Transit network effect becomes visible - in Los Angeles
The Los Angeles Daily News reported at mid-July 2012 that some commuters were traveling miles out of their way on a new light-rail (LRT) line between San Fernando Valley residences and employment locations along the new Expo Line.
(See "San Fernando Valley commuters flock to new Expo Line," by Dakota Smith, Los Angeles Daily News, July 15, 2012. This story was picked up by other media outlets; e.g. Commuters Pack Bus, Rail Lines to Dodge Sepulveda Pass Congestion, by Chris Sedens, CBS Los Angeles, July 16, 2012.)
As described by Dakota Smith, the new Expo Line is promoted as a transit alternative for downtown Los Angeles, Culver City and the "Westside." However, the "Valley" residents - who live some distance northwest of downtown - ride the Red Line subway from North Hollywood and Universal City to 7th Street / Metro Center1 station, then change to the Expo Line.
This example of the "transit network effect" - in brief, the value of one line is increased by the presence of other lines - does not surprise us - but did surprise some L.A. transportation officials, according to the L.A. Daily News story.
A bit of background:
1.) Phase 1 of the Expo Line extends from a junction at Washington Boulevard and Flower Streets (a location we have dubbed "Trade-Tech Junction"2), southward and westward to Culver City station, 14.0 km / 8.7 mi. It was opened in two stages, on April 30 and June 20, 20123. Phase 2 will extend from Culver City westward to Colorado / 4th Street terminal in Santa Monica 10.6 km / 6.6 mi, a few blocks from the Pacific Ocean. Construction is planned to start during 2012, and opening is planned for 2016.
2.) To those not familiar with Los Angeles, the dilemma facing commuters who travel by car between the eastern San Fernando Valley and western L.A. is perhaps not clear at quick glance (e.g. using "Google Maps" or "Google Earth").
One might expect that a North Hollywood resident traveling to work in Culver City would simply drive west from, say, Vineland Avenue via the Ventura Freeway to the San Diego Freeway, 9.3 km / 5.8 mi, then continue 19.7 km / 12.2 mi south to the Washington Boulevard / Culver Boulevard exit. However, this 29-km / 18-mi trip is anything but straightforward during peak travel times on weekdays (and at other times as well). The San Diego Freeway, officially Interstate-405, is known to residents as the "four-oh-five." It is also known (and cursed, and dreaded) for traffic congestion. The junction ("interchange") with the Ventura Freeway is ranked consistently among the five most-congested road junctions in the U.S. The segment which crosses the Santa Monica Mountains in Sepulveda Pass is also known for traffic congestion. Yes, there are alternate routes through the mountains (including one, Sepulveda Boulevard, which parallels the freeway) and yes, they do make interesting drives. However, these "alternates" are much slower and have much less capacity than the freeway (used by about 300,000 vehicles per day in the pass). In sum: a trip that might require 20 minutes on uncongested roads often requires 40 to 60 minutes, or longer given major disruptions caused by car crashes or other incidents.
Some media commentators express surprise about the fact that Los Angeles has a subway. This lame gag might still draw laughs in some circles, but the Red Line, opened in stages between 1993 and 2000, averaged more than 160,000 weekday boardings at June 2012. More to the point, the scheduled travel time between North Hollywood terminal and 7th Street / Metro Center, 22.9 km / 14.2 mi, is 24 minutes. This provides a commercial speed of more than 57 km/h / 35 mph.
The scheduled travel time between 7th Street / Metro Center and Culver City by Expo Line is 29 minutes, providing a commercial speed of 29 km/h / 18 mph. The total travel time, allowing for the transfer in downtown L.A., is about 60 min.
"The bus," commented an Expo Line passenger quoted by the L.A. Daily News, "is bumpy. This is so much smoother and quieter. I'll read. I'll do the emails going in."
The "network effect" is a concept dating back more than a century, and was first articulated with reference to telephone systems: as the number of people with telephones increases, the usefulness - and value - of each telephone also increases. The analogy to public transportation is obvious: the more locations served, the more valuable the network. However, much "network theory" pertains to wired and wireless communications systems. The movement of electric currents, light (in fiber-optics networks) or electromagnetic radiation is virtually instantaneous; the movement of people (and the vehicles in which they ride) is not. Waiting time (as for a vehicle) is not a characteristic of communications networks - and "transfers" between pathways (circuits or channels) pose virtually no issues.
The "transit network effect" should become visible given:
1.) High-quality service on each line (very high schedule adherence and good commercial speed, together with accessibility, comfort and security), and
2.) Interchange facilities that make it easy for passengers to transfer between lines.
That is exactly what has been reported in Los Angeles.
7th Street / Metro Center station in downtown L.A. is a well-designed passenger interchange. It requires a minimum of walking between lines, compared to what one may find in other U.S. cities (or even in L.A., between the Red Line and Gold Line LRT trains). The Red Line - a key element in this story - provides high commercial speed as noted above, frequent service and high schedule adherence. The Expo Line is not nearly so swift, but service is frequent - and reliable.
The "transit network effect" is cited by Mees (1997, 2000) as the primary explanation for why Toronto, Canada, has higher transit patronage per capita and a larger transit modal share than Melbourne, Australia. Woo (2009) found that the "network effect" was one of several factors which explained the better performance of Toronto transit for the years 1999-2001 and 2006.
Arbury (2010) provides an illustrated example (from Mees 2000) on how creation of a "grid" network would greatly increase the number of destinations accessible without transfer - and with transfer. The hypothetical "Squaresville:"
. . . has a grid road network, with ten north-south and ten east-west roads, at intervals of half a mile or 800m. travel patterns are completely random, with no dominant pattern of movement. Each of the city’s 100 square blocks produces 100 trips a day: one internal trip (made on foot), and one external trip to each of the 99 other blocks of the city – giving 9900 external trips in total.
The hypothetical "Squaresville" also has a transit system, consisting of ten north-south bus lines:
. . . each resident of Squaresville has a bus within 400m walking distance, but can only reach the nine other city blocks lying along her or his bus route, giving access to 900 daily trips out of the total of 9900. Assume that public transport attracts a third of the trips it can theoretically serve, this gives a total of 300 trips (a third of 900), or a city-wide mode share of only 3 per cent.
If "Squaresville" implements a "grid" network by adding ten new east-west bus lines,  makes transfers convenient, provides integrated fares, convenient facilities and coordinated schedules, then:
The number of trips served directly doubles, to 1800 [as there are now 20 routes], but by transferring between routes, passengers can now access the entire city, so the network also serves the remaining 8100 trips. Squaresville’s planners do everything possible to make transfers convenient, providing integrated fares, convenient facilities and coordinated timetables. But since so many transport analysts say that passengers dislike transferring, let’s assume that the mode share for trips requiring a transfer is only half that for direct trips, that is one-sixth. So the total number of public transport trips is one-third of 1800 plus one-sixth of 8100, giving a total of 1950.
Under the second model of service provision, public transport’s mode share has jumped dramatically, from 3 to 20 per cent. Service has increased 100 per cent, but patronage has grown 550 per cent, giving an elasticity of 5.5. Increased revenue would more than cover the costs of the additional service and occupancies would rise substantially, reducing subsidies and greenhouse emissions per passenger.
(Mees 2000, as quoted by Arbury 2010).
The extensive literature on transit "transfer penalties" (see, for example, Iseki, Taylor and Miller 2006) includes few observations of consumer behavior. It is one thing to write that:
. . . travelers tend to consider out-of-vehicle travel time (walking, waiting, transferring, etc.) to be substantially more burdensome than in-vehicle travel time (Iseki et al. 2006).
It is an entirely different - and, we assert, necessary - undertaking to observe the choices that people actually make in the "real world."
As described above, some San Fernando Valley residents now travel via downtown L.A. to jobs in Culver City and the Westside - transferring en route and going a significant distance "out of their way". This makes clear that further research is indicated into the "transit network effect" and the influence of the "transfer penalty" on same.
We will present additional comments on this subject in a subsequent post.
Arbury, Joshua. 2010. "'Squaresville' and the network effect." Auckland Transport Blog, 2010 February 24.
Iseki, Hiroyuki, Brian D. Taylor, and Mark Miller. 2006. The Effects of Out-of-Vehicle Time on Travel Behavior: Implications for Transit Transfers. Los Angeles: Institute of Transportation Studies, University of California, Los Angeles, School of Public Affairs, and Richmond (CA): California PATH Program, Institute of Transportation Studies, University of California, Berkeley. (Prepared for California Department of Transportation, Division of Research and Innovation.) Pdf document.
Mees, Paul .A. 1997. Public Transport Policy and Land Use in Melbourne and Toronto 1950-1990 (Thesis, PhD, Faculty of Architecture, Building and Planning, University of Melbourne, Melbourne, Australia).
__________. 2000 A Very Public Solution- Transport in the Dispersed City. Carlton South, Victoria: Melbourne University Press.
__________. 2010. Transport for Suburbia: Beyond the Automobile Age. London: Earthscan.
Woo, Karen Francis. 2009. Investigation of the relationship between transit network structure and the network effect - the Toronto & Melbourne experience (Thesis, Master of Applied Science, Department of Civil Engineering, University of Toronto). Pdf document.
For Further Reading:
CityRailTransit [Javier Martínez Cuevas]; see (Los Angeles Real Distance Metro Map).
Friends 4 Expo Transit (advocacy group).
The Source (Metro news blog).
1 The full official name of this station is 7th Street / Metro Center / Julian Dixon.
2 The location is at the north corner of the Los Angeles Trade-Technical College, which is known among Angelenos as "Trade-Tech."
3 Stated opening dates are those on which revenue service began, e.g. the dates on which fares were first charged.