How Can Cities Move More People Without Wider Streets? Hint: Not With Cars

Here’s how many people a single traffic lane can carry “with normal operations,” according to the National Association of City Transportation Officials.

How can cities make more efficient use of street space, so more people can get where they want to go?

This graphic from the new NACTO Transit Street Design Guide provides a great visual answer. (Hat tip to Sandy Johnston for plucking it out.) It shows how the capacity of a single lane of traffic varies according to the mode of travel it’s designed for.

Dedicating street space to transit, cycling, or walking is almost always a tenacious fight, opposed by people who insist that streets are for cars. But unless cities make room for pedestrians, cyclists, and transit riders, there’s no room for them to grow beyond a certain point.

NACTO writes:

While street performance is conventionally measured based on vehicle traffic throughput and speed, measuring the number of people moved on a street — its person throughput and capacity — presents a more complete picture of how a city’s residents and visitors get around. Whether making daily commutes or discretionary trips, city residents will choose the mode that is reliable, convenient, and comfortable.

Transit has the highest capacity for moving people in a constrained space. Where a single travel lane of private vehicle traffic on an urban street might move 600 to 1,600 people per hour (assuming one to two passengers per vehicle and 600 to 800 vehicles per hour), a dedicated bus lane can carry up to 8,000 passengers per hour. A transitway lane can serve up to 25,000 people per hour per travel direction.

Of course, it usually takes more than changing a single street to fully realize these benefits. A bike lane won’t reach its potential if it’s not part of a cohesive network of safe streets for biking, and a transit lane won’t be useful to many people if it doesn’t connect them to walkable destinations.

But this graphic is a useful tool to communicate how sidewalks, bike lanes, and transitways are essential for growing cities looking to move more people on their streets without the costs and dangers inherent in widening roads.

8 thoughts on How Can Cities Move More People Without Wider Streets? Hint: Not With Cars

  1. What is the difference here between “dedicated transit lanes” and “on-street transitway?”

  2. It may be the difference between paint on a lane that cars would still use (to make turns, for loading, or just illegally) and a real dedicated ROW at street level not accessible or usable by private cars. But you’re right, the distinction in the graphic is vague.

  3. Transportation facilities and services are very dependent upon the land use patterns being served. In spite of all the talk about “smart growth,” it appears that there is a lot of “dumb growth” going on. Economist Issi Romem has written an interesting article in Buildzoom, “Has the Expansion of American Cities Slowed Down?” (See Apparently, the amount of rural acreage being converted to urban
    uses has been relatively constant from the 1950s to the present time.

    Even cities with stable or declining populations are experiencing
    this type of expansion. (See the expansion maps in Romem’s article for
    Cleveland, Detroit and Pittsburgh.) In some cases, the outward
    expansion of urban areas was so robust (and disinvestment in the center
    was so severe), that land in some central cities declined in value
    sufficiently to become new low-cost frontiers so that urban infill could
    compete with exurban expansion where there was sufficient employment
    growth demanding workers who valued an urban environment. However,
    where infill development has been robust (Boston, San Francisco,
    Washington, DC & New York), rising urban land values (that helped
    trigger urban flight and sprawl with the advent of roads and cars in the
    1920s, 1930s and 1940s), creates gentrification problems and could
    eventually choke off urban infill in favor of cheaper outward expansion.

    Sprawl has been bad for the environment. It has also been bad for
    municipal budgets because it requires an expansion of infrastructure
    that exceeds the expansion of households and businesses. In other
    words, the per capita infrastructure requirements are much larger for
    sprawl than for compact development.

    The solution to environmental degradation and municipal bankruptcy
    requires more than mere good intentions about smart growth. (Maryland
    enacted substantial “smart-growth” legislation several decades ago, but
    it has made no discernible difference in development patterns according
    to a study by Gerrit Knaap, one of the architects of Maryland’s
    smart-growth program.) The economic and regulatory incentives that
    encourage sprawl must be addressed. These would include:

    * Mileage-based and congestion-based roadway user fees;

    * Performance-based parking fees (in lieu of subsidized parking);

    * Reductions in minimum parking requirements

    * Transformation of the traditional property tax into a “value-capture” fee.

    The property tax transformation is often overlooked. But the
    traditional property tax encourages land speculation which has played a
    key role in promoting sprawl. More information about this policy can be
    found in an article “Break The Boom and Bust Cycle” at .

  4. I’m also wondering if it might be the difference between a dedicated transit lane that is used by one route that stops in the lane to pick people up, and a transitway that is shared by many different routes on a long segment, where they either fork off or pull aside to stop and pick people up. If the vehicles stop in the lane, you can’t really get much past one vehicle per minute (and even that is going to be tough), while a shared transitway that functions like a freeway could have several vehicles per minute. (Of course, something like that would be most natural as a bridge or tunnel, or else function like an urban freeway, channeling lots of people over long distances towards local service at either end.)

  5. I know of a dedicated transitway that moves upwards of 50,000/hr/direction. Metrobus – Istanbul. IT was a reapportioning of space on the D-100. They didn’t widen the expressway, but they took away the emergency lanes to add the transitway in the middle.

  6. The problem with this sort of chart is what it represents. Individual travelers passing a single point in an hour. It does represent throughput at chokepoints, but for end to end trips in a typical urban setting it is not representative of either true average trip times or individual convenience of travel.

  7. Actually, one of the bigger issues is zoning laws. In expanding cities like DC, NY, and SF, the land prices skyrocket downtown. The normal response would be to build much taller buildings downtown, and there’s lots of private money which is ready to do that… *but zoning makes that illegal*, and sprawl is built instead.

  8. Zoning is very important. But even if the zoning is correct, landowners might not develop up to the limits provided and speculation will inflate land prices driving development to cheaper, but more remote sites (sprawl). This is why tax reform is so important. It makes zoning more robust and, by taking the profit out of land speculation, helps reduce the speculative demand for land and thereby makes prime sites more affordable for folks who wish to live or do business in these prime locations.

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