April 6, 2000
Wyoming Department of Transportation
5300 Bishop Boulevard
P.O. Box 1708
Cheyenne, Wyoming 82003-1708
Fax: (307) 777-4279
Dear Mr. Frederick:
Thank you for your offer to supply additional
information on the Wyoming steel-tube bridge railings.
Dharma Cloud Foundation has an ongoing interest in
improving the visual transparency of railings used on scenic highways in
California. The Wyoming railings are excellent candidates for this use.
Your department supplied me with information and
engineering drawings for the TL-3 railing in May of 1999. I obtained
information on the TL-4 railing from FHWY. I supplied this information
to the California Coastal Commission during a permit hearing for a bridge
proposed for the Noyo River in Fort Bragg, California on scenic Highway
1. The Commission requested Caltrans to provide additional information
on alternative railings. It did so in December, 1999.
Included in the railings that Caltrans told the
Commission that it was willing to consider for scenic highways was the
Wyoming TL-4 Railing. However, in presenting this railing, Caltrans
This rail falls in the
“not recommended” range for post set back criteria in the AASHTO bridge
rail Load and Resistance Factor Design (LRFD) Standards.
In addition to handrails and pickets [to meet pedestrian
and bicycle requirements], the size of the members would have to be
increased to meet ASHTO’s [sic] LFRD.
I have included the title page and pages 17 and 18
of the Caltrans Workshop presentation. In the photo of the modified
Wyoming railing on p. 18, the railings appear to at least twice as tall,
greatly reducing transparency.
I have attached a copy of the (3) pages of the
relevant LFRD standards cited by Caltrans, “Section 13 – Railings,
Specifications - Commentary, Appendix A.” My calculations show that both
the TL-3 and TL-4 Wyoming Railings meet these standards.
Would you please review your engineering drawings
and design materials to confirm that the TL-4 railing was designed to
meet the LFRD standards. Also, would you please assess whether or not
your TL-3 railing meets these standards.
I also want to direct your attention to the first
paragraph in CA13.1.1 of the LFRD standards:
The post setback shown
from the face of the rail for various post shapes is based upon a limited
amount crash test data. The potential for wheel snagging involved with a
given design should be evaluated as part of the crash test program.
This paragraph seems to clearly state that crash
test results are the ultimate determinant of the acceptability of post
setbacks. Would you concur with this statement? If so, the Wyoming
Railings obviously meet the LFRD standards, since they have passed more
stringent current test standards than those contained in the figures of
Appendix A, which are based on older NCHRP 230 test standards.
Your cooperation in this matter will be greatly
appreciated. The California Coastal Commission and Caltrans are
currently working together to identify railings and set criteria for
acceptable railings within the scenic coastal zone of California. I’ve
included copies of recent letters explaining their efforts. Your
information will assist them to reach good decisions.
I’ve sent copies of this letter to the Coastal
Commission. and to Caltrans. I would be grateful if you would send
copies of your response to them also.
Caltrans Bridge Rail Workshop, Presented to the California
Coastal Commission, December 1999, Title page and pp. 17-18.
LRFD Bridge Design Specifications, AASHTO, Second Edition,
1998, pp. A13-1, A13-2.
Memo from Steven Scholl to Bridge Railing Subcommittee, California
Coastal Commission, February 4, 2000.
Letter from John Allison, Caltrans, to Steven Scholl, California
Coastal Commission, February 11, 2000.
CC. (W/O Attachments):
Steven Scholl, California Coastal Commission, 45 Fremont Street,
S.F., CA 94105‑2219 (with LFRD attachment).
John Allison, Caltrans, P.O. Box 942874 MS 9, Sacramento, CA
Bob Coleman, Caltrans, PO Box 942873, Sacramento, CA 95814