Ridership vs coverage: The transport planner’s dilemma

Berlin. Image: Getty.

Is your transit agency succeeding? It depends on what it’s trying to do – and most transit agencies haven’t been given clear direction about what they should be trying to do.  Worse, they’re told to do contradictory things.  It’s as if you told your taxi driver to turned left and right at the same time, and then criticised them for turning the wrong direction.

On the one hand, we expect transit agencies to pursue a goal of ridership.  Yet we also demand that provide a little service to everyone, which is called a coverage goal.  The coverage goal requires an agency to run predictably low-ridership services, for non-ridership reasons, so it’s the opposite of a ridership goal

In the fictional town below, the little dots indicate dwellings and commercial buildings and other land uses. The lines indicate roads, and the 18 buses indicate the resources the town has to run transit. Most of the activity in the town is concentrated around a few roads, as in most towns.

A transit agency pursuing only a ridership goal would focus service on the streets where there are large numbers of people – where walking to transit stops is easy, and where the straight routes feel direct and fast to customers. Because service is concentrated into fewer routes, frequency is high and a bus is always coming soon.

This would result in a network like the one below.

All 18 buses are focused on the busiest areas. Waits for service are short but walks to service are longer for people in less populated areas. Frequency and ridership are high, but some places have no service.

Why is this the maximum ridership alternative? It has to do with the non-linear payoff of both high density and high frequency, as explained more fully here.

If the town were pursuing only a coverage goal, on the other hand, the transit agency would spread out services so that every street had a bus route, as in the network at below. Spreading it out sounds great – but it also means spreading it thin.

The 18 buses are spread around so that there is a route on every street. Everyone lives near a stop – but every route is infrequent, even those on main roads, and waits for service are long. Only a few people can bear to wait so long, so ridership is low.

In these two scenarios, the town is using the same number of buses. These two networks cost the same amount to operate, but they deliver very different outcomes.

Ridership-oriented networks serve several popular goals for transit, including:

  • Reducing environmental impact through lower Vehicle Miles Travelled;
  • Achieving low public subsidy per rider, through serving the more riders with the same resources, and through fares collected from more passengers;
  • Supporting continued urban development, at higher densities, without being constrained by traffic congestion;
  • Reducing the cost of for cities to build and maintain road and bridges by replacing automobile trips with transit trips, and by enabling car-free living for some people living near dense, walkable transit corridors.

On the other hand, coverage-oriented networks serve a different set of goals, including:

  • Ensuring that everyone has access to some transit service, no matter where they live;
  • Providing lifeline access to critical services for those who cannot drive;
  • Providing access for people with severe needs;
  • Providing a sense of political equity, by providing service to every municipality or electoral district.

Ridership and coverage goals are both laudable, but they lead us in opposite directions. Within a fixed budget, if a transit agency wants to do more of one, it must do less of the other.

Because of that, cities and transit agencies need to make a clear choice regarding the Ridership-Coverage trade off. In fact, we encourage cities to develop consensus on a Service Allocation Policy, which takes the form of a percentage split of resources between the different goals.


For example, an agency might decide to allocate 60 percent of its service towards the Ridership Goal and 40 percent towards the Coverage Goal.

Major network redesigns often shift this balance, intentionally and consciously.  When we led a redesign of the bus network in Houston, we led a discussion with the elected leaders about their priorities, and they decided to shift the focus of their network from 80 per cent coverage to 5per cent coverage. They knew in advance what the result would be: a more useful network, with the potential to grow more ridership, but also many angry people in areas no longer served.

What about your city? What do you think should be the split between ridership and coverage? The answer will depend on your preferences and values.  For cities, it should be up to elected officials, informed by the public, to decide.

Jarrett Walker is an international consultant in public transit network design and policy, based in Portland, Oregon. Christopher Yuen is an associate at Jarrett Walker+Associates.

Walker is also the author of “Human Transit: How clearer thinking about public transit can enrich our communities and our lives". This article was originally written for his blog, and is reposted here with permission

 
 
 
 

In many ways, smart cities are really very dumb

Rio de Janeiro’s control centre. Image: Getty.

It’s not news that anything and everything is increasingly being prefaced with “smart”: phones, watches, homes, fridges, and even water (yes, smartwater exists). And it’s not unintentional either. 

Marketeers know that we, the public, are often stupid enough to believe that thanks to their technology, life is better now than it was way back in, say, the primitive Nineties. Imagine having to, like a Neanderthal, remember how to spell words without an autocorrecting algorithm, or open the fridge door to check if you’d run out of milk, or, worse still, interact with actual people.

So it’s hardly surprising that we’re now also witnessing the rise of the so-called “smart cities”; a concept which presupposes that cities that are not technologically  “smart” are dumb, which, as anyone interested in the millennia-old history of cities — from the crypto-currency grain storage algorythms of ancient Mesopotamia to the complex waste infrastructure of ancient Rome, to London’s public transport infrastructure — will know, is not true.

Deployed in these smart cities are cameras and other networked information-gathering devices, load cells and other “sensing devices” detecting passing pedestrians and vehicles, audio surveillance devices listening for gunshots – and even vending machines equipped with biometric sensors to recognise your face. This is not to mention beacon technology — tiny anonymous looking black boxes hidden in trees and on lampposts — which transmits advertising, offers and other information directly to smart phones in the vicinity. 

If that doesn’t seem sinister enough, take, for example, Rio de Janeiro, where, in 2014, the International Business Machines Corporation designed a mammoth “control centre” that integrates data from 30 agencies for the city’s police. 

Described by the Guardian as having “the functionality of a Bond villian’s techno lair”, the then local mayor, Eduardo Paes, claimed the centre was making the city safer while using technology to deploy its “special” police unit to carry out the state’s “pacification programme”. Launched in 2008, the programme, which aims to push out drug gangs from Rio’s favelas, has been criticised by Amnesty International: “in January and February 2017 in Rio de Janeiro alone, at least 182 people were killed during police operations in marginalized neighbourhoods (favelas) – a 78 per cent increase in comparison to the same period in 2016”.

Sinister or not, as smart cities grow, they create new problems. For example, as urbanist Adam Greenfield writes in Radical Technologies: The Design of Everyday Life, neither the algorithms nor their designers are subject to the ordinary processes of democratic accountability – a problem that international academics are currently attempting to tackle.  


“We need to understand that the authorship of an algorithm intended to guide the distribution of civic resources is itself an inherently political act,” writes Greenfield. “The architects of the smart city have utterly failed to reckon with the reality of power.”

The Real Smart Cities project, founded by Dr Gerald Moore, Dr Noel Fitzpatrick and Professor Bernard Stiegler, is investigating the ways in which so-called “smart city” technologies present a threat to democracy and citizenship, and how digital tools might be used create new forms of community participation.

Fitzpatrick is critical of current discourses around smart cities, which he says “tend to be technical fixes, where technology is presented as a means to solve the problems of the city.” The philosophy underpinning the project is “that technologies function as forms of pharmacology”, he adds, meaning that they can be both positive and negative. “The addictive negative effects are being felt at an individual and collective level.” 

An example of this lies in the way that many of these smart cities replace human workers with disembodied voices — “Alexa we need more toilet roll” — like those used to control the Amazon Echo listening device — the high priestess of smart home. These disembodied voices travel at the speed of light to cavernous, so-called “fulfilment centres”, where an invisible workforce are called into action by our buy-it-now, one-click impulse commands; moving robotically down seemingly endless aisles of algorithmically organised products arranged according to purchase preferences the like of which we never knew we had — someone who buys a crime novel might be more likely to go on and buy cat food, a wireless router, a teapot and a screwdriver. 

Oh to be the archeologists of the future who while digging through mounds of silicon dust happen upon these vast repositories of disembodies voices. That the digital is inherently material and the binary of virtual/real does not hold — there is no cyberspace, just space. Space that is being increasingly populated by technologies that want to watch you, listen to you, get to know you and sense your presence.

One project looking to solve some of the problems of smart cities is that of the development of a “clinic of contribution” within Pleine Commune in greater Paris (an area where one in three live in poverty).This attempts to deal with issues of communication between parents and children where the widespread use of smartphones as parental devices from infancy is having effects on the attention of young children and on the communicative abilities between parents and children. 

This in turn forms part of a wider project in the area that Stiegler describes as “installing a true urban intelligence”, which moves beyond what he sees as the bankrupt idea of smart cities. The aim is to create a “contributory income” in the area that responds to the loss of salaried jobs due to automation and the growth and spread of digitisation. 

The idea being that an income could be paid to residents, on the condition that they perform a service to society. This, if you are unemployed, living in poverty and urban deprivation, sounds like quite a simple and smart idea to try and solve some of the dumb effcts of the digital technology that's implemented in cities under the ideology of being “smart”.