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Foothills Parkway Aluminum Railing and a Modified Version of the Foothills Parkway Railing

Question
State WI
Description Text

Our structures department received a bridge plan with a unique bridge rail (see pages 2-4 of attached PDF).  It appears to be similar to the Foothills Parkway Aluminum Railing that MwRSF crash tested in 1994.  However, we don't have a good copy of the crash test report (most of the pictures are gone).

 

The modified rail is being used on a raised sidewalk and needs to be tall enough to prevent pedestrians/bikes from falling off the bridge (that is why they added an extra railing).  It will be used on a roadway with a posted speed of 35 mph.

 

Would it be possible for MwRSF to provide some feedback about the rail modifications.  I know that I do not like what they are planning to due by the light pole.  Some concerns have been expressed about the reinforcement of the concrete under the rail.

Keywords
  • Bridge Rails
Other Keywords none
Date June 21, 2011
Attachment 20110621133738414.pdf


Response
Response

I have briefly reviewed your enclosed materials. From my best recollection, MwRSF crash tested the 2-tube Foothills Parkway Aluminum Bridge Railing (FPAR) in the early 90s according to the 1989 AASHTO Guide Specifications for Bridge Railings using Performance Level 1 (PL-1). In this testing, MwRSF conducted two pickup truck tests and one small car test. After an initial failed pickup truck test, the longitudinal aluminum tubes were sized up to double the wall thickness to 7/16 in. and modify the post anchorage system.

 

The proposed 3-Line Aluminum Railing utilizes one additional tubular rail section above the top rail provided in the FPAR system. Although the additional rail will provide increased barrier capacity, it may also result in higher vehicle loading to the barrier system, including the anchorage hardware within the concrete curb. At the present, no reinforcement details are provided for the concrete curb and deck to help demonstrate that equivalent or greater anchorage capacity is provided. Further, the new design concept contains three cables which pass through the web of the posts in addition to new structure on the face of the posts. Discontinuities have been incorporated into interior regions of the tubular railing system in order to accommodate vertical light pole systems. It is uncertain as to how these modifications will affect the safety performance of the railing system under the new MASH impact safety standards. With so many changes, one should consider testing at gaps and ends, something that was raised to the sponsor but not addressed or funded in the 1990 FHWA Guardrail Testing II program. These concerns remain for the ends as well as at any gap where poles exist.

Date June 22, 2011


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