Restoration

Why American Highway Engineers
Promote Demolition of Historic Bridges

A Story-Teller's Perspective

What, the reader/viewer might ask, does this European banter have to do with American highway engineering practice? Read on, my friend, and you shall learn of the mid-day rides of a later Paul Revere (i.e., Thomas H. McDonald, father of the Bureau of Public Roads). The perspectives of the entrepreneurial British nation of shop-keepers in sharp contrast with the agency-organized and bureaucratic preferences of the French have played out in unpredictable ways in the New World over time, leaving the story-teller with at least one more tale to relate.

In the beginning. . .
designer-builders and government men controlled construction of most of the bridges built in colonial America. They largely emulated the practices of the British motherland where design and construction were grounded in practice and experience with the designer-builder essentially interchangeable with the pre-professional architect and civil engineer. Like the ancient Greek architecton, the British master builder and his colonial counterpart operated as engineers or architects as the occasion required.

To secure their independence from the British, the Americans allied themselves with France. French troops and their military engineers joined in the fight. The French military played a far more significant role on the field in securing independence than most Yanks acknowledge on the Fourth of July, and they played an equally significant one in complicating or contaminating the cross-cultural dimensions imported from Europe into North American practice. The French influence was especially important in American engineering.

As early as 1672, Vauban had secured the organization of the Corps of Engineers in the French army, followed in 1716 by the establishment of the Corps des Ponts et Chaussees. As James K. Finch, Professor of Civil Engineering, Columbia University, reminded readers of the Engineering News-Record (ENR), "Through all the seventeenth and eighteenth centuries the leadership in engineering had been held by the French, and the modern engineer of any nationality owes a great debt to the French pioneers." This leadership completed "the rift between civil engineering and architecture" which started with the Renaissance, by shifting engineering decidedly from an art to a science. Increasingly under the influence of the Academy of Sciences at Paris, the engineering Corps leaders "made notable and valuable contributions to the mathematical theories of structures." "... These men were primarily theorists who favored mathematics rather than construction". Finch concluded that "the modern mathematical and rational methods of design were born in France, even if they were developed and extended by workers in other lands."¹ Thus the French military engineers planted their theory-based regime within the young North American army.

When, the American army established its West Point Academy in 1802, cadets for its nascent Army Corps of Engineers were taught by professors like D. H. Mahan who infused a good dose of French thought and practice into the curriculum. Mahan also drafted for the cadets the first American textbook on civil engineering and based significant parts of his work on French publications.²

Parallel and dominant throughout most of the first two-thirds of the nineteenth century, however, civilian practice continued on in the British entrepreneurial pattern of design and construction for roads and bridges.

After the Civil War, Republican leaders of the federal government gradually but profoundly altered the nature of higher education by encouraging the development of institutions that basically bypassed the liberal arts for the more practical. Riding the rising tide of industrialism, Republicans promoted land-grant colleges of engineering, agriculture, medicine, law, education, etc. for an increasingly applied-science society. In short order, graduate schools helped to organize the colleges into research universities. By emulating West Point's mathematically-based curricular practices, graduates of the land-grant colleges of engineering gradually brought French approaches to engineering out of the military and into the civilian realm, where they would become dominant in the twentieth century.³

French practice was not only theory-based; it was also agency-oriented and bureaucratic. The credentialed and government-employed made most engineering decisions in France -- a pattern that it took time for American civil engineers to import in a somewhat modified form.

Pledging allegiance to the flag and to the Republic for which it stands. . . .
Our founding fathers did at least establish a republic -- and not a democracy -- so the new United States was not to be governed by public opinion or, to use the founders' term, the "rabble." It was rather to be governed by a landed gentry. Largely college educated, the landed gentry underwent some continuing education from the college-educated Protestant ministers employed in their churches. The Civil War replaced governmental dominance by the landed gentry with, on the one hand, industrial and transportation entrepreneurs (e.g., Leland Stanford, Cornelius Vanderbilt, Andrew Carnegie, John D. Rockefeller). On another, the new land-grant universities began to create new leadership classes in America. It credentialed persons and professionalized a number of occupations -- engineers, medical doctors, lawyers, teachers, and professors -- some of whom soon aspired to people a new gentry capable of leading the citizenry to greater general welfare than they thought Robber Barons and industrial plutocrats would insure.

Like their French counterparts, American civil engineers thought of themselves as among those professionals with authority to speak on behalf of the citizenry. Indeed, Professor Finch reminded American engineers who read the ENR that the old French Corps of Engineers -- to which Yankee engineers owed so much without recognizing the debt -- exhibited a similar gentry esprit. The French Corps had "a tradition of service which took no thought of personal gain, which visualized engineering work as a great public service entrusted to the engineer and in which honor was to be achieved only by fidelity to this trust-- by an honest, unbiased search for the best solution of a problem which the economic conditions and knowledge of the day permits."⁴

Land-grant college engineers soon became the backbone of the Good Roads Movement, which began with bicyclists in the 1880s and became institutionalized in the federal Bureau of Public Roads (BPR) in 1893.⁵ The movement's leaders articulated a Progressive approach to road and bridge building. They favored the establishment of a system of improved farm-to-market roads and bridges designed by professional, government-employed engineers in each state. Only construction would be left to the marketplace, and even that would be highly regulated by the engineers now in charge. The BPR encouraged each state to establish a highway commission to oversee the state's farm-to-market roadways under the BPR-approved policy umbrella. Active, nationwide promotion in the press helped to launch the federal-state highway system. The addition of federal-aid provided carrots and sticks in 1916. Indiana was the last of the continental states to establish a state highway commission -- effectively in 1919.⁶

In the Weltansicht of Federal-State Highway Engineering . . . .
Even before Henry Ford dramatically increased the need for and the forms of the federal-state highway system -- from farm-to-market gravel wagon roads and bridges to paved interstates built to automotive speeds -- the BPR engineers standardized their theory-driven design functions. This would speed the design of bridges, eliminate some of the risk of design error in new construction, and simplify future maintenance and repair.

The search for standardized design using contemporary materials and technology also fit hand-in-glove with other characteristics of engineering education in land-grant research universities. Land-grant schools have typically required minimal work in history or the arts. Lack of historical context and artistic perspective lead to a form of cultural amnesia among many engineering graduates. The condition is sometimes termed "progress-thinking" or "presentism" -- a belief that we know and do better today than those who came and did before us. This provides a handy excuse for ignorance or disregard for older materials, technology, design, or construction practice. The professional engineer is further isolated from the structural heritage and craftsmen around him by academia's dismissal of hands-on experience with the structures populating the landscape.

Little wonder that soon after the Indiana State Highway Commission (ISHC) integrated a stretch of county roadway into its system, state engineers began a systematic effort to replace all the non-standard, county-constructed bridges it inherited. Time and budget, however, constrained the ability of the state engineers to immediately replace the hundreds of county-constructed bridges brought into the first five thousand miles of the system. Since it was easier to develop standard plans for small spans than for complicated crossings, and because replacements cost less, smaller county structures were in most cases demolished first. Budgetary constraints dictated that many of the larger inherited bridges needed to be retained on the state highways for some years. Consequently, a number of them required the state's engineers to design and supervise repairs to keep them in service.

William J. Titus, who served as Bridge Engineer for the ISHC in the early 1920s, held a graduate degree in Civil Engineering from the University of Wisconsin where he had worked under George A. Hool, a prolific analyst and writer about bridge design. Titus came to Wisconsin after completing an undergraduate major in mathematics at Indiana University followed by civil engineering courses at Purdue University.⁷

Following his graduate work, Titus worked in the engineering department of the Chicago, Milwaukee & St. Paul Railroad in Chicago where he surely witnessed the repair of metal-truss rail bridges in an entrepreneurial atmosphere where engineers and work crews knew about and commonly used blacksmith-wise repair procedures. Committed to protecting their bottom lines, American railroads sought safety with economy. Since replacement was a last resort in profit-making ventures, railroad engineers and work crews strove to keep the line's existing bridges well maintained and functioning at close to full strength.

Titus transferred a little of his railroad experience into his state highway work. Then -- chuffed with repairs he orchestrated in 1921 on a 158-foot, 1884 double-intersection Pratt span -- Titus drafted a page and a half article, and the editors of ENR published it under "From Job and Office: Hints that Cut Cost and Time". Titus consulted the metal fabricator who had won a contract to build a state-design approach span to this structure for direction on the repair of the loose, rattling, non-adjustable diagonals of the main span. R. T. Spencer -- "who was in direct charge of the work" for the Oregonia Bridge Company of Lebanon, Ohio -- "worked out largely ... the method of tightening the loop-bar diagonal members" through heating and upsetting in place to shorten the wrought iron bars. In all ten diagonals were tightened for $97.86. "By careful work on the part of the men, it was possible to so adjust the length of the diagonal members throughout the bridge that the unit stresses existing in them were believed to be very nearly uniform...and the strength of the truss was practically doubled."⁸

Note that the state highway Bridge Engineer did not design the repair. Rather, the main representative of the metal fabricating firm laid out the method of repair and supervised the work. The heat-shortening procedure was not novel, but had been in use for some time on American railroads, and Titus may have learned about it during his stint with the Milwaukee Road rail line.⁹

Tom Spencer, from whom the Indiana state Bridge Engineer had sought counsel and management, had almost half a century of experience with the materials, fabrication, and management of bridge members.¹⁰ Raised in Warren County, Ohio, Spencer developed an early interest in iron-working and bridge-building, in part by hanging around the blacksmith and wagon shop of John Bradbury, who had learned his trade in England and who set up business in Freeport or Oregonia, Ohio, in 1872. Spencer bought a half-interest in Bradbury's business in 1888 for $242, and within a year, Bradbury and Spencer built their first 40-foot iron bridge. The market for metal bridge fabrication proved so good that in 1896 the firm changed its name to the Oregonia Bridge Company. By 1903 the business had outgrown the old 20x30-foot shop in Oregonia. The owners, in response, moved their operations to Lebanon, Ohio, and built a large fabrication plant along a railroad siding. When Bradbury died in 1905, Tom Spencer, who had been general manager of the operation, became president of the firm as well. He held the firm's reigns until he retired in 1926.

The Indiana State Bridge Engineer's report about how he had managed low-cost design and repair with the assistance of a bridge fabricator ran against the federal-state highway system's ethos and met immediate resistance. It generated a sharp retort from Oliver A. Hall, Designing Engineer for the Alaska Road Commission. Hall criticized the editors of the ENR for publishing Titus' report and countenancing the Hoosier "quackery." No wonder, Hall proclaimed, "the general public refuses to recognize engineering as a profession, and classes the bridge engineer with stationary engine drivers, or plumbers, or carpenters."¹¹

"If," Hall concluded, "a mechanic or a plumber had tightened the tension member of a bridge in the manner described, it could be said with justification that he didn't know any better". "But for a professional engineer or an engineering journal to countenance it is another matter." "All the years of patient teaching, scientific research and careful preparation of specifications are thrown into the discard when such things are done -- and called 'ingenious.'" "Having seen, or having read about its being done in one case, on an unimportant structure," the public or the inexperienced engineer "is liable to attempt to do something of the same nature on an important structure, with disastrous results and consequent condemnation of the whole profession by the public."

Engineers who relied on blacksmiths, iron workers, or other craftsmen were, in the eyes of Hall and a host of other highway engineers in his own day and ours, unprofessional. How much more of this kind of "quackery" Titus and his ISHC colleagues subsequently undertook remains undetermined. Certainly the News-Record's editors did not publish additional reports of "unprofessional" Hoosier state bridge design and repair collaboration with metal, concrete, timber, or stone artisans.

The Will and the Way to Monopolize Bridge Design.
While the federal-state highway alliance focused primarily on the creation of state highway systems serviced by bridges of government design, from the start the BPR also promoted its bridge design for roads controlled by local governments. In Indiana, for example, the law establishing a state highway commission allowed the state's engineers to critique bridge plans under consideration by a unit of local government if either the local authorities so requested or by citizen petition. J. M. Henry, then former Office Engineer for the ISHC, reported that the state "Bridge Department has held out inducements to counties to do their designing for them at rates far below the commercial rates [of 5%]. Thus, designs for bridges costing nearly $100,000 have been made by the Bridge Department for County Engineers for less than $1,000, or approximately .75%." "In this way an attempt is made to put commercial engineers out of business so that the state may have a monopoly on the business of designing and supervising all public bridges, whether the funds be supplied by the states or by counties." "It means the complete socialization of the industry of bridge engineering in the State of Indiana."¹²

While there was logic to Henry's assessment in 1926, circumstances in the first decade and a half of the ISHC's existence limited the agency's reach. As stated above, the state system started in 1919 with the absorption of 5,000 miles of county roads. This was a lot of roadway and a large number of bridges for the state's engineers to digest, but even then it represented only 7% of the Indiana highways.¹³ Over the decade of the 1920s and the first half of the 1930s, the original 93% of Hoosier roads under local government control diminished by only approximately 10%. At least 8 out of 10 roadway bridges in the state remained beyond ISHC control unless the local government or a group of citizens sought state intervention.

Typically, local government decision-makers did not want to build to agency-controlled, state design, and local citizens only rarely petitioned against the judgments of their county leaders. The county commissioners continued to favor the more traditional entrepreneurial system inherited from the British in which both design and construction remained in the marketplace. State standard design and specifications were naturally oriented towards farm-to-market roadways with heavy traffic seeking to move at increasing speeds. County roads served a different clientele. Shorter, narrower, and lower load-bearing bridges could safely accommodate the slower and more familiar local traffic. Such bridges were also a lot cheaper to maintain or, where necessary, to construct. Without access to a federal or state gasoline tax, county commissioners had to keep an eye on the local property tax rates that their electorate paid. As a result, the ISHC and Hoosier counties operated largely separate bridge design and construction systems from 1919 to 1934, thus keeping elements of both the borrowed British and French engineering traditions operational in Indiana.

The Great Depression tipped the balance in Indiana (and beyond) towards the BPR's system of agency-controlled bridge design and construction. To deal with the high numbers of unemployed within the citizenry, Hoosier counties increasingly funneled their albeit decreased revenues into relief. Bridge construction stopped; even maintenance and repairs were held to a bare minimum.

Road and bridge construction inevitably played a role in various New Deal programs designed to prime the pump for recovery. As inheritors of the Progressive tradition within which the BPR was rooted, the New Dealers seem to have had no qualms about building the federal-state highway system's priorities into federal recovery aid for community roads and bridges. Structures built on local roads with Works Progress Administration funds were required to meet federal standards and specifications. In Indiana, that meant design drafted by professional engineers and approved by state highway engineers and construction contracted by the state and inspected by professional engineers. While federal-state system design and construction cost more per span-foot than local government would have expended, the counties bore little-to-none of the direct New Deal recovery costs.

World War II brought virtually all bridge construction to a halt. In the post-war years, though, federal-aid for local bridge construction moved well beyond the emergency recovery measures of the New Deal. The federal-state highway system took charge of a much expanded program conducted according to the system's preferences and requirements, increasing project costs from 50%-100% above what local leaders would likely have committed to on their own. Local government units could apply for federal aid at 80% and a community contribution of 20% of the construction costs from the Bridge Replacement and Rehabilitation fund. Given the high overhead costs associated with agency-controlled federal aid, it made no fiscal sense for counties to apply for maintenance or secondary repair support. Instead, many county commissioners voluntarily extended the no-service moratorium forced on them by necessity in the 1930s. From a local perspective, better to let the old structures decay and to replace them with federally-aided new construction than to play catch-up with 100% locally-funded maintenance and repair work. Preventive maintenance for old bridges hardly makes sense in a highway system predicated upon planned obsolescence. From a wider perspective, federal transportation policy increased the overall cost of transportation services.

To reinforce its system, the federal-state highway agencies also required biannual "safety inspection reports" which implicitly evaluated existing structures against the standards and requirements applied to federally-aided new bridge construction. In these structure inventory and appraisal reports, highway engineers routinely proposed a replacement date for almost every old span. If local government officials ignored the early-warning advisories on a given old span -- usually shown in ever-lower load limits -- the bridge inspection engineers would finally suggest closure of a structure. County officials who ignored an engineer's recommendation of closure exposed themselves to a level of liability that would be hard to contest.

Federal gas-tax dollars have been wasted in economic inefficiencies that by design have also diminished our transportation heritage. The more agency-employed, progress-thinking engineers came to dominate the whole highway system, the more timber-truss bridges rotted and metal-truss spans rusted away like old cars abandoned on blocks in a back pasture. Small wonder that, given the federal-state highway priorities, engineering colleges teach little about old bridge forms and materials, that the average consulting engineer has only limited experience with them, and that the skilled craftsmen once so necessary for fabricating these old trusses and arches and still essential for maintaining them are disappearing because of underemployment. No wonder the rural and urban landscapes have become invested with nondescript standard-design construction.

Some Hoosier Detours in and around The System

While -- as suggested in previous the commentary -- hundreds of old Hoosier spans have been demolished since federal-aid became dominant in the local as well as the state highway systems following the Second World War, there has been some evolution in highway agency policy and funding over time as well as some detours around it through which -- as illustrated in the case studies that will follow -- handfuls of historic bridges have been fixed in one manner or another.

Two developments in the highway agency system -- one imposed from without and the other adopted from within -- are significant markers in these developments:

First, Congress in the 1990s legislated a 10% set-aside of federal highway funds for "Transportation Enhancement" which in Indiana has been defined to include provision for pedestrians and cyclists, acquisition of historic sites, and rehabilitation or preservation of historic structures.¹⁴ This set-aside has been used in part to fund on a competitive basis the rehabilitation of a number of Indiana bridges either listed or determined eligible for the National Register of Historic Places, and it has loosened Indiana Department of Transportation (INDOT) rules in favor of restoration.

Second, the adoption by the American Association of State Highway and Transportation Officials (AASHTO) of Guidelines for...Low-Volume Local Roads in 2001-2002 (LVR) represented a major departure from the association's previous one-size-fits-all approach to roads and bridges.¹⁵ AASHTO allowed that narrower, lower load-limited, and marginally railed bridges with modest roadway sight lines for entrance or exit could be considered "safe." Indiana state highway representatives were reportedly among the minority opposing AASHTO's adoption of the LVR guidelines. This may explain why the standards that Indiana has implemented for LVR are far more limited than the national guidelines suggest. Still, the one-size pattern has been broken within the highway agency system, even in a reluctant INDOT.

Taken together, these two changes in the highway agency system facilitated the development of miles of Hoosier trails to which highway engineers could relegate some unwanted, on-system historic bridges for pedestrian use. They also removed agency objections to funding the fixing of some historic spans, mostly on low-volume local roads broadly defined. Even the Bridge Replacement and Rehabilitation (BPR) along with other federally-supported funds became over time more accessible for some kinds of rehabilitation, although the guidelines drafted for new construction still apply to all fund uses. Applications for BPR funding for rehabilitation require consultants to undertake considerable extra structural analysis and to complete requests for design exceptions where new construction rules clearly don't apply. This approximately doubles the engineering time needed for rehabilitation over new construction.

Confronted in Indiana after 1994 with a choice of federal-aid at 80% of cost for (a) new construction or (b) rehabilitation of an existing bridge, local government officials increasingly assessed their transportation needs and estimated their out-of-pocket costs for the options available. County commissioners have opted for the rehabilitation of existing structures at least some of the time. On occasion citizens who wanted to retain a particular historic bridge also influenced these decisions.

Local decisions to invest in fixing existing historic bridges have led to a variety of results. Highway engineers typically speak of 'rehabilitation' which includes any and all kinds of fixes. Preservation advocates refer to 'restoration,' a more limited and prescribed set of historically-sensitive fixes as defined in the U. S. Secretary of the Interior's Standards for Rehabilitation and Guidelines for Rehabilitating Historic Buildings.¹⁶ These Standards and Guidelines call for in-kind restoration where possible:

...When the physical condition of character-defining materials and features warrants additional work, repairing is recommended. Guidance for the repair of historic materials ... begins with the least degree of intervention possible such as patching, piecing-in, splicing, consolidating, or otherwise reinforcing or upgrading them according to recognized preservation methods. . . . Although using the same kind of material is always the preferred option, substitute material is acceptable if the form and design as well as the substitute material itself convey the visual appearance of the remaining parts of the feature and finish.

Following repair in the hierarchy, guidance is provided for replacing an entire character-defining feature with new material because the level of deterioration or damage of materials precludes repair. . . . Like the guidance for repair, the preferred option is always replacement of the entire feature in kind, that is, with the same material. . . . While the National Park Service guidelines recommend the replacement of an entire character-defining feature under certain well-defined circumstances, they never recommend removal and replacement with new material of a feature that -- although damaged or deteriorated -- could reasonably be repaired and thus preserved.

The Jerry-Fixed Span: Rehabilitation

If an inexperienced consulting engineer is fortunate enough to have access to the American Society of Civil Engineers' (ASCE) report on the Repair and Strengthening of Old Steel Truss Bridges, he could learn some short-term fixes: "In general, the consensus of the State Departments of Transportation is that these old metal truss bridges are functionally obsolete and that repair and strengthening are undertaken to add a few more years of service until the bridges can be replaced." Since they are intended to be temporary, only their functionality matters.

Indeed, the ASCE manual's authors understand that their recommendations do not address the restoration of historic bridges: "Research has begun to realize the value of many existing trusses as historical artifacts. Surveys of existing trusses, using guidelines available from federal agencies, should be made to ascertain the significance of older trusses. Given the pressure toward bridge replacement, this need may be critical." The ASCE report ends before recommending what is to be done with bridges identified as "historical artifacts" or museum pieces. The consultant, consequently, will find little specific advice about restorative design here.

Moreover, the consultant's computer program is also most unlikely to have been designed for old metal-truss or concrete bridges whose plans the county has long since tossed out. Practicing the profession's penchant for conservatism, the engineer is tempted to stay on the safe side by assuming that observable metal and concrete have a minimum of strength and that what can't be seen doesn't exist. Proposed designs for rehabilitation, then, may well range widely. Some, for example, may supplement old members that the engineer cannot easily assess with new ones, thus scaffolding the structure. At the extreme, some others may replace the bridge's original carrying system with a new one, thus relegating the original structure to the function of a railing.

Beyond Rehabilitation: The more you do, the less you have left of the historic artifact. A consultant’s so far unsuccessful proposal to place the existing Pennsylvania trusses over the Kankakee River between Lake and Newton Counties atop a new multiple-span prestressed structure. The complete floor system of the original would be removed and the upper bracing replaced with longer members to allow for a wider, contemporary deck. In this rendering, contemporary railings are also proposed, thus leaving the original trusses without any structural function.

Balancing Professionalism with Skilled Common Sense for Bridge Restoration

Much of the help that professional engineers and preservationists so desperately need to restore historic bridges is only an arm's length away, just outside the boundaries of their respective clans. If the professionals would "keep faith" with the makers and descendants of old spans by embracing the knowledge and honoring the skill of artisans, the collective judgment of professionals and craftsmen would be more than enough to restore antique bridge spans well. While not generally college-educated, the designers and builders of the old trusses and arches accumulated invaluable practical experience, albeit often with little theory behind them. They understood their materials, and they knew what worked although they did not necessarily explain it in scientific or technical language. Their successors offer a largely untapped resource for the proper and economic restoration of historic bridges. Here are some practical rules for a collaboration between professionals and craftsmen that can promote some of the best historic bridge preservation:

Honor what the experienced iron worker knows from the working of materials. A good blacksmith, for example, understands the properties of the most common metal used in nineteenth-century trusses, wrought iron, and can tell the differences between iron and steel under the hammer or stress -- something the professional engineer or preservationist has not felt. The composition of steel, the most common metal used in twentieth-century trusses, varied greatly over time. Steel used early in the century tended to contain less carbon and to handle much like wrought iron. Some engineers have failed to take these materials' differences into account in their structural assessments or designs for repair. A few, instead of determining the metal of the member and selecting a repair appropriate to the work at hand, wield an axe where a scalpel would do. In place of testing and yet to stay on the "safe" side, an occasional engineer assumes that an apparently troubled metal member combines the worst characteristics of wrought iron and of high-carbon steel. Instead of calling for appropriate welds on a worn eye or at a loosening forge-weld on a wrought iron or soft-steel tension member, the consultant treats it as though it will fracture like hard steel and declares it failed. Then the consultant might prescribe a supplementary rod to run around the allegedly-failed member from panel point to panel point as a crutch. Or he could order the original bar cut off at the panel points and fit it out with prosthetic harnesses that also distinctly identify it as disabled. This is the kind of "safe" butchery that the skilled iron worker, if called upon, could have avoided with an unobtrusive, in-kind, historically-sensitive repair.

Respect how earlier craftsmen assembled members. Most nineteenth- and twentieth-century trusses had a significant number of their members made from pieces of rolled stock riveted together. Given a hundred years, a few rivets that hold the sections together may have worked loose. In some documented cases, professional engineers have convinced professional preservationists to prescribe the removal of all the rivets, weld the sections together, and append fake rivet heads to give the visual appearance of the original.¹⁷ Here the engineer creates a box beam that he can analyze with his packaged computer program, the preservationist satisfies the architect's penchant for appearance, and the public gets an expensive, partly-faked member that works a bit differently than the original. An iron worker skilled in riveting, on the other hand, knows how to test the soundness of driven rivets and could have simply replaced doubtful or faulty ones with a little effort, at less cost, and without subterfuge. Professional ignorance is a costly substitute for the knowledge of the craftsman.

Apply the mason's knowledge about the strengths and weaknesses of the stone used in arches and account for the mortar used to secure structures in different periods. Too many professionals assume that because they see no mortar in an arch today, the stone blocks were dry laid. Let the historian, among professionals, remind the engineer and the preservationist of the great Vauban's commentary on his 1684 specifications for the locks off Dunkerqueharbor: "... if any of the masons be found laying up masonry dry and without mortar he will be driven from the work and thrown into jail and the contractor will be compelled to pay a fine of 100 francs."¹⁸ This is the kind of language any state-federal highway engineer should understand, even if the content is over his horizon.

Learn, respect, and identify for each late nineteenth and early twentieth century structure which of a number of reinforcing systems was used with concrete. Design rehabilitations with that system in mind.

Finally, acknowledge rather than demean the style of the original. In 1912, Henry Grattan Tyrrell branded some of his colleagues as "eminent engineers but professional vandals" for their indifference to aesthetic principles in design.¹⁹ Tyrrell's indictment would have been even stronger had he seen some of the stone and concrete bridge rehabilitations perpetrated in recent decades. Original design which Tyrrell might have considered as aesthetically inattentive has occasionally been even more dramatically confounded by rehabilitators who contradict the modest symmetry, proportion, or style of the original.

To keep the "vandals" away from our spans and to assure "eminent" as well as artful bridge restoration calls, in sum, for the harnessing of professionalism with craftsmanship. Proper historic bridge restoration requires the structural analysis of a professional engineer; it profits from the expertise of a preservation professional; and it needs the insight and labor of skilled craftsmen. As the case studies featured in some of the accompanying profiles illustrate, there are imaginative and dedicated engineers providing as sensitive rehabilitations and restorations of bridges in Indiana as they can with the tools at hand. But here, as elsewhere in the nation, we must do more to acknowledge, nurture, and include our craftsmen on whose skill and inventiveness this nation still needs to rely. High quality and economic bridge restoration is at least the sum of its parts; in fact, the social return is far greater than that.

copyright © April 2010
Dr. James L. Cooper
Indiana's Historic Bridges


Notes

1. James K. Finch, “French Pioneers in Engineering,” Engineering News-Record (24 April 1930) 104: 676-683. See also Terry S. Reynolds, “The Engineer in 19th Century America,” The Engineer in America (Chicago, 1991), 7-26.

2. D. H. Mahan, An Elementary Course of Civil Engineering, for the use of Cadets of the United States’ Military Academy (New York, 1837). This book remained in print in revised editions throughout much of the Nineteenth Century.

3. The focus in this essay on colleges of engineering in land-grant universities arises from their close association with the development of the Bureau of Public Roads and the federal-state highway alliance. This focus should not be understood as undervaluing the contributions of private colleges and universities to other significant developments in the engineering sciences in the United States. Founded in 1824, Rensselaer Polytechnic Institute was, for example, the nation’s first research university, and it was private. A multitude of important colleges of engineering were also established in the last third of the nineteenth century in other private institutions of higher learning.

4. Finch, “French Pioneers in Engineering,” ENR (24 April 1930) 104: 680.

5. Referred to herein as the BPR for convenience, the agency changed names over time: Office of Road Inquiry (1893); Office of Public Roads (1905); Bureau of Public Roads (1915); Public Roads Administration (1939); Bureau of Public Roads (1949); Federal Highway Works Administration (1967). For the most complete and analytical study of the BPR, see Bruce E. Seely, Building the American Highway System: Engineers as Policy Makers (Philadelphia, 1987).

6. James L. Cooper, Artistry and Ingenuity in Artificial Stone: Indiana’s Concrete Bridges, 1900-1942 (Greencastle, Indiana, 1997), chpts. IV-VIII.

7. William J. Titus, deposition (12 August 1916), District Court of the U. S., Daniel B. Luten vs The Dover Construction Company: Complainant’s Record (supplemental) (Indianapolis), 77-78; Purdue University, Alumni Directory, 1875-1934 (West Lafayette, 1934), 187; Indianapolis Star (16 July 1950), 2nd section: 5.

8. William J. Titus, “Tightening Tension Bars of a Bridge by Heating and Upsetting,” in “From Job and Office: Hints that Cut Cost and Time,” Engineering News-Record (22 March 1923), 90: 550-551.

9. See, for example, The Preliminary Report of the Committee of 15, “The Shortening of Eyebars to Equalize the Stress in Iron and Steel Structures,” Proceedings of the American Railway Association (Chicago, 1947), 48: 969-986. Reprinted in James L. Cooper, ed., Restoring Historic Metal-Truss Bridges: A Handbook for Keeping Faith with Their Makers (2001), 127-137.

10. Thanks to David A. Simmons of the Ohio Historical Society and Karen Young, Ohio Department of Transportation, for forwarding handwritten “Notes from the Thomas R. Spencer Family”. See also Victor C. Darnell, Directory of American Bridge-Building Companies, 1840-1900 (S.I.A., Washington, D.C., 1984), 54.

11. Oliver A. Hall to the Editor, “Tightening a Bridge Member by Heating and Upsetting,” Letters to the Editor, Engineering News-Record (3 May 1923), 90: 801-802.

12. J. M. Henry, A Short History of the Indiana State Highway Commission (Indianapolis, 1926), chpt III: 3. Henry resigned from the ISHC in August 1925 “in protest against the removal of C. Gray as Chief Engineer.”

13. Henry, Short History of ISHC, chpt. II: 2.

14. Indiana Department of Transportation, “Transportation Enhancement Activities: Program Guidelines for Application and Selection” (Indianapolis, 1994).

15. American Association of State Highway and Transportation Officials, Guidelines for Geometric Design of Very Low-Volume Local Roads (< 400) (Washington, D.C., 2002).

16. U.S. Department of the Interior, National Park Service, The Secretary of the Interior’s Standards for Rehabilitation and Guidelines for Rehabilitating Historic Buildings (Washington, D.C.: U.S. Government Printing Office, 1990).

17. Joseph P. Saldibar, III, “Rehabilitating a Historic Iron Bridge,” Preservation Tech Notes (Washington, D.C.: National Park Service, April 1997), 1-8.

18. Richard S. Kirby, Chairman of the Department of Engineering Drawing, Yale University, “Bidding Practice Two Centuries Ago,” Engineering News-Record (23 November 1939), 123: 712-713.

19. For a fuller discussion of this issue, see James L. Cooper, Artistry and Ingenuity in Artificial Stone: Indiana’s Concrete Bridges, 1900-1942 (Greencastle, 1997), 70-81.