Slopes and Resting Intervals for Outdoor Recreation Access Routes
Running slope is the lengthwise slope of an outdoor recreation access route, parallel to the direction of travel. Outdoor recreation access route sections of any length may have a running slope ratio of up to 1:20, a 5-percent grade (figure 37). Steeper terrain may make this difficult to achieve. Many visitors can negotiate steeper slopes for short distances, so short segments of outdoor recreation access routes may be steeper, as shown in table 2, but the slope of an outdoor recreation access route may never exceed 1:10, a 10-percent grade. In this guidebook, the terms running slope and grade often are used interchangeably.
Figure 37—The basic slope requirements for outdoor recreation access routes and beach access routes.
Cross slopes—the side-to-side slope of an outdoor recreation access route—must not exceed 1:33 (3 percent), as shown by figure 37. However, if the surface of the outdoor recreation access route is paved or built with boards, the cross slope must not be steeper than 1:48 (2 percent).
Design Tip
The cross slope requirement depends on what material is used.
Those who use a mobility device know that as cross slope increases, travel becomes more difficult. This is because working against the sideways pull of the cross slope can double the effort needed to make forward progress. However, in an outdoor environment, the cross slope has to be steep enough that water won't accumulate on the travel surface. While slope and drainage can be precisely controlled on surfaces that are paved (asphalt, concrete, paving blocks, and so forth) or built with boards (wood planks, heavy timber, concrete, fiberglass, or other manufactured material), it's more difficult to ensure drainage on natural or gravel surfaces. When water accumulates on natural or gravel surfaces, they often become muddy and impassible. That's why the cross slope is allowed to be steeper on natural or gravel surfaces than on surfaces that are paved or built with boards.
Resting intervals are relatively level areas that provide an opportunity for people to catch their breath before continuing along the outdoor recreation access route. These intervals are required between each outdoor recreation access route segment any time the running slope ratio exceeds 1:20 (5 percent) as shown on table 2. A resting interval must be at least 60 inches (1,525 millimeters) long and at least as wide as the widest segment of the outdoor recreation access route leading into it, if the resting interval is within the outdoor recreation access route. If the resting interval is beside the outdoor recreation access route, it has to be at least 60 inches (1,525 millimeters) long and at least 36 inches (915 millimeters) wide. Depending on the design and location, the intersection of two outdoor recreation access routes may act as a resting interval.
| Runnign [sic] Slopes on ORARs | Maximum Length of Segment Between Resting Intervals | |
|---|---|---|
| Steeper than | But not Steeper than | |
| 1:20 (5 percent) | 1:12 (8.33 percent) | 50 feet (15 meters) |
| 1:12 (8.33 percent) | 1:10 (10 percent) | 30 feet (9 meters) |
Construction Tip
Slope and grade terminology.
Slopes are often described as a ratio of vertical distance to horizontal distance, or rise to run. For instance, a slope ratio of 1:20 means that for every 1 foot of vertical rise, there are 20 feet of horizontal distance; for every meter of vertical rise, there are 20 meters of horizontal distance (figure 38). When the slope ratio is stated as a percent, it is referred to as the grade. A 1:20 slope stated as a percent would be a 5 percent grade.
Figure 38—Determining the slope ratio.
The slopes of a resting interval may not exceed a ratio of 1:33 (3 percent) in any direction (figure 39). However, if the surface is paved or is built with boards, the slope can't be steeper than 1:48 (2 percent) in any direction.
Figure 39—The basic resting interval requirements for outdoor recreation access routes.
Grade requirements for an outdoor recreation access route may be more difficult to meet when altering an existing site than during new construction. Accessibility was seldom considered when older recreation sites were designed. Many campgrounds and picnic areas were located in spectacularly scenic settings, but on steep terrain. Complying with the grade requirement in these areas may be difficult without a fundamental change to the recreation environment. A deviation is allowed for alteration projects where a condition for an exception exists.
In alterations only, if a condition for an exception prevents full compliance with a specific technical requirement on a portion of an outdoor recreation access route at camping and picnic facilities and at trailheads, that portion of the outdoor recreation access route is required to comply with the specific technical requirement only to the extent practicable.
This deviation from the technical requirement is not allowed to be used for new construction at camping and picnic facilities or at trailheads. When planning for a new outdoor recreation area, the natural terrain and the general accessibility of the natural environment should be part of the site selection criteria because compliance with outdoor recreation access route requirements is required for new construction.
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