Are bicycles allowed on the freeways?

• Did I just see someone bicycling on the freeway shoulder? Is that even allowed?? 

Well, if you were driving on specific stretches of some freeways, you probably did! 

Generally, bicycles and pedestrians are not allowed on the freeway, except for specific one-exit stretches where there is no reasonable surface street connecting point A to point B that a road bike can safely use.

These bike-legal stretches of the freeways are always only one-exit in length, and bikes are required to exit onto any rest area and to re-enter the freeway on the far side, so as to not cross any freeway access ramp. 

• How do you know which stretches of freeway are bike-legal?

If you are already driving on the freeway, you likely won't notice the bike-legal bits until it's almost over (there would be a little white sign on the right side of the freeway telling bicycles to exit, like the one in the last photo on this post). If you are entering the freeway at the start of a bike-legal stretch, the little white sign an the entrance of the on-ramp will not have 'bicycles' on its prohibited list. 

Above is the usual sign you see entering a freeway on-ramp.

This is the sign you see entering a bike-legal stretch of a freeway. Note the absence of 'bicycles' on the prohibited list.

Just to clarify, class I and class II E-bikes are also allowed where regular pedal bikes are. 

• In San Diego County, the designated bikeable stretches of the freeways are:

1. I-5 shoulder between Las Pulgas Rd (Camp Pendleton) and Oceanside Harbor Dr (and sometimes, between Basilone Dr and Las Pulgas Rd). 

This is due to USMC Camp Pendleton being an active military base. There is a designated bike route thru Camp P, but it requires a base access pass that is only available to US Citizens and Residents (how to apply for a Camp Pendleton base bike pass). And, even with the base pass, base access may also be suspended with little or no notice due to military activities. The I-5 shoulder between Las Pulgas Rd and Harbor Dr in Oceanside is therefore always bike-legal (except during construction/maintenance work on the freeway, in which case Caltrans will usually provide a shuttle service). 

2. I-15 shoulder between Via Rancho/Bear Valley Pkwy in Escondido and W Bernardo/Pomerado Rd in Rancho Bernardo (across San Dieguito River). There is a pedestrian/bicycle bridge running parallel to the west of I-15 accessible from Sunset Dr in Escondido and W Bernardo Dr in Rancho Bernardo, but it lies in the San Dieguito River Preserve, the north side of the bridge is a dirt trail and is closed at night between sunset and sunrise.

3. I-8 shoulder between E Willow Rd in Alpine/Viejas and Hwy 79/Japatul Valley Rd in Descanso. The only other ways to travel between Alpine and Descanso are the dirt Viejas Grade Rd and Tavern - Japatul Rd - Japatul Valley Rd. Both of which add significantly more climbing and/or distance. 

Please note that Caltrans is working on I-8 from the Vista Point rest area just east of E Willow Rd exit and on east for 10 miles starting in August 2022. This reduces eastbound lane to one travel lane, and no bicycles are allowed (a shuttle service for bikes needing to travel between E Willow and Hwy 79/Japatul Valley Rd, but you have to call, with likely significant wait time). More info at Caltrans. This only affects eastbound travel.

4. I-805 between Main St/Auto Park Dr and Palm Ave (Otay Valley). 

5. I-125 (South Bay Expressway) between Birch Rd (Otay Ranch) and Otay Mesa Rd (Otay Mesa).      

• The I-5 shoulder between Sorrento Valley Rd and Genessee Rd used to be bike-legal until a few years ago when the separated bikeway (a segment of the North Coast Corridor Bikeway) opened. Now bicycles are no longer allowed on that stretch of the freeway.  
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• In Imperial County to our east: 
• I-8 between In-Ko-Pah Rd. (Imperial County Line) and Junction with SR-98.
• I-8 between Imperial Hwy and Dunaway Rd.
• I-8 between Gordon’s Well Rd. and Ogilby Rd.
• I-8 between Sidewinder Rd. and SR-188/Araz Rd.

Heading west on I-8 from Japatul Rd to E Willow Rd.

Bikes must exit the freeway at any rest area (and re-enter on the far side), and off-ramp. No crossing of freeway access ramp allowed.

Most cyclists are really not keen on riding on these freeway shoulders at all. Sure, the shoulders are usually roomy and relatively clean, but the discomfort of having cars zoom by at 60+ mph just a few feet away quite offsets for it. A few of these freeway shoulders are also not good for riding during wind events (the bridge over the Sweetwater River on I-8 and the long bridge over the Otay River Valley on I-805 and Hwy 125 come to mind). 

If you see someone riding a bicycle on these stretches of freeway, they're doing it mostly out of necessity. Please be kind. They'll be taking the next exit off the freeway anyhow.