Snow, Mudslides, and Road Construction on the Adventure Cycling Route Network

March 30, 2018 - Carla Majernik is Adventure Cycling's Routes & Mapping Director.

A Glacier National Park plow clearing snow on Going-to-the-Sun Road.
A snow plow in Glacier National Park, late May 2017, clearing Going-to-the-Sun Road near the Rimrock area.

Snow, mudslides, and road construction may cause delays on the Adventure Cycling Route Network. Here’s what we know right now, and here’s where traveling cyclists can stay informed: Temporary ACA Route Road Closures.

Mother Nature Rules the Northern Rockies

The best laid travel plans can be thwarted by Mother Nature. You should be aware of the following if your plans include travel in the northern U.S. in late spring and early summer 2018.

Late winter storms have increased snow levels higher than normal in the Rocky Mountains of Canada and Montana. As a result, some mountain passes will be closed until later in the season.

If you are riding the Northern Tier or the northern part of the Great Divide Mountain Bike Route, you might want to delay beginning your trip by several weeks. Warm temperatures this spring may speed the disappearance of snow, but flooding is also predicted in some areas. And of course, a cool spring will slow the melting of the snow on all mountain passes.

In Glacier National Park, no date has been set for the opening of Going-to-the-Sun Road over Logan Pass. Updates on the status of the road can be found at the park website.

Road closure: Mud Creek slide on California's State Route 1.
Aerial photo of the Mud Creek slide on California's State Route 1 taken on May 27, 2017, one week after it occurred. The distance across is approximately 0.3 mi.

Mudslide Closes California’s State Route 1 (SR 1)

Though the collapsed Pfeiffer Canyon Bridge has been replaced on SR 1, California is still dealing with mudslide cleanup from 2017. The massive Mud Creek slide on our Pacific Coast bicycle route’s section 4, map 49, hasn’t been cleared yet and will keep 5.7 miles of SR 1 closed until September 30, 2018. The closure is north of Ragged Point in Monterey County. A detour and shuttle information is discussed in this forum:  Temporary ACA Route Road Closures

Other closures may occur periodically on SR 1 through the spring. Closures are listed at Caltrans Highway Conditions website, as well a wealth of information at the blog BigSurKateAdditionally, if we learn of further closures, we will post information to our Temporary ACA Route Road Closures forum discussion, and we encourage cyclists to do the same.

Highway construction status on U.S. Highway 12 and Adventure Cycling's Transamerica Trail in Idaho.

Construction Season Impacts the Adventure Cycling Route Network in Idaho

In Idaho, more than 50 miles of roadwork and two bridge replacements will occur between April and October 2018 on U.S. Highway 12 along the Lochsa River corridor. This affects the TransAmerica Trail, sections three and four on our maps, and the Lewis & Clark Trail, sections five and six on our maps.

There will be significant delays. Adventure Cycling is still talking to the Idaho Transportation Department (ITD) about options to help cyclists traverse the roadway. ITD is maintaining a project website to keep the public up to date. We will also add more information to the Temporary Route Road Closure Forum discussion for the TransAmerica Trail and Lewis & Clark Trail bicycle routes as we have it.

Photo 1 GlacierNPS Flickr album | Photo 2 U.S. Geological Survey.


GEOPOINTS BULLETIN is written by Jennifer ‘Jenn’ Hamelman, Routes & Mapping Assistant Director, and appears once a month, highlighting curious facts, figures, and persons from the Adventure Cycling Route Network with tips and hints for personal route creation thrown in for good measure. She also wants to remind you that map corrections and comments are always welcome via the online Map Correction Form.


Log in to post a comment

Forgot Password?

Enter your email address and we'll send you an email that will allow you to reset it. If you no longer have access to the email address call our memberships department at (800) 755-2453 or email us at

Not Registered? Create Account Now.