traffic barrier in parking lot

[Ben29]

I am designing a concrete retaining wall in a parking lot for a new restaurant. The retaining wall will retain 9ft max.

My questions is, at what height is a traffic barrier needed? The below picture is from my local Chipotle parking lot, where the retaining wall is retaining some 30+feet (probably).

 

[JStructsteel]

Use AASHTO dims. I would use 18" for a parking lot. TL-1 impact.

 

[phamENG]

If your question is at what height of retaining wall you need it (like you need a guardrail if your floor is 30" above the lower level), I don't know a codified answer. I'd also lean on the civil engineer (who is likely better versed in parking lot/traffic requirements) to say it's needed or not. Barring that, I'd say it's probably needed when there's a drop that could cause injury when somebody drives off the edge. Because they will. (I've had two 'wrong pedal, hit the building' jobs this month already.)

3 feet feels like a reasonable threshold to me.

 

[JStructsteel]

I read wrong what you were asking.

From IBC 406.4.3 Vehicle barriers.

Vehicle barriers not less than 2 feet 9 inches (835 mm) in height shall be placed where the vertical distance from the floor of a drive lane or parking space to the ground or surface directly below is greater than 1 foot (305 mm). Vehicle barriers shall comply with the loading requirements of Section 1607.8.3.

 

[JStructsteel]

Amit, 8-14ft tall??? That makes no sense. Do you have examples?

 

[Enable]

You need a vehicular barrier as a matter of prudence if nothing else.

See structural magazine article on the issue that points to IBC requirements. If you follow 406.4 you get to section 1015 which lands you back at the 30" drop before guards are required (like most things such as guards loads for railings/windows). The code appears somewhat murky in its separation of guards from vehicular barriers (uses the language of "if you need" to use a guard as a vehicular barrier). But in this situation you need at least a guard for pedestrians, and if it would be reasonable for users / occupants to look at your guard and go "hey that provides me some safety for my vehicle so I can drive a weee bit faster in this lot" then you need to design it for the vehicular loads.

That said the IBC is not my code so perhaps there are other clauses that render this situation exempt (donnu) but in my jurisdiction if you didn't put a guard (able to stand vehicular loading) in you'd be in a shit ton of trouble WHEN something goes wrong. I previously worked on parking garages for a living and every single one would have a vehicular barrier one way or the other.

 

[IRstuff]

Note that OP's image is of a guardrail, which is not the same thing as a bollard; bollards are expected to prevent penetration from direct, frontal impacts, while guardrails are only expected to prevent glancing impacts. The guardrail in the image would not necessarily prevent a car from going through it if directly hit.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[LittleInch]

Go to minute 0:30....

https://www.youtube.com/watch?v=2NLrU9kLvo4

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Ben29]

Thanks everyone. I will talk to the civil engineer and see what they recommend.