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Putting the Autonomous Brakes On: What it means for cities.

Brian E. O'Looney

The American legal system reinforces the prioritization of pedestrians over vehicles: under all state laws, walking is a right while driving is a privilege.

When discussing the upcoming impact of autonomous vehicles on society, a street video of urban life from over 110 years ago paradoxically provides clues on what urban life could become.   The film “A Trip down Market Street” shows the vitality of Market Street in San Francisco in 1906, from the perspective of a camera mounted to the front of a moving cable car as it progressed from 8th street to the front of the Ferry Building.



For our purposes, what is fascinating about this film is that it shows the way the streets were inhabited in 1906.  People walk anywhere and in whatever direction they wanted.  The automobile at the time was a very new innovation; streetcars, cable cars, and horse drawn buggies feature prominently in this transitional moment before the automobile asserted its dominance.[i]  There is a complete lack of traffic control for the street network.   The first road markings in the US are three years away, in Wayne County Michigan. The first electric streetlight won’t be invented until 1912 in Salt Lake City.  The first stop sign is 9 years away, also in Michigan.  Painted crosswalks are invented many years later in England in 1948, replacing raised beacons and posts. 

This video is not just about our past, it gives us a glimpse into a possible near future world with autonomous braking.  In just 5 years, with a push from the insurance industry, automakers and regulators have agreed to provide autonomous braking on all new vehicles in September of 2022.[ii]

Autonomous braking will make us reconsider whether jaywalking should be illegal in urban places.

For pedestrians, autonomous braking will likely be the most empowering of all autonomous innovations.  Anybody will have the power to stop traffic.  With automated breaking, pedestrians will KNOW that they can walk in front of a post-2022 car at any time.  There won’t be a safety issue, but there will be a tremendous traffic policy issue that will arise.  Pedestrians will be able to stop vehicles equipped with autonomous braking, and hold up traffic at anytime, anywhere.  Jaywalking will greatly increase, as individuals are emboldened by their newly given powers.

This will pose challenges for local traffic authorities, particularly in urban areas.   In many places, new vehicle vs. pedestrian conflicts will force jurisdictions to choose between defining their public realms as primarily for pedestrians, or alternately for the throughput of vehicle volume.

Traffic jam, India

If vehicle flow is given priority, measures to restrict access for pedestrians would need to be added, as currently established with the Controlled-Access design of the Interstate Highway system in the United States.  These measures can already be seen within urban areas of the American landscape, erected in the name of safety.  In the heart of the retail corridor in the center of the University of Maryland in College Park, MD along Baltimore Avenue, walls and fences have been erected at the edge of active sidewalks and in the center median to control jaywalking and allow vehicles to have priority over pedestrians, forcing pedestrians into defined crosswalks.  At bus transfer stations along other state highways, Montgomery County, MD is also erecting fencing along sidewalks and medians which prioritizes vehicle roadway travel over pedestrian flow to and from the station.

Fencing and walls along sidewalks and medians in the heart of College Park, MD

Internationally, particularly in Asia, urban pedestrian flow has been corralled, caged, tunneled and bridged when vehicular throughput has been deemed particularly important.  Examples abound in Shanghai and other cities in China; Shinjuku and many other locations in Tokyo, Japan, where pedestrians are caged to separate them from vehicular flow.

Caged pedestrian bridge in Odaiba, Tokyo, Japan
Caged Stairway to pedestrian bridge in Odaiba, Tokyo, Japan

The good news is that our American legal system reinforces the prioritization of pedestrians over vehicles: under all state laws, walking is a right while driving is only a privilege, a privilege that can be taken away at any time.  Some far-sighted civic leaders here in the US have already begun reinforcing that prioritization of the pedestrian over the vehicle.  Given that traffic deaths dramatically increase over 30mph, Mayor Muriel Bowser has mandated a 25mph limit across the entire District of Columbia in Washington DC’s “Vision Zero” goal to have no traffic deaths.  The City Council of Boston has done the same, mandating a 25mph speed limit throughout the city where no limit is posted.[iii]

Where jurisdictions decide the pedestrian shall have priority, a different design paradigm may arise.  In some city centers, traffic crosswalks will become antiquated and unnecessary, and the greatly increased jaywalking could become legitimate and a more shared model can govern, because safety risks and dangers have been mitigated by autonomous braking.  Woonerfs, or shared spaces, have existed in Europe for some time, where vehicles and pedestrians coexist in the public realm and are not segregated.  The theory is that vehicle drivers have a heightened sense of risk, understanding that the place they are driving is shared with pedestrians, and inherently drive slowly and are extra-cautious.  Some places converted from sidewalks/crosswalks to woonerfs have had less traffic fatalities after the conversion.[iv]

Woonerf, Norrköping, Sweden.  Image courtesy Ian Lockwood
Above: Intersection before construction of Woonerf, Norrköping, Sweden.  Below: Intersection after construction of Woonerf, Norrköping, Sweden. Image courtesy Ian Lockwood

With autonomous braking, entire downtowns have the capability of being shared spaces, and perhaps rid of traffic controls - be crosswalk, curb, and stoplight free.  But the cost of this would be that the overall speed of these places would be reduced back to that of the pedestrian, harkening back to the San Francisco of the early 1900s.  This would result in the intentional limitation of vehicular throughput, potentially segregating vehicles to outside conduits or public transit corridors in distinct guideways.

As we approach 2022, towns, cities and jurisdictions must think carefully about what model they want to follow – that of the caged pedestrian where vehicle traffic is prioritized, or the shared space street where the pedestrian has primacy.  Ultimately, both models may have their place, but we need to take the time to figure out which model is appropriate where and how we can implement them in ways that enhance the livability and viability of our towns and cities.

[i] There are a few cars in the video – some which circle the camera into posterity.   Some historians argue that some of the automobiles which circle the camera were staged by the film producers to present San Francisco as technologically advanced, while others believe a proud vehicle owner or two are showing off their new automobiles for the camera. (

[ii] Automatic emergency braking coming to 99% of cars in 2022. (Chris Woodward, USA Today, March 17, 2016)

[iii] District of Columbia,, accessed March 26, 2017; City of Boston,, accessed March 26, 2017.

[iv] A good case study for this impact is at Norrköping, Sweden, where traffic incidents went down when curbs and crosswalks were replaced by a uniform masonry paving plaza from building face to building face.

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