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"Guardrails should be designed with their ends buried in the ground so that vehicles can’t crash into them, for example" Maybe I'll read this because I shall l

"Guardrails should be designed with their ends buried in the ground so that vehicles can’t crash into them, for example" Maybe I'll read this because I shall like to see his reasoning. Many guardrails used to be like this. My recollection is that when guardrail ends are buried, vehicles can easily run over the end so the middle of the car rides up over the guardrail. This can flip the car over--either onto the road or onto whatever the guardrail was supposed to be guarding. So my understanding was that the reason guardrail ends are now simply exposed and capped off is because it's better to collide head on with a guardrail than it is to ride over a guardrail and flip over. [edit] this is further discussed at this link. Maybe the book discusses this better than the review did. http://www.crashforensics.com/papers.cfm?PaperID=53 http://www.crashforensics.com/papers.cfm?PaperID=53

the_mitsuhiko 11y ago
> Maybe I'll read this because I shall like to see his reasoning. Many guardrails used to be like this. My recollection is that when guardrail ends are buried, vehicles can easily run over the end so the middle of the car rides up over the guardrail. This can flip the car over--either onto the road or onto whatever the guardrail was supposed to be guarding. Yeah, I remember this coming up in discussions in Austria as well. The current design of guardrails involves moving the guardrail terminal out of harms way: http://www.land-der-erfinder.at/wp-content/uploads/Leitschiene.png http://www.land-der-erfinder.at/wp-content/uploads/Leitschie... And for retrofitting guard rails between lanes where there is not enough space, they installed shock absorbers: http://www.land-der-erfinder.at/wp-content/uploads/Aufpralld%C3%A4mpfer.png http://www.land-der-erfinder.at/wp-content/uploads/Aufpralld... If you crash into those it crumples.
- DrScump 11y ago
  <they installed shock absorbers> In the SF Bay Area, such junctions of guardrails tend to be preceded by what look like huge plastic garbage pails filled with sand, apparently to absorb as much energy as possible without (or, at least, before) bouncing such vehicles back into traffic. The other extreme was a freeway case (locals to the San Jose area can see this now, on 85 northbound in Cupertino between the onramp from 280 westbound and the Fremont Ave. exit) where the guardrail began about 10 feet from the side soundwall, leaving a car-width's gap to the right of the guardrail. A perpendicular soundwall was about 30 feet beyond. One evening, a car went right through the gap and into the perpendicular wall at full speed. Subsequently, the guardrail was extended at an angle to meet the side soundwall.
  - toast0 11y ago
    280 is a north/south freeway, despite the north side going due west in the area you describe.
hanniabu 11y ago
If you see some ends of hashed rails with these yellow and black striped block 'caps', those are actually designed to bend inward towards the road so that if a car hits the end of the rail head on, the way the rail is designed to crush will force(move) the car to continue moving forward on the road-side of the guard rail.

the_mitsuhiko 11y ago

> Maybe I'll read this because I shall like to see his reasoning. Many guardrails used to be like this. My recollection is that when guardrail ends are buried, vehicles can easily run over the end so the middle of the car rides up over the guardrail. This can flip the car over--either onto the road or onto whatever the guardrail was supposed to be guarding. Yeah, I remember this coming up in discussions in Austria as well. The current design of guardrails involves moving the guardrail terminal out of harms way: http://www.land-der-erfinder.at/wp-content/uploads/Leitschiene.png http://www.land-der-erfinder.at/wp-content/uploads/Leitschie... And for retrofitting guard rails between lanes where there is not enough space, they installed shock absorbers: http://www.land-der-erfinder.at/wp-content/uploads/Aufpralld%C3%A4mpfer.png http://www.land-der-erfinder.at/wp-content/uploads/Aufpralld... If you crash into those it crumples.

DrScump 11y ago
<they installed shock absorbers> In the SF Bay Area, such junctions of guardrails tend to be preceded by what look like huge plastic garbage pails filled with sand, apparently to absorb as much energy as possible without (or, at least, before) bouncing such vehicles back into traffic. The other extreme was a freeway case (locals to the San Jose area can see this now, on 85 northbound in Cupertino between the onramp from 280 westbound and the Fremont Ave. exit) where the guardrail began about 10 feet from the side soundwall, leaving a car-width's gap to the right of the guardrail. A perpendicular soundwall was about 30 feet beyond. One evening, a car went right through the gap and into the perpendicular wall at full speed. Subsequently, the guardrail was extended at an angle to meet the side soundwall.
- toast0 11y ago
  280 is a north/south freeway, despite the north side going due west in the area you describe.

hanniabu 11y ago

If you see some ends of hashed rails with these yellow and black striped block 'caps', those are actually designed to bend inward towards the road so that if a car hits the end of the rail head on, the way the rail is designed to crush will force(move) the car to continue moving forward on the road-side of the guard rail.