Plate I M-l ->» BRIDGES

Petit Jean State Park, Arkansas Deception Pass State Park, Washington

MINOR FOOT AND HORSE TRAIL BRIDGES

Surrounding are bridges of the most elementary pattern, mere platform bridging an obstacle, a type termed in France a passerelle. Enhanced by a sylvan setting, the casual simplicity of these seems the concordant note for a narrow trail in a wilder­ ness tract, wherein a narrow and shallow brook is hardly an obstacle to call for protective curb or handrail. The example with low curbs shown at lower left is transitional between this group and that shown on following page.

Denver Mountain Parks, Colorado

Sequoia National Park Parvin State Park, New Jersey

I77 BRIDGES «<- Plate I M-2

Deception Pass State Park, Washington Prairie Creek State Park, California

MINOR FOOT BRIDGES WITH SINGLE HANDRAIL Greater hazard in the obstacle to be crossed is met by the foot bridge with a single handrail. Each example here shown has distinct individuality. The Prairie Creek representative is two fallen redwood trees, one dressed on top to provide level walking surface, the other, still sending off living shoots, serving as picturesque guard on the off-handrail side. Equally novel are the bridge that changes handrails in the middle of the stream, the colloquial cantilever example in Great Smoky Mountains, and the stairway bridge in Moran State Park, notched from a fallen tree.

Great Smoky Mountains National Park

Grand Teton National Park Moran Stale Park, Washington

i78 Plate I M-3 A» BRIDGES

Turner Falls Stale Park, Oklahoma Custer State Park, South Dakota

FOOT BRIDGES WITH HANDRAIL AND CURB

On this page will be noted a vigorous scale which is at once the common bond between the five examples shown and the main point of difference between this group and that shown on the facing page. Another common factor is the employment of a handrail on one side and a curb on the other— the latter a mere log in every example save that at lower left where there is evidence of a developing second handrail. This promise becomes a fact in the bridges of the next group.

Loveland Mountain Metropolitan Park, Colorado

Humbug Mountain State Park, Oregon Devil's Den State Park, Arkansas

I 79 BRIDGES <«- Plate I M-4

Wildcat Hills Game Reserve, Nebraska

FOOT BRIDGES WITH TWO HANDRAILS

We put our best foot bridge forward in this initial feature certainly cannot be recommended to serve bursting into a half-page cut of a bridge and stoutly as a model. deny that we are victimized by the artful maneu­ All the bridges illustrated on these facing pages vering of a clever photographer. After faithful comprise a related group. There is great variation editorial effort to discount the unfair advantage in scale ranging between the pudgy example at this conscienceless fellow has heaped on it, the upper left and the rather attenuated construction bridge still seems to rate as a bull's-eye for those of the bridge at lower right. The former is so who designed and executed it. very ample for performing its obviously light task Pleasing overscale, the subtle camber of the that it may seem ridiculous to plead that the diag­ handrails, logical interrelation of the sizes of onal handrail braces (which might have been omit­ the various timbers, the exaggerated rake of the ted altogether with logic) should have taken the outrigger braces—all add up to a score that is other diagonal and made a pretense at functioning. impressive. The reader is implored to see only It should be noted that outrigger construction the good and to go along with us in being blind for bracing the railings, hardly encountered up to the inferior masonry of the abutment. This to this page, here becomes almost the rule.

180 Plate I M-5 ->» BRIDGES

Custer State Park, South Dakota Saratoga Hot Springs State Park, Wyoming

Lake Guernsey State Park, Wyoming Alderwood State Park, Oregon

Devil's Den State Park, Arkansas Savoy State Forest Park, Massachusetts

181 BRIDGES <«- Plate I M-6

Great Smoky Mountains National Park

FOOT AND HORSE TRAIL BRIDGES IN VARIETY

In the scale of the bridge shown above there is characteristic of oriental garden bridges. The happily present that visible assurance of adequate bridge in Clifty Falls State Park brings on the strength so strongly urged for park bridges. The scene for the first time squared timber members, suggestion of invitation with which the splayed and this bridge and the Wind Cave National Park approach invests the narrow foot bridge is here subject illustrate the possibilities for extending well exampled. the masonry abutment of a wood span bridge As a group the bridges on the facing page are to the height of the railing. Both also show a not so well integrated as the group just reviewed. sophisticated and careful masonry construction Individuality is more the note. Only the bridge that has not appeared in any of the bridges at Crater Lake National Park is comparable in shown up to this point. Such masonry is more sturdiness with the bridge shown above. A bridge typical of large bridges. The somewhat elaborate of the left hand column of the facing page, an rail pattern of the Scenic State Park bridge is example in Parvin State Park, borrows the grace­ more at home in its birch thicket setting than it ful and pleasing crown or segmental arch form would be either among larger trees or in the open.

182 Plate I M-7 ^> BRIDGES

Parvin State Park, New Jersey Crater Lake National Park

Parvin State Park, New Jersey Scenic State Park, Minnesota

Clifty Falls State Park, Indiana Wind Cave National Park

l83 BRIDGES m Plate I M-8

Fort Collins Mountain Metropolitan Park, Colorado

TIMBER FOOT BRIDGES OF MULTIPLE SPAN

In the examples shown on these pages, stone piers exaggerated crown sum up to a total effect that is in support of the bridge spans appear almost to be at once suggestive of strength and of skillful adap­ the rule, with but one bridge employing wood for tation to site. the purpose. This exception does not prove the The superiority—practical, logical, and aes­ rule, however, for there are possibilities in wood thetic—of a considerable batter to masonry bridge bents and log cribbing to bring greater variety to piers may be readily appreciated by a close study of multiple span foot and horse trail bridges than is this series. Noteworthy for this important feature manifested here. The multiple span vehicle bridges are the examples from Colorado, Oklahoma, and later shown give proof of this. Wyoming here pictured. Likewise does this group The Crowley's Ridge State Park and the Ponca afford a suitable opportunity for appraising the Lake Metropolitan Park bridges illustrate the re­ merits of outrigger bracing and of the scale of indi­ sults that can obtain when the terminations of the vidual wood members in relation to adjoining handrails are "brought to ground." Such satisfying parts, to length of span, and to length of the features as ample bearing, firm anchorage, and bridge itself.

184 Plate I M-9 ->» BRIDGES

Crowley's Ridge State Park, Arkansas Yosemite National Park

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South Mountain Reservation, New Jersey Saratoga Hot Springs State Park, Wyoming

Ponca Lake Metropolitan Park, Ponca, Oklahoma Ledges State Park, Iowa

185 BRIDGES m- Plate I M-10

New Salem Slate Park, Illinois

FOOT AND HORSE TRAIL BRIDGES

A common denominator of this aggregation of The crown or camber of the vigorous bridge at bridges is squared timber members. These may be Whitewater State Park, Minnesota, seems in very smooth-dressed, rough-sawn, or hewn and dressed proper amount and contributes, along with the with axe or adze. The aesthetic value of an axe- or sensibly trussed rail pattern, to the eye-appeal of adze-dressed surface is hardly apparent in a photo­ this bridge. graph, but the quality such surfaces bring to park Common to the bridges of the outer column of the construction is quickly sensed when observed in the facing page is the slender, segmental arch form. In actual. The two New Jersey bridges benefit greatly Illinois this is usually of laminated wood, occasion­ from hewn surfaces. ally of reinforced concrete with the offhand appear­ The bridge at New Salem State Park, wherein is ance of wood. The Rock Creek Park bridge is a reconstructed pioneer village, seeks and achieves frankly concrete. There is a soaring grace about a primitive quality related well to its surroundings bridges of this profile that is very appealing. Large by virtue of hand-split rails and hand-hewn posts, suspension bridges have made the profile familiar smoothed of all sharp edges to a convincing simula­ to us in this usage, and a present day streamline- tion of great age and long weathering. mindedness must on occasion be served.

186 Plate I M-ll ->» BRIDGES

Cooper River Parkway, New Jersey Gebhards Woods, I. & M. Canal State Park, Illinois

Egg Harbor River Parkway, New Jersey White Pine Forest State Park, Illinois

Whitewater State Park, Minnesota Rock Creek Park, Washington, D. C.

187 BRIDGES m- Plate I M-12

Custer State Park, South Dakota

MINOR VEHICLE BRIDGES

At this point the bridge comes of age and accom­ foot bridges, to the full-fledged bridges at the bot­ modates vehicles. Once again in the choice of the tom of the page, having abutments that grow into key illustration of this group, a clever photographer approaches. There is an appealing, humorous is suspect of having played friend-at-court, although quality about the little bridge at Goose Island State it is contended the bridge has real merit on its own. Park, Texas—Mother Goose is the name for it. The graceful birch may artfully mask formless As the illustrations well disclose, the droughts of masonry abutments but the wood span—its braces, recent years have made it difficult to obtain photo­ railing members, outriggers—all appear of pleasing- graphs of some bridges in any convincing relation­ proportion in an attractive pattern. ship to the obstacles involved. This is especially On the facing page is illustrated the development noticeable in this series and should not be held in of the vehicle bridge, from vehicular equivalent disparagement of these bridges in the light of more (at upper right) of the passerelle which ushered in normal function.

188 Plate I M-13 ->» BRIDGES

Roosevelt Regional State Park, North Dakota Goose Island State Park, Texas

Lctchworth State Park, New York Lewis and Clark State Park, Washington

Osage Hills State Park, Oklahoma Mohawk Metropolitan Park, Tulsa, Oklahoma

l89 BRIDGES m> Plate I M-14

Sequoia National Park

WOOD SPAN VEHICLE BRIDGES

There is in the bridge above-illustrated a robustness much the bridge above in miniature, and retains of scale that qualifies it for preeminence among the its heroic scale. Note in the bridge just below it examples shown on these facing pages. The posi­ that the abutment constructed of log cribbing tional as well as the scale relationship between the makes its entrance on the scene. posts of the railings and the log girders, and the In the trio of bridges of squared timbers we have great size of the latter members conspire to pro­ the grade-high abutment at the top, next it extends duce a bridge extraordinarily harmonious with the half the height of the rail, and finally to the full boulder-strewn creek and the wilderness setting. height of the rail and steps down to grade on the Facing are vehicle bridges which in the left col­ approach side. The refinements of axe- or adze- umn employ round timbers and in the right column dressed surfaces and of wood-pegged connections squared timbers. The bridge at upper left is very appear in these bridges.

190 Plate I M-15 ->» BRIDGES

Bandeher National Monument I & M Canal State Park, Illinois

Yellowstone National Park Cook County Forest. Preserve, Illinois

Lassen Volcanic National Park Spring Mill State Park, Indiana

l9l BRIDGES «f» Plate I M-16

Margaret Lewis Norrie State Park, New York

MINOR VEHICLE BRIDGES OF MASONRY

The masonry arch bridge offers variety by reason tion by choosing to substitute an arch fillet of of the many arch profiles, stone colors and textures, concrete for any mere vestige of a true stone arch. and masonry techniques it is possible to employ. There is informality in a stepped silhouette for The proportion between length of arch stones and the parapet wall of park bridges, as at Lockhart span of arch is an always important consideration. and Longhorn Cavern State Parks, which is held An arch that appears inadequate to support the to be in better "park character" than any use of a bridge is a major aesthetic blunder, even though thin, projecting, and more formal cap stone. the roadway is actually carried by a concrete con­ The little masonry bridge in Dutchess County, struction for which the stone wall is merely a New York, shown as tailpiece illustration on page surfacing. 8, belongs in the group shown here. If the infor­ The arch of the example above has in satisfying mation regarding this bridge is accurate, it is passed degree that look of being competent to perform its along with embarrassment, for it is said to be an job, as have also the arches of the Texas bridges ancient structure—not consciously created for its at the bottom of the facing page. In the others it superlative park character. Achievement will be exists in lesser degree. The Missouri bridge waives considerable, when, purposing to build park this consideration aside as unimportant, and bridges of distinction, actual accomplishment in brazenly "tells all" about modern bridge construc­ equivalent degree is more the rule.

192 Plate I M-17 -»> BRIDGES

October Mountain State Forest Park, Massachusetts Bennett Springs State Park, Missouri

Canyon Park, Oklahoma City, Oklahoma Wintersmith Metropolitan Park, Ada, Oklahoma

Lockhart State Park, Texas Longhorn Cavern Slate Park, Texas

r93 BRIDGES «& Plate I M-18

Enfield Glen State Park, New York

LARGER STONE VEHICLE BRIDGES

Unfortunate among larger stone arch bridges is a in this regard to the limits of the possible. The arch tendency to a thin and structurally weak appear­ stones of the bridge in Zion National Park seem ance at the crown of the arch. Even the annointed happily scaled to the size of the arch. of this group shown above suffers slightly from this Among this group are shown a variety of stone occupational defect. So also does the Arbuckle patterns and techniques and a varying merit. In an Trail, Oklahoma, bridge although not actually a age when the carrying arch is almost invariably of long span. It is more conspicuously present in concrete, and the stone sidewalls and their vestigial many otherwise pleasing and graceful park bridges arches are mere veneer, it is thrilling to observe that that are not here illustrated, and for that reason. the stone arch of the McCormick's Creek bridge is As the length of stone arch increases, it of course functional, carrying through the width of the follows that it is increasingly difficult to maintain bridge. The disillusionment when a veneer-arch the same arch-stones-to-arch-span proportion we barely turns the corner to give way to a character­ admire in the smaller arch bridge. We do not then less concrete surface comes always as something of bay the moon but adapt our standards of judgment a shock.

194 Plate I M-19 -»> BRIDGES

Cheaha State Park, Alabama Arbuckle Trail, Oklahoma

Yellowstone National Park 2jion National Park

AdcCormick's Creek State Park, Indiana Watkins Glen State Park, New York

[95 BRIDGES «f> Plate I M-20

DeviPs Den State Park, Arkansas

VEHICLE BRIDGES OF MULTIPLE WOOD SPAN

The conditions indicating" a bridge construction as The bridges of the left column on the facing page a succession of wood spans are usually a compara­ are of log construction (except for the stone abut­ tively shallow declivity, a considerable distance ments of the one) and illustrate that the interme­ between banks, and the absence of any necessity diate supports may be posts with bracing, bents, for maintaining a clear span. The highly interest­ cribbing, or any of these in combination, as at ing bridge on this page has greater height than any Mohawk Trail State Forest Park, Massachusetts. shown opposite, and the resulting lofty and massive The bridges shown in the outer column opposite piers are impressive. The observant will note that employ intermediate piers of masonry. The bridge many otherwise well-executed bridges terminate at the top has floor construction of wood, and the too abruptly after gaining what often seems a pre­ next below, steel and concrete masked by log string­ cariously slight bearing on the bank or abutment. ers. At the bottom will be seen a bridge of con­ The Devil's Den bridge rolls magnificently and crete floor construction undisguised, supported on hospitably on to join hands with the guard rails of stone piers and abutments, and utilizing log hand­ the transverse road construction with such unmis­ rails—a combination of modern and time-honored takable grace that it easily wins place as the key materials and methods that is both reasonable and example of this group. forthright.

196 Plate I M-21 -»> BRIDGES

Levi Jackson- Wilderness Road State Park, Kentucky Giant City State Park, Illinois

Mohawk Trail State Forest Park, Massachusetts Backbone State Park, Iowa

Yellowstone National Park Yellowstone National Park

J97 BRIDGES m Plate I M-22

Whitewater Slate Park, Minnesota

MULTIPLE ARCH AND SUSPENSION BRIDGES

Streamlining has not yet drummed the pleasing- is not glaringly disclosing of the concrete inner rhythm of the repeating arch form out of our construction. consciousness. And when the melody is echoed in The suspension constructions shown in the right still waters as it is above, we are reassured that hand column embrace two foot bridges, top and it will forever continue within the range of our bottom, and a vehicle bridge at Mount Rainier Na­ appreciation. tional Park. The suspension bridge probably more A pitfall in the designing of the multiple arch than any other type will provoke controversy stone bridge is insufficient mass in the piers. A among the park-minded as to its fitness in a wil­ tendency in this direction is noticeable in the bridge derness. There are those who will accept the log- illustrated at the bottom of the left hand column constructions and ban the type represented by the opposite. Pleasing in the top example are the sub­ example at Jay Cooke State Park, and there are tle crowning of the parapet silhouette and equally some who will approve, and others who will de­ subtle splay of the terminals, so that these suggest plore, both types. Space here permits the showing rather than actually become wing walls. The arch of these bridges, but by great good fortune does stones of this double-arched example are very hap­ not allow for comment or analysis disclosing of pily scaled and have a face-to-back thickness that other than a neutral position regarding them.

198 Plate I M-23 -»> BRIDGES

Mount Vernon Memorial Highway Rainbow Falls State Park, Washington

Cook County Forest Preserve, Illinois Mount Rainier National Park

Bennett Springs State Park, Missouri Jay Cooke State Park, Minnesota

199 BRIDGES m Plate I M-24

Quartz Mountain State Park, Oklahoma Roman Nose State Park, Oklahoma

LOW WATER BRIDGES

Where terrain and other affecting conditions arc such that the approach roads to the bridge and nearby streamside use areas are unusable during flood periods, it is purposeless to elevate the bridge above flood stage to a resulting awkward relation­ ship with the terrain. In such locations the low water bridge has proper place. Predicated on frequent submersions by flood, this type of bridge calls for a rugged, "weighted" scale that gives unmistakable assurance of permanence.

Palmetto State Park, Texas

Boyle Metropolitan Park, Little Rock, Arkansas Boyle Metropolitan Park, Little Rock, Arkansas

K9522-23-PART I 200