Summary: 

• select a suitable trail layout type,
• assess and select trail route alternatives,
• review maps and air photos,
• reconnoiter the site,
• select the optimum general trail corridor based on the site inventory and the "Limits of Acceptable Change" (L.A.C. ,) as determined by the proposed use,
• decide what type or classification of trail is required based on the inventory and the L. A. C. method,
• assess trail route gradients,
• estimate trailhead, parking and service requirements,
• assess trail plan impacts.

Trail system layout depends on anticipated use, topography, hydrology, existing road access and a host of other factors described in this manual. Use 1:50,000 scale topographic maps and air photos to help determine general trail layout options. Layout on the ground rarely matches the ideal forms shown below. Use these common layout forms as a guide to visualize potential routes and the links between the trailhead, parking, trail route and the different types of users. Stacked loops, for example, are ideally suited to ski trails since they allow for a variety of trail difficulties and lengths of loops. These drawings show the most common forms of trail layout: 

Linear: 

• Use linear trails for long distance trails and for goal-oriented trails, such as those providing access to semi-primitive areas or connections between facilities, such as parking lots and swimming areas. Add side trails to allow access to secondary recreation features. Linear trails are often a result of converting old roads to trail use.

Loop: 

• Use loops to guide the user back to the trailhead. Loop trails provide more interest than a linear trail because users do not retrace their steps. Loop trails result in less physical wear on the trail and the environment.

Stacked Loop: 

• Use stacked loops where you wish to offer a variety of travel distances and terrain which may include different levels of user ability.

• Use satellite loops to provide an even wider range of alternatives in terrain, solitude, interpretive opportunities and user ability. The central loop collects users allowing them to return to the trailhead.

• Use spoked wheels to offer a range of travel distance alternatives where users may turn back to the trailhead from a number of different points.

• Use a maze to make maximum use of an area by letting users explore their own routes. A maze provides a variety of terrain conditions, travel distances and interpretive themes. Mark such trails well, with directions and distances to prevent users from becoming lost or over-extending themselves.

2.6.2 Assess Trail Route Alternatives 

Once a general approach to trail layout is established, assess trail route alternatives. Review topographic maps and air photos to select potential trail corridors. Explore the site to find potential trail routes. Assess the feasibility of the proposed trail. Identify any obstacles to trail construction, for example poorly drained slopes or valley bottoms. 

• Plan the trail to a standard that will serve users well and minimize environmental effects and maintenance.
• Assess the length and difficulty of the proposed trail corridor(s).
• Consider the type of user, seasonal-use, and special needs such as horse hitches and wheel-chair access.
• Plan to separate conflicting uses.
• Assess water availability on the route.
• Select trail routes that avoid critical seasonal wildlife habitat areas.
• Avoid trail routes that cross hazardous rivers or creeks (unless bridges are planned), avalanche or debris flow ones, or other terrain hazards.
• Assess requirements for campsites, shelters or other services en route.
• Determine the trail length depending on the type of trail activity, the ability and interest level of the users and the terrain conditions of the trail route. Plan trail difficulty by matching the type of use to proposed trail gradients. Figure 1 shows various gradients by ratio, percentage and degrees.

Ease of travel along a trail is affected by the degree of slope, the length of sustained grade and the proportion of uphill to downhill and level sections along the trail. Plan for a level a-ail section at the end of steep or sustained grades. Select variations in a-ail gradients with gentler sections in between steep climbs. Avoid long, sustained grades. Consider switchbacks, steps or ladders for small sections of very steep slopes. For most trails, plan for a 20% maximum grade over a distance of 30 m. If only a few steep areas occur along the route, allow for greater maximum grades as required. 

Figure 1: Trail Gradients 

1 1:1 100% 45o 2 1:2 50% 27o 3 1:3 33% 18o 4 1:4 25% 14o 5 1:5 20% 11o 6 1:10 10% 6o

• Trailheads and parking facilities are an essential part of trail planning. Plan these facilities to reflect the trail character, the type of trail activity, and the anticipated number of users. Consider en route and destination service requirements when planning the trailhead facilities.
• Advocate the trailhead(s) to optimize access and services.
• If several trails are in the same area, locate the trailhead to provide access to as many of these trails as possible. In cases where different trails have different use requirements, such as for hikers and horse riders, then consider separate trailhead and parking facilities.
• Consider space requirements for larger vehicles, such as trailers or stock trucks, and the safety of unattended vehicles.
• Assess toilet and waste disposal requirements.
• Consider snow removal and winter maintenance on winter access routes and facilities.

• After the preliminary planning steps, review the likely environmental change to the area where the trail is proposed. Use the L.A.C. approach where appropriate.
• Assess the impacts of the proposed trail on park management, natural and cultural resources, users and maintenance. Use the L.A.C. approach where appropriate.
• Modify the overall trail layout as required to minimize negative impacts on the environment and expected users.