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MASH Temporary Barrier Deflection Vs NCHRP 350 Deflection

Question
State WI
Description Text
 I believe that MwRSF indicated that the use of MASH crash test vehicles is increasing barriers deflection distances.  How much has the temporary barrier deflection increased using MASH vehicles compared to NCHRP 350 vehicles?


Portable Barriers


Date August 16, 2010
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We have seen an increase in the deflected of the F-shape PCB when impacted with MASH vehicles.


Free-standing TCB deflections were significantly higher when testing was conducted with the 2270P vehicle under the MASH criteria as opposed to testing conducted with the 2000P vehicle under the NCHRP Report No. 350 criteria. TCB deflections increased 25 to 76 percent when the F-shape TCB was tested under MASH impact criteria. See attached table.


Test No.

Vehicle

Mass (kg)

Speed (km/h)

Angle

IS (kJ)

Dynamic Delfection (m)

Static Deflection (m)

ITMP-2

2000P

2005

100.3

27.1

161.5

1.15

1.14

TB-1

2270P

2268

99.5

25.7

162.9

1.44

1.44

TB-2

2270P

2268

99.7

25.4

160.0

2.023

1.854



This increase in deflection is due to a couple of factors

  1. Higher mass = more inertia transfer and higher load
  2. Higher vehicle stability encourages less climb and vehicle rotation which allows the vehicle to directly load the barrier longer.


In addition, the photos
(Figure 1 and Figure 2 attached)
show the damage from the 2270P testing. In this tests vertical cracks were observed completely through the barrier section. This amount of barrier damage was not observed in the 2000P testing and again suggests that our impact loads have increased.




Date August 16, 2010
Previous Views (116) Favorites (0)
Attachment PCB Deflection Summary_Free-standing.xlsx Attachment Figure 2.jpg Attachment Figure 1.jpg