Turns for the Better

Instructor: Christine Byl & Gabe Travis, Interior Trails
Cost: $300.00 per person (includes lunches both days)
Workshop Dates: March 17-18, 2017, 8 am - 5 pm each day


Learn how to design and lay out a perfect direction-reversing Sweep Turn or Switchback on various side slopes. Use standard survey tools to create a geometrically precise layout, minimize construction time, and connect trail leg approaches at the proper grade. Gain an understanding of the effects of different slope angles on layout, construction, traffic wear, drainage and maintenance. Discuss user groups and how those parameters affect decisions about turns. Learn how to minimize common mistakes made when laying out "by instinct" alone. One day of classroom instruction, one day of field exercises. Please bring a manual compass w/ protractor and a clinometer, if you have them available.

This class is largely about the structural geometry of direction-reversing turns (sweep turns, switchbacks, and some of their variants), and the fundamental role of both sideslope angle and soil integrity in that geometry. We will be focusing on turn layout, in particular how to make it accurately reflect the turn geometry and respond to site terrain limits, and on how layout choices predict construction difficulty, traffic flow through the turn, and long-term durability. We'll cover the geometry, angles and math behind turns (a pocket calculator will be handy at times), as well as more intuitive guidelines and a discussion of aesthetic components of layout. You will receive a binder of text covering everything we’ll talk about so note-taking should be minimized.

In the classroom segment, which will last from 4 to 6 hours, we’ll cover the basics of sweep turns (both slope-grade and controlled-grade), fishhook turns, banked turns, standard switchbacks, full-bench switchbacks, and “simple switchbacks”. In the field we’ll first acquaint ourselves with the role and use of the clinometer for turns in particular, and the magnetic compass used as a field protractor. Then in teams you will get to lay out a variety of turns on varying sideslopes, and decide which turn type best fits a particular site, weighing such factors as traffic type and volume, minimum tread width, minimum turn radius, drainage difficulties, and both tread and terrain stability. Class ratio should allow plenty of time for small group contact with instructors.


Day 1: Classroom discussion of above, with handouts, power-point, drawings & photos, and plenty of time for class discussion. Intro to layout tools in the field.

Day 2: Field Exercises: in small groups, laying out and staking turns in a variety of settings. There will be plenty of discussion on site as well as hands on instruction for folks at a variety of level of experience.


Appropriate field gear for the weather. Expect to be outside both days of the workshop. We are in the Pacific Northwest. Expect rain and be pleasantly surprised if it stays dry.


Christine Byl & Gabe Travis, co-owners of Interior Trails, have been building trails for more than 20 years. After 12 years working on federal trail crews in Glacier NP, Chugach NF and Denali NP, in 2008 they founded Interior Trails, specializing in sustainable trail design, layout, construction, consulting and training in Alaska. Christine & Gabe have layout and design to clients from across the country. They live on a few acres of tundra north of Denali National Park and spends as much time as possible in wild places by foot, bike, ski, boat and dog. For more information on Interior Trails, visit www.interior-trails.com.