NHTSA Motorcoach Roof Crush and Rollover Testing

[davidbrady]

Here's a couple fascinating documents on NHTSA rollover standards and allowable roof crush in transit motorcoaches. Check out the g's exerted on the roof during contact with the ground. I've also added the documents to our Library under Document Library -> Theory:


  NHTSA 2009 SAE Motorcoach Roof Crush and Rollover Testing.pdf (Size: 4.54 MB / Downloads: 1149)

  NHTSA 2009 SAE Motorcoach Roof Crush and Rollover Testing Discussion Paper.pdf (Size: 1.68 MB / Downloads: 1132)

[patticake]

That reminds me of Rick Archie laying his Wanderlodge II on it's side, but without the windshields popping out. His wife had to kick hers out to get out of it.

[Arcticdude]

Dayum!! 8G's!!!!!!!!! That's pretty extreme! Very interesting, to say the least. Good find!

[davidbrady]

From the "Discussion Paper":

"The FMVSS No. 220 test applies a uniformly distributed compressive load (equivalent to 1.5
times the unloaded vehicle weight of the bus), on the roof of the bus along its longitudinal
centerline using a 915 mm (3 feet) wide platen that is 305 mm (1 foot) shorter than the bus length.
The requirements are that the bus roof does not compress more than 130 mm (5.118 inches) and
the emergency exits remain operable. It was determined that the test protocol could be adapted to
test motorcoaches with only minor changes to the test device. However, neither the MCI nor the
Prevost bus was able to meet the 1.5 times the unloaded vehicle weight (UVW) required for
school buses. The MCI bus was able to achieve 0.91 x UVW prior to the front of the bus
collapsing and hydraulic test device running out of stroke. The Prevost bus was able to achieve
1.17 x UVW prior to the front of the bus collapsing and hydraulic test device running out of
stroke. It should be noted that neither of these buses were required or designed to meet the
FMVSS No. 220 requirements".

Methinks their performance in the School Bus crush test, FMVSS No. 220, is pretty remarkable given that they weren't designed to meet this standard. :-)

The unloaded vehicle weight (UVW) for the MCI is 27853# and for the Prevost 29270#. The UVW of a 36' Blue Bird All American School Bus is 18880#, from here, (or 20977# if we extrapolate this weight out to a 40 footer). For a 40' school bus to pass FMVSS No. 220 it must support 1.5*20977= 31466#. The MCI supported 0.91*27853 = 25346# and the Prevost 1.17*29270 = 34246#. (This doesn't say what the All American can support before crushing excessively, just what it needs to).

[lucaswillemse]

Attached is a picture of Rck Archie's coach, it did a lot better than the one used in the demo.

[davidbrady]

(09-16-2013 00:06)Arcticdude Wrote:  Dayum!! 8G's!!!!!!!!! That's pretty extreme! Very interesting, to say the least. Good find!

In the Discussion Paper they point out that the average g's are round 8, but the peak g's are as high as 70! Yikes!

(09-16-2013 14:49)lucaswillemse Wrote:  Attached is a picture of Rick Archie's coach, it did a lot better than the one used in the demo.

Rick's coach did very well indeed!