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Condition of Temporary Concrete Safety Barrier

Question
State KS
Description Text

I
had a question come in from KDOT field personnel regarding the condition of
TCSB and at what point the TCSB should be rejected on a KDOT project. KDOT
doesn’t currently have any published criteria, but I gave our field personnel
the direction that if the shape of the barrier or the structural integrity of
the barrier is compromised then it should not be allowed on the project. I
talked with Scott King and he seemed to think MwRSF might have looked into this
topic previously. I didn’t find anything on the Pooled Fund site directly
related to the condition/damage to TCSB. Do you know of any research that MwRSF
has done previously on this? I have some information I’ve found from a few
other states, but just wanted to check and see if you had anything MwRSF had
done. Please give me a call to discuss if needed or just send an e-mail
response.

Keywords
  • Temporary Barriers
Other Keywords none
Date May 27, 2015


Response
Response There has not been any formal research in this area, but it has come up as a research need several times in the past.

As such, I don’t have hard data or guidance, but I can note some areas for concern that we would consider when looking at barrier condition.

1. Deformed or damaged connections – If the barrier loops or the connection pin are significantly deformed or damaged, we would recommend replacing the barrier. Deformed loops or pins have lost some of the toughness/ductility. As such, a second impact may be sufficient to fracture those components. This would include deformation or partial tearing of those parts. Additionally, if the loop bars are necked or decreased in cross-section. Similarly, if the loops have been pulled out of the end of the barrier face partially, this would indicate that previous impacts have moved the bars in the concrete and that there is the potential for loss of development.
2. Damage to the barrier toes or ends – We often see damage to the toes of the barrier segments due to moving and placement, especially on the ends of the barriers . This is a significant problem as the engagement of the adjacent barrier toes when the segments rotate during impact is critical for generating the forces in the joint needed to redirect the vehicle. Thus, if the toes of the barrier segments are spalled off or broken, it would be a concern.
3. Structural cracking – If you observe any through cracking of the barrier or cracks wider than 1/8”, I would be concerned about barrier integrity.
4. Large sections of disengaged concrete – If large chucks or pieces of the barrier have been disengaged anywhere along the segment, it would be cause for concern. This missing concrete would degrade the structural capacity of the barrier and potentially act like asperities or snag areas along the face of the barrier that could promote vehicle instability or snag. I don’t know if I have an exact size for those disengaged pieces off the top of my head.
5. Exposed rebar – Exposed rebar would be cause for concern as it would indicate large regions of disengaged concrete and it would expose the reinforcing steel to corrosion.

Again, these are not hard guidance, as that kind of effort would take more research, but these are the types of things I would look out for.
Date May 27, 2015


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