Tools for Trails: Measuring and Surveying Tools

Before trail builders start digging, they first have to lay the trail, flag the line, and more to ensure a grade that not only matches the terrain but also is well throughout to prevent erosion.

by Tools for Trails


One of the most popular tools when doing survey work and planning the trail layout is the clinometer. This small, handheld device is used by trail designers to read the percent of grade between two points when looking through it and sighting a fixed point. The clinometer has a floating scale internally from which a grade is measured, but it cannot be set to a fixed grade.

Trail builders use a clinometer by holding it up to their eye while keeping both eyes open, using one to read the scale, and the other to sight the target. Using a clinometer is easier with a partner, using eye level to determine the 0 percent slope. If trail builders don’t have a partner, using a target at eye height also works. The person holding the clinometer then walks up or down the slope to the point where the reading should be taken. The reading taken from the percent scale is the percent slope, or the relationship between the amount of elevational rise, or drop, over a horizontal distance.

While there are clinometer apps on smartphones now, a lot of trail builders prefer the original clinometers for better accuracy.

Expressed as an equation: Percent of Grade = Rise/Run x 100 percent. A section of trail 100 feet long with 10 feet of elevation difference would be a 10 percent grade.

Tip: Both eyes must be kept open when sighting through the clinometer.

photo credit: Tools for Trails
Clinometer scale from Backslope Tools

Clinometer scale from Backslope Tools

Abney Level

Before the clinometer, the Abney level was used for survey work. This tool included a protractor that needed to be mounted on the side with the appropriate scale. The Abney scale is much larger than a clinometer, so most choose to use a clino instead.

Tip: Check the screw that fixes gradient often to make sure it is still tight and you have the preset grade you want.


When surveying more remote sites, a GPS system comes in handy. These devices are good for gathering waypoints along a proposed trail corridor or existing trail. These points will indicate where to build a trail or points for maintenance. These points can be stored for future reference, and superimposed on an existing map to quickly identify the trail alignment or maintenance areas.

Devices like those from Garmin are very accurate for marking these points. There are plenty of apps for smartphones that can be used as well. Gaia is a popular one and has different maps available for download depending on needs.

Tip: Download your maps ahead of time. Apps like Gaia only work with service or on a downloaded map. A GPS device will usually be more accurate.

Flagging (Ribbon/Wire Flag)

Flagging (roll of ribbon or wire flag) comes in a variety of colors and shapes. Flagging is used as a way of highlighting an area for trail alignment, construction, or maintenance. Ribbon or flag color should be chosen so that it is easily identifiable, and does not blend in with the surrounding terrain. More permanent trail markers may be nailed into trees later, marking trails in snowy conditions.

Tip: Keep in mind that flagging will take a while to deteriorate in the elements. It must be removed once the project is completed. If needed to mark a trail, use more permanent markers that are longer lasting.

Measuring Wheel

The measuring wheel is used to measure distance on the trail. It records the revolutions of a wheel and hence the distance traveled by the wheel on an existing trail or proposed trail corridor. Measuring wheels can be used to measure distance for guidebook descriptions and also noted in survey or assessment forms to pinpoint the location of work to be done along the trail.

Tip: Be sure the counter is set to zero before starting out.

photo credit: Tools for Trails

Tape Measures

A must-have for many trail projects, the tape measure works for measuring bridges and other structures.

Tip: Clean the tape as you rewind it to prevent clogging from debris.

Digital Level

Sometimes it can be hard to know if the trail tread is out-sloped. A digital level is useful for determining whether it is and to what degree. Professional trail builders use the SmartTool Electronic Level, which is available in 2- and 4-foot sizes. There are apps for this as well. Like others on this list, the apps don’t work quite as well as the real deal, but they’re handy when in a pinch.

Tip: Be sure to check your calibration regularly to keep your digital level reading properly.

Webinars on YouTube that you might like

Trail Assessment for Accessibility and Sustainability

Feb 29, 2024

This webinar will explore the process of assessing natural surface pedestrian trails for accessibility and sustainability and will focus on developing new trails as well as conversion of existing trails.

Systemic Condition Analysis and Management for Multi-Use Trails

Feb 8, 2024

This webinar addresses the critical need for cyclical assessment and repair of a multi-use trail system to keep up with the usage and level of service demands from the public with a limited budget.

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