Replacing Guard Rail

[shaneoden]

I am currently faced with a situation that will require me to replace a failing section of guard rail at the end of a old, underdeveloped road in Washington. The road travels down hill at a slope of about 15% where it dead ends. What types of structures are acceptable for handling head on impacts? If anyone can point me in the right direction of codes/standard plans, or even a contact in the State of Washington, I would greatly appreciate it.

 

[civilperson]

Two foot deep gravel in a pit beyond the road surface as in runaway truck escape lane terminus. (And the phone number of the nearest tow business).

 

[shaneoden]

Good suggestion. However, I should have mentioned that there is a 3:1 drop on the other side and then 50 ft. to a lake. Would a cable barrier system work?

 

[RWF7437]

http://www.wsdot.wa.gov/

 

[civilman72]

Standard guardrail and cable barrier systems are not designed for head-on vehicles. There are special guardrail designs where two guardrail sections at perpendicular roads meet - usually at intersections, where the chance of a head-on collision with the guardrail is much more possible. Page 11 on the CDOT link is where the intersection guardrail design is described, but I do not think any kind of guardrail is applicable for this situation.

I would look at crash-barriers such as sand barrels that are designed for head-on collisions.

 

[roncity]

1. Always better to replace what was there with the same stuff to preserve the original engineer's design.

2. On the other hand, if you want to upgrade to current standards, there should be a specific design recommended by the roads controlling authority. In most cases, for dead end roads, they will want some kind of highly reflective breakaway barrier at the end of the pavement, with a second impact resistant barrier closer to the drop-off. ( maybe set of sand filled drums or the gravel pit and then a solid concrete barrier ) You will need to sign and seal the plans...and take responsibility for the design. And get it approved by the controlling authority.