The concept of a freeway (a public way intended primarily for high speed travel over long distances) has resulted in a set of highways with engineering features such as long sight distances, wide marked lanes and the absence of cross traffic. These features provide faster and safer travel for all users.
Freeway users are usually limited to traveling by means of a motor vehicle with a certain minimum amount of power or weight; signs may be posted that prohibit other modes of travel (including bicyclist, pedestrian and equestrian), impose a minimum speed limit, or both. Non-motor vehicle travel on other facilities within the same right-of-way, such as sidewalks constructed along freeway-standard bridges) and multi-use paths constructed next to freeways (such as the Suncoast Trail along the Suncoast Parkway in Florida) is a commonly allowed exception.
In some jurisdictions, especially those where many of the freeways replaced rather than supplemented existing roads, non-motorized access on freeways is the rule rather than the exception. Different states of the United States of America have different laws and regulations. For example, bicycle use on freeways in Arizona may be prohibited only where an alternate route exists and that alternate route is judged by the state DOT to be equal or better for bicycle travel.
Should a freeway bridge or tunnel have no non-motorized access or alternate routes nearby, pedestrians and bicycles may be able to use buses if available, but they are rarely fare-free. If no buses, it may be possible to hire a taxi with higher fare payable. If no taxi is readily available or if a non-motorist has little or no fund, hitchhiking may become the last resort even if it may not be always legal, such as across the Bronx-Whitestone Bridge and the Verrazano Narrows Bridge with no more bike buses while hitchhiking is illegal in New York City, New York, USA and across the Delaware Memorial Bridge with very limited buses while hitchhiking is illegal in New Jersey, USA.
In some countries, such as the United Kingdom and Germany, the difference between a normal road and a freeway-class road (motorway/autobahn) is the restriction of low-speed traffic. Many roads are built to freeway standards but are not legally a freeway-class road for this reason. Indeed, some freeway-class roads are downgraded for short stretches, where no alternative route exists, to allow low-speed traffic to use that section; examples in the UK include the Cumberland Gap and Dartford Crossing, the latter being the furthest downstream public crossing of the Thames.
There is sometimes conflict between bicyclists and other users over this issue. According to research, 85% of all motor vehicle-bicycle crashes are a result of turning and crossing conflicts at intersections. Freeway travel eliminates almost all of those conflicts, save those at entrance and exit ramps - which, at least on those freeways where travel by bicycle has not been banned, have more than sufficient room and sight distance for reasonably safe interaction between cyclists and motorists. For example, an analysis of crashes in Arizona has shown no safety problems with bicycle traffic on freeways. Over an extended time period, less than one motor vehicle-bicycle crash per year was recorded on the nearly 2000 shoulder-miles open to bicycle travel in Arizona.
See also cycle path debate.