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April 6, 2000 Greg Frederick 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 said, 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. Required Modifications · 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. Sincerely,
Vince Taylor Attachments: 1) Caltrans Bridge Rail Workshop, Presented to the California Coastal Commission, December 1999, Title page and pp. 17-18. 2) LRFD Bridge Design Specifications, AASHTO, Second Edition, 1998, pp. A13-1, A13-2. 3) Memo from Steven Scholl to Bridge Railing Subcommittee, California Coastal Commission, February 4, 2000. 4) Letter from John Allison, Caltrans, to Steven Scholl, California Coastal Commission, February 11, 2000. CC. (W/O Attachments): 1) Steven Scholl, California Coastal Commission, 45 Fremont Street, S.F., CA 94105‑2219 (with LFRD attachment). 2) John Allison, Caltrans, P.O. Box 942874 MS 9, Sacramento, CA 94274-0001. 3) Bob Coleman, Caltrans, PO Box 942873, Sacramento, CA 95814 |
