Photo by Jesse Vermeulen, posted at Unsplash.
First Path
The 30-Minute City by David M. Levinson
In the beginning was the path. It was undifferentiated, shared by people and animals alike, and eventually wheeled vehicles pulled by humans and animals. While dating the First Path is impossible -- the very first First Path must have been a path that was reused once, and slightly better than the unimproved space around it -- it operated both in early settlements and on routes connecting nearby settlements.
Today's version of that is the sidewalk or footpath. It is now used for people walking, sometimes for people moving goods, and occasionally for people on scooters and bicycles. It should not be used for storing cars, though it is. New uses will include low speed delivery robots, as shown in the photo from Starship.
When we see a raised crosswalk, we know the First Path is given the pre-eminance its venerable status warrants. When we see shared spaces, we know those harken back to the early undifferentiated path-spaces of earlier centuries. When we see pedestrian-only zones, we see a First Path that has grown up.
Second Path
The Second Path diverges from the first path with the emergence of the first street or roads with sidewalks (footpaths). Spiro Kostof (1992) dates it to about 2000 BCE in Anatolia. And it is clear many Roman and Greek cities separated sidewalks from streets, which the Romans called Semita.
Post-Rome, sidewalks were rare, making appearances in London after the Great Fire, and in Paris after Haussman.
But to be clear, today's sidewalk is not the second path, it is the first. The second path is the road which is largely free of pedestrians, intended for the movement of vehicles. Originally these were animal powered vehicles, as well as human. Later fuel-powered machines took over the street and roads.
It is easier for a camel to go through the eye of a needle, than for a rich man to enter into the kingdom of God.
Third Path
The Third Path actually emerged well before the Second Path was colonized by motorized vehicles. It is for bicycles, and initially was paved in contrast with the unpaved streets and roads of its time. Given the first Velocipede was only 1817, and the first bike chain (which we associate with modern bicycles) was 1885, these came relatively quickly compared with the First and Second Paths. While ascertaining the first bike lane or separated bike path is tricky (there are many claims, differing in nuance), I have compiled some claimed firsts and earlies here (thanks to people who replied on Twitter):
Maliebaan, Utrecht, Netherlands (1885)
Seattle, 1890s
Copenhagen, Denmark Esplanaden (1892)
US Good Roads Movement (1880s-1920s)
Brooklyn, Ocean Parkway (1894)
St. Paul, Minnesota - Summit Avenue boulevard (1896)
Cyclists Avenue was opened in Centennial Park, Sydney in 1900
Oldest continuously operating bike lane (since 1907) in Germany
Davis, California (1966)
While bike lanes have now been around as a technology for well more than a century, throughout most of North America and Australia, bike lanes are not provisioned, so bicyclists have the Hobson's Choice of driving in traffic with much heavier and much faster automobiles and trucks on the Second Path, the roadbed or illegally in many cases on the First Path, the sidewalk.
With the advent of the smart phone, new modes are becoming feasible, most notably dockless shared bikes and scooters.
Regulations in many places limit the use of bikes on footpaths. The reasons for this are clear from the pedestrian's point of view, bikes are traveling up to 4 times faster than walkers, and collision can create injury. Dockless shared bikes emerged in Australia in 2017, after a few years on the road in China. Their main contribution has however not been transport (they are used about once every 3 days) but instead as a the recipient of complaint about sidewalk clutter (unlike say cars, which are always parked perfectly). As a consequences they have been targets of vandalism. The obvious solution will eventually get adopted, geofenced corrals for parking bikes (shared and private), taking away one parking space per block perhaps.
Given the disparities of speeds on the first (5 km/h) and second paths (30-120 km/h), there is a clear market niche for an infrastructure network for vehicles faster than foot and slower than cars. Physically, one imagines it generally lying between the existing kerb and removing a lane now devoted to the storage or movement of cars. And for many if not most urban places globally, this has been recognized and networks of third paths have been, or will be, built out.
This Third Path is important not just for bikes, but for electric bikes (which are becoming increasingly feasible with progress in battery technology) and electric scooters.
Fourth Path
A Fourth Path for buses (and other high occupancy vehicles) is also now considered. The first bus lane emerged in Chicago in 1940. The reason for bus lanes again is in part operational differences compared with existing road users. Buses start and stop in traffic much more frequently than cars. But a second reason is in fact the opposite, not because buses would block cars, but because cars would block buses. Buses carry more passengers than cars, and so should move faster, and can do so if they are not stuck in queues behind cars.
Interfaces
The Kerb - Once a nondescript piece of concrete now forms the edge (both physically and metaphorically) of the sharing economy: taxis, Ubers, autonomous mobility services. The Kerbspace differentiates and separates paths, but we now have new questions:
Who manages kerbspace?
How is it regulated?
Is it even mapped?
Comp(l)ete Streets
The complete streets movement advocates for streets with sidewalks, bike paths, and are otherwise designed to promote safety and efficiency. The figure below is not exactly what they have in mind.
Justicia Urbana by Todorovic (https://www.flickr.com/photos/unhabitat/23003427510)