The Pitfalls of “Silvestri-style” Transit

In, The Best Laid Plans – Our Planning and Affordable Housing Challenge in Marin Mill Valley resident Bob Silvestri lays out his thoughts on urban design, affordable housing and regional planning.  He also riffs on public transportation in Marin.

Silvestri is not a fan of rail transit like SMART or even our local and regional bus service with their fixed schedules and fixed routes.  He argues that transportation and infrastructure planning should take its cues from internet software design where everything is so dynamic that the software is nearly out of date before it’s even complete.  It should be “borderless” and “have no central control point” and be designed and developed “at the edges”.    

For Marin County transit service he proposes….. “a fleet of relatively inexpensive (as opposed to SMART trains) electrically powered shuttle buses monitored and managed in real time by a wireless “demand” sensing system (21st century street cars). Each shuttle would travel on a “flexible” route that can adapt to rider demand. Riders with registered accounts or pre-paid trip cards can “tell” the system that they need a pickup at a shuttle stop by inserting their card in a reader or notifying the system via a smartphone app.” 

Fortunately, a flexible service that doesn’t adhere to a fixed route or schedule, and that can be summoned by a telephone or internet message, already exists in Marin.  We know them as taxi cabs and they’re quite useful.

The challenge is that while a ride from Novato to Sausalito will cost you $60 in a taxi, it only costs $2 on the bus.  Our bus fares are subsidized, so the true public cost of that bus ride is probably closer to $8.   However, if taxi rides were subsidized like the bus and moved the same number of people, it would multiply the cost of transit to the taxpaying public by several times.  It would push the $70M per year that we currently spend on Marin Transit and Golden Gate Transit bus service into the hundreds of millions of dollars.  

Given the high cost of demand-responsive transit, it’s rare.  It exists mainly in the form of paratransit which offers limited service for a limited set of seniors and the disabled.   Partransit has an average cost of $50 per ride in Marin County. 

To understand why a high-quality, demand-responsive service is so expensive compared to fixed-route service with a fixed schedule, consider the following scenario.  It’s a sunny morning in Marin and between 7:00 a.m. and 7:30 a.m., 1,000 people press an app at a wide variety of shuttle stops (according to Silvestri’s recommendation) requesting service to wide variety of destinations [note: 22,000 rides are handled daily by Marin and Golden Gate Transit].   How will this 1,000 person demand be covered? 

The best service possible would deploy 1,000 drivers in 1,000 separate vehicles, each willing to meet every customer relatively quickly and then drop them off at their preferred destinations.   This would require a fleet and labor pool five times the combined size of the exiting Marin Transit and Golden Gate Transit, but that still wouldn’t be enough.  Rides to San Francisco would take a long time, making vehicles unavailable to help keep pace with demand.  Costs would be staggering.

To keep costs in the realm of feasibility, a transit operator could have a smaller fleet with larger vehicles and the objective of transporting numerous passengers (rather than just one) at a time.  Theoretically, without fixed routes and schedules, a “demand sensing system” could digest all the incoming requests for service and use an algorithm to assign routes to drivers dynamically on the fly.   However, passengers would have little certainty from day to day or even minute to minute about when a bus or shuttle would arrive or where it might be going when it did. 

This experience would be a little bit like going to SFO for a flight to L.A. and finding out that a flight just left but that another one might happen sometime within the next few hours.  But, it might need to stop in Salt Lake City to pick up a growing crowd there, depending on what the algorithm decides in real time.  In this situation, what’s “flexible” for the provider of transportation will appear more like chaos to the customer. 

Transit investments and services need not be so fickle and fearful of defined schedules or geographic commitment.

Fundamentally, the physical world is not the internet.  Our vehicles are not data packets that can be radically compressed to expand roadway capacity.  There is no Moore’s law for highways that allows them to process cars at double the rate higher rates every two years.  The built environment (location of our towns and key transportation corridors) changes at a glacial pace compared to the pace of change for information technology.  

The internet is ultimately an extremely limited metaphor for the design of transit or our communities in general. 


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John Ferguson September 17, 2013 at 01:52 AM
I dunno David - once the sooper Geniuses at Google figure out how to get us driverless cars I can imagine all sorts of communal travel situations. If cars can drive themselves, why do I need to own one? It could just pick me and my neighbor up and take us to a collection point where larger containers could whisk us to our destination. It's the final mile problem combined with the convenience factor. Judging by the conversations around the ferry these days, parking there is increasingly failing the convenience test for later commuters.
Stephen Nestel September 17, 2013 at 12:00 PM
Franz, Although we frequently disagree, I read your well written commentary. I am very disappointed that you need to take a slap at Bob Silvestri as a strawman. It degrades what otherwise is good commentary. There is no need to get personal.
Franz Listen September 17, 2013 at 01:46 PM
Stephen - Its not personal and I actually agree with some of Silvestri's critiques of our regional planning process. I have some disagreements too. The "strawman" in this case is Silvestri's own advocacy, in his own words, in both an ongoing blog and a book on that you can buy on Amazon. His bit on transit is relevant because its part and parcel of a larger philosophy, something that I couldn't get into too deeply in a single blog post.
Stephen Nestel September 17, 2013 at 03:29 PM
Franz, I think "on demand mass transit" is a proper name for the idea that Bob Silvestri is suggesting. The figures you use in the article actually prove the point that few mass transit options are financially or environmentally viable. You are correct that "on demand mass transit" is very expensive but compared to fixed route bus lines with low ridership, they are much less expensive. In the third world, it is not uncommon to see transit delivered this way. Frankly I think the only sensible solution is low polluting personal vehicles. Unless you live near the busline and work along a bus line, the costs and trade offs are too great. In our dynamic economy, the days of big factories and huge cubicle warehouses are a thing of the past. Better transportation management is the future, not cable cars.
David Edmondson September 17, 2013 at 07:20 PM
@Stephen - By what metric are they much less expensive? Even line whose productivity was so low it was cut, namely Route 222, the subsidy came to $22.58 per trip. Novato Dial-a-Ride, which is on demand transit in action, costs $29.17 per trip. Marin Transit's fixed route local service (like the 22) was subsidized just $3.87 per trip.


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