Alan Long and Anne Todd-Bockarie 1
1994 SS-FOR-5
Building Forest Recreation Opportunities
Recreation on forest land is an important concern for many public and private landowners. In some situations it is the primary goal for land management. Elsewhere, recreation is supplemental to other objectives such as wildlife enhancement or timber production. Non-industrial private landowners participating in the Forest Stewardship Program frequently include recreation as one of the primary objectives in their Stewardship Management Plans. Whether on public or private land, recreational opportunities are expanding in many directions. Hiking, biking, fishing, hunting, horseback riding and nature observation are only a few of the leisure activities pursued on forest lands. Some folks even view strenuous activities such as rock climbing and firewood cutting as forms of recreation. Recreational options may be exercised by individuals, large organized groups, or combinations between these two extremes.
For most recreational activities, trails are an important component of the management plan and infrastructure. Trails represent the main route of travel for hiking, riding and a variety of other pursuits. They are also important for access to recreational sites, such as the favorite fishing hole, archery target, beach or camping spot. Environmental education and nature observation rely on trails as "classrooms" for study and learning. All of these important functions depend upon carefully designed, constructed and maintained trail systems.
This paper will provide practical information for planning and developing recreational trails on forest land. Although the guidelines were collected from various sources listed at the end of the publication, they have been tailored to fit Florida conditions. We will describe general designs and construction methods as well as some of the structures that may be important components of your trails, such as bridges, boardwalks, and benches. Costs are mentioned with the cautionary disclaimer that they may be highly variable depending on how you implement your recreation plans. The references listed at the end of the paper will provide readers with additional details on many of these subjects.
Trail Design
The location and characteristics of a trail represent "a balance between beauty and function" (Proudman and Rajala 1981). Initial planning for any trail system requires careful evaluation of the general purpose for the trails, as well as the types of people that will use them and activities they will conduct. The options for trail development vary widely depending on these goals and functions. Common trail themes which meet landowner objectives include:
Landowners may focus on individual themes, or combine them to emphasize different educational, scenic or recreational values.
Several other important considerations in initial planning will influence general trail design. Specific site conditions or natural features on the property might be either highlighted or avoided. For example, sinkholes can provide interesting changes in vegetation and good stopping points on well-marked educational trails. On the other hand, they might represent safety hazards if unmarked and located adjacent to primitive-type riding or hiking trails. Similarly, historic farm sites are often key points of interest, but old wells or cisterns are safety hazards. Although wildlife observation may be a central theme for some trails, you may need to locate the trails away from areas on which endangered species are protected. All these examples illustrate that it is important for the landowner to identify conditions or situations that should be featured or avoided in trail design and location.
Trails on private land are frequently used only by the landowner, immediate family and friends, or groups that are granted permission to use the trails. However, some landowners also open their land for public use. If the latter is your intention, you may need to follow trail guidelines and specifications that meet requirements of the Americans with Disabilities Act (ADA). For example, under ADA, general use trails need well-packed or hard surfaces and gentle grades. These trails will preferably form a loop from start to finish, and be 1/2 to 2 miles in length. Landowners should seek professional advice on current ADA standards as they design trails that will be open to the general public.
Other considerations during initial planning may include the availability of funds for construction and maintenance, natural (on-site) materials that can be used for structures and trail surface, and building materials from commercial sources. Other resource constraints on design and function include site characteristics such as heavy brush in some areas, swamps and marshes, or railroads and fencelines. Possible limitations on trail design should be understood by the landowner prior to any detailed planning. They will influence construction options, thereby impacting costs and labor necessary to develop and maintain the trail system.
After initial planning is completed, the trail design process shifts to deciding where to locate the trail and general construction features. Important trail attributes that will be defined include the shape, or format, and the structural components of the trail corridor. Alternatives for trail format are loops, horseshoes and lines, as illustrated in the figure below.
(Courtesy of the Appalachian Mountain Club)
Loops return the trail user to the starting point without retracing part of the trail. They are good trails for nature study, day hikes, and use by both horses and hikers. Although day-use trails are generally less than 2 miles in length, longer loops can be designed for other purposes. Horseshoe-shaped trails are similar to loops except that the end points are at separated trailheads connected by easily accessible transportation. A third trail format is a line between the trailhead and destination, and users can only return to the starting point by retracing their steps. Examples range from a short access trail to a point of interest such as a lake or campsite, to the Florida Trail which extends several hundred miles across Florida.
The trail "corridor" is the total environment of the trail. It consists of: the walking surface (tread); the right-of-way (trail bed), including all area cleared for passage of the trail user; and the buffer zone, which is the area on both sides of the right-of-way that shields the trail from outside influences. Except for long-distance vistas and scenery, the trail corridor includes the immediate features that influence trail difficulty and the environment that is visible to the trail user. Thus, trail location and construction are inseparably related to the desired corridor conditions.
Once the general design and characteristics of the trail have been determined, the next step is on-the-ground location of the best route to meet the objectives and design requirements. Reconnaissance to identify and evaluate alternative routes begins with aerial photos, topographic maps, or other maps if neither of the first two are available. Aerial photos, or copies of them, are often available through ASCS, SCS, or county property appraiser offices. They help to identify exact locations of important features such as openings in forests, existing trails, old roads or railroad grades, sinkholes, and old homesites. They can be used to map vegetation types and special features on other base maps. Topographic maps provide additional information on slopes, waterways and the location of special features that might not be visible on aerial photos.
A detailed property map should be developed from, or modified by, these sources of information to include all items that might be considered in locating trail routes and that might have either positive or negative effects on trail location. Alternative routes can be drawn on the map to optimize the positive effects and minimize the negative ones.
Armed with the property map and aerial photos, the landowner should walk through all the alternative routes identified on the map. It is often helpful to conduct this "walk-through" with resource professionals who can provide valuable input and suggestions. During the on-site inspection, check all points of interest to be sure they are worthy of being featured along the trail. Also carefully check all possible water and road crossings to be sure stream banks are stable and road crossings are visible for at least 500 feet in both directions.
A variety of environmental conditions that will influence trail location can be identified in both the preliminary mapping and field evaluation. Soils with saturated conditions or high water tables need to be noted and checked after long periods of rainfall. Trail location should generally avoid such sites. Clay soils are more prone to erosion than the sandy soils that occur throughout much of Florida. Trail routes on clay soils need to be identified to plan for erosion control measures if on sloping land. Preferred soil conditions include sandy and loamy soils with no shallow hardpans. Ridges and high topographic routes generally are drier, require less construction and maintenance, and provide panoramic views. On the other hand, ravines may need to be avoided for safety and environmental protection, although they can provide points of interest with proper planning. Waterways, springs and sinkholes are often points of interest, but trail location and construction must allow for their protection. Dense vegetation in these areas is also a problem for initial construction and maintenance. Benches or terraces along waterways may be more favorable for trail location than the floodplain along streams. Access to the water is still possible by means of short spur trails. If your proposed trail routes happen to traverse moderately sloping ground, you will probably want to be sure that routes generally follow contours.
Vegetation along the proposed routes should be evaluated for both aesthetic and environmental protection concerns. For aesthetic purposes, plant diversity is often a desirable trail characteristic, and routes should be favored that expose trail users to as many different plant communities as possible. Thick understory, found near streams or ponds, may block views, decrease aesthetic values, and require more frequent trail maintenance than lighter vegetation. However, such thick vegetation can also be used to channel and contain hiker traffic, retard soil erosion (due to the abundance of roots under the tread), protect hikers from weather (eg cooling in summer), and act as a buffer between incompatible activities.
Final route selection involves connecting as many of the positive features marked on the map and avoiding as many of the negative features as possible. The route can be identified with plastic flagging at this point, which allows trail location to be adjusted during actual layout of the trail as described later in this paper. Conditions to favor in route selection include:
Avoid trail location in areas with:
| * Drainage constraints such as wet, flat, or frequently flooded
depressions (unless they are highlighted for nature study, or have crossings of some type) * Unstable or fragile soils (erosive or slides) * Steep slopes, bluffs and cliffs * Dense vegetation requiring excessive clearing and maintenance
* Vegetation and wildlife habitats that might be adversely affected
* Cultural and archeological sites that need to be protected and are not featured * Timbered areas subject to blowdown, falling limbs or other dangers * Old mine areas or other man-made hazards (wells, cisterns etc.) * Frequent stream corssings * Existing farmlands |
Trail construction involves clearing the vegetation along the right-of-way, cleaning or surfacing the tread, and building any planned structures. A variety of tools and materials can be used for these construction practices. Labor and costs will be significantly influenced by the selection of tools and materials. Be sure to carefully select the right equipment for each particular task.
Initial clearing and subsequent maintenance often requires cutting logs and various forms of vegetation. Axes, brush hooks and machetes are used for small (less than 2 inch) diameter stems and branches. They are quick and efficient, and many people have experience using them. Axes are especially useful for construction and maintenance of long distance trailsbecause of their versatility and light weight. They are also used for removing bark and for notching or flattening logs. All three of these tools generally leave pointed stubs or stumps, and if not correctly sharpened have the nasty habit of glancing off targets into shins or other objects. They should, therefore, be used with the utmost care, and protective leg guards are advisable.
Saws provide smoother cuts and are generally more efficient than axes or machetes for large diameter stems and logs. Chainsaws are, of course, the fastest, but they are heavier than the other alternatives and require more care, maintenance, and attention to safety than the others. Crosscut saws are not widely used anymore, but can be very efficient and light weight when used properly. Pruning and bow saws are the best option for many small to medium diameter stems and branches, and permit pruning branches flush with stems so as not to leave any stubs. Lopping shears and hand-held pruning shears also provide clean, flush cuts and are good for stems with diameters less than 1 inch. Gasoline-powered brush cutters or mowers, with circular blades, can be used for quick clearing of large areas, but they leave ragged cuts and stumps above ground line. Chisels and adzes should also be mentioned as cutting tools as they may be appropriate in the construction of various structures.
Another set of tools is required for removing roots and stems from treadways, excavation for sloped trails and erosion control structures, and other digging tasks. Shovels, with long or D-handles, are used primarily for moving soil or surface materials, and for digging out rocks. Mattocks, grub hoes, hazel hoes or Pulaskis can also be employed for digging roots and stones out of right-of-ways and for shaping erosion control devices such as water bars. Other related tools include fire rakes or yard rakes for leveling tread surfaces, and large crowbars for moving heavy objects (and avoiding shovel handle breaks).
Although these tools will accomplish the large majority of construction and maintenance tasks, several other tools provide specialized services. Sledge hammers, splitting mauls and wedges may be necessary for driving spikes and stakes in bridges and other structures, or for splitting logs that are used in construction. Various types of bars (peelers and bark spuds) are available for work that involves a substantial amount of bark peeling. Logs used in construction tend to rot faster if the bark is not removed. Peeling bark with axes is feasible if you have only a few trees, but it is a slow and laborious process. Finally, come-alongs, winches and timber carriers will greatly assist in moving large logs and rocks. Be careful in their use to have good connections and to not exceed weight limitations.
Trail construction often utilizes various materials for trail surfaces or borders, steps, signs, or more complex structures such as bridges. In general, natural and native materials are preferred for such purposes since they help the trail to blend with surroundings. Trail surfacing is not necessary for all trails, but should be considered for trails that will be heavily traveled or that cross poorly drained spots or clay soils that may be slippery or easily eroded. Sawdust, shavings, wood chips and mulch provide a soft surface for walking and prevent erosion, trail wear and resprouting of roots under the tread. However, they are expensive to spread on long trails since they must be transported from drop points or mulched on site. Pineneedles and regular leaf litter can provide the same effects and may already be on the trail surface, or can be collected in adjacent stands without disrupting aesthetic values along the trail. Rakes and plastic or burlap bags work well for such local collection and redistribution.
Gravel and rock are more expensive to purchase, transport and spread, but may be important in local spots of poorly drained or slippery soils. Gravel should also be considered for short trails that will receive heavy public use, if a solid packed surface will not otherwise be provided. Larger rocks may be used for a number of other trail purposes. Rocks with at least one flat surface serve as steps or stepping stones across wet areas, and more irregular shaped rocks can be used as ballast in building up trail subsurfaces or as anchors for waterbars, wood steps, bridges and other structures. Geotextiles, now widely used in road construction, can also be placed across poorly drained spots prior to gravel or rock, and will substantially reduce the amount of rock that is needed for surfacing.
Wood structures rely on either logs cut near the trail or pressure treated lumber or ties. Native logs blend nicely with trail environments and can be cut in whatever sizes are needed in trail construction. Pine, cedar and cypress logs will generally last longer than most of the hardwoods, but bark should be peeled off all logs to reduce rot and increase the useful life of the logs. Pressure-treated lumber, posts and beams have a much longer in-use life than untreated logs. However, they are obviously more expensive than using native materials and must be transported to the trail site. You may want to use them just for posts and beams that will be in contact with the soil, such as sign posts, bench supports and mud sills for bridges. If lumber has to be purchased, as for planks on bridges and boardwalks, rough sawn pressure-treated lumber should be more cost efficient because of its longer life than untreated lumber.
Trail Construction
These standards have been compiled from a number of trail manuals and are guidelines for enhancing a trail user's experience and for minimizing safety hazards. Width of clearing for the trail walking surface should be a minimum of 3 to 4 feet for most lightly used trails, with additional clearing of vegetation for 1 to 2 feet on each side of the walking surface. Fast growing brush species might also be cut back further to reduce the need for frequent maintenance. For trails that will receive heavy, or group use (eg interpretive trails), the cleared width for the walking surface should be a minimum of 6 to 8 feet. Equestrian and mountain bike trails should have a cleared width of at least 8 feet. If you will receive cost sharing for trail construction through the Stewardship Incentives Program (SIP), total right-of-way clearing should be 5 to 8 feet wide.
Where some type of surfacing material is added to the trail, the width of the surfaced tread should be at least: 18 to 24 inches for long distance trails with single-file traffic; 2 to 3 feet for bike trails; 2 to 5 feet for nature trails, depending on expected use; 6 feet for equestrian trails; and 4 feet of smooth tread surface for barrier-free trails that will be used by people with special needs.
Overhead clearance (hanging branches, vines, etc) should be at least 7 to 8 feet for hiking trails, 8 feet for bike trails and 10 to 11 feet over equestrian trails. Although most forest land in Florida has only gently sloping topography, if your land includes some steep grades, trail grade should be maintained at less than 10% except for very short pitches, as with spurs into large sinkholes or ravines. Steps may be necessary for such short steep grades to prevent soil erosion during heavy rains.
Other SIP specifications state that trails should follow the contour, minimize stream crossings and felling of large trees, and stay at least 35 feet from stream banks except at crossings. Areas cleared to expose scenic vistas may be no more than 100 feet in length, while areas cleared for access to riparian zones and waterways should be less than 8 feet wide.
Now it is time to implement all the preparation and planning. Trail layout involves marking the exact trail route, on the ground, so that construction can begin. The preliminary route selection should have left plastic flagging at distant intervals. Exact location of the complete trail is marked with additional brightly colored flagging. A compass and clinometer or Abney level may be used to relocate small portions of the trail or to locate the trail at the correct gradient if it traverses steep slopes. Your county forester can show you how to use the clinometer or Abney level.
Walk through the proposed route and hang flagging on live trees or branches or place brightly-colored stakes or flag pins frequently enough to make the route clearly visible. Even in open forest conditions the distance between stakes or flagging should probably be a maximum of 100 feet so that construction crews will always be able to see where they are headed. Once the complete trail is marked, rewalk the route from both directions to check visibility, aesthetics and all featured items, and move flagging if necessary. Have others walk the trail route to be sure it meets all your objectives. When you finish, remove all flagging or other markings except along the final selected route.
The following guidelines will be useful as you develop the exact route:
The initial preparation of the trail involves clearing trees and brush out of the trail right-of-way. Any of the cutting tools described previously can be used, but tools should be selected that will allow the task to be completed both efficiently and safely. First aid kits should always be immediately accessible to crews doing the clearing. Pine trees and other plants that will not sprout from stumps or roots can be cut flush with the ground line. Stumps and roots of plants that will sprout should be dug out of the ground if such excavation can be accomplished without substantially disrupting the trail surface. If vegetation outside the cleared part of the trail is so thick that visibility is restricted, you might selectively remove enough of it to facilitate hikers' views. Disperse cut materials away from, and out of sight of, the trail. Mechanized equipment can be used for the initial clearing, but the operator needs to avoid site disturbance and unsightly stumps and cut materials. SIP specifications allow cost sharing for clearing by hand labor, drum chopper or a rotary mower pulled behind a tractor.
Once the initial clearing is completed the trail can be used. However, additional preparation will enhance trail quality. Cut overhanging tree branches flush with tree trunks. Other overhanging vines and vegetation (especially poison ivy) should also be removed. Sections can be cut out of most fallen trees or logs, and loosely embedded rocks ought to be moved if they pose an obscured tripping hazard. However, the trail can also be detoured around, or over, large obstacles. Leaving a few such obstructions in the trail offers a challenge to hikers and serves as a deterrent to use of the trail by motorized vehicles. Small clearings or turnouts should be created near points of interest if the trail is to be used for group instruction. Whenever possible, try to avoid clearing more than the minimum necessary on both sides of the trail to keep trail users feeling "close" to the natural environment.
The last step in trail preparation involves installation of water drainage features, if necessary, and surfacing the tread on trails that will require more than the natural surface that is left after clearing. This can be the most time consuming and laborious stage in trail construction, but it may not be necessary for many nature trails in Florida's flat topography. Water drainage features will be discussed more completely in the next section since they are a critical method to prevent soil erosion from water that is channeled down a sloping trail. If non-native surface materials will be added to the tread, loose materials that might stick through the surfacing should first be raked from the tread surface. Mulch, chips, gravel or other surfaces can then be spread with a wheelbarrow and rake to meet the minimum tread specifications for your particular trail. Mowing may be all that is necessary where trails pass through grassy vegetation.
As previously mentioned, water drainage features are necessary to prevent erosion along trails on slopes and to avoid standing water on trails on flat ground. An important objective in designing any of these structures will be to minimize visual effects of construction efforts. The frequency, size and type of control structures depends on erosion potential of the soils under the trail. For example, sandy soils are less erodible than clay soils because of the large grain size and porosity of sands. Two other important factors include the velocity of water along the trail, which depends on the slope, and the length of time, or distance, running water is allowed on the trail. Most erosion control measures are designed to reduce the velocity and/or the distance of water running on the trail. SIP specifications for trail construction require that such measures be installed immediately after clearing.
Trails that follow an undulating contour rather than long steady grades will provide frequent points of water drainage and avoid increases in water velocity. Similarly, a trail that is descending a slope can be curved to follow the contour for a short distance before continuing down slope. At this "water curve" the trail tread is sloped outward so water will run off the trail into adjacent vegetation. On slopes less than 5 to 10%, the same effect is possible by sloping the trail tread to the outer (downhill) side, and/or by crowning the middle or inside of the trail so that the center of the trail is higher than the edges. The latter two measures will be more important on soils with clay than the very sandy soils of much of central Florida.
(Illustration of Water Curves)
Drainage dips can also be constructed on gentle slopes to reduce water flow along a trail. Dips are small trenches dug across a trail, usually at an angle toward the downhill side. Soil from the trench is mounded on the downhill side of the trench to be sure water running down the trail is directed into the trench and off the trail. The mound can be stabilized by burying logs or rocks under the mound. Rocks on the outflow end of the trench will prevent additional erosion as the water flows from the trench. Other small drainage ditches may be used to drain water from wet areas through which trails pass before a problem develops.
A waterbar is a larger version of the drainage dip, and is used on trails and roads that exceed 10% grade. As with drainage dips, the basic objective is to divert water off the trail without increasing erosion downslope from the trail. The number of waterbars on a particular slope will depend on the grade and soil type. Place the first waterbar close to the source of water that is entering the trail, and subsequent waterbars at distances that will prevent the development of any gullies in the trail. Rock, peeled logs or ties are angled 30 to 60 degrees across the trail, and are partially buried or anchored with soil, steel pins, reinforcing bar, wooden stakes or large rocks. Crowbars and shovels may be necessary for this construction. Logs should be at least 6 to 8 in. diameter at the small end, and stakes should be driven in at both ends of the log(s), as an inverted V, to hold the log in place.
The waterbar must extend 1 to 3 feet beyond the outside edge of the treadway to be sure water doesn't return to the trail. A ditch may be needed for this extension to ensure drainage off the trail. The trail on the upgrade side of the waterbar must be well below the top of the barrier to be sure water running down the trail does not run over it rather than being diverted off the trail. The downgrade trail tread can be built up with packed soil and rock to be flush with the top of the barrier. Install a rock spillway where water runs off the trail to disperse the erosive energy into surrounding vegetation.
Wherever trails cross small drainages, culverts located under the trail will channel water and prevent trail washouts. Corrugated metal, concrete pipe or wood boxes can be used as culverts, and they must be of sufficient size to handle the maximum anticipated flow. Culverts should be installed so that the bottom is at ground level, with a rock spillway on the downslope end to disperse the water as it exits the culvert.
On short steep grades, steps can be installed to control erosion, similar to waterbars, and to assist hikers climbing up and down the slopes. Steps are built with flat-sided rocks (at least 50 to 100 lbs each), treated wood or native logs. Logs need to be well anchored and buried at least one third of their diameter for stability. The top surfaces of each step must be rough, and should slope into the uphill side slightly to reduce slipping. Steps should extend beyond the edge of the trail to prevent erosion along the trail edge. The surface between steps should have a slight downhill slope to avoid water settling between the steps, and it should also slope to one side to reduce the effect of water cascading down the steps. Widely spaced steps may be installed above waterbars to prevent clogging the waterbars with sediments. Such steps should also be sloped to the outside of the trail to divert water off the trail. Steps ought to rise a maximum of 16 inches, but preferably less than 12 inches.
Without regular maintenance, trails will become overgrown and disappear in a few years in many of Florida's vegetation communities. Maintenance efforts will be minimized if done annually, probably during winter months when temperatures are cool and visibility is good. However, sprouting shrubs will be more easily controlled if cut in late spring or early summer, after they have leafed out and when starch reserves in the roots are at their lowest level. Maintenance activities include: clearing new vegetative growth; removing loose rocks, roots, or dead trees; replacing surfacing material if necessary; litter cleanup; and sign repair. It is especially important to remove dead trees or branches that could fall on trail users.
Trail width and clearance should be returned to original standards by pruning, cutting through or removing blowdowns, and removing new growth from the trail tread. As with initial clearing, select the right tool for the type of vegetation and clearing work, do not leave pointed stubs and stumps, and scatter (don't pile) cut material off the trail, out of obvious sight. Waterbars, ditches and other erosion control structures need to be cleaned out at least annually. Material excavated from above the waterbar can be placed on the mound below the bar to reinforce it.
Consider relocating trail segments that have become gullies or wide and muddy if the relocation will not create the same conditions elsewhere. Otherwise, use log mats (short logs laid side by side), the rock treadway in the next figure, or one of the methods described in the section on Bridges, Boardwalks and Other Wetland Crossings, to stabilize the trail. Whatever method is used, short drainage ditches into surrounding vegetation or one of the erosion control measures described previously should also be constructed to reduce the source of water that caused the problem.
Rock treadway across a poorly drained spot
(Courtesy of the Appalachian Mountain Club)
Gather wood, soil or rock materials used for maintenance from sites away from the trail and cover or fill those sites with brush and debris when finished.
Bridges, Boardwalks and Other Wetland Crossings
Sooner or later, many trails must cross rivers, streams, marshes or other wetland areas. For trails designed to provide hikers with primitive conditions or challenges, natural trail crossings can be left unbridged or undeveloped. However, most trails will be used by people seeking safer, or at least drier, recreational pursuits. Crossing structures increase the likelihood the trail will be used, and they protect stream banks and wetland environments. Trails through wet meadows and marshes are prone to a common pattern of breakdown in the local soil and vegetation. As trail use in these areas increases, trails become soggy and muddy and hikers tend to walk on the edge of the trail on drier ground. Gradually the trail widens as increasingly larger muddy holes develop.
All stream crossings have several common requirements. Trail crossings should be located at the narrowest, and most stable, spots along a river or stream. Straight sections of the waterway, away from curves where stream banks tend to erode, are the most stable areas. The stream channel needs to be well defined at the point of crossing, and a flat stream gradient is desirable to avoid high velocity water flow against the bridge. Slopes leading to the crossing on both sides of the stream need to be stable and well vegetated. Careful location of crossings is critical because of high construction and maintenance costs.
Boardwalks provide interesting access routes into swamps and similar large wetlands, and are often designed for aesthetic and recreational purposes. Elsewhere, crossing structures may be used to avoid poorly drained spots in trails. In the latter situation, you should consider relocating the trail around the wet spot if it cannot be drained into adjacent vegetation.
All crossings represent limitations to certain trail users, such as horses, bikes and motorized vehicles. Constraints include weight limits and slippery or poor (for tire or hoof) surfaces. Potential users must be considered in designing all crossing structures, and weight limits should be well in excess of maximum expected loading.
Crossing structures must be well anchored to stream banks, dry spots, or in the underlying soil in the case of boardwalks. Footings or mud sills are usually perpendicular to the crossing logs or planks, and anchored into stream banks with large rocks, long spikes or bars, or even concrete if the site is easily accessible. Wherever logs and planks are connected, spikes should be driven at least 3 in. into the second board or log, and countersunk if the spike would be a tripping hazard.
Railings should be used on all crossings that are more than 2 feet off the ground or above water, and are advisable on many lower structures. (See picture of crossing with railing) They are usually 36 in. high and firmly attached to the crossing structure. The trail tread on any crossing should be at least 12 in. wide, although some narrower treads are acceptable for single log bridges in marshes (where a slip will only muddy your feet).
Although a variety of structures might be used for crossing distances of up to 15 feet, the three most common are log crossings, short bridges and various rock structures.
Log crossings are basically one or more log stringers laid side by side, with a flattened top surface for the treadway. Stringers are usually at least 8 to 10 ft long. In "topped log" bridges, one side of logs 6 inches in diameter or larger is removed to provide a flat surface. Up to 1/3 of the diameter of the log is removed in this process. In "split log" crossings, larger logs are split in half to produce a flat surface. For both types, the ends of the stringers are supported by mud sills that are short logs (3 to 4 ft long, 8 to 10 in. diameter) or squared timbers. The sills are notched to hold the rounded lower surface of the logs, and the logs are attached to the sills with pins or spikes with at least 4-in. penetration into the sill.
Simple log crossings
(Courtesy of the Appalachian Mountain Club)
Small log cribs (logs stacked in a square pattern) can replace one or both mud sills if additional height is needed at one or both ends of the bridge. For better traction, tread surfaces can be roughened with pieces of wood nailed to the log surfaces, with tacked down chicken wire, or with tar and sand.
Short bridges, or catwalks (See Illustration), may be as simple as two logs laid across the water, 2 to 4 feet apart. They are anchored directly to the crossing banks at both ends, or may be attached to mud sills. Planks or small logs are then attached perpendicularly to the logs to form the walking surface. Large planks or beams can be used in place of the logs, and handrails may be added for safety or convenience.
Rock structures are frequently used for shallow stream and gully crossings. At stream crossings, a barrier of large rock is usually placed on the downstream side of the crossing, level with the trail tread. This barrier slows water flow over the crossing immediately upstream from it. Small rock, gravel, or flat stepping stones spaced no more than 2 feet apart, serve as the crossing tread. The rock barrier should be extended at least 12 inches into the banks on both sides to prevent water flowing around the ends and undercutting the crossing. A peeled log, extending 4 feet into each bank, could also be used to anchor the gravel tread. Large native rock placed on the downstream side of the log will help hold it in place. For shallow crossings, rock barriers may not be needed and stepping stones or a bed of gravel or rock may suffice for all except those who want a 100% guarantee of dry feet.
(Illustration of a Rock base shallow stream crossing)
Spans up to 40 feet can be crossed with log stringer bridges. Although single logs have been used, bridges more commonly use two or three logs supported at both ends by single base (mud sill) logs or cribs. Longer distances can be bridged with the use of midspan cribs. Minimum diameters of the stringers depends on the length of the span and tree species used for the logs. Tables in the Forest Service Trails Management Handbook and the Trail Manual of the Florida Trail define acceptable log diameters.
(Illustration of a simple log stringer bridge)
Once the logs are in place, which may require significant manual labor, winches or small pieces of equipment, the top surfaces are patterned or shaved to provide a bearing surface at least 2 in. wide. Decking from small split logs or rough sawn 2-inch planks are spaced to allow drainage and spiked to the logs with a minimum 3-inch penetration. If cribs are used for supporting the ends they should be constructed with logs that are at least 8 to 10 in. diameter, and the cribs should be filled with rock or soil as they are built. They must also be anchored on the outside with large rocks. Stringers are anchored to cribs or sills with large spikes or galvanized bolts. Handrails are advisable on all long bridges. One end of the stringers can be cabled to nearby trees to save the bridge in case of a flood. If both ends are cabled the pressure of both flood water and debris in it may destroy the bridge more quickly than if one end broke loose and the bridge swung against the bank.
For shorter spans (up to 24 feet), log stringers can be replaced by pressure treated 2 x 10 in. lumber, bolted together. Pressure treated 2 x 8 in. planking may be used for the walking surface. Diagonal braces (2 x 10's) on the underside of the frame will provide additional support and reduce lateral movement. Other bridge designs are described in various trail manuals. If you are considering construction of any large bridge it would be wise to contact local engineers, contractors, utility companies or even National Guard units for possible assistance with design or materials.
The two most common uses of boardwalks in Florida are for nature trails through swamps and marshes, and for beach ramps across sandy areas to waterfront activities. They may be constructed as permanent fixtures or in easily transportable sections to facilitaterelocation when necessary. Permanent boardwalks require pressure-treated posts, poles or piers be sunk into underlying soils or rock for stability.
(Courtesy of Dr. Dirk DeWaard)
Cross braces or beams connect pairs of posts (see end view in next figure). Planks laid perpendicular, and connected, to the cross braces may serve as the walkway (top view). Using this pattern with boards of 1- or 2-inch thickness, Dr. Dirk DeWaard, a Stewardship landowner in north Florida, constructed a 560-foot boardwalk at a cost of about $2 per linear foot. Working alone, he built the boardwalk in 12 ft. sections, completing two sections a day.
Basic boardwalk construction plan
(Courtesy of Dr. Dirk DeWaard)
Alternatively, only two planks might be used to connect adjacent pairs of posts and cross braces. Short planking laid perpendicular to the long planks would provide the walkway, and side rails could be added for safety. Size of posts, timbers and planks used in boardwalk construction will depend on the intended use of, and numbers of hikers on, the boardwalk.
Portable sections are constructed in a similar pattern except that the supporting vertical posts rest on the soil or sand surface and are only as long as necessary to raise the boardwalk the desired distance above the sand or water. Individual sections can be connected end to end with planks and large bolts, and should be small enough that two to four people can move them when necessary.
Boardwalks are especially useful where trails traverse large areas with year-round standing water. Elsewhere, trails may cross small areas that are only intermittently wet or have saturated soils without deep standing water. If a small wet area cannot, or should not, be drained, and trail relocation would be impractical, various types of rock trails will help stabilize the trail surface. Flat rocks set into mud no more than 2 feet apart provide dry and stable stepping stones. If a trail is to receive fairly heavy traffic, a more intensive use of rocks may be necessary. Rock treadways (illustrated in "Trail Construction"/ Maintenance section) are created with large flat rocks laid side by side.
If flat rock is not available, rock boxes can be constructed as log frames filled with rock. Boxes only need to be high enough to allow the trail to pass over a wet spot. If possible, spread soil as a fill material before rock placement. Finally, if no rock is available, drainage ditches can be dug along the side of the trail through the wet spot. Soil dug from the ditches is spread in the center of the trail to raise the tread out of the wet zone and create a "turnpike" in trail lingo.
Another simple crossing for saturated, but not regularly flooded, wetlands is a "bog bridge", consisting of logs extended end to end across the wet area. Logs should be topped or split to provide a flat walking surface and can lay flat on the ground or be mounted on notched mud sills. The crossings may be one or two logs wide. They do not require handrails since the tread is barely above the ground surface. Life expectancy may be 7 to 10 years with softwoods such as pine or cypress, and shorter with most hardwoods.
As with other parts of the trail system, all bridges and crossings should be checked at least annually; more frequent evaluation of bridges is recommended. Many of these structures represent the greatest safety hazard on a trail, and careful inspection and maintenance are essential. All connections should be checked for tightness. Lumber, planks and logs should be monitored for cracking or rot and must be replaced if there is any likelihood of the structural component failing in the near future. Periodic treatment of wood components with paint or preservatives every three to five years should substantially prolong the life of the structure. Steel beams, cables, or other hardware should be treated with rust-resistant paint.
Other Trail Structures
A variety of simple structures can add significantly to the enjoyment and use of your trail. Benches located at key resting points such as vista openings or nature study areas offer both rest and a chance to ponder the surroundings from a different perspective. On barrier free trails, benches should be located at approximately 150-foot intervals. Benches can have four posts for support, or be as simple as two posts with a log rail connected to the top of each post. Posts should be well buried for support and security.
Railings have been mentioned for bridges and other crossings, but they should also be considered where trails are adjacent to possible hazards such as the edge of streams, steep sinkholes or pits, or cliff overlooks (which are rare, but not absent, in Florida). Railings can also provide a partial barrier for protecting endangered plants or portions of the trail that you might be rehabilitating. Most rails should be 30 to 36 inches high and secured to deeply buried, pressure-treated posts.
Stiles come in many acceptable designs, all with the purpose of allowing hikers to cross over, or walk through, a fence without breaking it or defeating its purpose. A ladder stile (See Illustration) consists of two vertical posts along the fence line (usually a wire fence), with steps nailed to the posts on both sides of the fence. A step stile resembles two ladders leaning against each other at the top of the fence. Rail stiles are triangular ladders leaning against fence posts with the widest step at the bottom. Different length posts or poles can also be partially buried along a fence to provide a series of "stepping stones" on both sides of a fence.
Narrow openings in a fence, with two short fence sections forming a sharply-angled V at the opening, will allow hikers to walk through the sharp V at the opening while preventing animals from doing the same. (See Illustration)
Trails can be marked with both signs and blazes to assist hikers following the trail or using it for nature study. Signs should generally be placed on pressure-treated posts and backs, and not nailed to trees. Signs can be created by routing and painting lumber such as redwood, or by printing information on material that is waterproofed with plastic, lacquer or other laminates. Large signs, such as at a trail entrance, are often mounted vertically between two posts. Other locations for signs include warnings near features that might be safety hazards, such as sinkholes and road crossings, and trail junctions (to identify trail destinations and distances).
On more primitive (less developed) trails, tree blazes are often used to clearly identify trail location. Blazes should be the same size and color throughout the trail, although colors may be varied for different trails within a larger trail system. Rectangles, approximately 2 x 6 inches are scraped on the bark of live, trail-side trees and painted with oil-based or other boundary marking paints. Place blazes on both sides of the tree at eye level. The distance between blazes depends on the nature of the trail. A good rule of thumb is that hikers should never walk more than 100 paces without being able to see a blaze in front of, or behind, them. Another is that as a hiker passes one blaze the next blaze should be in view.
Costs
Cost estimates for construction and maintenance of trails and associated structures are influenced by the level of improvement, site characteristics, and source of labor to carry out the work. For simple nature trails, the major cost may be just the landowner's time for clearing. On the other hand, bridge and boardwalk construction may require many hours of hired labor plus materials.
Under the Stewardship Incentive Program, the SIP 9 practice (Forest Recreation Enhancement) currently provides cost sharing for 50% of actual trail, boardwalk or foot bridge construction costs, with a maximum of $0.50 per linear foot for trail construction and $5.00 per linear foot for boardwalks. Distances are measured with a fiberglass or metal tape, measuring wheel or hip chain. Pacing is not an acceptable measuring technique. Cost sharing is authorized for: 1) clearing vegetation for trails, boardwalks, scenic vistas, access to perennial bodies of water and semi-open areas for recreation; and 2) constructing boardwalks in wetland areas or small foot bridges across streams. It is not authorized for routine maintenance of trails, nor for construction or maintenance of other recreational facilities or structures. To be eligible for cost sharing, trails must be constructed according to a forest stewardship management plan for the property, and must be maintained for a minimum of 10 years following installation. Other requirements for receiving cost shares were described in the sections on standards and procedures for trail clearing and construction.
Legal Considerations
Planning for recreational opportunities on private land usually includes questions about landowner liability for trail-user accidents. The following comments were extracted from the Appalachian Mountain Club Field Guide to Trail Building and Maintenance. They provide important information on certain legal considerations, but are not a substitute for counsel with an attorney concerning each individual situation.
Many questions about liability center on the concept of negligence, which is partially defined as the failure to prevent hazardous conditions or to warn visitors of hazardous conditions. Recreational users of private land generally fall into three legal categories, with landowners having different obligations for each category. "Trespassers" enter someone's property without invitation, and often in disregard for posted signs. The landowner has no legal duty toward these users, with the possible exception of young children. "Licensees" have been granted permission to use another person's property, but with no benefit of use going to the owner. Many hikers fit into this category when no entrance fees or other benefits are collected. For this category of user, the landowner should warn about unseen hazards, but has no obligation to warn of obvious hazards. A landowner receives a benefit (such as an entrance fee) from "invitees", although this category has also been interpreted to include situations in which land is just open for public use. Landowner responsibilities are much greater for invitees than for the other two user categories. Users must be protected against both known hazards and those that might be discovered during inspection of the land. Many states, including Florida, limit the liability of owners who open trails for public use without collecting fees in an attempt to maintain hikers in the "licensee" category, and to keep landowner liability insurance rates reasonable (ie, Florida Annotated Statute 375.251).
In Closing
Trails represent the landowner's main routes for recreational activities such as walking, sightseeing, horseback riding and bicycling. They provide access to, and through, forest land and other natural resources. They play an important role in protecting and preserving soil, water, plant and animal resources. They can be the source of endless hours of enjoyment and relaxation. Plan your trails wisely, construct them carefully, and then ENJOY them to the fullest.
References
Florida Trail Association, Inc. 1991. Trail Manual of the Florida Trail. 69 p. FTA, P.O. Box 13708, Gainesville, FL 32604.
Hooper, Lennon. 1983. National Park Service Trails Management Handbook. U.S. Dept. Interior. 53 p.
Larsen, D.M. and W. R. Miles. Nature Trails. Agricultural Extension Service, Univ. of Minn. Extension Bulletin #368. 15 p.
Proudman, R.D. and R. Rajala. 1981. AMC Field Guide to Trail Building and Maintenance, 2nd Ed. Appalachian Mountain Club. Boston. 286 p.
Tennessee Division of Parks and Recreation. 1992. Recreation Trails Manual. Tennessee Dept. of Environment and Conservation. 22 p.
U.S.D.A. Forest Service. 1991. Trails Management Handbook. Forest Service Handbook FSH 2309.18.
[TOP] [Extension Publications]
