General

We are going to get back to more frequent posting here soon, but I hope this post explains why it’s been a busy time.  First, a bit about the interesting range of places we’re looking forward to working this year.  Then a bit about our hiring.  (Yes, we are still looking for senior staff!)

Meanwhile, we’ll be working an a great spectrum of places this year, including:

• San Jose and Silicon Valley.  We’re helping out the local transit agency, VTA, think through their bus network design in the context of updated goals and the arrival of rapid transit from Oakland and San Francisco.  We’re excited to be working in the backyard of so many tech giants, and wading into the debates about how disruptable (to use their favorite word) transit is, or should be.
• Richmond, Virginia.  We’ll be helping the city think about how its bus network should evolve, including but not limited to the impact of a new Bus Rapid Transit line.
• Anchorage.  We’ll be running some transit visioning workshops for Alaska’s big city.  This is not our northernmost client, however, because of:
• Reykjavík. We had a great time doing stakeholder workshops and elected official briefings in Iceland last year, and we’ll be doing further analysis of their bus system this year, to help them think about their options.  And most exotically:
• Yekaterinburg, the Russian city where the last czar’s family was assassinated, now an industrial and university town.  We’ll be working through the local NGO Gorod.pro to help the City explore options for simplifying its amazingly complex transit system.  (This is just the tram network, for example.)  The legal issues have been daunting, but if all goes well with visas and geopolitics, I’ll be there for a week in late April for the intensive work.  Here (in Russian) is how they are pitching the plan.

Hiring

We’re really grateful to everyone who’s applied for positions with us.

From last fall’s search we’re happy to announce Daniel Costantino will be joining us as a new Senior Associate.  Dan has been an emergency planner in recent years but has strong bus network planning credentials from earlier in his career, including a fine thesis on bus network redesign in Montréal.  His French is also better than mine.

We’ve also added GIS analyst and planner Gavin Pritchard and planner Tam Guy.  These folks join our longtime Senior Associates Michelle Poyourow and Evan Landman to help us excel at delivering more projects at once.

And yes, we are still looking for an experienced transit planner to join our team in a more senior role, but there’s no deadline on that.  This is such a consequential hire that it’s more like finding a romantic partner: we’ll know it when we see it, and there’s no point in trying to rush the process.

So we all want to write New Years posts about resolutions we should make — mostly resolutions we could have made last year and will probably make again next year.  To me, this is a good time to make conceptual resolutions — not about what we’ll do, but about how we’ll think, and especially what questions we will ask.  Two years ago, for example, I suggested a resolution against binary thinking — that is, to reject any formation of a problem that is “either-or” or “us vs them” or “win-lose”.

For 2016, let me propose a resolution that’s a little more concrete, maybe a little easier to bring to bear in any situation.

Whatever room I’m in, I resolve to ask “Who is not in the room?”

In other words, ask:  What real points of view, and real dimensions of the human experience, are not represented in this conversation? How could their absence lead us to make a bad decision even with the best of intentions, and how do we compensate for that?

Why this?  Because in many parts of society, including urban planning, the rooms in which decisions are made are getting smaller and less diverse, and that can make for worse decisions, no matter how well-intentioned the people in the room are.  What’s more, creating a diverse room is harder and harder, because people are just less interested in spending any time in rooms with people who don’t share their experience — either physically or online.

So it is easier than ever, in this historical moment, for us to forge a seemingly complete society of people who think just the way we do.  Not just on the internet, but also in physical space: Because I live where I do, and go where I go, I tend to meet people like me.  Every day, I sadly scan my Twitter feed seeking some sentiment that isn’t just reinforcing my own beliefs.  I have this reaction because I want to live in the presence of the real, and this constant emotional reinforcement of my opinions is the opposite.  It makes me feel like a CEO or elected official who is only told what staff thinks they want to hear, and who therefore ends up completely unaware of what’s actually going on.

We can all identify urban planning disasters that arose from only certain people being in the room.  One thing that happens in small rooms, for example, is that people agree too quickly that an ideal implies a technology or product.  Tools are so cool that we mistake the tool for its purpose.  For example: “freedom means cars which means more highways,” (even if that leads to freedom-destroying congestion).   But another example is: “urban redevelopment means rails in the street, but done fast and cheaply, which means streetcars” (even streetcars that don’t function well as transit, because they are stuck in traffic or don’t follow real patterns of demand).

I suspect transit consultants notice the small-room problem more than the average professional does, because in our field we don’t have an organized circle of professionals who reinforce each other’s habits and ways of thought.   Architects and traffic engineers and developers and emergency services planners spend lots of time in rooms with people like them, in conferences and professional organizations.  But transit planning isn’t an especially recognized and accredited profession.  Many powerful people have no idea that it even exists as an expertise.  So transit planners don’t spend much time in rooms where everyone shares their professional knowledge and assumptions.

Like anyone, though, we notice decisions that were made in our absence.  Decisions about street design (often arising from small-room project definitions like “add a bike lane”) may inadvertently wreck the transit operations.  Ditto decisions about land use — such as putting a transit-dependent land use (medical center, senior center, social security office) in a transit-inaccessible location because the land was cheap there, and then expecting transit to run an expensive empty bus just to get to that remote location.   (Businesses make those decisions in small rooms too.  Sometimes they really do move from a downtown office tower to a remote business park, and then ask the transit agency: “Hey, what happened to our transit service?”)

The larger reason transit planners tend to notice small-room problems is that transit is intrinsically a win-win proposition with a long-term payoff.  In fact, the longer-term your view, the more win-win it is.  The most successful transit services of all — rail rapid transit in big cities — work because of the huge diversity of people who find them useful, and because they’ve had a chance to pay off in the long run, by helping the city grow around them. These are the consummate win-win services, not just because there are so many riders from every part of the society, but because so many people benefit from the economic, environmental, and social opportunities that these services create.

But it’s politically hard to develop those kinds of services, because so many people assume that all issues are win-lose.  An elected official will cut short my briefing by asking: “Who are the winners and losers here?”  And let’s admit: Most of us sometimes like winning in ways that require there to be losers.  If we didn’t, nobody would care about sports, or relish the drama of competition.

But if you need there to be losers, then you need there to be people outside the room.  And that will prevent you from designing transit to do what transit does best, which to provide liberation and economic prosperity to a vast diversity of people.

So this is good advice in any field, but it’s really important when hatching transit ideas:  Look around you in your meeting room, or professional conference, or party of like-minded friends, or online forum, and ask:  “Who isn’t here?  And how would this issue look different if they were?”

As you can see, this afternoon, the Human Transit blog has had some visual tweaks and changes as we’ve moved our operations over to WordPress. We’re excited to share the new, cleaner look and feel with everyone, and hope that you agree that its a welcome evolution towards a more readable, easier-to-navigate site.

All the old content and comments should still be here.  But moving to a new platform is always a big change, so we hope you’ll pardon our dust as we comb through the back catalog of posts over the coming weeks and make sure everything’s still working. If you see something that doesn’t look right, leave a comment here.

If you read Human Transit using an RSS reader, you may need to update your feed settings to point to here.

Meanwhile, we’ve also updated the firm website, and so we encourage everyone to have a look at that as well.

We're starting to see professional reports echoing long-standing concerns about how driverless cars will affect our cities. This new one from KPMG, in particular, is getting a lot of press.  It's actually a focus group study about the transport desires of different generations, but it confirms the thought experiments that many of us have already been laying out for a while.  

Much depends on whether these cars are owned or spontaneously hired like taxis, Uber, and Lyft.  A taxi model is definitely better in its congestion impacts, but that doesn't mean it will happen.  The ownership model is closer to the status quo, and the status quo always has enormous power.  Driverless taxis will not always be available on demand, especially in suburban and rural areas, so a legitimate fear of being stranded will make people in those areas prefer the security of having a car just for them. And of course, that's just the effect of rational concerns about relying on taxis.  Less rational desires for car ownership, as an expression of identity or symbol of liberty, will also not vanish overnight.

This leads to a nightmare scenario that University of Washington's Mark Hollenbeck laid out in our recent Seattle Times panel.  Paraphrasing Mark:  A suburban father rides his driverless car to work, maybe dropping his daughter off at school.  But rather than park the car downtown, he simply tells it to drive back home to his house in the suburbs.  During the day, it runs some other errands for his family.  At 3 pm, it goes to the school to bring his daughter home or chauffeur her to after-school activities.  Then it's time for it to drive back into the city to pick up Dad from work.  But then, on a lark, Dad decides to go shopping at a downtown department store after work, so he tells his car to just circle the block for an hour while he shops, before finally hailing it to go home.

This is really easy and obvious behavior for a driverless car owner.  It reduces the number of cars someone needs to own, and reduces pressure on inner city parking, but would cause an explosive growth in vehicle trips, and thus in congestion (not to mention emissions and other impacts).  Just the commute behavior doubles car volumes, because the car now makes a two-way trip for each direction of the commute, instead of just one.  And if everyone shopping downtown has a car circling the block waiting for them, well, that level of congestion will far exceed what's generated by cars circling for parking today.  It could pretty well shut down the city.

This is the good old problem of induced demand, which is what happens when you make a resource available at an artificially low price – as we do with most urban roads today.  If you don't pay the true cost of something in money, you will pay it in time, and that's what congestion is.  (It's also why in the old Soviet Union, people spent hours waiting to buy bread: Soviet price controls made the price too low to compensate the suppliers, so there wasn't enough bread, so everyone waited in line.  Congestion — waiting in line to use an underpriced road — works the same way.)  

Pricing of some kind will be the solution, but we tend to do this only when things get really bad.  Notice how bad congestion has to be today before solutions like toll lanes and transit lanes are finally accepted as necessary.  

As always, the very worst scenario won't happen, but some really bad ones still can.  If the economic functioning of downtown is too badly impaired by driverless cars circling the block waiting for their owners, the government will intervene to save the economy, as it always does, probably with some kind of downtown street pricing on the London or Singapore model.  But this only happens when congestion threatens the economy.  That's a very high bar.  Long before that point, congestion will be bad enough to be ruining people's lives, wrecking the urban environment, strangling public transit, worsening climate change, and so on.  

As always, the scary thing about congestion is how bad people (and therefore governments) allow it to get before they start making different choices to avoid it.  The level of congestion we (justifiably) complain about is much lower than the level that we choose to tolerate, and this is the real reason for pessimism about how bad congestion could potentially get, if driverless car ownership — like cars today — are so massively underpriced even in the context of high urban demand.

The Boston Globe has a story about the region's transit agency, the MBTA, launching a pilot program with local taxis to provide paratransit service.  This is worth watching because of the potential to unlock resources for fixed route transit services.

Paratransit, in the strictest sense, is door-to-door service for people with disabilities who cannot use fixed route transit.  In the United States, the Americans with Disabilities mandates that transit agencies provide paratransit wherever and whenever they run fixed route service, and charge no more than double the fixed route fare.  

In the agency budget, this mandated service competes with the services that everyone else uses.  It's common for over 30% of a transit agency's operating budget to be paratransit.  

Subsidizing taxis has always been an option to meet the paratransit requirement, but in big cities the routine solution has been paratransit van services.  These vans can theoretically serve multiple people at once, but the sparseness of paratransit demand means they often carry just one person, or zero between runs.  So paratransit operating cost is often over $30/passenger trip, as compared to more like $5 for an effective fixed route service.

MBTA is now testing using taxis — or in the future, taxi competitors like Uber and Lyft — in the same way that small towns often do.  It will encourage some customers to use taxis instead of paratransit vans — which is not hard to do, since taxi service is much more flexible.  (Paratransit vans must be booked 24 hours in advance, but these taxis can be called spontaneously.)  The customer will pay a reasonable transit fare, $2, and MBTA will add an average of $13/trip to round out a typical average taxi fare of $15.  

That's $13 per ride for the transit agency instead of (usually) over $30.  For service that is more useful to the paratransit customer.  

Remember, paratransit expenditures by US transit agencies often exceed 30% of the operating budget.  Cut that in half, and you can expand fixed route service dramatically.  

This is so important!  Crosspost of an essay by Daniel Kay Hertz,  from the excellent City Observatory blog, where it was titled "Urban residents aren't abandoning buses: buses are abandoning them."  

“Pity the poor city bus,” writes Jacob Anbinder in an interesting essay at The Century Foundation’s website. Anbinder brings some of his own data to a finding that’s been bouncing around the web for a while: that even as American subways and light rail systems experience a renaissance across the country, bus ridership has been falling nationally since the start of the Great Recession.

But it’s not buses that are being abandoned. It’s bus riders.

The drop in bus ridership over the last several years has been mirrored by a decline in bus service, even as transit agencies have managed to resume increasing frequency and hours on all types of rail lines – heavy, light, and commuter.* (In this post, "service" means vehicle revenue miles – literally, multiplying a city's bus or rail vehicles by the number of miles they run on their routes.) After a post-recession low in 2011, by 2013 rail service had increased by over 4% nationally in urban areas of at least one million people. Light rail in particular has continued its decade-plus boom, with a service increase of more than 12% in just two years. By contrast, bus service – which already took a heavier hit in the first years of the recession – was cut an additional 5.8%.

  And it turns out that when you disaggregate the national data by urban area, there’s a very tight relationship between places that cut bus service between 2000 and 2013 and those that saw the largest drops in ridership. If you live in a city where bus service has been increased, it’s likely that your city has actually grown its bus ridership, despite the national trends. In other words, the problem doesn't seem to be that bus riders are deciding they’d rather just walk, bike, or take their city’s new light rail line. It’s that too many cities are cutting bus service to the point that people are giving up on them.

  Admittedly, this is a crude way to demonstrate a very complicated relationship. To rigorously test the impact of bus service on ridership, you’d want to take into account all sorts of other things: the presence of other transit services; population density; gas prices; demographics; and so on.

Fortunately, we don't have to do that, because researchers at San Jose State University’s Mineta Transportation Institute just did it for us. And they found that even if you control for those other factors, service levels are still the number one predictor of bus ridership.

Still, I can imagine two big objections to the idea that cuts to bus operations are behind ridership declines. First, a lot of cities have opened new rail lines since 2000 – many of which, if not most, replaced heavily-trafficked bus routes. In those cases, cities are adding rail service and reducing bus service, but it obviously wouldn’t be right to say that those bus riders are being abandoned.

But while that has surely happened in some places, it just doesn’t match the overall data. Rail service, including new lines, has been booming since long before the recession – but up until about 2009, bus service was growing, too, or at least holding steady. If rail expansions were driving bus cuts, you’d expect to see those cuts all the way back to the beginning of the data. But you don’t. Instead, cuts to bus routes appear right as transit funding was hit hard by the recession.

Second, you might argue that service and ridership are linked, but the other way around: as ridership declines, agencies cut back on hours and frequency to match demand. Teasing out which way the causation runs would be difficult – and the answer would almost certainly include at least some examples in both directions. One quick-and-dirty way to get an idea, though, is to compare ridership changes from one year to service changes in the next year. If agencies cut service because of earlier ridership declines, then you’d expect to see that places with larger drops in ridership in “Year One” tend to be the places with larger cuts to service in “Year Two.”

  But, again, they don’t. In fact, just 3% of the variation in service cuts is explained by ridership changes from the year before.

So while that’s hardly ironclad – and I look forward to further research that sheds more light on this problem – it does appear that a major part of the divergence in bus and rail ridership is a result of a divergence in bus and rail service: since the recession, transit agencies have cut bus service year after year, while returning service to rail relatively quickly.

Why did they do that? I don’t know. But I can speculate that it has something to do with the fact that bus transit supporters are not always the same kinds of people as rail transit supporters. Even though more people take buses than trains in nearly every metropolitan area in the country, train riders, on average, tend to be wealthier and whiter. Not only that, but many civic and business leaders who don’t use transit at all are heavily invested in rail service as an economic development catalyst for central city neighborhoods. In other words, rail tends to have a more politically powerful constituency behind it than buses.

As a result, when the recession blew a hole in transit budgets around the country, it may have been politically easier for local governments to fill those holes by sustaining cuts to bus lines, rather than rail.

To be clear, the problem here has nothing to do with whether transit agencies are running more services that are rubber-on-asphalt or steel-on-tracks. As Jarrett Walker has eloquently argued, the technology used by a particular line matters far less than the quality of service: how often it runs, how quickly, for how much of the day.

But there are at least two problems here. First, because of the spread-out nature of even relatively dense American cities, it will be a very, very long time before rail transit can connect truly large numbers of people to large numbers of jobs and amenities. When Minneapolis opened the 12-mile Blue Line light rail in 2004, for example, it was a major step forward for Twin Cities transit – but still, only 2% of the region’s population lived close enough to walk to one of the stations. For everyone else, transit still meant taking the bus, even if they were taking the bus to a train station.

And even in places with well-developed rail networks, those systems are usually oriented to serve downtown commuters. Especially in outer neighborhoods, crosstown trips in places like Chicago, Boston, or DC are heavily reliant on buses. Abandoning buses means abandoning those trips, and the people who depend on them.  

 Boston's T reaches both Dorchester and Jamaica Plain, but a bus is by far the easiest way to get from one to the other on transit. Credit: Google Maps

Second, there are serious equity issues with shifting resources from bus to rail – again, not because of anything inherent to those technologies, but simply because of who happens to use them in modern American cities. In most cases, shifting funding from bus to rail means shifting funding from services disproportionately used by lower-income people to ones with with a stronger middle- and upper-middle-class constituency. And while transit ought to be viewed as much more than just a service for the poor, we can’t ignore the equity impacts of transit policy.

In light of all this, we have to stop talking about America’s bus woes as a ridership problem. All the evidence suggests that when service is strong, and buses are a reliable way to get to work, school, or the grocery store, people will take them. Instead, the problem is that fewer and fewer people have access to that kind of strong bus line. If we care about ridership, we need to restore and enhance the kind of transit services that people can rely on.

* “Heavy rail” includes traditional subways and elevated trains found in cities like New York, Washington, and Chicago. “Light rail” includes many newer systems, with smaller train sets that are sometimes designed to run on streets as well as in their own right of way. Rail lines in Seattle, the Twin Cities, and Dallas are typical of light rail. “Commuter rail” services generally reach from central business districts far out into the suburbs, and are meant almost exclusively for peak-hour workers.

Antonio Loro is an urban planner who focuses on the planning implications of emerging road vehicle automation technologies. He has conducted research with TransLink and Metrolinx on the potential impacts of automated vehicles, and is currently with the Ministry of Transportation of Ontario. This article was written by Antonio Loro in his personal capacity. The views expressed in this article are the author's own and do not necessarily represent the views of the previously mentioned organizations.

As efforts to develop automated vehicles continue to speed forward, researchers have begun to explore how driverless taxis in particular could play a prominent role in the future mix of urban transportation options. Some of these early findings raise the provocative argument that driverless taxis (or self-driving or fully-automated taxis, if you prefer) could hugely reduce or even eliminate the need for buses and trains. However, careful interpretation of this research reveals that vehicles with high passenger capacities (bus and rail transit, in other words) could be superseded by lower-capacity vehicles only where there is plenty of road space to spare. Where road lanes are in shorter supply, buses and trains – which could themselves get a huge productivity boost from automation – will continue to be indispensable for moving large volumes of passengers. In such cases, driverless taxis, especially share taxis, will be ideally suited to complement higher-capacity transit, generally by focusing on areas with a surplus of road space. And in the near-term, even before such advanced automation is perfected, automated buses could start improving mobility for large numbers of urban travelers.

Researchers have begun to explore future scenarios where vehicle automation technologies have advanced to a level that enables taxis to drive without human intervention through the full network of urban roads. Recently, the ITF (International Transport Forum), a think tank within the OECD, modeled a number of scenarios to examine how these driverless taxis, once they are commonplace, could serve urban travelers on a typical weekday in Lisbon. Among the outputs of their model, one is particularly attention-grabbing: even in a scenario where 8% of trips go by foot or bike, none go by transit, and the remaining 92% go by driverless taxis that serve single passengers, ITF researchers say that the number of taxis needed would be less than a quarter of the number of cars currently in use in the Portuguese capital. Such a reduction in the size of the overall fleet of cars in the city would greatly diminish parking demand. Unsurprisingly, though, in order to serve so many trips, the fleet of taxis would be used very intensively, and the total vehicle kilometres traveled (VKT) in the city would more than double.

Remarkably, the ITF team say that despite the upsurge in VKT in this scenario, travel times would be slowed very little. Underpinning this result is a noteworthy assumption in the model: currently, according to the ITF researchers, less than 40% of available capacity on Lisbon’s roads is in use during peak periods. (The authors caution that their figures are underestimates, as they do not account for bus travel, which makes up 13% of VKT in Lisbon.) The upshot is that even in a scenario where new taxi trips and empty taxis driving to their next passengers cause VKT to double, the ITF model’s outputs suggest  that there should be road capacity to spare.

The model shows the previously very lightly used local roads absorbing much of the new VKT. Meanwhile, the most heavily traveled category of roads (“local traffic distributor roads”) rises from 43% to 69% of road capacity used. That 69% doesn’t necessarily mean traffic will be flowing smoothly, however. These percentages refer to the average capacity in use on different categories of roads – even if there is a low percentage of capacity in use on a given category of road, there could nevertheless be congestion focused at some locations on those roads. Interestingly, according to the TomTom Traffic Index, congestion may already be an issue in Lisbon, as travel times during peak periods are currently 45% to 70% longer than they would be under free-flow conditions.

 The crucial implication to highlight here is that single-passenger driverless taxis could supplant buses and trains – but only where the roads have the capacity to absorb potentially huge increases in traffic without becoming congested.

A 2014 study by the Singapore-MIT Alliance for Research and Technology (SMART) arrived at results similar to those in the ITF study, though the SMART team modeled travel speeds in a much simpler way. The SMART researchers examined a scenario with single-passenger driverless taxis (or car-share vehicles) serving all trips in Singapore. They concluded that a fleet sized at one-third of the total number of passenger vehicles currently in use in the city could serve all trips while keeping peak period waiting times for the average passenger under 15 minutes. Such a dramatic result follows from a simplifying assumption in the model: the SMART team first estimated the current average speed that taxis drive at – including both the denser and the more dispersed areas of the city – and then assumed that future driverless taxis would drive at that particular speed, regardless of their location in the road network.

Less optimistically, the taxis would be bogged down in congestion of their own making. Currently in Singapore, 63% of peak period trips go via public transit. Shifting all of those trips to taxis would generate an abundance of new VKT – including VKT produced by empty taxis moving to their next passengers. Currently, peak period travel times on Singapore’s roads are 50% to 80% longer than they would be under free-flow conditions, according to TomTom; a massive increase in VKT wouldn’t help much. 

A more recent article from the SMART team includes a brief exploration of the congestion effects of empty taxis repositioning themselves in a very simple road network. They find that their algorithm generally results in the empty vehicles traveling mainly on less busy roads, though the repositioning process could cause heavy congestion in networks where there is already congestion. This preliminary analysis suggests that much of the traffic produced by driverless taxi repositioning could be focused on the roads that are least congested to begin with. This suggestion lines up with the results of the ITF team. Interestingly, the ITF’s model of Lisbon has the biggest increases in traffic showing up on local streets in particular – which could unfortunately make them less attractive places to live, the authors caution. Such streets serve purposes other than being conduits for cars – they may be quiet routes for walking and cycling, or safe places for children to play, or inviting public spaces, for example – so injecting new car traffic could produce impacts other than congestion that are worth considering. Furthermore, while the SMART team suggests that much of the traffic created by repositioning per se might be focused on the roads that were previously least congested, the taxis that are actually carrying passengers could of course be the more important source of congestion – especially when large mode shifts, such as those seen in the scenarios described above, inevitably produce large VKT increases.

The ability of automated vehicles to use roads more efficiently could mitigate congestion resulting from increased VKT – with some caveats. Combining automation and V2V (vehicle-to-vehicle communication) technologies would enable vehicles to drive safely with short following gaps. However, the large potential capacity increases resulting from this “platooning”, where vehicles are grouped into closely-packed files, would mainly materialize on freeways, where traffic flows are less turbulent than on city streets. Automation with V2V could also boost flows through intersections by coordinating the movements of vehicles far more efficiently than traffic signals. These improvements would be constrained, though, wherever intersections are shared with entities not equipped with the requisite tech – not just cars, but pedestrians and cyclists as well. More radically, vehicles themselves could be smaller, thus occupying less road space, if the crash avoidance capabilities of automation eliminate the need for bulky, crashworthy construction. However, such a revolution in vehicle design would not be able to take over the streets until automation technologies are advanced enough and adopted widely enough to guarantee occupant safety.

 The capacity limits of roads could be less of an impediment for multi-passenger driverless taxis. Hypothetically, if 8% of trips in Lisbon were taken on foot or bike and the remaining 92% were served by driverless taxis carrying multiple passengers (most commonly three to five, but as many as eight), the ITF team estimates peak period VKT would rise by 25%. It’s a substantial increase, but much smaller than the 103% jump in the single-passenger taxi scenario discussed above. Not surprisingly, providing public transit service would further mitigate VKT. In a scenario where 22% of trips go by subway, 8% go by foot or bike, and the remaining 70% go by driverless share taxi, the model estimates peak period VKT would rise by a relatively modest 9%.

Taxis serving multiple rather than single passengers would also mean an even smaller taxi fleet would suffice. Fewer cars in the city, kept busy serving dozens of trips a day, would drastically cut the need for parking. Sidewalks and bike lanes would be among the potential uses for the freed-up land. If taxi passengers share rides, and if 22% of trips go by public transit, the ITF figures that close to 95% of all parking spaces in Lisbon could be made redundant. (This outcome depends on traffic still flowing smoothly despite a 9% increase in VKT – if traffic is slowed, a larger taxi fleet would be needed to effectively serve all trips, so more parking would be needed during periods of low demand).

The discussion above just scratches the surface of the ITF and SMART studies – it’s definitely worth reading the original articles to explore their insights and to understand how the models were constructed. Higher-fidelity models that build on the ITF and SMART efforts will improve our estimates of the potential for driverless taxis to serve urban trips; however, even without complex models, it is clear that automation won’t eliminate the need for buses and trains when large numbers of people have to move through limited space. This is one of the straightforward geometric arguments that Jarrett has made before in this blog: larger vehicles fit more people into a given length and width of right-of-way than convoys of small vehicles can carry. (To illustrate, a freeway lane might have a capacity as high as 2400 cars per hour, while Bogotá’s TransMilenio bus rapid transit system has a capacity of 45,000 people per hour per direction.)

Of course, it’s a contentious question when we will attain the holy grail of automation technology sufficiently sophisticated to enable taxis or other vehicles to drive on any road in any conditions. It may appear further in the future than some suppose; nevertheless, even before this “Level 5” technology (as defined by the Society of Automotive Engineers) is mature, there will be vehicles capable of fully automated operation under more restricted conditions. There already are – such “Level 4” vehicles are currently capable of driving themselves at low speeds when segregated from challenging traffic environments. Beginning in the near-term, these kinds of low-speed automated vehicles, perhaps looking something like Google’s famously cute prototype, could carry passengers in settings like retirement communities. They could also circulate through networks of low-speed roads in suburban neighbourhoods or business parks to provide “first and last mile” access to and from transit routes.

Both in the near-term and the long-term, one of the most effective ways to reap the mobility benefits of automation will be to apply it to buses. Even with current technology, driverless operation would be feasible for buses running on busways with adequate exclusion of other vehicles and potential hazards. And even for buses on streets with mixed traffic, some of the technical challenges of achieving full automation are eased. For example, since bus routes run along only a small subset of the larger urban road network, the challenges of building and maintaining exquisitely detailed, meticulously annotated, continually updated maps would be substantially reduced – this would be advantageous for mapping-reliant approaches to automated driving, such as Google’s approach. The drop in labour costs from automation would enable dramatically increased frequencies, and the precision of automated control could also improve reliability. Because of the imminent potential to significantly improve mobility for large numbers of travelers, buses are a key priority for the application of automation.

With Level 5 automation, driverless taxis would become feasible. But rather than usurping the place of buses, they could play a complementary role. Level 5 would of course expand the domain of driverless buses, enabling them to provide service on any road; but it’s simply because buses can move numerous passengers in little road space that they will remain indispensable. Buses could ply heavily traveled corridors; driverless taxis could operate in less dense areas and during periods of lighter travel, whether serving complete trips or feeding into bus and train networks.

Interestingly, since low labour costs for driverless buses would enable higher frequencies, smaller vehicles would suffice to provide effective service in some areas. At a certain point, it could be difficult to distinguish in appearance between a small driverless bus and a driverless share taxi. However, their functions could be distinct: for example, driverless buses could provide frequent, predictable service on fixed routes according to schedules or headways, and driverless share taxis could provide on-demand, flexible route service. On the other hand, because diverting routes to pick up and drop off multiple passengers at numerous origins and destinations would cut into the travel time and cost benefits of taxi travel, some driverless share taxis could end up providing service with more fixed routing.

The take-home message from all this is that it’s critical to strategically deploy vehicle automation technologies according to their strengths and weaknesses. At some point, Level 5 automation will be achieved and driverless taxis will become feasible – but it’s important to think beyond just driverless taxis. To create the best possible mix of urban transportation options, it’s essential to consider the advantages and disadvantages of a range of potential automated vehicles and services – including buses, driverless taxis, and low-speed vehicles. Even more important, there's no need to wait for a Level 5 world with fully-fledged driverless taxis to appear before reaping the benefits of automation – and transit agencies have an opportunity to take the lead.

 [My thoughts on this piece are at the top of the comments! — Jarrett]

Photo: Rotterdam driverless bus prototype, 2getthere.eu 

On June 1 and 2 in Tampa, Florida, I'll be teaching another session of our popular Interactive Course in Transit Network Design.  It's part of the Community Transportation Association of America conference, but you can attend the course without attending the conference.  

The price is $750 if you or your organization doesn't belong to CTAA, $650 if you do.  Yes, this is higher than we charge when we teach it directly, but at this stage we don't have another direct offering until October in Portland.

We designed this course to fill a gap in the training of most planning professionals.  Few graduate programs teach public transit "from the inside," building an understanding of its unique opportunities and limitations through the experience of actually working with the tool.  Still fewer hire teachers who are both seasoned practitioners and skilled in relating public transit to larger narratives that motivate people.  If you care about public transit as part of your future city, invite your favorite land use planner to take this course!   They'll come out much savvier about how to recognize development proposals that truly work with public transit, as distinct from those that are just paying lip-service in order to "paint development green."  

Register here.  Select "2-Day Intensive Training" and "Transit Network Design."  You can also use this paper form:   Download Expo2015regform-9