Dharma Cloud Foundation
PO Box 1066
Mendocino, CA  95460


December 21, 2000

Sara Wan, Chair  
California Coastal Commission
45 Fremont Ave, Suite 2000
San Francisco, CA  94105

Dear Sara:

This letter clarifies and adds to the information in my letter to you of December 13, 2000.  Both of these letters are my response to the letter from John Allison, Caltrans, to Peter Douglas, dated December 5, 2000 (but received by the Commission on December 12, 2000, via fax). 

In his letter, Mr. Allison states that, in applying American Association of State Highway Organizations (AASHTO) LRFD requirements, it is Caltrans policy to require that “all railing criteria [in Appendix A of Section 13] fall in the preferred zone to reduce the potential for wheel, bumper or hood impact with the barrier posts, thus increasing the safety of the public.” (Emphasis added.)  This assertion of increased safety is used to justify Caltrans’s modification of the Wyoming rail.

It is essential to understand that the railing design criteria of Appendix A specified by Mr. Allison are “static design criteria”, based on engineering calculations, as opposed to the dynamic evaluation of performance provided by crash tests.  The use of static design criteria to judge railing safety has been completely abandoned by the highway engineering community.  The reason for this abandonment was summarized by J. W. Hatton of the Federal Highway Association in a 1996 presentation to AASHTO [1]

 Until the late 1980’s, designers relied on precedent, the information contained in the most recent edition of the AASHTO “Standard Specifications for Highway Bridges”, and their judgment to design a bridge railing appropriate for a given site.  The Standard Specifications, as they still do, called for the application of a 10-Kip static load … as well as some dimensional requirements for the openings between rail elements and other cross section geometry [the requirements of Appendix A of Section 13 of the LRFD document cited by Mr. Allison]…. 

In the late 1970’s and early 1980’s, actual tests were run on several commonly-used railings that had been designed under the static loading procedures.  The results were unexpected: several of the railings failed quite dramatically and it was shown that static design loadings were not sufficient to ensure adequate railing performance. 

As a consequence of the test results, both the Federal Highway Administration and AASHTO have replaced static design criteria and engineering judgment with crash tests to measure the safety performance of bridge railings.   NCHRP Report 350 provides the current specifications for testing and assigning safety levels. Caltrans has also stated that Report 350 provides the primary design criteria used by it to develop and select bridge rails.[2]

Mr. Allison may well have misled the Commission into thinking that the railing design criteria on post setback cited by him are a mandatory part of the LRFD standards.  Nothing could be further from the truth.  The two pages of Appendix A of Section constitute a minor part of the bridge railing section (Section 13) of the LRFD standards.  They contain optional guides for designing a bridge railing to subject to crash tests. As the appended excerpts from the LRFD document show, whether or not these design guides are followed is immaterial to judging the safety of a railing. A reading of the entire Section 13 makes clear that the AASHTO LRFD standards mandate use of Report 350 crash tests and safety-level classifications as the sole basis for judging the safety performance of bridge railings. 

The Wyoming Rail has been tested according to Report 350 specifications and been accepted by the Federal Highway Administration as a Test-Level 4 (TL-4) railing for general use on the National Highway System. Note well that the TL-4 safety rating would not have been earned by the Wyoming Rail if the tests had shown any “wheel, bumper or hood impact with the barrier posts” – the safety concern that Mr. Allison focuses on in his letter.

According to the LRFD standards, Test Level 4 is “taken to be generally acceptable for the majority of applications on high-speed highways, freeways, expressways, and Interstate Highways with a mixture of trucks and heavy vehicles.”[3] The Wyoming Rail is judged safe for traffic conditions that are more extreme than those experienced on Highway 1. 

In my letter of December 13, 2000, I documented that Caltrans erred when it told the Commission that the Wyoming Rail fell in the “not recommended” range for post setback and therefore needed to be modified.[4] I showed that Wyoming Rail satisfied the post setback design criteria of the LRFD standard.  I have documented in this letter that, contrary to the assertions of Mr. Allison, the static LRFD design guidelines provide no safety basis for rejecting the Wyoming Rail.  These instances of erroneous and misleading information are only the most recent in a long string of similar instances. 

I wish that I could believe that this latest exposure of Caltrans errors and deceptions would signal the end of the road and that Caltrans would now accept the Wyoming Rail for use in California.  Based on the experience of the last two years, however, such a belief would be naïve. 

So long as the Commission allows Caltrans to set “engineering requirements” for highway projects without regard for environmental concerns and without scientific justification, Caltrans can easily generate a new “requirement” that rules out the Wyoming Rail.  If the Commission is to uphold its responsibility to protect coastal resources, it needs to require Caltrans to provide scientific data on the safety tradeoffs among alternatives, and then the Commissioners must determine which alternative provides the appropriate balance between protecting the public’s safety and protecting the public’s coastal resources.  If Caltrans is required to do this for alternative scenic railings, there is no doubt in my mind that the Wyoming Rail will be the clear choice of the overwhelming majority of the Commissioners. 

The Commission has invested a great deal of time and energy to get the best possible scenic railing for the coastal zone.  The evidence shows that the Wyoming Rail is as safe as any of the alternative rails being considered and visually far superior.  To have this railing adopted, the Commission now needs only to exercise the powers vested in it by the Coastal Act.



Vince Taylor

Executive Director

cc: Peter Douglas (for distribution to all Commissioners), Christine Desser, Shirley Detloff, Pedro Nava

[1] J. W. Hatton, Bridge Railing Design and Testing, a Discussion with the AASHTO Highway Subcommittee on Bridges and Structures, Technical Committeee (T-7) for Guardrail and Bridge Rail, May 14, 1996.

[2] Caltrans Bridge Rail Workshop, presented to the California Coastal Commission, December 1999, p. 4.

[3] Section 13.7.2, “Test Level Selection Criteria,” AASHTO LRFD Bridge Design Specifications, Second Edition¸1998.

[4] Rick Land, Engineering Service Center, Head of Structure Design Department, Caltrans, acknowledged this error in the meeting of the Bridge Railing Subcommittee of the Coastal Commission, December 14, 2000. 


 AASHTO LRFD Excerpts on Determining Rail Safety[1]

The two pages of Appendix A of Section13 are a minor part of the bridge railing section (Section 13) of the LRFD standards.  A reading of the entire Section 13 makes crystal clear that the AASHTO LRFD standards mandate use of Report 350 crash tests and safety-level classifications as the sole basis for judging the safety performance of bridge railings: 

Commentary:  13.7.3 Railing Design General:  … A railing system and its connection to the deck shall be approved only after they have been shown through crash testing to be satisfactory for the desired test level…. New Systems: New railing systems may be used, provided that acceptable performance is demonstrated through full-scale crash tests.

The crash test specimen for a railing system may be designed to resist the applied loads in accordance with Appendix A of this section or the NCHRP Report 350 with its revisions.

[Emphases added.]

These citations make clear that the static design standards of Appendix A of Section 13 are irrelevant to the acceptability of the Wyoming Rail under AASHTO LRFD standards.  They are provided only as guidance that may be used to design a railing.  The acceptability of a railing is determined solely by demonstrating its performance “through full-scale crash tests.” 

Further, the LRFD document specifies that the crash tests to be used are those of NCHRP Report 350:

13.2 Definitions

Crash testing of Bridge Railings – Conducting a series of full-scale impact tests of a bridge railing in accordance with the recommended guidelines in NCHRP Report No. 350 in order to evaluate the railing’s strength and safety performance.

[1] AASHTO LRFD Bridge Design Specifications, Second Edition¸1998.