Thrill Ride: Historic Dips and Timber Trestle Bridges on SBC’s Route 66

By Ruth Musser-Lopez
(May 1) Unpredictable and wild, circa eighty-five year old dips and timber trestle bridges are among those extraordinary characteristics of San Bernardino County’s desert section of California U.S. Highway Route 66 which make for a thrilling, one-of-a-kind ride. Yet, for safety reasons, timber trestle bridges cause government officials to shudder.
Just west of Daggett, “catching some air” driving fast across the dips on old Route 66 is a cheap but perhaps dangerous thrill that some bikers seek at their own risk.  It seems to be the general consensus of the public actively participating in assisting with the development of the Bureau of Land Management’s Route 66 Corridor Management Plan (CMP) that despite the inherent dangers of those driving irresponsibly there, to smooth the road out would be to alter the historic route’s integrity and lose some of its intrinsic charm.
Photo Courtesy Lardner/Klein
On the other hand, the timber trestle bridges are the “something old” along the corridor that some government officials seem to think are of immediate concern—they may not be that safe. If you drive the abandoned de-designated state route…you apparently may be doing so at considerable risk.
In a recent analysis by the County of San Bernardino, 128 “aging” 80-year (+/-) old timber trestle bridges are in the area between Daggett and Mountain Springs Road, reported Lardner/Klein Associates.  This number is “staggering,” according to Lardner/Klein  These 128 are “opposed to only 30 currently carrying automobile and truck traffic on U.S. Highway 66 across all other states and counties (including Los Angeles County, California) combined.”
Lardner/Klein also reported that according to the county analysis, the 128 bridges were constructed during the period of time from 1929 to 1935 and are included within a total of 136 bridges and large culverts in this portion of Route 66. Of the remainder, four are reinforced concrete bridges, three are pipe culverts, and one is a concrete box culvert.
However, maintaining the original character and charm of the route including the dips and bridges, is important to tourism with an increasingly large number of foreign tourists from Europe and Asia arriving each year desiring to visit the Grand Canyon via Route 66 from Los Angeles.  According to a study conducted by Rutgers University, these are high-income visitors who are staying longer and spending more than the typical passerby.
Stewardship strategies for Route 66 including the bridges and dips are proposed for consideration by the Route 66 Ad Hoc CMP Planning Committee – abbreviated simply as the “AHPC.”  The AHPC’s first “webinar” meeting took place on April 28, 2014, lead by Lardner/Klein Landscape Architects, P.C., a firm contracted by the Bureau of Land Management to assist with corridor management plan development.  According to Lardner/Klein, the proposed stewardship strategies are based on issues identified in public outreach conducted during initial scoping phases that took place between November 2013 through March 2014 at which time there was a bus tour, small group meetings, conference calls, public meetings, including a web-based meeting all conducted by Lardner/Klein.  The photographs in this article are courtesy of their contracted work for the federal agency.
Jim Klein, acting on behalf of the firm, said with regard to the strength of the bridges, that the route between Barstow and Needles built 80 years ago was never intended to bear the type of tonnage now being pulled by diesel trucks.  With maintenance, the bridges have held up under over-capacity weight even during an emergency redirect when I-40 was closed down due to a temporary hazardous condition.  In reference to the timber trestle bridges, he said that according to the county’s historian Roger G. Hatheway, “You can stick a pencil through them.”
Upon hearing this, one scenario that has been posed more or less as a question by San Bernardino County Sentinel editor Mark Gutglueck, “What are the odds of a catastrophic bridge collapse on Route 66 in the middle of the desert during the ‘perfect storm’ where two heavily-laden 18-wheelers, moving in opposite direction at the same time across a weak timber trestle bridge?”
The County of San Bernardino which maintains the section of Route 66 between Daggett and Mountain Springs Road, is currently conducting a study as a part of the “Dola and Lanzit Bridge replacement projects.”
Nearly all of the distinct segments of the road paralleling I-40 access have some bridges that are weight limited. According to Lardner/Klein, “San Bernardino County is faced with a difficult challenge of keeping the road open to all vehicles. A consulting firm for the San Bernardino County Department of Public Works is currently preparing a study evaluating the manner in which the state inspects and evaluates bridges on historic Route 66 in San Bernardino County, and how this translates into the posting of load limits.”
Timber trestle bridges may have originally been built to support the National Old Trails Road (circa 1912).  Made of what appears to be materials similar to modified railroad ties and cut up utility poles, they were not uncommon nationwide in the first couple of decades of the twentieth century—1900 through 1920 according to Lardner/Klein.  “Beginning about 1920, however, they began to be regarded by many highway design engineers as temporary structures, although they continued to be used in specific locales due to the fact that they could be erected quickly and inexpensively.
Lardner/Klein cited a 1920 book, by Milo S. Ketchum, C.E., entitled
“The Design of Highway Bridges of Steel, Timber and Concrete,” which states that “Timber Highway bridges were formerly quite generally used, and are still in use for temporary structures and in localities where transportation is difficult and where suitable timber is available.” In very simple terms, timber trestle highway bridges were built nationwide with a limited anticipated lifespan.
At the April 28, 2014 meeting of the AHPC, safety concern over the timber trestle bridges were on the agenda as the main subject topic.
The Archaeological Heritage Association suggested that the timber trestle bridges be studied by engineers as an example of what works in the desert’s arid environment.  “The bridges have proven to be durable and strong.  They have held up under tremendous weight over the years.  Perhaps the aridity of the desert has something to do with it. The wooden structures don’t deteriorate as quickly here as in wetter conditions back east.  So that we don’t lose the integrity and charm of the road’s character, maybe all that is needed is some in-kind buttress work to preserve these historic bridge features in place.  As far as weight limits, perhaps its time to consider making this portion of Route 66 a toll road, limit the weight of the vehicles coming across and use the tolls for maintenance of the route.”
Some protection for the road appears to be available through its potential listing on the National Register of Historic Places (NRHP).   Lardner/Klein said that in their review to date, the general consensus of preservation professionals is that the Route 66 alignment itself is eligible for the National Register, however, the transportation and related roadside features such as wooden trestle bridge structures or roadside architectural features will need to be evaluated separately for eligibility.  This opinion seems to imply that the bridges would not automatically be protected under a future Route 66 National Register status by simply being a feature of the road itself.   A study evaluating for NRHP status the individual eligibility of all of the 136 bridges and large culverts between Daggett and Mountain Springs Road on historic Route 66 is currently being prepared as part of the County of San Bernardino’s “Dola and Lanzit Bridge replacement projects.”
Lardner/Klein also reported the following findings with regard to that study:  “The County of San Bernardino currently maintains the 128 timber trestle bridges.  Of these 128 timber trestle bridges 127 are on National Trails Highway (NTH) the predecessor to Route 66, and one timber trestle bridge is on Ludlow Road, an original portion of the Route 66 alignment immediately to the west of Crucero Road.  Of the 127 timber trestle bridges/structures on NTH, 31 are not eligible for federal historic bridge repair and/or replacement funding as they are less than 20 feet in length and are officially classed as culverts and not bridges.
“By the mid-1940s, the State of California recognized the need to rebuild its aging timber trestle highway bridges statewide, and several articles were published by the Division of Highways detailing the need for reconstruction.  At this time, the State of California clearly recognized that all U.S Highway 66 timber trestle bridges between Daggett and Mountain Springs Road were quickly approaching the end of their design and economical service life.”
Yet, Lardner/Klein states,  “Seventy years later, the county of San Bernardino is attempting to maintain the same bridges—a very expensive and difficult task.”  But, the “California’s State Historical Building Code ( – provides a tool for historic preservation,” which would alleviate some of the expense of maintaining historic properties.  The law provides that qualified historic structures would not be required to comply with current code standards. Alternative provisions in California Code Section 18961 provides for consultation with the State Historical Building Safety Board regarding the treatment of qualified historical buildings or structures.
Even so, raised are two potential issues and/or concerns with the application of the California State Historical Building Code as it applies to historic Route 66 on federal lands.  First, if any given bridge is determined not eligible for the National Register of Historic Places, then it cannot be considered to be a qualified historic property thus it appears the alternative historic building code would not apply.  Second, if a property is considered to be eligible for listing, it is unclear whether utilization of a less restrictive State Code on federal historic properties is allowable if federal funds are involved.   Further, if the Federal Highway Administration’s funding process requires review under the National Environmental Policy Act and Section 106 of the National Historic Preservation Act guidelines then the utilization of a State Code may not be feasible.  Resolution of these issues and concerns over the course of the corridor management plan  project is anticipated.
Route 66/National Trails Highway is an important emergency alternative when Interstate 40 is closed due to a maintenance issue or emergency situations such as an accident on the highway.  It thus serves an important transportation function in addition to its historic scenic, recreational and local business uses.  It is used by at least two state agencies, the California Highway Patrol and Caltrans. However, according to Lardner/Klein the alignment has never been officially designated as an emergency corridor by the State of California despite repeated requests by the county of San Bernardino.  Failure to designate the road as an emergency corridor has rendered the route ineligible to receive federal or state funding targeted specifically for emergency detour routes.
We need to hear all of our San Bernardino County region candidates for state assembly and senate positions this election season say that they will endeavor to obtain designation of Route 66 through San Bernardino County as an emergency detour route. Consider this:  other bridges such as the “Big Mac,” the Mackinac suspension bridge in Michigan is under constant maintenance 9 months out of the year.  Isn’t an emergency escape corridor for the millions living in Los Angeles and the “Inland Empire” just as important?

Syndicated 2014, Ruth Musser-Lopez—Small quotes citing author, the Sentinel and publication date are permissible under copyright law.  Please respect the rights of those quoted herein by referencing source:  Lardner/Klein may be contacted at  Permission to reprint this article may be obtained by contacting Ruth at the Archaeological Heritage Association (AHA) 760/885-9374 or via email at

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