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|Description Text||The IL Tollway has openings in the concrete median barrier to allow emergency vehicles to make a U-turn. These openings vary from 100' to 130' measured between the ends of the concrete barrier wall. Each blunt end is protected by an impact attenuator which is either a GREAT or a Quadguard. During construction projects when vehicles are riding on the inside shoulder there is a desire to fill in this median opening. In the past, several methods have been used. One way was to remove the attenuators and place precast temporary barrier wall sections in the opening. To completely fill in the opening, one section of wall had to be cut to fit. Making the connection between the temporary barrier wall and permanent median barrier was difficult because of the different widths.
Another method was to use precast barrier wall sections placed on a diagonal within the opening so that the barrier did not need to be cut and also so there was no blunt end to protect. One drawback to this method was that the temporary barrier wall extends onto each inside shoulder. The temporary barrier was not attached to the existing median barrier or to the attenuators.
As you can see, each of these options has problems. I know MwRSF has tested several connections between temporary barrier wall and permanent concrete barrier. Is there a TL-3 system that we can employ to safely fill in these median openings for the duration of the project?
The system should accommodate:
1. 32" F-shape temporary barrier wall, 22.5" wide at base
2. 32" Jersey shape or 42" F-shape permanent median barrier, 36" wide at base
3. Possible presence of slotted drain in the center of median opening running parallel to roadway.
|Date||January 30, 2011|
|Response||We do have a system for transitioning between free-standing PCBs and rigid, concrete median barrier. I have attached a report detailing its design and testing.
Refer to MwRSF Report No. TRP-03-208-10. I believe that this system can be used in your situation.
You may note that it might be more desirable to simply anchor or pin all of the barriers in the installation rather than use the transition. However, we have seen in past testing that pins on the backside of a barrier may cause excess rotation and tipping of the barrier which in turn can produce vehicle instability. Thus, we currently do not recommend pinning on both sides of the PCB when placed in the median except for the transition section which we tested.
This issue of anchoring barriers in the median comes up a great deal and is something that we need to test in order to be confident that it is safe.
|Date||February 15, 2012|
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Lincoln, NE 68583-0853
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