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|Description Text||We would like your comments on the use of a double-sided road closure gate based on the single arm
gate that was tested for South Dakota.
|Date||July 25, 2014|
The South Dakota Road Closure Gate does not pose any significant hazard for vehicles impacting the gate in a stowed position. The crash tests were conducted on the road closure gate oriented in a stowed position as opposed to a closed position, since it was believed that it would result in the most severe impact. In addition, SDDOT reasoned that vehicle impacts into road closure gates in the closed position rather than the stowed position would not be as likely to occur due to the significant increase in delineation and subsequent lower driving speeds. Head-on tests were conducted since the vehicle would be required to break both the gate support post and the hold back post. The impact location, consisting of the centerline of the hinged connection, was selected because the post and gate weights were approximately equal.
We have some basic comments on the use of the double-sided gate.
1. Switching to a double-sided gate would not affect the performance of the gate in the open position. This would basically be the same as the single-sided gate that was tested.
2. When the double-sided gate was in the closed position, there are some concerns. If the closed gate has too strong of a connection, there is concerns that impacts on the gate in the closed position may not cause the support posts and hinges to breakaway easily enough and may post a risk to vehicle occupants. The concerns would include occupant impact velocity and ridedown acceleration increases and the potential to cause vehicle instability. Thus, any closure of a double-sided gate would have to release under very low loads. With a breakaway or weak connection at the connection between the gate arms, the potential for impact safety issues may exist, but the potential is much less.
3. Gate closure capacity would need to be very small to reduce concerns for impact with the double-sided gate. Ultimate capacities of the closure between 1-2 kips or less would be recommended. This is roughly equal to the capacity of two 1/8” dia. A307 bolts or a single ¼” dia. A307 bolt.
Let me know if you need further information.
|Date||July 25, 2014|
130 Whittier Research Center
2200 Vine Street
Lincoln, NE 68583-0853
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