Category Archives: Wooden Bridge

Numbers as Great as They Now are Few

A different shake of the box this go, no external wonder over maddening happenstance. This time a glimpse of history and not from my typical perspective, this go we will look at what was, simply because it is so little looked at, and with that somewhat under-realized.

We are about to look at wooden Pony Truss bridges and in the doing, we will explore what was with photographs in numbers greater than is typical of our explorations. Though unlike the allusion of our chosen title, which speaks to how common Wooden Ponies once were and how remarkably those numbers have dwindled, dwindled to a point just short of totality, from untold hundreds if not thousands, to a count which depending on how you categorize the type, which can arguably be seen as countable on one hand.

Old Russell Hill

The Old Russell Bridge of Wilton New Hampshire is sometimes also known as The Livermore

Wingwall

The Russell Hill carried traffic until recent years and is in all likelihood this was the last Boxed Pony Truss Bridge to have done so

Pilaster

The Russell Hill is a Town Lattice Truss – The Pilaster (and the concrete pad which supports them) seen lower right was added to take up load inboard of the compromised Chord ends to keep the bridge in service – The decayed Chords are likely a result of unchecked leaf litter building up between the Back walls and the Truss ends which slowly decomposed into a soil like matter holding moisture borne of rainfall against the Chord lamanie for weeks and months until they likewise decomposed – This an entirly preventable set of circumstance

Pony Trusses were a common solution for short span situations bridging waterways of twenty to sixty feet. In essence a Pony is a Truss short in stature, of a height less than that which is typical of a “Through Truss” – Perhaps the most common approach to weatherproofing Ponies was to “Box” them in, to simply board in both sides of both trusses and to put a little Roof-ette over each of them individually.

This is almost certainly why the landscape is now almost devoid of “Boxed Ponies” – This approach left the Flooring and the Floor Beams exposed to the ravages of the sun and rain and the oxidation and decay such exposure encourages. My educated guess is that long ago replacements were about the need for the regular maintenance wood exposed to the elements requires. With the maintenance regime such exposure demands, Boxed Ponies were in time replaced with Creosoted timber stringer and bent piling bridges and concrete box culverts.

Moose Brook Conwill

The B&M built Moose Brook Bridge seen here while still in service nineteen years prior to its loss to arson – This photo was taken by Joseph D. Conwill – Joseph over a period of decades has visited every wooden bridge in North America, many such as The Moose Brook no longer exist

New Hampshire through a collection of happenstance, climate, Yankee thrift, and the sheer numbers in late examples built by the Boston & Maine Railroad stands as home to most of the Boxed Ponies still standing. One of these was lost to arson in 2004, several years later I helped Barns & Bridges of New England, The National Society for the Preservation of Covered Bridges and NPS-HAER in the replication of its trusses with salvaged iron Rods and Angle Blocks from the original. These were used as full-scale models at Case Western Reserve University in an engineering study and have now returned to NH and are in search of a future home.

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An As-Built drawing of The Moose Brook created by the Historic American Engineering Record – Seen here as a courtesy of NPS-HEAR and the Library of Congress

Rod Clearance Cuts

10 X 16 X 48 Chord Lams laid down on edge to allow for the cutting of clearance cuts for the Moose Brooks massive Truss Rods

Ready for Placement

Angle Block Abutments and a bird’s eye view of the Truss Rod clearance Cuts – Though a Howe truss differs from most other types in that Iron parts join those of wood this is still necessarily done with the high levels of tolerance required for Truss Framing to sustain intended geometry under the massive loads they are designed to bear

This video, though a bit grainy, does drive home the tolerance of fit strived for in wooden bridge framing. Here, Tim Andrews of Barns & Bridges of New England guides a Truss Terminus Angle Block into place as I lower it with hydraulic assistance

Reynolds

The Reynolds Covered Bridge stood on Blue Ball Road in Cecil County Maryland until 1949 – This Queen Post Pony was built by Joseph G. Johnson the same year he built the Gilpin’s Falls – This Image is seen here as a courtesy of Jim Smedley and mdcoveredbridges.com

Not all Ponies were Boxed, sometimes the choice was to protect the Trusses from the weather by adding a “House” as opposed to Boxing the Trusses independently, whether this choice was made to provide protection to the Floor Beams and the flooring they carried or if this was seen as money better spent, and a more affordable alternative over the service life of a bridge is something the record has yet to suggest.

The Colvin

This image of the Colvin Covered Bridge of Schellsburg Pennsylvania is seen here as a courtesy of Carolyn Williams – I find The Colvin a particularly clever and visually appealing MKP Pony and should you find yourself in need of a short span bridge I’d love to build you a copy

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Light for the Bridge & Roofs for the Girls

A return to history this go…

And an exploration of a funky bridge now almost one hundred and thirty-five years gone.

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This image from the Robert N. Dennis Collection of Stereoscopic Views is seen here as a courtesy of The New York City Public Library and the Digital Public Library of America

The roofed sidewalks on this ornate example “Village Bridge” would have at least twice daily protected some of Lowell’s Mill Girls from the elements on their way to and from their long demanding shifts.

The following video photo gallery, primarily showcasing images taken by child labor activist Louis Hine is seen here as a courtesy of Selena Marie Perez.

Do bear with me for the few coming days in that the current gig has me tripping through Lowell Mass with regularity, though with this last month being the depths of Winter, stops in the shop are either side of Sun’s up and don’t allow for my taking the few additional photographs I’d like to include in the entry.

Do click back in the coming days, as I’ll add those, and what is known of this one of a kind crossing, and conjecturalize a bit about the funk in its unique details.

Meanwhile, wonder after those details and this through-truss uncovered allowing us to see if we might arrive at like conclusions.


Remarkable

 

Typically I work to vary my entries, to switch up themes from go to go, so as not to bore the readership or disappoint anyone, including myself.

However somehow, just like déjà vu all over again, just as happened last month, another historic wooden through truss, this time rehabbed not a decade ago, but literally at the dawn of this one, has been removed from service.

My continuing ire about this oddly continuing story, is not so much about how this came to pass. (from my perspective, this is less than surprising) It is more about how it might be possible, absolutely no one is asking why or pointing out the absurdity of it all.

Part of my incentive in writing this web-log, and likewise, part of why I engage with wooden bridge enthusiasts through “social media” is both to lend others a view to their interest from my inside perspective, and to also lick a finger and test the winds. This to try to understand what it is aficionados of this aspect of our built transportation heritage bring to our table.

Remarkably, what I seldom see in this community is anyone asking why. And the why in why is it joined wooden through truss rehabilitation’s are sometimes awarded to the wholly unqualified is a beyond big why.

Likewise the design of such rehabs executed by firms with zero background in such structures is equally absurd. Yet seldom, if ever, does anyone ask why in either circumstance.

I see contracting a construction firm that specializes in building concrete deck bridges, (simply because they know how to bid public works projects and are silly enough to think they’ll be able to work it out as they go along) to rebuild a joined timber truss as akin to dropping off a car in need of a transmission rebuild at an appliance repair shop.

I’ll not be apologetic about pointing out how patently absurd it is to point a crew of concrete form carpenters at something as complex as a joined timber truss. Wholly different trades, different tooling, different skill sets and a far differing knowledge base.

The only thing about this sad reality that is remarkable is the wonder in how it is possible this both continues to happen and how it is possible next to nobody is asking why?

 

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Bridgewrighting is advanced carpentry requiring precise high tolerance fits to avoid crush of wood grain under load and distortions to intended geometry in truss-work

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This specialist branch of carpentry requires specialty power tooling and the skilled use of hand tooling once standard in the common era of wooden through truss construction though now little used

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A Trait de Jupiter / Bolt ‘o Lightning multiple abutment Bottom Chord tension splice executed by the author – The need for precise uncompromising fit in such circumstance being obvious.


Appropriate Technology – Appropriate Methodology

Well, things churn, and a turn of events has my ire up – This something measurable as more than “a little”, something beyond a bit more than can’t push it aside, all the same, let’s describe my ire, as up, just a bit…

Many regulars among the readership will be aware that my intent, my work here on the Bridgewright Blog is as much about advocating for preservation of this “Trade” as much as it is an advocacy for the preservation of the historic bridges that are the fruit borne of that tree.

I am a practitioner of two allied trades, Timber framing and Bridgewrighting. Both, seemingly superseded, were briefly lost. In the but generation plus period of time in which both trades had fallen out of practice, (I have spoken to this in prior entries, this perhaps best articulated in Living Memory – And the reasoning as to why best described in Meritocracy) much was lost.

In both instances, in their long running period of practice, too little of the everyday was written down. Though there are some few notable exceptions on the timberframing side, with little of practice preserved in the written record, this break in the chain of day to day practice, of lifelong practitioners passing down the intricacies and the nuances of the everyday to an up and coming body of Apprentices – Much, much too much, was lost.

It is not an ability to look at and understand a patent truss drawing that makes a timber savvy carpenter a Bridgewright. Bridgewrighting is only an allied trade, there are subtle though highly important differences in approach in building long-span trusses. A full understanding of these subtleties being born only of the almost unspoken day to day understandings found in a lifetime of practice, or years in working alongside someone who already possesses a lifetime of doing and has a willingness to share all they know.

All of this of the sense of last months entry, that it is with a simple line that it all begins, that such is the key in unraveling and unwinding the secrets of timber. Of how full hard up full bearing in every joint cut and how to get there is the not so secret of how a knowing carpenter gets a truss to hold its intended geometry. And this continues with an understanding of the material with which we work, with which species is appropriate to the task at hand, with how center, pith and balance and the presence of sapwood effects how any given piece will behave as it seasons, and how that understanding is (or should be) what drives every decision as to how any given piece should be oriented in bridge truss framing and might be used to its greatest potential advantage.

Winding Sticks

Two Framing Squares used as Winding sticks – A black Eagle backed up by a Horizon Board is seen riding the mid-length Level Mark in the distance stands in contrast to the stainless Square in the foreground allowing for adjustment and compensation for both bow & wind in the pinging of snapline Datums

Much was lost, and much of that, with practice and research and perseverance, has been recovered…

Though it is only with regular opportunity for the practice of these skills, and the conveyance of the understandings and nuances that are the bedrock of those skillsets from today’s practicing craftsmen to a coming generation, that there lies any opportunity to pass on either to an up and coming group of practitioners.

And here is where my ire lies, with near miss opportunities lost. And opportunities ill spent.

A new covered wooden though truss was recently constructed, though it was of the dumbed down bolted together type now growing in commonality. It holds no passion, its construction requiring no specialized skills or knowledge base, and so sadly, holds no promise of sharing any. Though this truss was launched with the low tech promise that holds the possibility to share how simple rigging allows the moving of large objects with surprising simplicity and ease. That promise was buried in needless complexity, and even were there the opportunity to relay simple rigging wisdom, it is doubtful that anyone with a passion for this trade was there to receive it.

Un-Stayed Gin

Though requiring now uncommon know-how, time proven Appropriate Technologies are often the most cost effective way to make things done

And sadder still, and none so far from that opportunity lost, an 18th Century bridge rehabilitated but a decade ago and said to now have a full foot of “sag” has just been awarded to a second low bidder – And somehow no mention is made of poorly designed repairs equally poorly executed by people in both instances who had little sense of what they were doing. Instead it is intimated in the announcement, that old wooden bridges, of their own accord, just up and go haywire.

Without either neglect (a lack of routine maintenance to siding and roofing and the removal of dirt and leaf litter from the bridge and its underpinnings) or poorly executed interventions, the time proven service lives of these structures more than suggests that such could not be farther from the truth.


The Most Important Tool in the Kit

With this entry we speak to tools, or at least the simplest and most important of tools in our kit, and the one which therefore allows for the accurate and proper use of all those that follow.

String is the most important tool in any box – It is a line running though time and history and most every building that ever was or ever will ever be. It is the very beginning, and is even now like a living truth and a real world Möbius Strip, a concept ever connected to an end that never comes…

String, in all likelihood developed from a simple tool used to bind items together for storage or transport, to then be used to build snares and traps and then towards its slightly more complex use in defining strait and true, none so long after our long ago ancestors first pounded and separated natural fibers apart and then twisted them back into cohesion and a potentially unending bit of cordage. This perhaps within generations of that first great leap forward.

All this development coming about long before recorded history. How much time had or has since passed before the first human mind noticed a taut line was strait and then went on to run a string through powdered charcoal with the intent of marking a strait line on something he wished to straiten and to then affix a line to Batters is something we can never know.

It is fitting that those beginnings are yet still just that, the beginnings of most any construction – It all begins with a taut line and Batter Boards, plumbs and the snapping of lines.

My focus on it as still being primary amongst the many tools we have since developed is in part to do with my traditional approach/es to timber layout, though in truth this goes back to my first week in my first carpentry job, in being taught the proper way to string a line and my asking my then mentor who it had been who had taught him the technique he had just demonstrated. His eyes acted almost as a line that day as they belayed the thoughtful recollections and truths spinning in his mind as he thought about it a moment, then he simply said “Well hell, I don’t know, that goes back to way on before the pyramids”

THE_MERCHET

This image of a Merchet and its companion Plumb is seen here as a courtesy of Wikimedia Commons

In part this focus goes to my primary chosen system of timber layout being Plumb-Line Scribe. Though no matter the chosen layout,  (Square Rule or Scribe) I am datum-dependent. I almost without exception snap lines on every stick, more often than not I do so on all four sides. These lines physically represent two perfectly perpendicular planes of reference.

In Square Rule these snapline planes of reference are used to accurately cancel out bow and wind and to overcome any lack of squareness not achieved in the milling of the timbers, as well as lending reliable accuracy to an organic and imperfect timber in the layout and shaping of timbers to chosen mathematical constants at each of their connections. In Scribe Rule these snaplines likewise are used to cancel out bow and wind as each timber is lined out and are then used to place each timber into scribe layups aligning the two planes of reference to Plumb and Level, this often over a lofting floor on which is drawn a full sized diagram, itself described with snaplines, pinged not with a line enveloped in charcoal or chalk but one dampened with ink. Upon such placement in these layups timbers and the inconsistencies (unlike the smaller pieces of wood found in benchwork, timbers cannot reliably be milled strait and true – Timberwork requires systems of layout which therefore deal with those expected and natural inconsistencies) found in their surfaces, are scribed to each other, often with the use of a Plumb-line used to gauge those inconsistencies.

IMG_0319

Note the Level Mark adjacent to the 6″ Level – It is from that mark that the Datums are unwound – It is with both the Datums and the Level Mark that the timber is placed in the layup over the Lofting Floor – This allowing use of the Plumb Line to covey quantifiable information from each timber to the other

A snapped line, like a line on paper or a computer screen can also be used as a base line from which to develop the geometry to layout any required angles or an Arch or a desired radius or as a control line from which a trusses camber is re-conditioned in a bridge rehab/restoration or developed in a new build.

And in all forms of construction, lines then go onto be used all through the assembly and erection process as a constant reference to insure things are both strait and true and plumb and level.

Though recent advances and circumstance will sometimes demand a laser be the line of choice in the field, reels of string, be they Dry or Chalk Boxes or Ink Lines, will forever and always be, the most important of tools in our kit.


Model of Improvement

I had long heard of a model of Col. Long’s Truss in the collection of the The New Hampshire Antiquarian Society, and long had it in mind to arrange a visit as part of research in piecing together my multiple blog entries on the Colonel and his Truss. Though I did not work to do so until coming upon this curious passage in an article titled – An Hour in the Antiquarian Room in Vol XXXII No. 1 of The Granite Monthly, published in 1902.

That initial inquiry to the Antiquarian Society was spurred by some seeming confusion found in the passage, (none of the Childs brothers have or had C.B. as their initials, nor where any of them still living in 1902) and a curiosity as to if there was any possibility that the Society perhaps also had in their collection a model of a Childs truss.

As it turns out, it was a Childs (likely Horace – visit the search bar to the right for information on the man and his truss, or for greater information on the good Col. Long) who donated this Long Truss model to the society, this sometime in the 1870’s. This would stand to reason being that Horace was a cousin of the Colonel’s and his bridge building firm was counted as among the earliest of those named as agent and sanctioned to build Long Trusses, and such a model would have been a useful tool in selling bridges of this truss type.

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Col. Long’s Bridge – The Model fits in its box like a hand in a glove

It was a rare thrill to examine the model, which is truly joined with well executed wood to wood joints and holds features I have not yet seen (such as the upper lateral bracing details, and the thrust blocks on the terminal ends of iron rod wind stays) on any still standing Long Truss bridge. It was also an honor and a privilege to examine this tiny construction, it being perhaps wrought by, and likely held by the hands of one or both of these storied bridge truss patent holders.

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The Bridgewright Blog would like to thank the NHAS / Hopkinton Historical Society for their willingness and cooperation in providing access to this rare piece of both area and wooden bridge history.

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Genuinely joined and richly detailed

 


Heritage Does Matter

Heritage Matters is a favored catch-phrase of mine, perhaps familiar to many of you as being the chosen name of newsletters and magazines published by those in the preservation / conservation community seemingly the whole world over.

I’m choosing to cite this phrase in this months entry in that I am penning it as a response to a number of recent news “stories” – stealth missions really, thinly veiled opinion pieces questioning the use of public monies to fund Covered Bridge preservation. The piece that touched a nerve, visited a single bypassed bridge, and suggests spending dime one to maintain such is wholly unreasonable, then goes on to intimate that funding maintenance on any example is money poorly spent.

I would ask those suggesting zero maintenance what alternative is it they see or might suggest. The funding of immediate demolition? The gating of Portals and simply letting time and neglect take the bridge to the river, someday accepting the inevitable expense of in stream cleanup and removal?

These are the only alternatives – Both are as silly as zero maintenance, and I would contend the cost of either would exceed the cost of decade upon decade of maintenance.

Postponing simple maintenance, is the unspoken of multiplier that drives up the cost of bridge rehabilitation’s. Timber does not simply go bad – Unchecked leaks in roofing or siding, and the buildup of dirt and leaf-litter, these all too easily preventable and correctable issues, are the causal factor in most all problems requiring any more than simple maintenance.

Putting aside that heritage tourism inarguably though indirectly offsets the cost of simple maintenance, (though perhaps not the costs of neglect) lets talk about heritage…

Unwittingly, even to those who care not one iota about history or historic preservation, Built Heritage still matters. In that this is where our sense of selves and place come from. The barns and historic homes we pass each day are our sense of place.

The Brownstones of Boston, Brooklyn and Harlem, the Victorian rowhouses of the Haight-Asbury, the Triple-Deckers of Mattapan, Manchester and Pawtucket, the Log Crib Barns of Appalachia, the Forebay Barns of Pennsylvania and beyond, all provide our sense of region and place.

This sense of place is also carried by the Howe Truss bridges of Oregon and the place-bound iconic Kennedy Portals of central Indiana – These things are all part of the landscapes which tell us who both we, and our Grandparents are. These things are who we are.

Forsythe Covered Bridge, Orange Township Indiana - Photo credit  James W. Rosenthal - Use courtesy of The Library of Congress, Prints and Photograph Division HAER: IN-106-2.

Forsythe Covered Bridge, Orange Township Indiana, Built by Emmett L. Kennedy & Sons
Photo credit James W. Rosenthal – Use courtesy of The Library of Congress, Prints and Photograph Division HAER: IN-106-2.

Transportation Heritage like all Built Heritage is part of this little thought of, almost subconscious sense of who we are. With any and every example of our built heritage forever removed from our landscape, part of who we are is also lost.

Our sense of place is now being endlessly eroded and homogenized, as it is re-placed with strip-malls, chain restaurants and tract-mansions.

Heritage lost, is the loss of who and what we are, both as a culture and a people.

Why would we want to intentionally fail to maintain any of it?


The Last Master Builder

In our delayed return to things Trussed Arch, we must first acknowledge two Bridgewrights we have already touched on here on the weblog. Both built in this form and tradition, both were contemporaries of the subject of this entry – Timothy Palmer of Great Arch & Permanant Bridge fame, and Theodore Burr, his name forever appended to Arch type bridges, though paradoxically not for his ahead of its time Delaware River masterwork.

Both were Master Builders, an archetype then long recognized – Those not just who had reached the complete command in a “physical” ability in their chosen craft at a skill level beyond their brethren, and also that uncommon ability, to see every layer of intricacy necessary to the planning and management of any project – And somehow also, an innate ability to visualize, design, and then draw, anything, (no matter how complicated) they were planning to build.

We cannot fully explore this Truss Type without discussing Lewis Wernwag, the Bridgewright whose works suggest he was the master of this typology. His prolific life’s work is most often exemplified in descriptions of his 340′ clearspan Schuylkill River masterwork known to history as The Colossus. This best illustrated in Lee H. Nelson’s highly recommendable book devoted to this single bridge – The Colossus of 1812: An American Engineering Superlative.

So much in fact has been written about the man and his works that we’ll not directly discuss his life in any bio type format, nor will we have a full hard look at The Colossus.

“A View of Fairmount and the Waterworks” by John Rubens Smith painted just three years prior to its loss to fire – Image courtesy of The Library of Congress

Our exploration will center around aspects of his design that suggest his understanding of his use of materials, choices which exemplify his complete understanding of his primary chosen material. And then discuss how his work moved beyond the Arch type bridges so common to this early period of bridge innovation

My intrigue with his chosen detailing goes to two things which deeply illustrate his understanding of wood as a building material, details that are today too often overlooked. These being that unwritten bridgewrighting rule of all timber needing be with every opportunity, spaced apart. In the case of The Colossus, in part by wrought iron “Links” These links, a clamp of sorts to serve as part of the Chord assembly, they also secondarily, though no less importantly served as spacers to provide airflow, and prevent large areas of wood to wood contact. ( The Colossus made great use of Iron – 40 Tons – Wernwag purchased an area nailworks & foundry in anticipation of the project ) And though it went unsaid this was obviously also to provide and maximize the ever- important airflow that affects the quick drying of any unintended wetting. The other detail I find interesting is one often cited in descriptions of this bridge, this of all its timber being “Slit through the heart” Always with this citation too much is seemingly made of his reference that this was done to “Show any defect” – Yes this was a secondary benefit of milling smaller baulks from large diameter sawlogs, (as was the norm to the period) this was without doubt also about other benefits wrought from such milling. His chosen six inch breadth is not just about staggering splices, it is also about rapid seasoning and thereby reducing the dead load of the bridge superstructure as quickly as was possible. It was also probable that in the doing at least twice the amount of curved Chord leaves were realized in the milling of his candidate sawlogs. (in all probability naturally curved – We know Palmer chose such for his Chord Lams) And the benefits of such milling do not end there. I would contend “Slit through the heart” is period jargon for what has come to be known as “Free of heart center” One of the betterment’s gained in FOHC milling is a reduced tendency in season checking, greatly reduced both in size and number. Lewis’ long experience in millwrighting would have him understanding what encouraged rot in wet environment constructions. Large leak catching open checks caked full of moisture holding dirt are one of those avoidable encouragements. And the aspect of FOHC that most overlook is the term Center, meaning heartwood, and the complete absence of sapwood. Sapwood is highly susceptible to the fungi that cause Brown Rot, and in my opinion its use should be avoided in the framing of bridges. With longevity and rot susceptibility clearly being high in his mind as he designed The Fairmount, I think it not a stretch to suggest this is an opinion he and I share. We are also of the same mind that Eastern White Pine for reasons which still hold true, is the go to choice in species for bridge framing.

Somehow today those who specify material for wooden bridges and the rehabilitation of historic spans, rarely spec dense ring count or FOHC even though both are readily available in their go to species of Douglas Fir. A species I do not see as across the board appropriate for all truss types, or to certain timber joints. This though is perhaps a discussion for another time.

Some might see some of what I suggest as just so much supposition. (and I am among those who revile revisionism based on groundless conjecture ) However I am in part reacting to such seen in earlier descriptions of Wernwag’s Collossus, and my conjecture is grounded in an intimate knowledge of these constructions, their methods, and their materials.

It is interesting that unlike his early Arch Bridge contemporaries, Wernwag transcended the Arch and also built in what some call true trusses. This was perhaps driven by an interest in keeping costs down by eliminating the needed mass and added complexities in abutments designed to carry Arches. This interest was perhaps driven by movement requiring repair, which developed in his abutment there on the western bank of the Schuylkill.

A detail from Lewis’ Neshinemy Bridge included because it is an example from one of his “Truss” bridges. That, and I simply love Strong-Arcs, (aka – Trussed Beams) and I see them as under appreciated. This, and with that the source material seen here, dates from the mans very lifetime.

As dusk descended on Wernwag’s life and time, a new age was slowly dawning. The role then long existing in mankind (from the dawning of man’s great works, from standing stones to our ancient temples and pyramids, to builders of tunnels & aqueducts to those who designed and oversaw the building of the great Cathedrals) which he had filled so well, that of a highly technical designer who was also a highly skilled rigger and builder, was then stratifying into specialties seen to no longer overlap, and to be seen by some to have very different places on the societal and hierarchical ladder. In truth, we are perhaps little the better for it. It is only with the possession of both skill sets, and both sets of understanding, each equally and finely honed, that anyone can truly be, a Master Builder.


A Confluence with the Timeless Flow of a Storied River

I have recently been tasked with designing a “Covered” Wooden Through Truss Bridge for one of the worlds most storied rivers…

That said, though that would be the word that is bandied about, I don’t really feel “design” is what I am engaged in. It is more about using a broad depth of knowledge to facilitate a design. To upon reflection, use a potential projects set of circumstance to then choose from a palette of time proven truss types. And wrap that around site circumstance of span and lay of the land, and how a rivers people work with and navigate its eternal flow. Couple that with cultural influences, and something once common to the table in bridge design, and too often for reasons which I will ever fail to understand, something that is now commonly left off that table – This the simple and recurring desire in mankind to surround ourselves in beauty – And in the end, the design, has chosen itself.

All that is left is the detailing of fit and finish, and that too, in good and thoughtful design, simply chooses itself. As is also, with quantifying what and how much this or any bridge might carry, and the requisite engineering this demands, such things as the sizing of the timbers are a given.

For this project we have chosen not a patent truss, but one, like the River we propose to span, which is far more timeless –

So for a time my attentions and research return to a truss type we last explored in At the Beginnings, the Trussed Arch –

More, as this trickle now just beginning, reaches steady flow, and our design fully reveals itself in the coming weeks.

If you find yourself in need of a way to reach that opposite bank, do reach out, and we might find our way across the water, together.


A Riddle Unsolved

I have, in prior entries, (See April ’12 archived entry Sticks and Stones and Service Life) alluded to how my coming up within seasonal sight of, and always within earshot of Watt’s Brook, and none so far from its confluence with the Merrimack River did much to form my understanding of how our world works. My relationship with this River goes back even farther, with one of my earliest memories going back to a time when I was still toddling, still pre-school, when my parents influences and those of my surrounding world provided my education. This just after our moving north from Rhode Island, when repeated new neighborhood unavoidable bridge crossings provided a growing awareness of my Mother’s almost quietly kept to herself, thinly veiled terror of bridges. A why is she acting differently realization which grew with each and and every time we needed cross “The Triple Bridges” at Hooksett Village. A realization which saw me looking at the river scenery flicking by the cars window with a sense of wonder just in some small way, different, than what was found in our woodlands and farm fields and city-scapes.

The Merrimack, long an aspect of my daily life, with an abundance of empty bridge piers would go on to provide much of the wonder which would in time grow into a fascination with both history, and the bridges mankind has provided for itself to help navigate our world.

Photo courtesy of C. Hanchey - The piers for both the Village Bridge and the neighboring RR triple span were formerly home to a series of covered wooden examples of various truss types - This Riveted Pratt was designed by John Williams Storrs (paste to search box for more info) was built in 1909 and bypassed in 1976

Photo courtesy of C. Hanchey – The piers for both the Hooksett Village Bridge and the neighboring RR triple span were formerly home to a series of covered wooden examples of various truss types including those of Briggs and Childs – This Riveted Pratt was designed by John Williams Storrs (Copy & paste to the blog search box for more info) It was built in 1909 and bypassed in 1976

In researching last months piece on Timothy Palmer, a Bridgewright who had spanned The Merrimack not once but twice, I again came across mention of another 18th century long multiple span example on my home River, this one once having stood in the twenty five mile stretch of the river I know best. It served at a point on that stretch of The Merrimack known now and then better than any other to the areas inhabitants. This being the Falls known as Amoskeag. This bridge then connected two villages, on the west bank a former part of Goffstown, on the east bank a second village then known as Derryfield – Both banks are now encompassed by the City of Manchester.

In both local histories, and in some of those many describing the history of bridge building, this 1792 example is often described like other contemporaneous examples built the same decade within the States borders, Hale’s at Walpole and Palmer’s Great Arch. This Merrimack example described as another first, as in this following excerpt from Wm. Hubert Burr’s Ancient and Modern Engineering – “The first long span timber bridge, where genuine bridge trussing or framing was used”

I have in coming across such description in the past, of a bridge on a part of the river well known to me, one still bridged at this location, with this hint at such a first, and one within sight of some of those empty sets of piers which have given me so much wonder…

Worked and searched in a quest of sorts to find deeper information, on both this bridge and its builder.

As it turns out, though information on the often named builder showed itself when I recently scratched again for more. It more than appears that neither he nor his firm built the 1792 span. Though record suggests one of his numerous companies was engaged in bridge building, and did span the Merrimack at Manchester – In 1792 Wm. was but three years old, and his bridge building concern was years away from formation.

So somehow, long ago in the chain of record, Col. Riddle was named as builder of this bridge in error. And as all too often happens, an error is repeated and then somehow repeated time and again.

Here this chain breaks. And with the seemingly strange irony, that a realized understanding raises a greater question. This mystery, like The Merrimack in our coming Springtime – deepens.

Who was it that did build this bridge? And was it as described, a first in true timber truss bridges, is now the Riddle which needs solving.

So road gig wrapped, and now home again – For me a trip to The City, its Historical Society, and The Falls is just over the coming horizon.