Category Archives: cycling environment


David Levinson and I authored, “The Shapes of Streets to Come – How New Transport Technology will Reshape Urban Space” which appeared in European Financial Review (registration required) (reprinted below). [PDF version here: TEFR AugSep 2016 – The Shapes of Streets to Come – How New Transport Technology will Reshape Urban Space]


By David M. Levinson and Kevin J. Krizek

Autonomous vehicles are coming. At their best, AVs are stimulating an impulse to drive genuine innovation. At its worst, they are a hubris that causes us to overthink the solutions to transport problems in cities.

Big changes are coming for how people will get around in cities across the globe. The most important change will hinge on the introduction of autonomous vehicles (AVs). Simultaneously, cities will witness the conversion of the vehicle fleet to being primarily electric-powered (from a grid rapidly converting to renewable energy and off-the-grid solar charging) and new ownership models like shared mobility become more common.

The overall pace of deployment of AVs and their effects will vary by the size of the city, the cost of labour, and the desire for politicians and their constituents to innovate. How all of these factors play out on the multiple stages and multiple scales (e.g. the neighbourhood, metropolitan, and national levels) will prove exciting to watch. The best part is that you not only get to observe how things will play out; you get to participate as well. We preview many of the prevailing tensions of this emerging landscape below.

Autonomous Vehicles

After decades of technological slumber in the automobile industry, self-driving cars are here. Rolling on the roads today in semi-urban environments are cars that can recognise speed limits and adjust their speed instantly. They can maintain a safe following distance from other cars, and brake when needed. They can even recognise the difference between cars, buses, and cyclists. The technology is at the cusp of being widely deployed, something that will take place over the next two decades. Significant other hurdles, however, lie ahead. These impediments include how cultures might adapt (e.g. how quickly will people surrender control, and their comfort with technology), legal regimes might change (e.g. standards, reconciling responsibility in crashes, the role of licensing), and street designs will be altered (e.g. the extent to which AVs will be apportioned separated lanes on different types of roads, and how soon human-controlled vehicles will be prohibited in places). We focus on the last hurdle here.

One of the strongest but often unrealised arguments for the advent of AVs relates to street capacity. Where today a freeway travel lane is typically 3.6 meters wide, with AVs, a standard lane might only have to be 2 meters (just wider than the width of a full- size car or SUV). This alone nearly doubles capacity. Farther into the future, lanes might be dynamically resized rather than permanently fixed in paint. Being automated, these cars can trail one another more closely as well. Instead of following at two seconds or one-and-a-half seconds, they might follow at one second or less, increasing throughput.

Today the average vehicle carries only one or two people, yet the average vehicle has seats for four or six or eight passengers. The fleet is oversized, especially in the US. Americans have a propensity to buy large cars for the few times when they may need it. The extra seats, however, sit unused most of the time. Automation, combined with mobility-as-a-service presents opportunities for new vehicle forms.

New Types and Forms of Cars

Smaller one and two-person vehicles can be the new standard, and larger cars the exception, only summoned on demand when needed. In lower density areas, travel distances remain large, but the use of AVs will allow suburbs and small towns to wring out more road capacity, provide good arguments against road expansion, and claw-back space that has been given over to parking.

A city can start to realise large benefits because it can get more capacity out of that smaller vehicle, more energy efficiency, a greater range for the battery, and so on. One of the more noticeable elements will be a transformation of the shape of the car. Vehicles will begin to sport new designs whose markets will be defined by required use. Consider an enclosed motorcycle that’s electric, quiet, safe, stabilised, and automated. It is safe because, not only is the vehicle designed well, with a roll bar and all that, and because it is driven by a computer with nearly instant reaction times, but because all the other vehicles are also automated. Small cars require less space and it is easy to see how future cars will starkly contrast with their ancestors. Meanwhile, sensors and computers replace the human-facing control functions; electrification is changing the entire motor system, so future cars will be simpler to manufacture and maintain than the internal combustion engine.

Innovations in Related Modes

The complexity of how and when – not if – to accommodate AVs will be further complicated because other modes of transport are re-inventing themselves as well. Different types of mobility-as-a-service are coming on line. These include new forms of taxis and transit services that are both smaller and bigger than a standard bus. Taxis will be more extensively used because the vehicles are smaller and driverless, and so cheaper. In urban areas, there will be more frequent transit services in selected corridors, which will be less expensive to provide as labour is automated away. Elsewhere, today’s infrequent bus and commuter rail services will be replaced by mobility-as-a-service type of options; instead of having a bus that comes once an hour, people will be using taxis – often single passenger taxis, maybe shared ride taxis. While the exact market configuration (who owns, who rents, who shares a ride, who rides alone) will be sorted out over time, it is clearer to see how, like today in Manhattan, people who live in dense cities won’t be owning cars, but instead will subscribe to a service, buy the services on demand, or find it provided by the public as a “free” utility, like the elevator in an office building

Role of Walking and Bicycling

Amidst this uncertainty, bicycling and walking will thrive for shorter and medium distance trips. These might be trips where people yearn for physical activity or just want to be outside. Their use will continue to be constrained by weather and hills, though e-bikes, with electrical pedal assistance, will mitigate some of that. This is one of the reasons we will likely see an increase in the attention devoted to physically powered movement for next few years. It is green and energy efficient. It makes many people feel better. Most importantly, bicycling and walking are modes that are relatively known and proven in selected markets.

All of this is to say that traditional modes, bicycling and walking will continue to exist and begin to thrive even in the US. This owes to increased population densities in central cities (and trip distances therefore decreasing), increased safety because AVs are less likely to kill them than human driven vehicles are, and a growing inclination to more fully connect with others and their environment.

Infrastructure Needs and Who Gets What Space

How will street space be appropriated in a manner that will allow multiple modes to harmoniously co-exist? Answers to this question will play out differently between and within cities. Fundamental geometric limits ultimately dictate the usefulness of these improvements. Where the intensity of development is higher, several modes will compete for the same space. Different modes can safely mix in the same shared space at slow speeds, as is now found in historic sections of many European cities. Further away from these cores in lower density areas, where space allows, the infrastructure provision for modes will be more segregated.

Typically, local municipalities operate the local streets and state or regional agencies maintain the connecting the backbone. On the backbone, we envision special (managed) lanes for automated cars for a period of time, just as today we have express, HOV, or high occupancy/toll lanes. It may even be the same lanes will benefit all users, as separated lanes will allow reaping the benefits of closer following distances than possible with mixed (human plus automated) traffic. As all vehicles become automated, all lanes will be managed.

Shapes of Streets and Shapes of Cities

The ability for cities to dynamically reconfigure lanes and repurpose streets will be the central challenge. The speed and manner in which cities and regions respond to the onset of these big changes will vary. Some places will move quicker than others. Politics and openness to innovation will be important. But ideas are light baggage, and successful policies will be quickly copied and emulated.

Shapes and patterns of development of communities determine how most people get around. The size and nature of buildings and roads are important. The prevailing perspective is that cities have evolved under different technological and political regimes; they therefore embody the DNA of their continents. Granting exceptions, North American cities have a DNA that is distinct from their Asian, European, or Latin American counterparts. Cities in Europe are smaller in size, they were mostly formulated in an era prior to automobile, and their networks for movement are more multi-modal. It’s sometimes easier to get things done without a car, automated or not. Hundreds of European cities already have an extensive track record severely limiting automobile traffic in historic districts. The Italians call it the ZTL (Zona a Traffico Limitato). We expect European cities will be keener to take back even more street space from the new AV, and use it for landscaping, linear parks, cycle tracks, and high-frequency transit services. Places in other parts of the world will follow suit.

AVs and the Future of Cities

At their best, AVs are stimulating an impulse to drive genuine innovation that will make lives richer and more connected, faster and safer, and more productive. At its worst, they are a hubris that causes us to overthink and over-engineer the solutions to transport problems in cities. Either way, AVs are coming. It is just a matter of when and how.

Political and legal systems in cities will be forced to play catch up with technological systems. The cities that do will win the 21st century. The others are building unnecessary capacity justified by extrapolating the exhausted trends of the past. The aim of transport should be ensuring people and goods can reach their destination safely and efficiently. This requires focusing on what will improve access tomorrow, not what might have increased access yesterday.

Featured image courtesy of the author Kevin J. Krizek

About the Authors

David Levinson and Kevin J. Krizek are the authors of The End of Traffic and the Future of Transport, available on Amazon Kindle and Apple iBooks.


David M. Levinson is Professor in the Department of Civil, Environmental, and Geo-Engineering at the University of Minnesota and will soon be joining the University of Sydney. He holds the RP Braun/CTS Chair in Transportation.


Kevin J. Krizek is Professor and Director of the Environmental Design Program at the University of Colorado-Boulder. He also serves as the visiting professor of “Cycling in Changing Urban Regions” at Radboud University in the Netherlands. Krizek was a 2013 fellow of the Leopold Leadership Program and was awarded a 2014 US-Italy Fulbright Scholarship.

Is Ferrara’s (Italy) bicycle success not IN the water but BECAUSE of it? |

cartello 2-1Part 2 of the EU BICI is up, focusing on Ferrara (Italy). Part 1 was on Seville. 

“It’s hard to figure out how Ferrara (Italy) achieved legendary status among Europe’s top cycling towns. The answer might not be in the water; but it could be because of it. The ferraresi embrace the bike as much as any place I have seen. But in way lacking self-consciousness, most residents fail to consider themselves exceptional in this respect among neighboring cities.”


Bicycle infrastructure in Seville (Spain) |

IMG_6058Seville (Spain) starts a series for my newly launched 2014 EU BICI (European Union Bicycling Information Collection Initiative) which is airing at

“When one thinks about cycling in cities and Europe, all eyes turn north. But Seville has made valiant cycling strides in just six years. Their strategy clearly borrows from the Dutch for inspiration (i.e., separate cycle paths appear to be the divine wisdom); and, their relative ‘overnight’ stardom deserves attention.”

National Academies of Engineering, Frontiers of Engineering – the Future of Transportation

This past weekend I was at the US-EU Frontiers of Engineering Workshop in Paris. The National Academies of Engineering asked me to co-chair the session on “The Future of Transportation.” Three researchers who are well known in the U.S. dazzled the collection of 50+ other engineers who represented other engineering fields.

Why Traffic Management Works…And Why Coordinated Traffic Management will Work Even Better
 – Serge Hoogendoorn, Technical University Delft, The Netherlands

Nash-Stackelberg Games in Transportation Networks: Leveraging the Power of Smartphones for Traffic Monitoring and Management
 - Alexandre Bayen, University of California, Berkeley

Impacts of the Sharing Economy in Transportation
 - Kari Edison Watkins, Georgia Institute of Technology

Here are two observations based on the session:

1. The last speaker, Prof. Watkins, offered several perspectives in the her presentation that got most of the Q & A session talking about issues of how to harness car travel; there was even a focused discussion about the role of cycling in all of this. Yes, some of the world’s brightest engineers were talking specifically about spurring more cycling as part of our transportation system for almost 15 minutes  (really, I had little to do with this).

2. A key element of Watkins’ presentation stressed elements of the “shared economy” and implications for transportation—in terms of sharing space and information.

For us transport folks, there are seemingly endless implications of the shared economy. One framework might be to approach this by thinking about different elements of non-auto using behavior vis-à-vis different considerations that are important for adoption.

Different elements of transportation and transportation information, of course, include: Transit information (e.g., when is the next bus), Bike and Car sharing (e.g., where are the stations), Cycle tracks (e.g., how do people use the network), Ride sharing or slugging (e.g., sharing space in a conventional car), Destination knowledge (e.g., where is the closest pizza)…the list can go on.

Considerations that are important for adoption would include:

-Are there general safety fears of the transport device being used (e.g., am I using someone else’s car whose brakes don’t work)?

-Are there specific safety and security fears with procuring access to the transport device (i.e., do I have to meet someone I don’t know to get a hold of the device)?

-Are you concurrently sharing a physical space with another person (e.g., sitting shotgun in their car)?

-How much reliability of the trip is needed (e.g., you absolutely need to get there now)?

-To what degree can the information exchange be public, done via open wiki or otherwise open source?

-To what degree would my anxiety about sharing space (e.g., a spot in their car) be overcome via forms of social media (e.g., leveraging facebook and 6 degrees of separation.

…the list can also go on.

The main point: to successfully leverage all the different forms of the shared economy for transportation, different forms of transport information have different criteria to “make it work.”

Diminishing returns of off-street bicycle facilities |

At, I have the following post: Diminishing returns of off-street bicycle facilities.

“Some attention to my previous post seemed to stem from the incredulity of implying anything negative about the Midtown Greenway—one of America’s most beloved darlings of a bike path […]“

The paths that people take (5 part series)

As part of an interesting FIVE part series focusing on different considerations in the paths that people take for travel (i.e., why is it not always the shortest?), the Transportationist discusses our bicycle route choice experiment.

The perfect is the enemy of the good; making lemonade is sufficient

Some bike paths serve as semi-icons for their city. The Creek Path in Boulder, Colorado (US) ranks up there with the Seattle’s Burke Gilman Trail and the Chain of Lakes network in Minneapolis (both US). But the origin of the path’s construction had some rough beginnings.

A bit of history: The area around the path was originally called for in Boulder’s Creek Corridor plan (1984), which stipulated the use of the creek corridor as a linear, topographically sensitive park. This park would incorporate riparian zones and wetland sensitive elements[1]. The creek comprised one of the primary watersheds for the city and a few years later, the city purchased adjoining land to the creek for a wetland and greenway program. This led to further integration of habitat restoration and water quality augmentation elements into the use of once forlorn features of Boulder’s ecological fabric. But over time, community-wide momentum was building for how the area could also enhance flood mitigation efforts together with more “mainstream modes” of transportation such as walking and cycling (in addition to kayaking)[2].

Rather than scour for the pennies that were available at the time to build bicycle facilities, the city tapped into federal grants for flood control and environmental remediation; these coffers were three to four times larger. The city creatively parlayed bike trails into this process. The flood mitigation efforts were considered to have largely passed the extreme test that the city experienced owing to biblical floods in September of 2013.

But the specific planning of the bike portion of the Boulder Creek Path was somewhat of a separate issue. And, Gary Lacy, a recreation planner for the city at the time, approached it with vengeance. He focused on ensuring it got built—not planned for—but built. Lacy considered formal permits a nuisance; conscientious and collaborative plan-making was too time consuming. He relied on a “Robert Moses-esque” philosophy and sometimes took a page out of Chicago Mayor Daley’s planning playbook[3]. Rather than abide by city protocol, he went solo and blazed sections of the trail by moonlight. He took to the backhoe to move obstinate boulders along the way. Where the earth would not move, he built the path around it.

Lacy’s semi-barbarian approach to make the path is etched into local folklore. And the path itself would have made the hair stand up on the neck of the authors who penned the 4th edition Guide for the Development of Bicycle Facilities by the American Association for State and Highway Transportation Officials (AASHTO)[4],[5]. Sight lines are jeopardized, travel lanes were inconsistently wide, and some right-angled turns (frowned on in bike path planning) continue to be sprinkled throughout. Friends in town claim the trail is hazardous and a downright safety hazard. But the path got built—the city has since smoothed out some of the path’s rough edges—and it now serves as a beacon for the city and a seminal spine for the rest of the its cycling network.

The development of Boulder’s Creek Path represents a planning story where the perfect was not the enemy of the good. Things got done, despite not being perfect. There were some issues along the way—some of them safety oriented, others process oriented. But its evolution begs the question in the world of bicycle planning, when is a facility “good enough.”

Similarly, the “so-called” bicycle facility outside my home in Bologna (Italy) is a meandering stripe that bobs and weaves, literally at right angles between newsstands and trees. It sometimes pinches the rider down to mere inches. I presume it was laid by an Italian public works employee after too much grappa. But do these sketchy attributes warrant it as a non-useful facility? Is providing substandard bicycle facilities worse than none at all?

The dilemma reminds me of a scene in Cher’s 1987 Academy award winning film, Moonstruck (the movie, likewise shares Italian origins). The father, Cosmo Castorini, is a plumber who is explaining to a client in his deep Italian accent his philosophy of preferred plumbing materials.

“There are three kinds of pipe. There’s what you have [aluminum], which is garbage – and you can see where that’s gotten you. There’s bronze, which is pretty good, unless something goes wrong. And something always goes wrong. Then, there’s copper, which is the only pipe I use. It costs money. It costs money because it saves money.

Did Cosmo have it right? Are there problems in the bike planning world that stem from constructing the equivalent of ‘aluminum’ or ‘bronze’ facilities?

The biggest risk of substandard facilities are the unmet expectations that they create. Cyclists, seeing signs, markings or other might are comforted into letting down their safety guard, for example. There is subsequent confusion about the role, rights, and responsibilities in the transportation hierarchy. Cyclists are all too familiar with the bike lane painted within mere inches of the impending car door opening. Or the bike facility that, in a pinch, mixes you with pedestrians and then switches the side on which bikes are supposed to ride. Then there is the blissful cycling corridor that abruptly dumps you into four lanes of auto traffic. In my own research, I found that users particularly struggle with these later situations when facilities end at bigger intersections, locations with on-street parking, and locations with relatively narrow travel lanes[6].

With most transportation networks being surface oriented, mainly along streets and primarily occupied by cars, it is useful to have prescriptions, guidelines, and even sometimes standards to guard against these situations. In an ideal world, a planner would take stock of the context, consult the guidelines, prepare the design, and execute. If only it were that easy. History gets in the way. Cultural peculiarities get way. Nature gets in the way.

There are many cities—almost all of them in industrialized countries—who are moving toward this consistent model. If you ask Dutch cycle planners, they immediately pull off the shelf their tattered Design Manual for Bicycle Traffic[7]. They leaf to dog-eared section 4.4.2 where they point to a figure with two axes—how many cars are along a particular route (e.g., traffic volume) and the speed of those cars. Five different types of suggested facilities are depicted based on these two factors alone. Adhering to some core principles put forth by the prototype model is gaining steam in the US[8] and cycling treatments are approached with increasing method and consistency.

At the other end of the spectrum lie cases where bicycling treatments are less than satisfactorily completed. That might be an overstatement. They are downright dangerous. These might consist of the cavalier bike path that was laid through a stretch of road—lacking attention to its connecting points—to enable a politician could deliver on a promise to a constituency. It might be the case where road engineers are blindly following a city’s guidelines; they might measure three feet from a street curb’s edge, lay a stripe, and call it a day regardless of the context. It might be the proverbial case where a bike facility passes over a storm sewer with drainage slots that miraculously measure the same width as a bicycle tire. No self-respecting transportation professional would endorse these outcomes. They present unexpected conditions, safety hazards, and problematic signals to both cyclists and car drivers.

In the broad spectrum of bicycle facility planning contexts, there are environments that are shy of falling into the above category. But, they don’t lend themselves to rigid standards (or expectations) offered in guidebooks. Try finding room for a bike path in the historic center of any city that was inhabited by the Romans. The typical right-of-way might be three meters wide and shared between five or more different modes each traveling in two different directions. While most situations are not this stark, the bulk of planning contexts—especially in historic cities across the globe—are in situations where the bike planner is dolled a bunch lemons. Cosmo might have had it wrong. Realizing that not everywhere in a city can be built with ‘copper pipe’ cycling conditions, bike planners must make due and prescribe treatments that are far from perfect. They must make lemonade, even thought it carries some risks.

Otherwise, what are their options? They could sharpen their pencils designing the perfect intersection which might come to fruition once the political will arrives. Alternatively, they could do nothing.

Making lemonade means that formal standards might be abandoned. Cyclists need to adjust their expectations. Car drivers need to acclimate. Life goes on. Bike facilities need to start somewhere. They need to be granted freedom to experiment without backlash. What might be considered a substandard intersection treatment today will eventually graduate to something more mature. For example, a painted stripe that winds through a parking lot, might be upgraded to a perimeter route next year, which would then eventually be dovetailed into a larger separated network. A green swath at an intersection now would convert to a bike box next year which would then be complemented with a prioritized cycling traffic signal in the following year. Doing “something” provides a much-needed nod to the cyclists. It is usually better than doing nothing at all and helps set in motion a process whereby facilities can mature. Cities are constantly evolving. This includes their transportation infrastructure. That is, over time, the lemonade gets sweeter and sweeter. Cycling treatments usually pale in comparison to the costs of auto or transit infrastructure. As long as lives are not gravely put at risk and accidents largely avoided—a big caveat, I admit—cycling treatments are inexpensive experiments. If they succeed, they are built on and further developed. If they clearly fail, they can be erased.

[1] A portion of the creek was reconfigured as a white water recreation park, thereby incorporating another level of complexity to the flood mitigation strategy. Gary Lacy, a recreation planner for Boulder and an avid kayaker, would reportedly boat to his downtown work location along the creek.

[2] Greenways Master Plan.   City of Boulder2001 update. Accessed January, 2012

[3] Daley’s playbook: Meig’s field was a fully functioning private airport runway strip on Chicago’s pristine lakefrong. Citing security concerns in 2003, Mayor Daley ordered the bulldozers tear up the runway and they did so in the middle of the night to avoid obstruction and protesting efforts.

[4] American Association of State Highway and Transportation Officials (2012). Guide for the Development of Bicycle Facilities, 4th Edition. ISBN: 1-56051-527-2.

[5] This is a document that ASHTO was so proud about that they produced a video for its release, see:

[6] Krizek, Kevin J. and Rio Roland (2005). What is at the End of the Road? Understanding Discontinuities of On-Street Bicycle Lanes in Urban Settings. Transportation Research, Part D. 10(1): p.55-68

[7] This report is the world’s most authoritative manual on bikeway design and is published by CROW—a Dutch acronym of the Information and Technology Platform for Transport, Infrastructure and Public space, a Dutch non-profit collaboration between government and businesses.

[8] As is evidenced by AASHTO publishing their 4th edition, American Association of State Highway and Transportation Officials (2012). Guide for the Development of Bicycle Facilities, 4th Edition. ISBN: 1-56051-527-2.

Heated paths — which first and what of salt?

Snow season is coming (at least in northern places in the northern hemisphere). I have read two accounts in the past week calling for heated bike paths and heated sidewalks.

Heating coils are one option. Retaining summer heat is the other. Both seem pretty expensive. But it does beg two questions, assuming it can be done and paid for,

1. Is it best to start with the sidewalks, bike paths or roads? I am less convinced the roads need it. The cars are relatively stable in moderate snow.

2. Can we really kick the salt habit?