Trails Manual Section2

8/14/2019 Trails Manual Section2

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Hard Surface Multiple Use Trails

SECTION 2


HARD SURFACE TRAILS should serve as many types and numbers of users as possible, and should be asphysically close to as many potential users as possible. As a recreational resource, these paths shouldprovide a good trail experience to residents and visitors alike in all seasons. As a transportation resource,these trails should also serve as a viable and practical alternative to motorized travel. For both recreation andtransportation, its essential that the trails be well designed, well constructed, and properly maintained.

The Goals of the Simcoe County Trails Network are for these trails to:

Accommodate a large variety and number of users safely.

Provide, not just for multiple uses, but also for multiple purposes. For example,recreation as well as commuting. All parts of the trail network should serve more than onepurpose.

Provide a quality recreational experience regardless of the main purpose of eachindividual user (a user may be primarily commuting but should also enjoy the commute).

Link multiple activity centers, population hubs, and a variety of destinations.

Connect to other trails of all types whenever possible. Hard surface trails should bethe arteries of the regional trail network.

Be accessible (or at least barrier-free) to the physically challenged wheneverpossible.

Have an adjacent soft-surface (natural surface or crusher fines) trail for joggers andhikers. This not only expands the use of the trail, it also reinforces the idea that the openspace is a corridor.

Be built to high-quality construction and aesthetic standards to encourage people touse, enjoy, and support the path system.

Be consistent in design yet have enough spontaneity to avoid the master-plannedfeel.

Keep within the character of Siimcoe Couunty. Signs, trailhead design, railings, andother path features are designed to soften the feeling of the hard surface and give the path amore rustic feeling. The desired effect is a relaxed feel, which is clean, honest, practical,and appropriate rather than touristy, decorative, or overdone.

Conform to the landscape so that the path seems as though its always been there.

Minimize user conflicts, where practical, through design and user education.

Be easy to maintain (less than 6% cost/year).

2-1 Trails Design and Management Planning Handbook


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Usage and Site Parameters

Usage Parameters

Multiple use hard surface trails are high-use trails, which can accommodate the widest variety and volume ofmotorized or non-motorized vehicles and users. Hard surface paths should meet ADA guidelines (orCanadian equivalent) for accessibility to the physically challenged. These paths usually serve as part of analternate transportation system and should be designed for both recreation and transportation. Depending onthe trail, site, and environmental conditions, the hard surface trail may be plowed in winter or can be leftsnow covered (ungroomed) or even be groomed for cross-country skiing or snowmobiles.

User Types

Unconditional usage Multiple use hard surface trails are designed to accommodate:

Baby carriagesBicyclists, both road and mountain bikeHikersInline skatersJoggersRunnersWalkersWheelchair users

Adjacent soft surface trail usage The adjacent soft surface trail creates better conditions for:

Equestrians (where appropriate and permitted)HikersJoggersRunnersWalkers

Conditional usage

Cross-country skiers may be able to use the hard surface trail in winter depending on snowconditions. Grooming is optional.

Snowmobiles where Town By-laws allow.ATVs where County and Town By-laws allow.



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Site Parameters

Trail width

Hard surface multiple use paths are to be 9 or 12 wide with wider sections in hazard zones (see Hazard

Zones and Side Clearance, p. 2-9). Trails widths depend on usage:

moderate or less use: 9 10 width high use: 12 width preferred, 10 minimum very high use: 10 width is required, 12 is preferred.

With an adjacent soft surface trail of 4-8 in width, the minimum trail corridor is wide. The soft surface trailshould be separated from the hard surface whenever possible, further widening the trail corridor. SeeCorridor Selection and Width, p. 2-5.

Construction on slopes

Because of the width of the trail, trail construction on flat or gently sloped sites is much less expensive thanbuilding on steeper cross slopes. On cross slopes of 30% or more, retaining walls may be needed to providea trail bench with minimal site disturbance. See Minimum Final and Construction Easement Widths, p. 2-6,for minimum widths of hard surface trail corridors. See Hard Surface Trail Cross-Sections, p. 2-30 forconstruction methods.

Subgrade type and hard surface specifications

The quality of the subgrade for the hard surface is a major factor in the cost of the trail. Concrete can be laiddirectly on a compacted subgrade rated excellent to medium; a base course of road base must be laid overpoor subgrades. Asphalt requires a base course even on good and excellent subgrade soils, and this basecourse must be thicker over medium subgrade soils and in wetter conditions. Asphalt cannot be used withpoor subgrade soils or in conditions with substantial surface or subsurface water. See Hard SurfaceMaterials: Concrete and Asphalt, p. 2-17, Concrete Path Specifications, p. 2-21, and Asphalt PathSpecifications, p. 2-26.

Alignment guidelines

Hard surface trails have to meet a number of alignment guidelines. See Grades, Sightlines, Curve Radii, andVertical Clearance, p. 2-7, Use of Curves in Alignment, p. 2-13, Use of Grades in Alignment, p.2-14, andSwitchbacks, p. 2-15, for guidelines on these subjects.

Intersections

Intersections between paths are critical points in the trail system. See Intersections between Multiple UseHard Surface Paths, p. 2-16. If the trail needs to cross a busy highway, an underpass is preferable to agrade crossing. See Underpasses, p. 2-38, and Grade Crossings, p. 2-40.

Trailheads

All places where a trail meets a road or a non-trail access point are considered trailheads, including gradecrossings and the beginnings of trail access spurs. See Trailheads, p. 2-44.

Path drainage, culverts, and bridges

The trail surface needs to drain at all points. See Path Drainage, p. 2-36, and Superelevation, p. 2-35, forsurface pitch and surface drainage. See Bridges, p. 2-56, for bridge guidelines.



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Signs

A sign program exists for many aspects of hard surface trails - see Signs, p. 2-68.Soft surface trail

This trail has more freedom to wind and roll with the terrain and should be designed as a way to access andexplore quiet areas that cant be reached on the hard surface path. See Adjacent Soft Surface Trails, p. 2-83.

Retaining walls, railings, and fences

Various types of retaining walls can be used above or below trail surfaces as needed - see Retaining Walls,p. 2-74. Safety railings are required where vertical drop offs or other hazards exist beside trails - seeRailings, p. 2-77. A number of fence types can be used both for user circulation control and animal/livestockcontainment - see Fences, p. 2-80.

Boardwalk

In and near wetlands, boardwalks can be used to create a recreational trail. See Boardwalk, p. 2-88.

Site preservation, restoration, and revegetation

The preservation and restoration of sites is critically important to the Trails Network, and this specificationemphasizes preservation along with appropriate restoration and revegetation. Guidelines are also given forclosing and restoring existing trails. See Site Preservation, Restoration, and Revegetation, p. 2-103.

Features for the physically challenged

A number of small design considerations can make a trail system much more accessible to physicallychallenged individuals, and these elements should be incorporated where practical. See Features for thePhysically Challenged, p. 2-107.

Equestrian and Cross-Country ski trail use

Guidelines are given for equestrian and cross-country ski use of trails - see Equestrian Trails, p. 2-109, andCross-Country ski trails, p. 2-110.

Trail maintenance

In order to detect and correct problems while they are still small, the maintenance program is based onfrequent inspections and immediate repairs. Inspection and maintenance schedules and checklists are givenin Hard Surface Multiple Use Trail Maintenance, p. 2-112.



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Corridor Selection and Width

Corridor selection guidelines

The corridor selection guidelines given in Section 1.E apply here.

Corridor width

Corridors for multiple use hard surface trails can vary in width depending on the features of the corridor andthe physical space needed by the hard surface and soft surface trails. An adjacent soft surface trail should beprovided whenever possible and the trail is optimally separated from the hard surface by 15-100 (seeAdjacent Soft Surface Trails, p. 2-83).

Corridors of 150 or wider are preferable in order to preserve scenic, natural, historic, and geologic featuresas well create or preserve open space, greenbelt, wildlife habitat, and floodplain values. A wide corridor canalso serve to avoid dividing land into unusable or inaccessible parcels.

If the corridor is wide and rich in features, the soft surface trail can fully explore the features without theconstraints of the hard surface trail. The soft surface trail can become an entirely new way to enjoy thecorridor, essentially creating a completely separate trail experience from the hard surface path andmultiplying the usefulness of the corridor. The soft surface trail should be separated from the hard surface byvarying distances depending on the width of the corridor and what features the soft surface trail can explore(see Adjacent Soft Surface Trails, p. 2-83). Preliminary planning should locate the soft surface trail as well asthe hard surface in order to develop the best corridor.

The width of the corridor can (and, for user interest, should) vary continually, but the minimum recommendedwidth is 50'. The corridor can be narrower where any of the following occur:

a. Land or easements for a wider corridor are difficult to obtain.b. The trail is primarily a commuter trail.c. The width is restricted only along 25% or less of the trail length.d. The surrounding land is protected from development through perpetual easements or

binding agreements with the owner(s), or because the surrounding land is permanentlyimpractical or impossible to develop because of excessively steep slopes, lack of access,zoning, etc.



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Minimum Final and Construction Easements

For planning and land acquisition purposes, minimum final and construction easement widths based on trailtype and construction are given below. See Corridor Selection and Width, p.2-5, for details on the width ofthe corridor.

The minimum easement width and the width of the construction easement depend on four factors:

1. The width of the hard surface path2. Whether or not there is to be an adjacent soft surface trail3. The cross slope of the site4. Whether cut/fill or full bench construction is used

These factors will usually vary at different points along the trail. If minimum width easements are being used,determine the above factors along the best proposed alignment in order to obtain the necessary easementwidths.

The table below gives easement widths for different trail configurations at various cross slopes for both cut/filland full bench construction (see Hard Surface Path Cross Sections for details). The abbreviation C/F is forcut/fill, FB is for full bench construction.

Note that the table gives only minimum widths. Where a soft surface trail is included, it is assumed to be 4wide at the edge of the hard surface trail. Note that the soft surface trail is best separated from the hardsurface path by as much as possible. Where feasible, the construction width can serve as a minimum widthfor the final easement.

Minimum widths of final and construction easements

Widths are shown in feet as final/construction. For example, 21/25 is a final easement of 21 with a construction easement of 25.

C/F = Cut/Fill construction, FB Full Bench construction.

Cross slope

Grades, Sightlines, Curve Radii, and Vertical Clearance

Grades

Grades up to 5% can be used on standard trail sections (intersections should have grades below 3%).

Grades above 5%, however, will not be considered accessible to wheelchair users. Grades above 5% can beused for limited lengths of path (see table below). An 8% grade is a practical maximum, and every effort mustbe made to avoid grades above 8%. Grades should not exceed 10% at any point.

Avoid steep grades on sharp curves

Avoid grades exceeding 5% on curves with a radius less than or equal to 35. A hill combined with a curve isfun to ride downhill, but the speed combined with the curve may lead to accidents between fast and slowusers. Where a path must curve on a grade, provide long sightlines and a transition zone at the top andbottom of the grade.


ple:dor widens incant grove of trees,rface trail goes

gh the grove


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Signs for steep grades

At the tops of grades of 7% or more where the length of the grade is 100 or more (or where the end of thegrade is not visible), path signs must warn users of the steep downgrade ahead. Provide a transition zone atthe top and bottom of the grade.

Path length limits on grades

Grade Limit on length at that grade


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Bicycle 35 (@15mph)* 35 (@15mph) 8

Equestrian 12 10

*This is a switchback radius. Normal curves should have a greater radius.

Vertical Clearance

Hard surface paths require 10 vertical clearance, and more may be necessary or desirable to accommodateconstruction or maintenance vehicles. Paths used for cross-country skiing, snowmobile or other motorizedvehicles may require additional clearance (up to 16 depending on expected snow depth).

Hazard Zones and Side Clearance

The widths of the hard surface and soft surface trails vary in critical points such as hazard zones and placeswhere side clearance is constrained for more than 15 continuous feet.

Hazard Zones

Hazard zones are places where users can be expected to slow down or stop. Hazard zones include:

Unusually busy trail sections

Busy intersections and intersections with directional signs

Intersections at the bottom of or along a sustained grade*

Curves of less than 55 radius and more than 20 running length Blind or near-blind curves*

Beneath a bridge overpass*

Long or interesting bridges where users are likely to stop*

Boardwalks or other crossings over unusual or special terrain or ecosystems

Places with scenic views

Places with low side clearance for 15 or more running feet (see below)

*On trails with high or very high use, these situations may be considered extreme hazard zones (see below).

Other hazard zones may exist in addition to the above. Both hard and soft surface trails should widen in



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hazard zones to create room for through traffic to pass safely.

Extreme hazard zones

Extreme hazard zones are specific instances from the above list where trail usage is either very high orconditions are particularly adverse. These zones should be widened even more. See the table below for theincreased trail widths in hazard zones.

Width change zone

Upon entering and leaving hazard zones, the changes in trail width should not be sudden or even noticeableby users. For hard surface trails, a 2 change in width should be tapered over at least 50 of the trail. A 4change should be tapered over at least 100 of trail. The tapering begins at the end of the widest part andextends into the standard width zone. If two widened zones are less than twice the width change zone apart,the trail should remain wide through the width change zone rather than narrow down and widen again.

For soft surface trails, the width can change over any distance that makes sense at that location - typicallythis will be from 3 to 15 feet. See the illustration on the next page for examples.

Trails of less than normal width

See Constricted Trail Width, p. 2-12, for working with obstacles that constrict the width of the trail to less thannormal.

Side Clearance

Standard side clearance for hard surface trails is a minimum of 3 on each side.

Side clearance exceptions

The edge of either the hard or soft surface trails can, if necessary, extend to the edge of significant objects



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such as occasional tree trunks, slow-growing trees and shrubs, boulders, and retaining walls. Theseoccasional exceptions to side clearance tend to make the trail more interesting as long as the exception isclearly necessary and appropriate. Clearance exceptions should not pose a safety hazard.

Trail width changes with extended low side clearance

If side clearance is limited on one or both sides for 15 or more running feet, the section with low clearanceshould be treated as a hazard zone. The trail need not change width in passing discrete and limited lowclearance points as long as the length of the clearance exception is less than 15 continuous feet. See thetable below for the increases in trail width. See the illustration on the next page for examples.

Hazard zones and low side clearance zones

The values given are the number of feet to add to the normal trail width in the given cases. Low clearance on one side and Low

clearance on both sides are for cases where side clearance is restricted for 15 or more continuous feet.

Path Type Hazard

Zone*

Extreme

hazardzone*

Low clearance

on one side**

Low clearance

on bothsides**

Lengt

h ofwidth

chang

e

zone

Hard surface +2 +4 +2 +2-4 50-100

Adjacent soft

surface+1-2 +2-4 +1 +2 3-15

* See definition of hazard zone, above.

**Applies only where clearance is restricted for 15 or more continuous feet.



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Hazard Zones and Side Clearance

In this hypothetical plan view of a rural streamside trail, note how the width and side clearance are treated inhazard zones and low clearance areas. The normal width is 8. On a long bridge and where there is limitedclearance, width increases to 10. In an underpass beneath a highway bridge, width increases to 12.

On a high-use path, the same situation would have a normal path width of 10, increasing to 12 on thestream crossing and in low clearance areas, and possibly increasing again to 14 beneath the highway bridge

if the curve is very blind.



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Constricted Trail Width

The normal width of the trailcan narrow for a shortdistance in cases whereunavoidable obstacles on bothsides constrict the trail. Note

that such constrictions are tobe used only when there is nofeasible alternative. Forinstance, a normal 10 trail cannarrow to 8 between a cliffand the edge of a road. Sideclearance can be zero withinthe constriction zone.Depending on the width of thenarrowed trail and sightlines inand approaching theconstriction, it can be handledas a minor or majorconstriction:

A Minor constriction is onewhere both: the width of the trail within

the constriction is at least8, and

sightlines approaching,within, and through theconstricted zone are 120or longer.

A minor constriction can betreated as a width changezone. The width shouldchange smoothly over at least

50 of trail. A Trail Narrowssign at the beginning of thewidth change zone is recom-mended if the transition feelsat all abrupt.A Major constriction is onewhere any of the following istrue: the trail needs to narrow to

less than 8, or

sightlines approaching theconstricted zone are lessthan 120, or

sightlines within or throughthe constricted zone areless than 120.

For a major constriction, highlyvisible flexible posts shouldmark each side of each end ofthe constriction zone. If theposts cannot be seen from atleast 120 away, a TrailNarrows sign should beplaced 90-120 from the posts.



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Use of Curves in Alignment

Use continual flowing curvesIn using curves, a comparison with modernhighway design is instructive. Modern high-speedhighways are designed as straight segments

joined by wide curves of constant radius. Thisconfiguration is the safest for high-speed traffic,but massive cuts, fills, and site disturbance arenecessary to achieve this result. The end effect issafe and predictable but sanitized, and thehighway seems almost to not exist in thelandscape rather than be an integral inseparablepart of it.Hard surface paths, in contrast, should keep thelong sightlines for safety but use continual curvesof non-constant radius instead of straight sectionsconnected by regular curves. Continual curvesgive the path a fluid feeling, and having the radius

vary continually makes the path slightly lesspredictable but much more interesting. At thelower speeds of a bike path, the continualvariance in curve radius greatly adds to theexperience of the trail without compromisingsafety. Use landforms and natural features asobvious and intuitive reasons to align the path asa series of rhythmic yet non-monotonous curves.The best way to select the curving alignment is to

walk the site without using surveying instruments(use instruments as guides when grades becomesteep or curves sharp).

Avoid abrupt curves and numerous tightcurvesAvoid having too many tight curves in a shortlength of path - this is disorienting to users andpotentially dangerous. Use cuts and fills sparinglyto even out landforms.

Avoid long straight sectionsNo part of a hard surface path should be perfectlystraight for more than 300 unless there areabsolutely no landforms or natural features thatthe path can acknowledge. In this case, give thepath a subtle curve to keep it from being perfectly

straight.

Avoid contrived curvesOn the other hand, avoid curves that areobviously contrived. Also avoid creating artificialobstacles such as directing a path toward thecenter of a grove of trees and then deflectingaround it.



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Use of Grades in Alignment

Traverse slopesThe hard surface trail should traverse slopesrather than follow the fall line, even when theslope is within the grade restrictions for the trail.A traversal alignment feels more natural, drainsbetter, and is more comfortable to use than an

alignment that takes on a grade directly. Theadjacent soft surface trail should also traverseslopes (see Adjacent Soft Surface Trails, p. 2-83).

Follow contoursIn addition to traversing slopes the trail shouldfollow elevation contours as much as feasible inorder to minimize an excessively up-and-downroller coaster trail profile. Some up and down isnecessary and desirable, such as in crossing acreek. Other situations, however, such as tryingto minimize curves while crossing a number of

small steep hills and drainage, create a trailwhich is tiring to use (and often dangerous aswell since sight lines are limited and the speed

of downhill users can become excessive).

Optimize grades over curvesSteep grades, or a number of up-and-down gradesin succession, are less desirable then sharpcurves. Hence, try to optimize the grade first toavoid a roller coaster effect, and then optimize

curves. For example, if a number of steep smallhills and drainage need to be crossed insuccession, try to follow the contours first andchange the grade only when individual curvesbecome excessive. Sharp curves can sometimesbe flattened out by using cuts and fills in thecourse of minimizing the grade. If substantial cutsor fills are required, an alternate alignment needsto be considered. Try to avoid creating asuccession of sharp curves. For safety avoidcreating sharp curves on grades more than 3%.

Undesirable: Part traverse, Optimal: Full

fall line alignment traverse on contour

Switchbacks

Where necessary, switchbacks can be used to reduce trail grades. Since switchbacks are frustrating tousers, land-intensive, more expensive to construct, and tempting to shortcut, use switchbacks as a lastresort. Study alternate alignments first. Because of the minimum turning radius of the trail, it is impractical toconstruct a switchback on more than a moderate cross slope. Moderate to large cuts and fills are usuallyneeded.

Switchbacks are classified as hazard zones and need to be widened accordingly (see Hazard Zones and

Side Clearance, p. 2-9). In order to increase the predictability of the curve, the curve should have a constantradius of no less than 35 as measured to the center of the path. The switchback curve is also subject tosuperelevation (see Superelevation, p. 2-35).

Dont stack switchbacksIf land permits, dont stack short switchbacks near each other. Instead, minimize the number of switchbacksby using long sections of climbing trail between them. This is most effective when the bottom of the trail is notimmediately below the top or when it is otherwise impossible or not tempting to shortcut the trail.

Use site features to anchor switchbacksSwitchbacks can sometimes be used to highlight site features. For example, a tree can form the center of aswitchback and help anchor the switchback by giving it a clear reason to exist where it does. A vertical orhighly visible feature is desirable in order to give an intermediate path goal for users. Encircling a feature witha hard surface path with many users, however, tends to remove the feature from use - for example, in the

case of the tree no one would want to sit under it.

Land requirementsFor preliminary planning, allow between 130 and 160 of width at the curve of the switchback. The actualamount depends on the steepness of the slope (the steeper the slope, the more width will be required).



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Intersections between Multiple Use Hard Surface Paths

Intersections as hazard zones Create T-shaped intersections

Create good sightlines at

intersections



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Hard Surface Materials: Concrete and Asphalt

The surface of a hard surface trail is often the largest single cost in the trail project. The built surface shouldlast as long as possible and be usable for as much of its lifespan as possible. The lifespan of the surfaceshould be measured in terms of 15-30 years for asphalt and 50 or more years for concrete.

Criteria for selection should include:

Initial costLong-term cost (including scheduled maintenance)Useful lifespanSite characteristicsTrail characteristicsSubsoils and subgrade preparationAvailability of material and laborSite clearance for construction machineryAccess for the physically challengedAestheticsMatching or complementing existing trailsSafety

Concrete versus Asphalt

The Simcoe County Trails Network believes that there are advantages to either type of hardsurface and preference should be given to the type that suits the environment and user in whichthe trail is being developed. For example, in-line skating requires a concrete surface whereascycling requires either concrete or asphalt. Typically concrete surfaces are designed in high useareas, within the Town center cores and asphalt surfaces are designed in medium use areas,branching from the Town center core to the County limits. Crusher Fines surfaces areencouraged for a more natural trail experience and can also be used as a beginning stage asfunds allow them to be developed into either concrete or asphalt.

Concrete

The sustainability of concrete trails has mostly to do with the concrete mix and the way the concrete ishandled. The correct mix and proper handling, combined with modern finishing techniques, can produce theultimate hard surface trail that will be virtually maintenance free for decades. The mix must be precise, theconcrete cannot be excessively handled in the forms, and the concrete must be cured correctly or spalling(surface deterioration) will occur later. Choose the contractor carefully - controlling the mix and handling theconcrete properly are not difficult, but they are the contractors responsibility and absolutely must be donecorrectly or the money spent on concrete will be wasted. A major advantage of concrete, however, is that theinherent strength of concrete can largely compensate for a wet or less than optimal foundation, and hencesubgrade preparation costs are usually lower than for asphalt. On well-drained subgrade soils, concretepaths can be laid directly on the compacted subgrade. The major disadvantage of concrete is a marginally

higher initial cost.

Other features of concrete are:

Concrete trails have a much longer life, usually a minimum of 30 to 50 years if properlyconstructed.

Concrete trails are not as likely as asphalt to bend and buckle due to tree roots andvegetation.

Concrete trails will bridge imperfections in the subgrade or areas that become undermined.A smooth, continuous surface will be maintained.

If done properly, the surface of a concrete trail will remain the same for several decades as



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the day it was poured.

Concrete trails hold their edges. Asphalt trail edges can crumble away over time, effectivelyreducing the width of the path.

In erosion and flood prone areas, and near lakes and streams where water tables are high orfoundations unstable, or where grass (and pavement) is regularly irrigated, concrete performs farbetter than asphalt. Concrete will withstand periodic small flooding where asphalt will break up and

wash away. The initial cost of installing concrete trails is marginally more expensive, but due to the lowermaintenance costs and longer life, the concrete can be justified by its lower long-term costs.

Concrete trails are normally easier for the physically challenged due to their consistentsmooth surface.

Properly placed and cured concrete will perform in extreme temperatures. Proper crackcontrol and surfacing is important. The 6x6 mesh holds the concrete level in a position even if theconcrete cracks.

The natural light color of concrete makes the surface more visible and safer at night.

A broom finish makes the surface skid resistant.

Concrete can be formed into curves, variable-width paths, intersections, and precise surfacecharacteristics more precisely than asphalt.

Spot repairs to concrete can be made flush to the surface.

Saw cut joints and smooth expansion and construction joints create an extremely smoothpath and remove the user irritation of bumping over older-style trowel-formed joints every ten feet.

Asphalt

Unlike concrete, the sustainability of asphalt trails has mostly to do with their foundation and subgrade -factors that are often much more difficult and expensive to control than concrete. If the base course andsubgrade beneath it can be kept dry, drain extremely well, and dont contain clays or other soils that expandwhen wet, asphalt will hold up well; otherwise, crumbling edges, cracking, doming, heaving, and settling arelikely.

Characteristics of asphalt

The dark thin mat of asphalt tends to heat rapidly in the winter sun, warming both it and the base coarse andsubgrade beneath it. The warming tends to form condensation on the bottom of the asphalt mat, and otherwater almost always works its way into the base coarse and subgrade from the sides of the narrow path (i.e.,narrow relative to an asphalt road or parking lot). At night, the asphalt, unprotected by snow, cools rapidly,and the freezing water beneath tends to frost heave the mat (or at least crumble the edges where there isusually more subsurface water). On a road, the live load of traffic helps to keep the asphalt matcompressed, but the live load is largely missing on a trail. The daytime temperature differential between thewarmer base coarse and the cooler surrounding soil also creates a tendency toward heaving. Vegetation andtree roots can also heave and buckle asphalt.

Favorable and unfavorable site conditions

The best condition for sustainable asphalt trails is to have a dry subgrade of well-draining soils topped by awell-draining base course free of clays and materials that expand when wet. Mixing a small amount of limeinto the base course further increases base course stability. An ideal location for an asphalt trail would be ona dry rocky south-facing slope with a subgrade of bedrock and clean sharp sands with no clay or plasticmaterials. An inappropriate location would be on clay-silt subgrade in an area with a high water table wherethe trail is surrounded by trees with aggressive root systems (willow, poplar, and sumac). A location thatcould be successful is on well-drained cuts in rocky ground and on filled embankments made of theexcavated rocky soils (sand, rock, and river run). If the trail is regularly irrigated by sprinklers, summertimeheaving from water vapor and temperature differentials in the base course could eventually damage thosetrail sections even when they have an excellent base course which drains extremely well. The subgrade and



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base course preparation to be used on an asphalt trail may vary drastically from one end of the trail to theother, complicating planning and cost estimates.

Subgrade preparation

If the trail and subgrade cannot be kept dry and the subgrade does not have well-draining soils, the subgradewill need to be excavated and replaced with a deep layer of river run (pit run) topped with a suitable base

course. The width and depth of replacement depend on the subgrade, but even a major replacement may nosolve the problem if the surrounding sub-grade soils are often damp or drain so poorly that moisture remainstrapped in the base course beneath the asphalt. The cost of the subgrade replacement may raise the totalinitial cost of asphalt, as much or more than concrete, yet the lifespan of the asphalt material itself is muchshorter than that of concrete. In addition, even asphalt on the best foundation requires much more frequentand extensive maintenance than concrete because the surface dries out without a heavy live load tocirculate the oils inside the asphalt mat. Asphalt trails hence need to be sealed more often than roads.

Other features and factors of asphalt

The lifespan of asphalt material can be doubled or tripled by sealing it in its second year andalternate years thereafter.

Asphalt is less expensive to install (although the installation of the subgrade may substan-

tially raise the initial cost). The darker color of asphalt melts snow faster than concrete (a potential advantage wherequick snowmelt is desired).

The construction season for asphalt is longer than for concrete because of the requirementto keep concrete from freezing for the first week (and preferably longer).

Runners prefer asphalt to concrete because asphalt has a softer surface.

Spot repairs to asphalt are easier than to concrete because the affected section can besawed out and replaced more readily due to the relatively soft surface of asphalt.

Concrete and Asphalt Maintenance

Concrete

Scheduled maintenance

Concrete trail surfaces require no regular scheduled maintenance other than occasionalsweeping.

Repairs

Concrete reaches 98% of its full strength in the first 28 days if temperatures are at 550 F orhigher. Maintenance expenses may be reduced if heavy traffic stays off of new concrete for the firstmonth.

The first year for concrete is the most critical. In the second year, replace any sections (i.e.,10 sections) that have cracked, heaved, or settled in the first year (see below).

Cracks should be joint sealed as soon as possible to prevent further moisture from reachingthe base course.

If a section should extensively crack or heave, the section should be broken out, the baserecompacted, and the section repoured. If the concrete was correctly laid, very few sections shouldcrack or heave for the life of the trail.



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Budgeting

Properly laid concrete exhibits few problems that almost no money is required for mainte-nance of the concrete itself.

A small percentage of the initial cost of the concrete material should be budgeted for secondyear replacement of sections that cracked, heaved, or settled in the first year. Experience elsewheresuggests that no more than 1-2% of the 10 sections should develop cracks in the first year. In theinitial bidding for the project, get a bid for replacing 1% to 2% of the sections - this should be morethan sufficient.

Asphalt

Scheduled maintenance

Seal the entire asphalt surface in the second year. Sealing is expensive but the lifespan ofthe asphalt material can be easily doubled or even tripled by sealing it during its second year. Early

sealing greatly helps to keep out the moisture that destroys asphalt, helps prevent the surface fromdrying out in the absence of a live load, and prevents raveling (the loss of individual rocks from thesurface). Use sand slurry to form a more skid-resistant seal coat.

Depending on the condition of the asphalt after the second year seal, the trail should besealed for the second time in 5 to 8 years.

The trail should be resealed every 3 to 5 years thereafter for the life of the trail. (Asphalttrails require more frequent sealing than roads because paths dry out faster - trails lack the liveload of roads that kneads the asphalt and circulates oil to up the surface.)

Repairs



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Asphalt generally shows no problems for the first 3 to 5 years.

After the first 3 to 5 years, crack sealing should be done before each winter (and preferablyalso as early in spring as possible).

Cracks should be sealed as soon as they appear to prevent further moisture from reachingthe base coarse. An early sealing of an extensively cracking area will extend the life of that sectionby several years.

Asphalt can be damaged by snowplows and other machines that scrape the surface andbreak the seal coat, and by heavy equipment with tractor tires, caterpillar treads, or other wheels that

can dent the surface. Maintenance may need to be more frequent and extensive on sections that areregularly plowed.

Single potholes and a number of potholes in a small area are evidence of one or a combina-tion of subsurface moisture, a deficiency in the base course, the wrong asphalt mix, or a defect in theway the asphalt was laid. Seams, handwork, roller dents, and attempts to patch imperfectionsbefore initial rolling of the original asphalt are all likely to be problem areas in the future. Saw out theoffending area, recompact the base course, install geotextile underlayment (see Asphalt PathSpecification p.2-26), and relay asphalt.

If the edges extensively crumble or a large number of cracks appear in a section, eithersurface traffic (trucks and maintenance vehicles) or subsurface moisture has destroyed that section.The section should be sawed out and removed, the base course recompacted, and the asphaltrelaid. One or more seal coats should be applied over the patch to help even out the patch seams ifneeded. If the surface shows no sign of traffic damage, consider solving a moisture problem by

replacing that section of the trail with concrete poured on the base course of the asphalt. (Concretecan also be laid over broken asphalt, but this is not recommended since it raises the surface heightof the path.)

If the asphalt surface begins to look dry and ravels (loses rocks from the surface), the path islong overdue for a seal coat and the lifespan of the asphalt may have already been shortened. Sealcoats should be applied before raveling begins.

Budgeting

The second year seal should be budgeted along with the initial project.

The first 3 to 5 years will likely be almost maintenance free and almost no money will need tobe budgeted for maintenance or repair. After that, crack sealing should be budgeted annually.

Subsequent seal coats can be budgeted as needed on the schedule given above. The

schedule can be modified given the actual condition of each trail. As mentioned above, sealingshould be done before the surface looks like it needs it - by that time, some of the damage hasalready been done and the lifespan of the asphalt may have been shortened.

If the subgrade and base course preparation were done correctly, moisture problems weremitigated, the asphalt was laid and rolled correctly, and seal coats are applied on schedule and asneeded, very few sections should fail. Individual cracks can be sealed effectively.

Concrete vs. Asphalt vs. Stonedust

The Simcoe County Trails Network is meant to be a multi-use facility that can be utilized by awide variety of different user groups while fulfilling a dual role as both an active transportationnetwork and recreational network. The primary goal of this network is to conveniently

accommodate as many different user groups as possible while providing a safe facility for all.These major user groups include:

walkers/hiker runners dog walkersRecreational bikers road bikers people with disabilitiesChildren snowshoers X-couuntry skiers

A number of different factors must be considered when attempting to determine the bestsurfacing for the trails network:

Useability/Flexibility



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Although all surfaces are suitable for the majority of users, the surface of the trail to some degreeimpacts the ability of the various users to fully enjoy the trail experience. People who walk, hike,or run prefer stone dusted (limestone screenings) trail since its more forgiving on their jointsthan either asphalt or concrete. People with dogs wish to avoid an asphalt trail because itabsorbs heat in the summer and can be very hot for the dog paws. Active bike riders who wonroad bikes would prefer an asphalt trail because it is smoother and provides less rollingresistance for narrow street tires. People with disabilities who use power scooters or wheel

chairs for mobility would also prefer an asphalted trail for the same reasons. None of thewheeled user groups enjoys concrete sidewalks because of the constant clickety clack causeby the expansion grooves between the slabs.

Cost

Cost is also a critical issue for trail surfaces. Concrete is clearly the most expensive surface toinstall as it is completed in 5 to 6 thick pours, but once placed required little or no annualmaintenance for up to and sometimes beyond 75 years. Concrete, if installed correctly, isimmune to cracking on the edges, frost heave, and will not allow vegetation to encroach. It hasbecome the de facto standard for pedestrian sidewalks and high volume trails in urban areas inNorth America. If any section does crack or break down, the existing slab(s) can be removed anda new one poured.

Asphalt is somewhat cheaper to install but is definitely not as durable as concrete since it isnormally thinner, does not have the same structural rigidity, is subject to frost heave andcracking and is not impervious to vegetation. As with concrete, any asphalt section that cracks orheaves must be removed and repaved.

Stone dust is clearly the cheapest surface to install, but it does involve additional maintenanceactivity to keep it in peak shape, is subject to erosion if water is allowed to flow across it, and isnot impervious to vegetation which can creep in from the sides of the trail. It is however, notsubject to noticeable frost heave or cracking and can be easily re-graded or top dressed withstone dust if the surface becomes uneven.

Location

As identified by most active transportation experts, the ideal situation within a road allowance isfor pedestrians, bicycles and cars to all be separate from one another in a transportationcorridor. Although the solution is obviously the safest for all user groups, it is usually not possibleto create 3 distinct parallel transportation routes within the road allowance due to the width ofexisting allowances. When the road allowance width is only capable of supporting 2 routes, adecision must be made to either combine the cyclists and automobiles on the roadway usingseparate lanes for bicycles and vehicles coupled with a standard sidewalk for pedestrians, orcombine a the cyclists with the pedestrians on a separate multi-use trail distinct from theroadway.

Conclusions

Based on the above information, It is recommended that;

1) Stone dust should be the surface of choice for most trails within Simcoe County for the followingreasons:

a. Initial installation cost is the lowest of the 3 surfaces and the ongoing maintenance costs can becontrolled through effective grading of trails

b. Although an asphalt trail would be slightly smoother than stone dust for the first couple of years andmight be preferred by some wheeled users a potential outcome would be higher speeds on trails andthe displeasure of pedestrian users who are by far the largest group of the trail network. The extra



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cost and poor utility for an asphalt surface cannot be easily justified as the benefits do not supportthe additional expenditure.

c. Simcoe County has little high density urban development. Many of the trails are located along creeksand rivers, off-road through parks or woodlots, along waterfront or along watercourses. A stone dusttrail is a more natural surface and more in keeping with the County itself.

d. Based on the information at the time it would appear stone dust is the most overall environmentallyfriendly trail surface.



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2) Along arterial roads in more urban sections of the county where both vehicular and pedestrianvolumes are expected to be high create concrete multi-use trails physically separated from theroadway. Although not the first choice for active road bikers, it is a good choice and the solutionrepresents the best alternative when all user groups are taken into account.

Trails Manual Section2

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