For information, contact: Albert Crowsky, 847-809-4593
Prestressed Triple Walkway Bridge
Author: Scout Pioneering
Scouting America Volunteer
The Monkey Bridge at the 2013 National Jamboree
For those familiar with the traditional Double A-Frame Monkey Bridge design, a couple of noticeable modifications will be apparent from the outset. (Click on the photos for larger views.) Scout Engineering is a fluid undertaking, and frequently variations are necessary. Just as frequently an alteration or change can be deemed a desirable improvement. In the case of this double A-frame design, the consensus of opinion is these modifications are really neat, and I’m sure Adolph Peschke would concur.
- Instead of separate shorter ledgers for each pair of adjoining A-frames, connect four legs with one longer ledger. The length can actually be the same as that of the legs, e.g. four 8-foot legs and one 8-foot ledger at the bottom, or for a larger structure, 10 or 12-foot legs and ledger. (A spar longer than the legs does yield more flexibility when lashing together the four legs.)
- Ladder rungs! Lashing a couple of cross pieces between the legs of the left A-frame cancels the need to climb on board the bridge using the foot and hand ropes! Same thing of the other side. Crossers use the rungs and have a safe and easy way to get on and off the bridge, AND eliminate the often awkward balancing act on the ropes between the A-frames and the anchors. There’s an added advantage too: no more excess stress and strain on the ropes near the anchors.
JAMBOREE PIONEERING AREA: BRIDGES
JAMBOREE PIONEERING AREA: MAIN PAGE
Jamboree Pioneering Area: Bridges
The bridges featured in the pioneering area of the 2013 National Jamboree were a modified Double A-Frame Monkey Bridge, a specially designed pre-stressed triple walkway bridge, and two Single A-Frame Bridges that Scouts could put together from a couple of kits we supplied.
Single A-Frame Bridge Building. The kits we supplied for the construction of a Single A-Frame Bridge afforded crews an opportunity to build their own simple crossing bridge. Each group’s success was gauged by how they all could use it to cross the ditch and then all stand on it and pose for a group photo. So the activity wouldn’t be too time consuming, the walkway subassemblies were pre-made. Click here for photos of the crews.
Modified Double A-Frame Monkey Bridge. By far, the bridge that received the most play was the monkey bridge. There’s just something about making your way on a foot rope that appeals to young folks, and frequently there was a line of Scouts waiting to make the crossing. This bridge illustrates a nice approach to the double A-frame construction. Click here for photos and information about the modified design.
Prestressed Triple Walkway Bridge. The most sophisticated and by far most substantial bridge erected up on Garden Ground Mountain on the occasion of the 2013 National Jamboree was this well-designed prestressed bridge. Without getting technical about compressive forces and tension and stress mechanics, suffice it to say the bridge was impressively well-built and strong. Click here for information and photos.
JAMBOREE PIONEERING AREA: MAIN PAGE
Jamboree Pioneering: The Building Process
After the spars were skinned and the initial supply of ropes were cut and whipped, there were about three days to build the pioneering area and batten down the hatches in readiness for the first troops to take the hike up to Garden Ground. There were thirty projects and structures to build and fifty pioneering area staffers to do the work, so the staff was split into construction crews and assigned various tasks.
Here are some photos revealing a bit of the work entailed in the overall building process. All thirty projects and structures can be seen and reviewed by following the links on the jamboree pioneering area: main page. The entire jamboree project area layout can be seen here.
What hasn’t been described or captured in photographs is the initial and ongoing process to gather and prepare mallet heads and handles for the Mallet Making Station. The demand for more and more materials was so great, each morning, mallet handle foraging expeditions were in full swing!
Jamboree Pioneering Area: Initial Preparations
Ropes. For thirty different pioneering projects and structures, plenty of rope had to be measured, cut, and whipped for lashings, anchors, and guylines. We had plenty of manila and appropriate synthetic fiber rope in a variety of diameters on hand, and thanks to a well-organized storage arrangement and experienced quartermaster, ongoing supplies were readily available.
“We’ve got spars!” Of course the spars for our pioneering projects were a major consideration. Where would they come from, and how would we get them? By emailing this photo (on right) with the simple statement, “We’ve got spars!”, our director, Jim Keller let us know that spars for our projects and structures had been delivered to Garden Ground Mountain! Naturally, before we could build anything, they’d have to be skinned!
Skinning Spars. Starting full swing on the 11th of July morning, and continuing through the end of the 12th, amidst pouring rain with steadfast purpose and draw knives, a full crew persistently and methodically set upon the pile of heavy, hardwood spars. In spite of the tedious and often bent-over, backbreaking work, sloshing through mud in water-logged boots, spirits were high! There was something about working hard up on that mountain along with a like-minded, jovial crew that kept us going in fine form up to and after the very last spar had been relieved of its bark.
After spars were skinned, they were transported to central locations throughout the pioneering area and selected by crews in accordance with their length and diameter to meet the material requirements for specific pioneering structures and projects. Most often, they’d be sawed to the desired lengths before being carried off to various construction sites. The total pioneering area was later dubbed: Peschke Field (named after pioneering legend, Adolph Peschke).
Why skin the spars? Basically, there are three reasons:
- If tied on top of bark, lashings are prone to slip, if the bark shifts or loosens under the strain during use.
- Skinned spars last longer than those left with the bark on. Unskinned spars are more subject to rotting from moisture and more susceptible to weakening from insects.
- Pioneering projects with skinned spars look really nice.
Transporting heavy spars. An extra long spar for the flagpole and larger-diameter spars for the climbing area had to be moved by entire crews. The 30′ poplar flagpole was dragged by tying butterfly knots for handholds in the dragging line. The uprights for the climbing area were lifted and carried by joining the ends of a rope and threading it under the log so that a series of two carriers grabbing a hold of the rope could walk the spar along on either side.
Pioneering Area, 2013 National Jamboree
The Pioneering Area was named Peschke Field after Adolph Peschke, who through the years had motivated and inspired so many with his high standards, creativity, and pioneering know-how.
The following layout is a depiction of the pioneering projects and activities featured at the 2013 national jamboree up on Garden Ground Mountain at the Summit Bechtel Reserve. For a larger view, click on the layout once. Then, for a closer view, click on any section you choose:
Single A-Frame Bridge Pictorial
The Single A-Frame Bridge is made up of three subassemblies. Please refer to Bridge Walkways as a point of reference for two of the three of these subassemblies. The following photos will enliven the text and instructions featured in Adolph Peschke’s informative, older pioneering merit badge pamphlet. Click on the photos for larger views:
Single A-Frame Bridges at the Jamboree
In the Pioneering Area of the 2013 national jamboree, we put together a couple of Single A-Frame Bridge kits, so Scouts and Venturers could build this simple crossing bridge during their visit to Garden Ground Mountain. Each kit included:
- two pre-constructed walkways
- two 12-foot leg spars (shear legs)
- one 5-foot transom spar
- one 6-foot ledger spar
- two pre-positioned anchors
- four pioneering stakes
- two guylines
- five lashing ropes
Whenever a crew wanted to build a bridge, we provided an overview of the design and gave them a quick introduction to tying a rope tackle and the Japanese Mark II Square Lashing. What follows are some photo montages of the Single A-Frame bridges built from the kits during the jamboree. For larger and largest views, click on the photos once, and then once again:
On occasion, a pair of Scouts wanted to build a bridge, and with persistence, and the help of staff or friendly Scouter, they were able to get it done.
JAMBOREE PIONEERING AREA: BRIDGES
JAMBOREE PIONEERING AREA: MAIN PAGE
Related article
- Single A-Frame Bridge (scoutpioneering.com)
Membership and Retention
Premise: When Scouting is WELL-PROMOTED in its true and irresistible light, as a value-based movement providing experiences found nowhere else, there will be a manifold increase in membership comprised of those families who not only want to get involved, but who will knock on the doors of individual Scout units and their local councils to learn how.
MEMBERSHIP
- Promote the FACTS! Redirect the focus of the general public with an exciting and impactive presentation of these facts brought to life in an impressive 60 second video advertised in the national media.
- Mount a multifaceted “Scouting is Both” print ad campaign. (inquire here.)
RETENTION
Premise: In conjunction with Rocketry, Robotics, STEM, and the advances in lightweight, no-impact, backpacking techniques, re-emphasize the traditional campcraft skills. They are timeless and carry with them the mystique and fascination that forever remains attractive to youth! Revitalize these skills as a central feature of the Scouting program, and in so doing, not only increase incentive to join and stay involved, but counteract the consensus that over the years the BSA’s outdoor skills requirements have undergone what has been construed as an unfortunate “dumbing down” yielding an influx of higher ranking Scouts that can’t put up a dining fly of light a fire in the rain.
- Revise the campcraft advancement requirements, providing the grounds for the acquisition and use of campcraft skills that are appealing, relevant and continually used as part of a troop’s outdoor program.
- Across the board, in publications and training materials, emphasize and promote the inclusion of traditional methods of camp cooking and campsite set up, for front-country camping, that do not impact the environment.
- Hold inspiring adult training sessions, initially at the Summit and Philmont, introducing and teaching relevant, old-school campcraft and pionerering skills and how to include them as an integral, challenging, and fun part of the unit’s program.
- Provide action-based program materials enabling units to deliver a program that not only teaches the skills, but brings them to life, so that Scouts can actively experience their use in a way that is enriching and fun.
- Train district and council trainers to present an Advanced OLS course replete with methods and activities designed to deliver these skills as part of their troops’ programs.
- Following a well-working, field-tested design, provide the wherewithal to councils and/or OA lodges to implement their own pioneering and advanced campcraft programs.
Check the Facts!
FACT
The purpose of the Boy Scouts of America, incorporated on February 8, 1910, and chartered by Congress in 1916, is to provide an educational program for boys and young adults to build character, to train in the responsibilities of participating citizenship, and to develop personal fitness.
FACT
In addition to traditional Scout and campcraft skills, Scouting also incorporates modern technology. NOTHING has changed—only expanded.
FACT
The Boy Scouts of America provides the most effective program of youth protection in the world.
FACT
The mission of the Boy Scouts of America is to prepare young people to make ethical and moral choices over their lifetimes by instilling in them the values of the Scout Oath and Scout Law.
| Scout Oath (or Promise) | Scout Law |
| On my honor I will do my best To do my duty to God and my country and to obey the Scout Law; To help other people at all times; To keep myself physically strong, mentally awake, and morally straight. | A Scout is trustworthy, loyal, helpful, friendly, courteous, kind, obedient, cheerful, thrifty, brave, clean, and reverent. |
Single Trestle Bridge: Photos & Commentary
CLICK HERE FOR SINGLE TRESTLE BRIDGE PROCEDURE, MATERIALS, AND INFORMATION.
CLICK HERE FOR SINGLE TRESTLE BRIDGE PROCEDURE, MATERIALS, AND INFORMATION.
Single Lock Bridge: Photos & Commentary
This fundamental trestle bridge design yields a solid structure. With Adolph Peschke’s text as the main point of reference, under the following photos there are some guidelines that will help in its successful construction:
- When using the length of spars in the list of materials, choose a ravine or stream that is at least wide enough to assure the interlocking trestles can be spread at a distance that will allow the formation of a comfortable angle of just about 45°.
- Make it a priority to lash the top ledgers as low as necessary to assure they will end up about 1 foot above the level of the banks. Whatever the height, they need to be at least 6 inches from the end of the trestle legs, so when the trestles interlock, the “V” that is formed on each side is deep enough to rest the 3 inch-diameter transom in between.
- The bottom ledgers need to be lashed at least 6 inches up from the butt ends of the trestle legs to assure there’s enough leg to heel in as necessary when it comes time to even the transom and add stability.
Pioneering Bridges and the Saga of the Bridge of Fifteen Nations
Bridge Walkways
The following text is by Adolph E. Peschke as presented in the 1998 printing of the 1993 edition of the Pioneering Merit Badge Pamphlet:
Bridges are very popular pioneering projects. Essentially, a bridge consists of one or more trestles that support some sort of walkway. In the case of a monkey bridge, the walkway is just a rope that you walk on. But for many other bridges, you can build a walkway from spars that’s easier to walk on than is a monkey bridge.
In the Single Trestle Bridge, the Single Lock Bridge, and the A-Frame Bridge, the same type of walkway can be used. Each walkway can be 10 feet long and consists of two lateral spars and several cross spars. A 10-foot length of 2-inch x 10-inch construction lumber can be added as the plank to walk on.
MAKING A WALKWAY
To make a 10 foot section of walkway, select two spars with a butt diameter of 3-1/2 inches. These spars should be matched in the amount of sag they have when you stand on them with the ends supported above the ground. If one spar sags more than the other, it will make the walkway slant from side to side, making it hard to walk on.
Cross spars. The cross spars for the walkway should be approximately 2 to 2-1/2 inches in diameter and 3 feet long. You will need two additional cross spars that are 3-1/2 feet long for each walkway section. (The longer spars go at each end of the walkway.)
All of the cross spars are lashed to the lateral spars with 1/4-inch manila. Since the lashing is made only to hold the cross spars in position and not support weight, you can use a double strand of binder twine.
If you use binder twine, double it over and twist it a few times before you start the lashing. Make sure you have enough to complete the full lashing with the doubled-over binder twine. Don’t finish the lashing with only one strand if you run short. Instead, tie on more binder twine to complete the lashing.
Each of the cross spars is lashed to the lateral spars with a square lashing, making three wraps and two fraps. The Japanese Mark II is the easiest and quickest to tie.
There are two ways to approach lashing on the cross spars. If you are going to add a plank over the top of the cross spars, you will need a total of eight cross spars for each walkway. That is, six 3-foot cross spars, and two 3-1/2-foot cross spars (see Drawing 1).
Start by lashing one of the 3-1/2-foot cross spars about 6 inches from the butt end of the lateral spars. Place this spar on top of the lateral spars so that the ends of the cross spar extend 3 to 4 inches out over both sides of the lateral spars. This additional length hanging out is used to lash the cross spar to the stakes, which anchors the ends of the walkway in place.
After the first cross spar is lashed in place, add six more 3-foot cross spars every 16 to 18 inches down the length of the lateral spars. The last cross spar should be lashed about 12 inches from the ends of the lateral spars to allow room for the “underspar.”
Underspar. An important feature of this type of walkway is to lash one 3-1/2-foot cross spar to the underside of the lateral spars 6 inches from the end. When the two walkway sections are placed on the trestle(s) to form the bridge, these underspars should contact the transom of the trestle(s). Then the three spars [two underspars on the two walkways and the transom spar of the trestle(s)] are lashed together at three points using a strop lashing (see Drawing 3).
Walkway plank. Before lashing the walkway to the trestle, the walkway plank should be lashed in at least three places using a strop lashing.
To make a strop lashing, use a length of doubled-over binder twine. Reach down and wrap the middle of this length of binder twine under one of the cross spars (see Drawing 2). Then wrap the binder twine over the walkway plank and down under the cross spar at the other side of the plank. Do this two or three times and finish with a square Knot.
If you are going to walk directly on the cross spars (with no plank on top), you will need enough cross spars to make a safe walkway, one that your foot cannot slip through. Start making the walkway as described before by lashing a 3-1/2-foot cross spar at the butt end of the lateral spars. Then lash the 3-foot cross spars about 3-inch apart, using as many cross spars as necessary to go the entire length of the walkway, ending about 1′ from the other end. Finally, add the 3-1/2-foot long underspar.
Anchoring the walkway. After the walkway is assembled, the butt ends are placed on the bank of the creek or ravine. This end is anchored in place by driving stakes in the outside corners formed by the lateral spars and the first (3-1/2′) cross spar. Lash this cross spar of the walkway to the stakes with a strop lashing.
The small ends of the walkway are attached to the trestle to form the bridge. On most bridges, walkways come from both directions to meet at the trestle(s). The ends of the walkways rest on a transom spar of the trestle(s). Then the two underspars of the walkways are lashed to the transom spar at three points with a strop lashing (see Drawing 2).
When the walkways are lashed to the stakes and to the trestle(s), all the walkway sections become joined to form a single unit that is very strong.
If you put together a pioneering kit, take some time to save the matched lateral spars to be used for walkways only.
While the above text describes how to make 10-foot walkways, you can make 8 or 12-foot sections the same way. If you use the longer walkways, be sure to test the strength of the spars before lashing them into a walkway that could be unsafe.
Related articles
- Single Lock Bridge (scoutpioneering.com)
- Single Trestle Bridge (scoutpioneering.com)
- Single A-Frame Bridge (scoutpioneering.com)
Barrel Hitch
One never knows when this specialized hitch might be needed. The barrel hitch can come in handy for hoisting up or suspending a bucket or other container that has no attached bail or handle. Forming the hitch is a very easy operation stemming from the tying of a simple overhand knot.
The following text is by Adolph E. Peschke as presented in the 1998 printing of the 1993 edition of the Pioneering Merit Badge Pamphlet:
A barrel presents an awkward shape when you’re trying to tie a rope to it to lift it. If the barrel is turned on its side (horizontally), a rope grommet can be made into a sling and slipped over a hook to hoist the barrel.
If the barrel has to be lifted while remaining upright, the barrel hitch is a special knot that does the job with ease. Most books show only one loop around the center of the barrel, but a second loop will help stabilize the barrel in the upright position.
Foolproof Way to ALWAYS Tie a Square Knot Right
VIEW VIDEO: How to Always Tie a Square Knot Right
First of all, the square knot (Reef Knot) is primarily a binding knot. That is, it’s used to secure a rope or line around an object. In Pioneering, its most basic function is to commonly finish off a strop lashing, Mark II Square Lashing, Filipino Diagonal Lashing, West Country Round Lashing, and both the West Country and Sailmaker’s Whipping.
A square knot is formed by tying a left-handed half knot and then a right-handed half knot, or vice versa, and is regularly taught and learned by passing on the familiar, “right-over-left, left-over-right,” or “over-under, under-over.” However, frequently in the midst of tying the knot, it can be easy to forget what was done or how it began, e.g. right over left, or left over right, and which end was used. Therefore, here’s the sure-fire way to ALWAYS tie it right, every time! Simply tie a half knot, then tie another, BUT, keep the ends on the side they’re already on! In other words, don’t cross them over. Stay on the same side! One running end is nearer to you (in front) and the other is farther away (behind). Keep them there as you begin to tie the second half knot. Simple! In the illustration, red and blue ropes have been used and are referred to for clarity sake.
The beauty of this simplistic, little approach is you can see how to tie that second half knot without knowing (or remembering) how the first one was tied.
SCOUT PIONEERING 