (6-7 ft)
Post Type & Width:
- H posts: 150×75 mm or 150×100 mm
- C posts: 150×76 mm to 120×80 mm
Post Depth (Below Ground): Around 1.1 m (3.5 ft) or more
Rail Height Above Ground: 750 to 810 mm (approx. 30–32 in)
Guardrail Post Spacing
On highways and high speed paths, you can install guardrail posts 6 to 8 feet apart. This keeps the guardrail strong enough to stop vehicles. But remember, this gap can change based on slope or terrain to make the rail more stable.
Suppose, you need to place guardrail posts on slower roads, then you must leave the space between posts around 10 to 12 feet.
Guardrail Size By Regions
Europe (EN 1317)
Europe (EN 1317) is a European safety standard for guardrails and other road barriers. It tells you about the right strength and size of the guardrail.
| Guardrail Specifications | Standard Dimensions in Europe |
| Height of Guardrail | 750 to 900 mm or 2. 5-3 feet |
| Performance class of guardrail | N2, H1 and H2 |
Australia (AS 1657)
AS 1657 is an Australian standard which you must follow for fixed platforms, walkways, stairways and ladders including guardrails.
| Features | Required Size of Guardrail in Australia |
| Height of rails | Approximately 700 mm |
| Rail height for walking surface (1000 mm in width) | 1200 mm |
| Length of guardrails | 3.81 meters (12.5 feet) |
| Guardrail height for elevated platform | 900 mm |
| Distance between rails | Not more than 450 mm |
| Post distance | Maximum gap is 2000 mm |
United States (AASHTO M180)
United States AASHTO M180 is an American standard for guardrails and highway safety barriers. These standards regulate rules for design and strength, so guardrails can guide vehicles during a crash.
| Guardrail Features | Measurements |
| Length | 3.81 m or 12.5 ft (12’6″) |
| Height | 790 mm or nearly 2.6 feet (31″) |
| Distance between posts | Approx. 6.25 feet or 1.905 m (6’3″) |
OSHA Guardrail Requirements
For the safety of workers and drivers from fall, Occupational Safety and Health Administration (OSHA) made some regulations for guardrail design and size. Keep in mind, these rules apply to work surfaces that are 4 feet (1.2 m) or higher and anywhere a fall can lead to injury.
According to OSHA 1910.29(b) section, the top rail of a guardrail must be 42 inches (107 cm) above the walking surface. A variance of 3 inches above or below inches (8 cm) is allowed. So basically, the top rail can be anywhere between 39 inches (99 cm) and 45 inches (115 cm).
Alberta OHS Guardrail Code: Alberta OHS Guardrail Code actually regulates safety rules for guardrails in Alberta (Canada). The OHS Code (Part 9, Sections 138-161) requires guardrails whenever workers have chances of fall 3 m (9.8 ft) or more. Guardrails should be 42 inches (107 cm) tall and you need to install them around open edges or platforms.
People Also Ask
Can Guardrail Height Be Adjusted?
Yes, you can customize the guardrail height in construction and industrial settings. The adjustment of these structures mostly required according to road condition and accident history on that road. But it is important for you to follow safety guidelines to keep the guardrail effective.
Are Guardrails and Handrails the Same Thing?
No, guardrail and handrail are not same and built for different safety needs. For example: guardrails are designed to stop or guide vehicles. But handrails give support to people on stairs or ramps.
When is Guardrail Required?
Guardrails are required by OSHA and other safety rules when a work surface is 4 feet or higher. You must install them when falling could cause injury near dangerous equipment. Further, you need them on unprotected edges.
Who Regulates Guardrail Standards in Canada?
In Canada, guardrails must follow both national and provincial rules. Canadian Standards Association (CSA) and local Occupational Health and Safety (OHS) laws are the main guidelines.
Conclusion
Many engineers and safety professionals have studied the impact of guardrails on driver behavior. So, they conclude that guardrail size has a direct effect on how drivers position their vehicles. For example: if the guardrail is tall, drivers will stay farther from it. But when you install a short heighted guardrail, it keeps the drivers closer to it.
If you want to buy guardrail or need customized size for your road and workplace, we are ready to help you. Contact us now and our team will make it easy for you to get right guardrails for your business.
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