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Please see below the concern from one of our districts. Could you please provide the vertical taper rate recommendation that temporary concrete barriers can be install on?

Based on the information provided below, they want to do all the resurfacing (approach and roadway) at the end of the project. To do that, they have to install a temporary ramp (due to the differential height of 1.75”) between the existing approach pavement and the bridge joint area (which will be completed first that the approach and roadway), and then install the PCB on this temporary ramp. The question they have, is there any recommended ramp slope or ramp vertical rates to install the PCB on it, in which the barriers connections (pin and loop), and any other part of the barrier will perform well if those get hit?

Each PCB section length is 12.5’, as an example, if they would install a PCB section on the proposed ramp that will have a drop off of 1.75”, the taper rate would be 86:1.

Any comments/suggestions are welcome.

Thank you,

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Can temporary concrete barrier wall be set up over a change in pavement elevation? Say there’s a difference of 1.75” between a bridge joint and an existing approach pavement?

In the below instance the bridge repair work is done and the concrete overlay is done, but the proposed HMA Surface isn’t. I’d like to do all the resurfacing at the end of the project when the barrier wall is gone.

In terms of placing the PCBs on a ramp, we don’t have any real data to provide guidance with. Potential issues would include:

1. You may encounter some issues with the PCB joint alignment. There are a couple of cases that could show up. In one case, a PCB would sit on the upper portion of the elevation change. This barrier would remain horizontal and extend 1.75” above the adjacent barrier. This may cause misalignment of the joint connection vertically and it leaves the upper face of the barrier partially exposed to snag.
2. Another case would be that one barrier sits at an angle. This can also cause significant joint alignment issues. See below. The level of joint alignment will vary depending on where the barrier lands relative to the grade change.
3. Finally, you may face a situation where the end of on PCB section butts against the elevation change. This may prevent the barrier from moving effectively when impacted as it will not be able to rotate or translate longitudinally. This would be undesirable.

Thus, there are some drawbacks that one can foresee in this type of installation. The first two might be acceptable if the connection between segments can be made. The third case should be avoided.

Thanks