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Some more comments from a recently completed 72 day, 4,100 kilometres cycling touring trip through the States of Montana, Idaho, Washington, Oregon, and California with the southern terminus being Santa Barbara.
Cycling on Interstate Highways
Questions frequently asked: “You cycle on interstate highways? Why would you want to cycle on interstate highways? Why would you not use frontage roads beside interstate highways instead?”
Cycling on Interstate Highways.
I-90, Ritzville, WA
©Photograph by H-JEH Becker, 2012
Well, I do and enjoy the opportunity to do so in the mid-western states where there are very few access limitations to cyclists.
Cycling on Interstate Highways with trucks, buses, motorcycles, and other vehicles.
I-90. Missoula, MT
©Photograph by H-JEH Becker, 2012
There are many reasons for this. One does have to accept the noise of trucks, cars, and motorcycles passing continuously by.
Rethreaded tire litter on Interstate Highway shoulders.
I-90, Washington State
©Photograph by H-JEH
Becker, 2012
Somes steel removed from the front tire of the touring bicycle. It was difficult to get out. Fortunately, no flat tire.
Interstate Highway I-5, Williams CA
©Photograph by H-JEH Becker, 2012
One has to put up with unmaintained highway shoulders littered with junks of rethreaded tires cast dangerously out on road shoulders by fast speeding trucks. One has to put up with risks of tire flats from the steel sticking out from these junks of rethread tires or broken off steel pieces deposited on highway shoulders. Flats can happen at the most undesirable time late in the day, during rain downpours, on steep hills, when time is getting late to reach the night’s destination, when energy has been burned up, and so on. On has to be continuously aware of other garbage thrown out of cars and trucks that could cause problems for cyclists. Ah, nothing like cycling on the shoulders of interstate highways after a cleaning.
Wide shoulders on interstate highways with rumble strip separation of motor traffic and cyclists.
I-90, Missoula, MT
©Photograph by H-JEH Becker, 2012
Noise from passing trucks and wind effect on cyclists.
I-5, Weed, CA
©Photograph by H-JEH Becker, 2012
Interstate shoulders provide a cyclist with the comfort of exclusively cycling on a surface with a width of a traffic lane while separated from motorized traffic usually by rumble strips. There is the glory of cycling on such a wide shoulder where passing traffic does not require attention. The noise is the nuisance not the behaviours of motorists. Wind effects of passing trucks and buses are usually nullified, except for very strong crosswinds.
Interstate highways tend to have hills with less grade than frontage roads.
I-5 Chehalis, WA
©Photograph by H-JEH Becker, 2012
Frequently there are frontage roads next to interstate highways. How far do these roads go? Are there intersections at the end of these roads to cycle onto the interstate highways?
I-90 Moses Lake, WA
©Photograph by H-JEH Becker, 2012
When time is a consideration, interstate highways provide a cycling surface with the least amount of grades in the most direct way to that day’s destination. Frontage roads tend to have steeper grades and more wind, and seem to attract drivers’ speed and drift through curbs using the full road width.
One is never certain how long there will be a frontage road and how to continue the trip without doubling back to the last intersection or lifting a bicycle and its panniers over a fence onto an interstate highway.
Oh yes, one might actually come upon a convenience stop once a day on interstate highways.
Rest stops along interstate highways. At least one for each cycling day.
I-90, Washington State
©Photograph by H-JEH Becker, 2012
Rest stops along interstate highways. At least one for each cycling day.
I-90, Moses Lake, WA
©Photograph by H-JEH Becker, 2012
Rest stops along interstate highways. Windmill powered electricity for the rest stop.
I-90, Washington State
©Photograph by H-JEH Becker, 2012
When sections of highways restricted for cyclists use are reached, some states provide signed alternate routes until they are allowed back onto the interstate again (I-90 Bike Trail, for example).
The sign that cyclists hate to see when on a trip.
©Photograph by H-JEH Becker, 2012
Cycling on interstate highway is restricted. Alternate cycling route is signed.
I-5, Spokane, WA
©Photograph by H-JEH Becker, 2012
An alternate cycling routing along a bike trail parallel to an interstate highway.
The Coeur d’Alene Trail parallel to the I-90.
From Mullen to Harrison, ID
©Photograph by H-JEH Becker, 2012
An alternate cycling routing along a bike trail parallel to an interstate highway.
©Photograph by H-JEH Becker, 2012
So, when there are no alternative roads readily available, interstate and other restricted-access highways provide more direct routes for cyclists. When the scenery is the same for all parallel roads, then interstate highways provide less demanding hills for cyclists.
Interstate highways with wide, paved shoulders, with wide shoulders or bike paths on bridges, with rumble strips providing separation between motor vehicles and cyclists, with maintenance programs calling for frequent removal of debris from highway shoulders, with convenience stops comfortably spaced apart for senior-aged cyclists, with signed, alternate cycling routes for section of highways restricted to cycling, with underpasses at high-traffic intersections, then these highways provide a pleasant alternative for cyclists who can handle the noise. Government banning of rethreaded tires would also take away the concern of flats on trips, especially for those cyclists that are not adept at changing flat tires or would not make a trip by bicycle because of fear of flats.
Third Wave Cycling Blog 
I am thinking about cycling coast to coast. I would prefer to cycle on the interstate. As you mentioned it is relative flat and it is relatively straight too. I don’t know much about the cycling rules/laws as they apply to the interstates across America. Is cycling on all of the interstates permissible? Where can I find more information about cycling on the interstates in the 48 contiguous states.
It takes a lot of internet searches and patience to find out where one can cycle on interstate highways and not. Try the various states’ Department of Transportation websites. Try this website from Adventure Cycling Association for alternate routes – http://www.adventurecycling.org/routes-and-maps/us-bicycle-route-system/usbrs-101/. “The U.S. Bicycle Route System (USBRS) is a developing national network of bicycle routes, which will link urban, suburban, and rural areas using a variety of appropriate cycling facilities. To date, 10 U.S. Bike Routes have been established in 9 states: Alaska, Kentucky, Illinois, Maine, Michigan, Minnesota, New Hampshire, North Carolina, and Virginia. Presently, more than 40 states are working to create U.S. Bicycle Routes.”