Transit Phases

Urban Transit in the United States has six major phases**:

1. Street Railroads
2. Subways/Elevated
3. Street rail
4. Bus-titution
5. M/ART
6. Light Rail

Street Railroads is exactly as advertised: Railroads reaching the city center, run on city streets. Noisy and dangerous, they are largely extinct. Most cities relocated several of them to a common corridor (typically as part of a Union Station effort). Building a 'viaduct' over them was a popular addition after WW2. Never electrified, they belched smoke and scalding steam as they traveled

Subways/Elevated were the first round of solutions to street railroads. Two solutions emerged: elevating them, and under-grounding them. As elevating is cheaper than excavating, it was the preferred alternative. (And railroads already knew how to build viaducts). Manhattan once had elevated rail-lines running down second and 9th avenue (of which the High line is the remainder). London forced another solution. The 'City of London', the original Roman square mile inside the greater metropolis of London has its own municipal government. Disliking the nuisance effects of railways, they simply banned them on city streets. (And now you know why London has so many railroad stations). But the value of bringing a rail-line INTO the center of London was simply too great, and so the Under-grounding began, in 1863. Chicago, with it's plethora of railways, still maintains its elevated stations ('The El').

Street rail: Everyplace with even a presumption of being a 'city' built a street railway. Using railroad track, these were smaller, lighter vehicles called 'trolleys'. There were a handful of attempts to draw them using engines, but electrification (using the pantograph) became endemic.* 

Inter-Urbans: A hybrid streetcar/railroad deserves a passing mention, if only for it's later importance for light rail. Combining street-running sections in urban centers, and railroad right of way between cities, they filled a niche market, typically by connecting urban destinations to entertainment or educational institutions. Some used trolleys, and some were special 'school trains'. 

Bus-stitution represents the dark age of urban transit. (To those who love trains, at least). Worn out trolleys were replaced were shiny new buses. (Cue Roger Rabbit). Streetcars were already in decline beforehand. The only rail routes to survive were underground/elevated systems, or places with awkwardly narrow tunnels. 

M/ART refers to the period between WW2 & the advent of light rail in the United States.  But in 1970, we recognized we had 'an urban transportation problem', which is the preferred euphemism for the explosive growth in traffic congestion.
Transit was the clear solution. But even the solution was a problem. Private companies had built most of the transit infrastructure before 1928, and municipalities getting into the game only in response to their failure. But no private entity was willing to build transit in 1970--competition from the automobile was just too fierce. Conservative pundits love to argue that this reflects the innate attractiveness of the automobile. They also love to ignore the billions of dollars in Federal subsidy provided for the Interstate Highway system. So, it order to compete with the automobile, transit projects required a subsidy. Given that the 70's were sort of the high-water mark of 'big government' and centralized planning, it became a Federal project.


None of them did terribly well, at least at first. They had very high costs per rider. For some of the systems, for some years, it would have been better to either a) buy everyone a cheap car, or b) put all of the money into buses. They've done better over time, as traffic congestion has worsened, and developers have responded to the accessibility premium of locations near them, so more things are near them. BART won its spurs when the Bay Bridge collapsed. The DC metro has become the most-ridden transit system in the US.

Light Rail The return of the inter-urban! Known as 'City-Rail' (Stadtbahn) in Germany, it made use of freight right of way, with street running portions in the center of cities. APTA called them 'light rail' so suburbs would accept them. Successful, at least judging by their popularity.  They make use of a variety of types of running-way.

Streetcars are history repeating itself. They are street-rail come again--trolleys operating in mixed traffic.  Portland has made them famous, and their use as a successful economic development project means that every major city in America is either building one, or planning to. The dividing line between street cars and light rail is not a clean one. (Salt Lake has a 'streetcar' in its own railroad corridor, and a 'light rail' on a city street'.)
Both make use of all types of running way. Streetcars generally have shorter lines, smaller vehicles, lower speeds, and more frequent stops. My analysis showed that average stop spacing is most distinctive. Portland, Tucson and the Tacoma Central Link all have an average stop spacing about half that for other systems. 

*Yes, cable-cars existed. Yes, a number of hilly places used them, most notably San Francisco. But even more places used funiculars, and I'm not mentioning them. Today, they are both simply exotic survivals. 

**BRT will require discussion elsewhere

**CRT too.