Traffic barrier

[ruready]

Does the 10kip load in AASHTO only apply to traffic barriers on bridges and atop retaining walls? I am designing a barrier at bus stops.... There is no way that designing it for impact loads based off of speed and vehicle weight will be financially feasible.

 

[Qshake]

The 10 kip load is only a portion of the impact load and so the main function of the barrier is to divert a wayward vehicle back onto the roadway, not to stop it elastically.

There are crash-tested barriers that are approved by the FHWA which may be applicable to your situation. I would recommend that you search the FHWA website for safety barrier curb info or safety railing etc. Also the AASHTO Green Book may be of service to you.



Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[bridgebuster]

We've done something similar but it's just standard concrete barrier for roadway. If you're planning on guiderail, it might no work well because you have to construct an anchorage and a transition before reaching a normal section.

On a recent project, we used an FHWA crash-tested p/c concrete barrier with integral masonry veneer as a barrier between a highway & pedestrian walkway.

The supplier was Stonecast Inc, Queensbury NY 518-745-8035

 

[miecz]

With no other code criteria, the AASHTO Highway Design Loading for Traffic Railings has become the only standard available. As such, I would say that it applies to your case. However, the 10 kips load, from figure 2.7.4B of the Standard Specification has been superseded. A vehicle collision force is designed as Extreme Event II with forces from the Railing Test Level Criteria of Section 13 of the LRFD Bridge Design Specs.

 

[ruready]

Miecz,
Could you do me a favor and tell me what that is? Thanks

There is no way I can get the book in time and I need to get info to these guys as fast as I can. I have been on the phon with NDOT and Caltrans, everyone has such different opinions on this matter, sucks.

 

[miecz]

There are six force levels, called Test Levels. Which level you fall under is a matter of judgement. The railing design force is listed in parentheses. Keep in mind these are limit state loads, with a load factor of 1.0, to be used with LRFD resistances.

TL-4 is used for most Interstate Highways with Trucks and Heavy Vehicles. (54 kips)

Tl-3 is for high speed arterial highways with very low mixture of heavy vehicles. (54 kips)

TL-2 is for local and collector roads with small number of heavy vehicles. (27 kips)

TL-1 is for low speed, low volume local streets. (13.5 kips)

 

[ruready]

What is the actual section in AASHTO that gives those loads? From my understanding the load can be distributed over 10lf, is that correct? I really really appreciate your help.

 

[ruready]

For more background, the "bollards" will be embedded into the grou and use caisson ftgs to resist the overturning from the impact... At 10 kips and using the non-constrained eq's from the IBC and allowing 1/2" deflection, my ftg is 6' deep.

 

[bridgebuster]

normally bollards aren't used as a traffic barrier in the sense that they're meant to stop a truck, although hitting one or more would slow it down. We did use them on a bridge as part of the urban design. Bollards are more of a warning devive, although they can be and are used for building security to keep potential truck bombs away.

See the attached file for an important design consideration when using bollards.

 

[miecz]

The loads are given in Table A13.2-1 of Appendix "A" of Section 13 of AASHTO's LRFD Bridge Design Specifications. The load gets distributed by yield line theory.