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

 
 
 
 

The best bike maps are made by volunteers

A cyclist in Vancouver, Canada. Image: Getty.

Not all bike routes are equal. Some places that are marked as bike routes on a map feel precarious when traversed on two wheels, including shoulders covered in debris and places where you can feel the wind from speeding cars.

North American cities are building more bicycling routes, by adding on-street painted lanes, physically separated cycle tracks, bicycle-only or multi-use paths and local street bikeways. These different kinds of routes appeal to different types of users, from the interested but concerned cyclist to the keen road rider.

Despite this boost in biking infrastructure, a city’s website may not immediately reflect the changes or it may lack important information that can make cycling safer or more enjoyable.

Web-based maps that allow people to add information about bike routes give riders detailed data about the type of route, what it might feel like to ride there (do you have to ride close to cars?) and where it can take them (for example, shopping, work or school).

They can also tell us which cities are the most bike-friendly.

Measuring bike routes

We set out to assemble a dataset of bike routes in Canadian cities using their open data websites. But we found it was nearly impossible to keep it up-to-date because cities are constantly changing and the data are shared using different standards.

A physically separated cycle track in Victoria, British Columbia. Image: E. Gatti (TeamInteract.ca).

The solution was OpenStreetMap, which creates and distributes free geographic data. Anyone can add data or make edits to OpenStreetMap, whether they want to build a better bike map or make a navigation app.

We looked at OpenStreetMap data for three large cities (Vancouver, Toronto and Montréal) and three mid-sized cities (Victoria, Kelowna and Halifax) in Canada.

Not only did the data in OpenStreetMap agree reasonably well with the cities’ open data: in many cases it was more up-to-date. OpenStreetMap tended to include more local details such as where painted bike lanes ended and often marked the short cuts connecting suburban streets.

How did OpenStreetMap measure up?

Our analysis focused on how well different types of routes were mapped. We measured cycle tracks (which physically separate bikes from motorised traffic), on-street painted bike lanes (which use painted lines to separate bikes from motorised traffic), bike paths (which are located away from streets) and local street bikeways (which include traffic-calming features and where bicycling is encouraged).

Painted bike lanes are the most common type of route and also the most consistently well mapped. This makes sense, because the definition of a painted bike lane may be clearest across time and place. There is also a straightforward way for volunteers to tag it on OpenStreetMap.

But it was harder for us to distinguish cycle tracks from on-street painted lanes or paths (bicycle-only or multi-use) using OpenStreetMap. Local street bikeways were challenging to identify because of the wide range of ways cities design these kinds of routes along residential roads. Some use traffic-calming measures such as curb extensions, traffic islands, speed humps and raised traffic crossings to slow vehicle traffic and encourage safety, or greenery, reduced speed limits and bike-friendly markings on signs and the road surface.

Correspondence between OpenStreetMap and Open Data for categories of bicycling infrastructure. Image: author provided.

Bicycle routes that are physically separated from motor vehicles and pedestrians, like cycle tracks and bicycle-only paths, have the greatest benefits for bicycling safety and encourage bike use.

Ease of access to bicycle routes is important to a city’s overall bicycle friendliness, but there are other important things to consider including the distance to destinations, the number, slope and length of hills, number of riders and how the transportation culture of a city can influence its safety.


Bike-friendly Canadian cities

Our results showed that Montréal has the greatest total distance in cycle tracks in Canada. As cities continue building more bicycle routes, researchers and planners can use OpenStreetMap to measure these changes on the ground.

The perfect bicycle map is up-to-date, covers the entire globe and gives riders an idea of the kinds of experiences to expect on different trails, roads and paths. People cycling in cities can contribute to the high-quality geographic data needed to understand changes in bicycle friendliness.

But OpenStreetMap is only as good as its contributions. The exciting thing is that anyone who wants a better bike map — city planners, researchers and everyday riders — can join the bike-mapping revolution by logging in to OpenStreetMap and mapping the features that are important to bicyclists.

The Conversation

Colin Ferster, Post-doctoral fellow, University of Victoria and Meghan Winters, Associate Professor, Faculty of Health Sciences, Simon Fraser University

This article is republished from The Conversation under a Creative Commons license. Read the original article.