December 21, 2000
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
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
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
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.
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.”
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.
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.