Cable Barriers 

Guardrails are an essential part of highway infrastructure and have saved countless lives over the years. Cable barriers are being implemented increasingly on many roads and highways in North America, and are now installed on some newer Nova Scotia highways. The most common benefits noted about these cable barriers, reference the cost effectiveness and faster repair times required after crashes compared to steel or concrete barriers. 

Nova Scotia’s Highway 101

Although the safety improvements are undeniable, there are some disadvantages to this type of guardrail, particularly to drivers of exotic cars and motorcyclists. In a YouTube video listed below, a professional race car driver shares his concerns about these types of guardrails and also discusses an accident that had severe injuries for one exotic car driver. 

Traditional guardrails.

These types of guardrails have other advantages such as, they allow snow to blow across the highway instead of having it build up like it would with a traditional guardrail, and require less workers to install or repair. Let’s have a look at some of the advantages and disadvantages of this type of safety solution. 

National Library of Medicine

“One study found a guardrail should be preferred over a concrete wall and a cable barrier should be preferred over a guardrail where the road and traffic conditions allow. The occupants of a vehicle that travels off the road are the least likely to be injured if cable barriers are installed on the roadside.”

“Roadway departure crashes tend to be severe. As a cost-effective method when the clear zone width is insufficient, road barriers are often installed to prevent vehicles from colliding with dangerous obstacles or traversing steep slopes.”

https://pubmed.ncbi.nlm.nih.gov/25003970/

“One study identified 1364 motorcyclists injured as a result of single-vehicle collisions with roadside barriers, trees, utility poles, and other fixed roadside infrastructure. These hazards provided higher risks of serious injury to motorcyclists compared to barriers in particular body regions, such as the head, spine, and torso.”

“Roadside barriers provide a significant reduction in the risk of serious injury to motorcyclists compared to other roadside hazards. However, a more realistic estimation might be derived by increasing the severity numbers for barriers by around 25 percent for motorcyclists.”

https://pubmed.ncbi.nlm.nih.gov/23944155/

Traditional steel and concrete guardrails/barriers.

Safety Implications

“In Iowa, a decreased risk of severe injuries has been noted with this barrier system because cable barriers provide a “softer hit” than W-beam or concrete barriers. Also, repairs are quicker than with W-beam barriers, which reduces maintenance crews’ exposure to traffic. In Missouri, these systems increase safety in areas where sight distance is a challenge, but there are concerns about vehicles traveling under the right shoulder cables due to deflections and slopes.”

https://dot.ca.gov/-/media/dot-media/programs/research-innovation-system-information/documents/preliminary-investigations/pi-0255v2-a11y.pdf

Newly installed cable barriers on Highway 101.

CASS® (manufacturer)

“The CASS® C-Channel cable barrier system assists in redirecting errant vehicles that would otherwise traverse the median of a roadway. The post employs a unique wave-shaped slot, which works in tandem with a strategically positioned, widened cable spread designed to help restrain various types of vehicles that impact the system within NCHRP Report 350 crash test standards.”

https://trinityhighway.com/product/cass-c-channel-cable/

California Department of Transportation

“California Department of Transportation (Caltrans) has installed a high-tension cable barrier on a section of Interstate 15; the barrier has performed well and has been easy to repair. When this barrier is impacted, repair time is about 15 to 20 minutes compared to an hour or more to repair the same length of guardrail. These safety systems are also cost-effective, oftentimes costing up to 50% less than traditional thrie-beam barrier systems.Given the potential to significantly reduce the time that repair crews are exposed to traffic, and that high-tension cable barrier can be installed in more conditions than traditional thrie-beam barriers.”

https://dot.ca.gov/-/media/dot-media/programs/research-innovation-system-information/documents/preliminary-investigations/pi-0255v2-a11y.pdf
Newly installed cable guardrails on Highway 101.

Nova Scotia Department of Public Works

https://novascotia.ca/tran/highways/standarddrawings.asp

Video of a Cable Barrier Crash

Cable Guardrail Benefits

Casey Putsch Video on the Dangers of Cable Guardrails

Overall, cable guardrails seem to be a more cost effective and practical solution for transportation departments across North America, but they can be an extreme hazard to vulnerable highway users as well as drivers of lower sitting vehicles such as exotic cars.

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