trails manual section7

8/14/2019 Trails Manual Section7

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Hard Surface Multiple Use Trails

LocatorsLocators may optionally be placed at major trailheads or facilities within the Trails System. The contents of locators can include the current status of the County Trails (map and other info), usage regulations, specialnotices pertinent to the area, allowed trail uses, seasonal and other closure information, and other usageinformation.

A local area map and features accessed by the trail is highly desirable.

If placed at a trailhead, the locator is to be placed in the user area (see Trailheads, p. 2-44). In remote areasor areas likely to be vandalized, locating the information board 100 or more feet from the road or parkingarea may reduce vandalism.

Finish all exterior wood surfaces with polyurethane. Recoat as needed.

Example of simple wood locator

2-82 Trails Design and Management Planning Handbook


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Side view of wooden Trail Locator.



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Adjacent Soft Surface Trails

This only describes the relationship between the hard surface trail and an adjacent soft surface trail.For adjacent soft surface trail design and construction specifications, see Section 3 for crusher finestrails.

Purpose of an adjacent soft surface trail

An adjacent soft surface trail can greatly enhance the recreational opportunities of a trail corridor.Rather than just serve as a softer surface for runners, joggers, and walkers, the adjacent trail should bedesigned to provide a richer and more intimate recreational experience that expands the benefits of the trailcorridor.

The soft surface trail serves two distinct recreational functions:

1. provide for more and for different types of users, and2. provide access to small or difficult-to-reach landscape features that are best enjoyed at pedestrianspeeds in a setting closer to nature.

To help maximize its recreational role, the experience of following the soft surface trail should be verydifferent from the hard surface: different views, tighter turns, shorter sightlines, lower and tighter clearance,


look along soft surface trail motes lingering, trail is

ned at overlook


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possibly more grade changes, with a focus on intimate site features. To help achieve this, the soft surfacetrail should not continually touch the edge of the hard surface - instead, it should access some of the moreinteresting parts of the site bypassed by the hard surface trail. A physically separated soft surface trail canoptionally have its own smaller-scale bridges and customized drainage crossings, greatly enhancing thefeeling of a separate recreation-only trail.

Provide an adjacent soft surface trail whenever feasible In general, the more urban the area, the more important a soft surface adjacent trail becomes - the two trailsbecome a corridor which can comfortably accommodate more numbers and more types of users.

The adjacent trail can be omitted when: physical restraints make it impossible (insufficient space, bridge or underpass, gradecrossing) construction costs or environmental impacts become prohibitive (ex: steep crossslope with narrow easement) land costs become excessive

The soft surface trail can be discontinuous as necessary. For instance, the soft surface may end before amajor bridge, a grade crossing, or a steep cross slope, and then resume on the other side of the constriction.

The width of the soft surface trail is typically 4-8 but may range depending on uses and amount of use.

Plan both the hard surface and soft surface trails together



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In general, the wider and more highly engineered hard surface path is located where it can meet itsrequirements with minimal site disturbance, and the narrower adjacent soft surface trail has much morefreedom to explore the more difficult to reach parts and smaller scale features of the site. The range of quality recreational experiences is richest when the two trails are designed to contrast each other in manyways. While striving for contrast, design the hard surface and soft surface trails to each follow its ownoptimum route, running together when that makes sense, and running apart when the soft surface can getthe user closer to a recreational opportunity or a more undisturbed setting.

Intersections between the two trails, and with other trails, should be carefully considered for safety and toavoid confusion. Try to avoid having two through paths cross each other at one point. Where the two trailsare separated, soft-surface connecting spurs or intersections between the trails should occur at logical andconvenient locations every 600-1500.

Soft surface trail users Adjacent soft surface trails should be not be used for a purpose of transportation in order to preserve the softsurface for pedestrians, joggers, runners, and possibly equestrians. Small regulatory signs (see SpecialUsage Regulation Signs under Signs, p. 2-71) should post the closure where needed.

Where feasible, design and construct all or part of the soft surface trail to be barrier-free to wheelchair usersand those with other mobility impairments. Even though the hard surface trail is usually accessible, the soft

surface trail offers a very different recreational experience and should be accessible where feasible.

Soft surface spur trails

During the planning and acquisition process, look for and plan for, potential soft surface spur trails for river access, viewpoints, ties with other trails, neighborhood access, etc. Spurs such as these greatly enhance the



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interest of a trail and help provide a rich recreational experience.

Spurs can be long or short, looped or dead-end, and can even form a separate trail system that connects toother trails or neighborhood access points (see below for bicycle usage).

Separate adjacent soft surface trails from soft surface bike paths Where a soft surface path open to bicyclists intersects the hard surface path, try to avoid creating a directconnection between the soft surface bike path and the adjacent trail that is closed to bikes. Discontinue theadjacent soft surface path approximately 80-150 on either side of the intersection. It may be necessary tosign for bicycle closure on the ends of the adjacent soft surface trail.

Soft surface spurs which connect to points outside the trail system should be open to bicycle users unlessphysical constraints do not allow feasible construction of a Type 1 or Type 2 crusher fines trail. Theintersection of these spurs with the adjacent soft surface path should be handled as described above(preferable). If breaking the adjacent trail is not desirable, a last resort is to sign the adjacent trail as closed tobicycles. In which case, readily apparent physical aspects of the adjacent trail should explain the rationalefor bicycle closure, such as a flight of steps or obvious pedestrian-only facilities visible from the bike trail, aswell as other visual clues of pedestrian-only usage.

Protect wildlife habitat, site values, and the recreational experience

Any trail can disturb wildlife habitat or other site values, and the County Trails system, in planning a trailcorridor in the first place, will have already determined that at least one trail in this corridor is acceptable.



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In planning the adjacent soft surface trail, however, situations may arise where attempting to leave spacebetween the soft surface and the hard surface trails would cause an unacceptable amount of disturbance towildlife habitat or other site values. In these situations, both hard and soft surface trails should run together,or the soft surface trail can be discontinued in order to narrow the trail corridor.

Lastly, in places where having an adjacent soft surface trail seems to crowd the site or in other ways tends todiminish the recreational quality of the trail corridor, it can be omitted or discontinued.

Soft surface trail design and construction specificationsAdjacent soft surface trails will usually be surfaced with crusher fines and designed as a Type 2 (primarilypedestrian with bicycle and/or wheelchair access) or Type 3 (pedestrian only) crusher fines trail. See belowfor widths and the relationship between the hard and soft surface trails when the two physically touch. SeeSection 3 for crusher fines specifications.

Some soils, cross slopes, and usage patterns will permit natural surface adjacent trails. In particular, lightlyused trails on well-drained mineral soil (no silt, clay, or loam) on cross slopes 15% may be well suited for anatural surface trail. This Handbook does not give specifications for natural surface trails, but such trails canbe designed, constructed, and maintained on a case-by-case basis by special arrangement with the County.

Boardwalk

A boardwalk can be used to cross damp or occasionally flooded areas with minimal disturbance. A commonuse is to provide a stable and intrinsically interesting means of access to shorelines and wetland features of



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general interest to all users. Because the cost of boardwalk can be very high, however, costs can be keptdown by limiting usage to a few key areas in each site. Two types of boardwalk, differing mostly in their anchoring methods, can be used.

Boardwalk Type 1: Decking supported by piers

The structure is supported on piers that can be used in wet (even submerged) areas. This type typically israised above the ground or water level on zinc-plated screw anchor piers, making this type more resistant to

frost heaving and thereby more suitable for wheelchair users. Most parts of the deck have a simple wheelguard, and some observation areas may optionally have railings. The screw anchor of the piers may be asfar as 6 below ground level, but depending on the site, even at this depth it may still heave or settle.

Boardwalk supported by poured concrete piers.



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Boardwalk supported by railway ties are not the best material for silt pads as they are subject to deteriorationover time.

Boardwalk supported by railway tie a concrete silt pad (lower right) is the proper way to begin boardwalkconstruction.



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Typically, this boardwalk type is used as part of a wetland exploration/education facility and is optimized for recreation rather than transportation. Adding widened observation decks and designing the boardwalk with acurving shape enhance its appeal to users (see below). Standard deck widths are 6 or 8. A 6 widthprovides more intimacy with the site and creates fewer disturbances, while an 8 width is more suitable for heavily used boardwalks. Decks can be wider than 8 in heavily used zones. At overlooks, intersections, andheavily used zones, widen the deck to provide additional passing room.


Boardwalks as a Recreational AmenityAs a major recreational feature along a trail, boardwalks should be designed to enhance the visitors experience of the

environment. Through alignment and optional observation decks, the boardwalk should act to focus the visitors attention onsalient site features. The overall shape of the boardwalk itself can also add to the experience - using straight lumber in small

sections with irregular angles, boardwalks can form fluid curves and angles that complement yet contrast with the typically softand rounded shapes found in wetlands. This simultaneous complement and contrast forms one of the fascinating features of

boardwalks and adds greatly to their recreational and aesthetic value.


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Boardwalk Type 2: Decking supported by ground-level sleepers This is a limited-use, simple, flexible, light-duty wood decking which rests on timber sleepers in dry to damp(but not soggy) areas. It creates the option for a low-key alternative to a full Type I boardwalk for lightly usedtrails or sensitive sites.

Type 2 can only be used where the soil has sufficient load bearing capacity (in all seasons) to keep thetimber sleepers from sinking. Typically, this could be used in limited cases as an alternative to crusher fineswhere the ground is wet in spring but only damp (or even dry) in other seasons.

The width of Type 2 boardwalks is usually 4-6. Narrow widths are to be used only when wider widths wouldbe out of scale in the site or for the trail. The maximum width is 8.

The dimension and length of stringers can vary. Lower-height stringers can be combined with mostly-buriedsleepers to suspend the deck surface just above the ground, creating a low-key effect that is much lessintrusive than a Type I boardwalk.

Because only a low wheel guard is used as a railing (and only where the boardwalk is accessible towheelchairs) and because expensive piers are avoided, this is a simple and relatively low cost boardwalk.The deck, however, can be expected to heave and move with frost movement, possibly becoming sloped inall directions - for this reason, this boardwalk type should only be used for light-duty situations for pedestrians

only, not on mainline high-traffic paths. Depending on the site-specific amount of heaving, this type of boardwalk may be inaccessible to wheelchair users. Also, because the very low clearance beneath the deckcan be an impediment to low flood waters and because the structure is anchored mostly by gravity, this typeof boardwalk may not be suitable for areas with moving water or with fluctuating water levels.

Boardwalk design strength and users

Boardwalks are essentially bridges and must be designed to bear the live loads of users and snow loads of the site (see Bridges, p. 2-56). The specifications given here for boardwalks are designed to carrypedestrian-weight users and snow loads, but not vehicles or equestrians.



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Users of boardwalk should typically be limited to pedestrians and wheelchair users only. Where boardwalksare used in wetlands and have an educational and interpretational value, bicycles should be excluded toprevent user conflicts. In addition, boardwalk decks can become slippery when wet, making them dangerousto bicycles.

Design Features for Boardwalks

A lighter feel

The nature of wetland areas is characterized by soft lush vegetation, slender plant and shrub stems, tufts of rounded earth and grass, rich moist smells, and perhaps standing or moving water. This specification intendsto create boardwalks that accentuate the contrast between the softness of wetlands and the grounded feelingof solid land.

Because boardwalks float above land and water, this specification gives boardwalks a lighter feel than thesolid, heavy, and grounded feel given to trails on the ground. This lighter feel is achieved through the use of curving irregular shapes, angles other than 90 degrees, smaller-size dimension lumber, lighter-weightrailings, and deck designs that conceal the foundations (hence enhancing the floating appearance of theboardwalk).

Curve and vary the deck, creating complex shapes

Typically, boardwalks are used as part of a wetland exploration/ education facility and are optimized for recreation rather than transportation. A boardwalk is intrinsically interesting to users and has a universalappeal, and the linear wooden structure has a great potential for recreation. Designing the boardwalk with acurving shape, adding spurs, adding widened observation decks, and varying the width of the deck atintersections enhances its appeal to users. Avoid creating long straight sections with right angle turns, or medium length straight sections connected by abrupt angles. Instead, each segment should be part of thecurve, and the entire structure curves through the area on a logical yet aesthetically pleasing course.

When feasible and appropriate, give viewing decks and spurs complex shapes of angles and curves.Octagonal decks, irregular angles, and angles other than right angles make boardwalks much moreinteresting. The deck can also surround trees and other natural objects that may already exist onsite.



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Grade changes add interest

Boardwalks can change grades, adding a new dimension of movement that is very appealing in a boardwalk.A 5% grade on the deck is a practical maximum for the main deck, and grades must not exceed 8% at anypoint. Consider adding non-skid material to sections with a grade of 5% or more. Boardwalks can also existon different levels connected by ramps.

Being able to access an island of dry ground in a wetland is appealing to everyone. For longer boardwalks,consider adding access ramps from the boardwalk down to dry ground, possibly to a hardened earth or crusher fines surface. If the boardwalk is accessible to wheelchairs, the ramp and the surface on the groundshould also be accessible.

Provide access to a number of wetland features

Wetlands have many types and aspects, and the boardwalk can make the most of these by providing accessto as many of them as feasible or desirable.

Providing boardwalk access to open water is always appealing, especially if the deck is widened and has arailing to lean over. For a river or stream, consider modifying the stream channel to improve fishing wheredesirable and feasible.

Boardwalks and bridges

Bridges greatly add to the appeal of boardwalks, and boardwalks can incorporate bridges of any acceptabledesign to cross open channels of moving water (for acceptable designs, see Bridges, p. 2-56).



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Other boardwalk features

Benches, railings, and interpretive signs can optionally be built into the boardwalk. Benches arepsychologically more comfortable to use when a large solid object (such as dense shrubs) is at your back.Benches placed where people can walk behind you are not as psychologically comfortable to use.



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Railings (as opposed to wheel-guards) are a visual clue that something here is meant to be studied, and sorailings should be provided at overlook decks and other places where user comfort is increased by having arailing to lean on or over.

Safety railings



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Proper boardwalk railings in the form of wooden deck pickets meet building code requirements, are virtuallyvandal proof and add strength to the boardwalk structure.

Railings must be provided where it is possible to fall off into deep or fast-moving water, or where the decksurface is 30 above the ground or water surface below.

If the deck surface is


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Screw anchor piers

Galvanized helical screw piers (screw anchors) can be installed with minimal environmental disturbance andwithout affecting the chemistry of wetlands (both concrete and creosote create contamination). While thescrew anchors themselves are expensive, this is the least expensive method because no holes need to bedug and installation is simple. The screw also holds the pier at the specified depth, unlike wooden or concrete piers, which can be heaved by frost action at the sides of the pier. Screw anchors will move and soilin wetlands can move even at 6 below the surface.

Helical screw anchor Screw anchors are to be installed according to manufacturers specifications. The anchors are torqued intothe ground using a special adapter mounted on a Bobcat or other small piece of heavy equipment. To avoidexcess wetland disturbance, this equipment should stay beneath where the boardwalk will be built so that thedeck covers the disturbed area. In wet soils, equipment with caterpillar tracks does not get stuck as easily asBobcats. Screw anchors can also be installed in early spring while the ground is still frozen.



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Screw anchors in place ready for stringers and braces.

In rocky soils, it will often not be possible to set the screws to the desired minimum depth of 6. The screwcan get past some small rocks but is stopped by larger ones - from the surface; however, there is no way toknow what stopped the screw. The first option is to remove the anchor and place it as close as practical to itsoriginal position. The second, if at least a 3 depth was reached, is to use the anchor as is. The final height of the pier is achieved by torquing the screw anchor up or down.



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Screw anchors holding deck frame ready for top deck material and railing.

Anchors are sold as lead sections (with the screw), extensions to get the lead section deeper into the ground,and terminators to attach the boardwalk deck to the top of the pier. Drilling contractors can install the piers,as can anyone with the adapter (available from the screw anchor manufacturer) and the appropriate heavyequipment.

Other types of piersIn extremely rocky soils where screw anchors cannot be used, concrete piles are recommended.

Boardwalk MaintenanceThe single biggest problem is likely to be frost heaving or settling of anchor posts in damp soils. If theproblem occurs once with a given post and the post does not readjust, there are two options: 1) allow theproblem to remain or 2) reset the post. Small amounts of heaving are not serious and can remain if wheelchair access is not imperiled. If the post is a screw anchor, it may be possible to remove the screwanchor terminator bolts so that the anchor can turn, torque the anchor by hand using a long lever, and reboltthe terminator.



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Photo showing Out-Rigger Maintenance system used to repair old boardwalks. System involves using anoutrigger anchor and braces placed on roughly 45 degrees to existing boardwalk. This system can beadjusted as boardwalk settles and heaves. Using this method for maintaining unstable sections of boardwalkcould increase the life span of the structure over 5 yrs as long as the other deck components havemaintained their structural integrity.

Sleepers on Type 2 boardwalks can also heave or settle. In serious cases, it may be necessary to raise or lower the sleepers (possibly partially dismantling the structure in the process). If unacceptable heaving or settling continues, it may be necessary to replace the boardwalk with a Type 1 structure.

Deck, rail, and wheelguard lumber may exhibit excessive warping or splitting after the first year. Excessivelywarped or deformed lumber should be replaced in the second year (or during the first if the problemmanifests then).

Bolts and screws may become loose if the wood shrinks as it dries. In the second and third years, all boltsand screws should be checked for tightness.

Railings, wheelguards, and other vertical elements in the boardwalk are subject to a great deal of wear andtear. These shall be checked every year and repaired or replaced as needed. In particular, wheelguardshave a tendency to split around boltholes near the ends - these should be repaired or replaced as needed.

Any vandalism should be repaired immediately.

Sleepers on Type 2 boardwalks may need to be replaced every decade or so depending on the effectivenessof the wood preservative treatment and site conditions.



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