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Anchored PCB placed behind free standing crash cushion - Shielding Piers

Question
State UT
Description Text  See photo below of a stand alone crash cushion with 2 sections of anchored PCBs installed around 2 sign poles.
I thought of 3 options as stated below.
1. Remove the PCBs and relocate the crash cushion up to the first pole. It would be highly unlikely for an errant to impact the second pole in this case. For a car to impact the pole, the vehicle would be impacting the pole at such a high angle that it would be similar to impacting a cast-in-place concrete barrier.
2. Install seven anchored barrier with three barrier upstream of the beginning of LON and three barrier downstream of the end of LON as suggested in the response to IA: https://mwrsf-qa.unl.edu/view.php?id=1227
3. Install 40 feet of CIP barrier on both sides with foundation design. As I understand it a study for minimum length CIP barrier is not available but TTI is currently working on something similar with Texdot.
Question:
Would you agree that these are viable options?
Would you agree that option 1 would be the better choice because placing additional barrier would be more of a hazard than just placing the crash cushion placed in-front of the poles?
Thank you for your time,  
Keywords
  • Bullnose Median Barrier & Short Radius
  • End Treatments & Crash Cushions
Other Keywords none
Date October 9, 2018
Attachment utah pier.jpg


Response
Response

I have provided a few thoughts below. By appearance, the site seems to have same direction traffic on both sides of the poles.

 

One option would be to utilize a thrie-beam bullnose guardrail envelope with the downstream end left open The upstream end would incorporate the rounded, slotted head with containment cables. This system would not require a concrete pad.

 

A second option would utilize the FLEAT median version that allows both rails to gradually spread apart such that the poles were adequately shielded from impacting vehicles with tolerable working width. This system would be long and not require a concrete pad.

 

A wide crash cushion with backup structure might be used here if backup structure is nearly touching poles. It is holed that the wider CC would protect against oblique impact near the downstream end of CC. However, the wide CC would need to be placed in CAD to determine if this solution is effective.

 

I do not like placement of PCBs on soil foundations. If PCBs were to be used, the ends of the PCBs would need to be treated with CC or sand barrels. The PCBs would also need to have sufficient clear area between poles and PCBs. The PCBs would need to have sufficient overlap of barriers past the poles as well per guidance. The upstream anchorage system would be needed on each column of PCBs. Asphalt should be under the PCBs too.

 

Overall, I like option 1 of 4 above the best.

Date October 9, 2018


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