Categorizing vehicle types

The following categorization of land vehicle and pedestrian types may be helpful in understanding infrastructure issues. I am leaving out snow modes — travel on snowshoes, cross-country skis, or in sleds, sleighs, snowmobiles. They exist in a world unto themselves, serving mostly when and where snow makes other travel modes impractical.

Otherwise, the two fundamental categories are pedestrians and vehicles. Pedestrians generally travel at a walking pace and have the ability to turn in place, or to sidestep. Vehicles can only turn by steering, and travel at a speed which poses a hazard to pedestrians.

Categories generally considered pedestrians:

• walkers
• people in wheelchairs
• people in electric wheelchairs
• small children on tricycles and sidewalk bicycles
• slow novice cyclists on bicycles, following pedestrian rules
• skaters
• people on push scooters
• people on roller skis
• skateboarders
• Segways — they can turn in place, though their 18 mph speed potential and limited cornering ability make their definition as pedestrians controversial.

Vehicles generally considered bicycles:

• unicycles
• bicycles ridden by teen and adult cyclists
• cargo tricycles
• bakfiets (long bicycles and tricycles with a front compartment for cargo)
• electrically-assisted bicycles
• adult tricycles and quadracycles, both upright and recumbent
• pedicabs
• bicycles with baggage trailers and child trailers
• especially-long bicycle rigs such as tandems, tandem bicycles with trailers

Animal-powered, foot-powered vehicles (“the First Vehicles” — thanks to Mighk Wilson of the Orlando, Florida metropolitan planning organization for that observation):

• riders on horseback or on other animals (donkeys, oxen…)
• animal-drawn vehicles
• rickshaws
• pushcarts

Narrow, motorized vehicles:

• mopeds; electric and gasoline-powered motor scooters
• motorcycles

Wider motorized vehicles or quasi-vehicles:

• Tricycle motorcycles
• Motorcycles with sidecars
• Motorcycles pulling trailers
• “Golf cars”, “neighborhood electric vehicles”
• Microcars
• Cars
• Trucks
• Buses
• Tractors, farm vehicles
• Construction equipment
• Trackless trolleys
• Streetcars

Now, the point of this discussion: Many bicycling advocates favor separate paths, or parts of the width of streets set aside for bicyclists and separated by barriers from travel lanes for motor vehicles. But this rigid approach to use of space makes an awkward fit to the diversity of vehicle types and their overlapping operating characteristics. A few examples:

• As has often been stated: any so-called bike path also will be used by pedestrians, slowing the bicyclists and leading to conflicts and danger.
• Inline skaters don’t fall neatly into the category of pedestrians, but still use paths. Also, bike lanes often are designated for the use of skaters. With flailing arms and legs, inline skaters are more difficult than other pedestrians for bicyclists to overtake.
• Pedicabs fit into the category of bicycles in terms of their speed and how they are powered, but pedicabs are banned from separate bikeways in New York City because they are wide. Result: they slow motorists in the roadway, which already provides less room for other vehicles to overtake because it has been narrowed to construct the bikeway.
• The vestigial pedals of mopeds are generally used to conform them to the legal definition of bicycles, as footrests, and to start the motor. Still, mopeds are generally prohibited from shared-use paths because they are faster than most bicyclists and because of smoke and noise. Electrically-assisted bicycles, on the other hand, are more often permitted on paths.
• Long bicycles and bicycles with trailers can not pass through the bicycle mazes intended to prevent motor vehicles from entering some paths. Single-track motorized vehicles (mopeds, motor scooters and motorcycles) can.
• Golf cars can have all of the equipment required of other motor vehicles to be street legal (lights, horn, seat belts, etc.) and they are non-polluting too, but are prohibited from many roads because they are not capable of high speed. Construction equipment, which has the same speed disadvantage and often a smoke-belching diesel engine, and usually is larger, is permitted on most roadways.

All of these examples point to the conclusion that the distinction between pedestrian and vehicle operator is important, but otherwise, infrastructure can generally best accommodate the different categories of users if roadway width is not split up by vehicle type. Once that is attempted, inconsistencies begin to multiply.

Also, and probably even of more importance, a fundamental issue in road design is to not prevent the application of standard, simple rules of the road. The rules become more complicated and confusing when accommodating different categories of vehicles in separate lanes or barrier-separated parts of the same roadway.

Separation is most commonly suggested for bicyclists, but my observation applies to motorists as well. For example, prohibiting trucks from the leftmost lane on limited-access highways increases truckers’ incentive to tailgate other motorists in the lanes to its right.

I favor instead the designation of different streets, roads and highways for different uses as needed. I think that it makes sense to designate streets, roads and highways to favor different types of use (local, collector, arterial) while, importantly, not denying access to all destinations in any type of vehicles. So, we might designate truck routes for through travel by the larger and more cumbersome vehicles. Bicycle boulevards — (through routes for bicycles on streets only usable for local access by motorists) also can be useful.

Limited-access highways — those with no destinations except other roads — may serve only faster vehicles without violating this principle, as long as there is shoulder access or an alternate route for slower vehicles. Paths, despite their deficiencies, also can be useful to bicyclists as shortcuts and for access to locations (for example, in parklands) not served by roads.

And — skaters, skateboarders, streetcars and perhaps other devices not yet seen, don’t fit comfortably into the category either of vehicle or of pedestrian. These will continue to pose design and legal challenges, no matter how accommodated, or not accommodated!