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As you are probably well aware, WisDOT has been in the process of redeveloping our concrete barrier design.  MwRSF has been a highly valued resource in this process.  Recently, I've been ask "How well does the Caltrans single slope design would perform in a climate similar to ours"

After some internal discussions, I believe that the question is twofold:

1. When compared to other concrete barrier designs, has a Caltrans experienced problem with the accident performance of the barrier system in colder/snowier climates.
2. Does the barrier have cracking problems similar to the attached pictures. The pictures depict two different scenarios.  The photo labeled as impact, is from accident impact on one of our freeway sections.  The photo labeled construction cracking is develops typically within 48 hours of construction near a tooled in joint.

Does MwRSF have any insight into these matters?  I've also attached a file with the Caltrans design.

For question no. 1, MwRSF does not have information on the real-world crash performance of the CALTRANS TYPE 60 barrier systems.

Your question no. 2 pertains to WsDOT's experience with cracks occurring near tooled-in joints shortly after construction. To date, I have not seen nor heard of this cracking pattern in other states. In the provided construction photograph, cracks appear to have occurred at the man-made joints in both barriers. When and how was the tooled-in joint made? Did the cracks occur after the man-made joint was placed. I assume the answer is yes. If yes, then this cracking is likely due to either the joint type, or its fabrication process, the reinforcement layout used within the barrier, the footing design, or combinations thereof.

Based on everything you have described previously, WsDOT has limited longitudinal rebar in the barrier and no/limited vertical steel as interior locations. It is unclear as to how the barrier is anchored. If the steel is not distributed well in the cross section, I question whether the concrete may want to shrink at one elevation where no steel exists, but it may not shrink as much at other elevations if a greater steel percentage exists in that region, thus causing the diagonal cracking pattern shown in the photograph. At this time, this is only an untested hypothesis.

I suspect that this cracking pattern would not occur if you would use a higher level of longitudinal and vertical reinforcement. But, I must ask why this type of joint is placed when rebar and concrete remain intact within the barrier. If a joint is desired, it would seem more reasonable to provide a through-joint in the barrier where increased reinforcement is used adjacent to the expansion joint.

In the accident photograph, two damage locations are depicted. The noted concrete damage resulted from a motor vehicle impact into the barrier, although the conditions are unknown. What is shown is excessive damage that has occurred due to inadequate longitudinal steel reinforcement and no shear reinforcement. Moderate changes in the design reinforcement would greatly improve impact performance and reduce maintenance requirements resulting from this crash as well as from other environmental influences.