Tag Archives: street design

10-foot lanes

Here’s an article arguing compellingly for 10-foot lanes on city streets. 12-foot lanes might save time and lives on highways, but on city streets they waste space and kill people.

On city streets, most drivers ignore posted speed limits, and instead drive the speed at which they feel safe. That speed is set by the cues provided by the environment. Are there other cars near me? Is an intersection approaching? Can I see around that corner? Are there trees and buildings near the road? Are there people walking or biking nearby? And: How wide is my lane?

All of these factors matter, and others, too. The simplest one to discuss, and probably the most impactful, is lane width. When lanes are built too wide, many bad things happen. In a sentence: pedestrians are forced to walk further across streets on which cars are moving too fast and bikes don’t fit.

I think we need to move toward safe, multi-modal streets on the Dutch and Danish models worldwide. This will be truly sustainable – safe, healthy, low-energy, low-carbon, and supportive of creative, innovative urban ecosystems where people can come together to solve problems. These are major capital investments with tax dollars, so a cost-effective way to do them is to develop the new standards, adopt them as business as usual, and then upgrade our streets to the new standards as they wear out.

That is a vision, but I see some cheap, easy short-term retrofits that could be done right away without major capital investment. Repainting with narrower lanes (streets need to be painted periodically anyway), and giving the saved space to pedestrians, bicycles, and green infrastructure would be pretty easy. Once streets get repainted, the next incremental step is bollards or other physical protections for pedestrians and cyclists. Some more short-term parking and loading zones would be helpful in a lot of cities – if we had more of those in Philadelphia you wouldn’t have so many people blocking the bike lanes we do have. Another short-term thing that could be done is to turn off stoplights and go back to stop signs on a lot of lower-traffic streets – this should even save a little energy and money. Stop signs are much safer for pedestrians, because all the vehicles have to stop or at least almost stop. You don’t have people gunning the engine on a yellow light to clear the intersection or make a quick turn – that is when pedestrians and cyclists die. Finally, on higher-traffic streets, light signals can be reprogrammed so that pedestrians are not in conflict with cars. Left turns on green just absolutely have to go away. I think right turns on green can be made a lot safer by  small curb extension requiring a sharper turn, but we should think seriously about whether we want any turns on green. Let’s think about the pedestrian scramble model, where all traffic stops and pedestrians can cross diagonally. Cyclists could be allowed to treat this like a stop sign. Then, add turn arrows for all turns and it’s pretty safe for everyone.

transportation news

Transportation is today’s topic.

First, a fantastic set of facts and figures on just how much space cars actually take up in cities.

According to the FHWA’s Highway Statistics report, large U.S. cities average 4.7 road-miles per 1,000 residents, or 25 road-feet per capita. Assuming 50-foot average road width, this is 1,240 square feet of road area per capita, or about 1,500 per motor vehicle. In addition, there are typically 2-6 off-street parking spaces per vehicle. These parking spaces, including their driveways, require, on average, about 300 square feet, or 600 to 2,400 square feet total…

As a result, in automobile-dependent communities with road and parking supply sufficient to keep traffic congestion to the level typical in U.S. cities, plus parking spaces at most destinations, a city must devote between 2,000 and 4,000 square feet (200-400 square meters) of land to roads and off-street parking per automobile. This exceeds the amount of land devoted to housing per capita for moderate to high development densities (i.e., more than 10 residents per acre, which means less than about 4,000 square feet per capita), and is far more land than most urban neighborhoods devote to public parks. This illustrates the problems that growing cities face if they try to develop automobile-oriented transport systems where most residents own a private car: they will need to devote more land to roads and parking than to housing.

Second, an interview with a Swede:

If we can create a system where people are safe, why shouldn’t we? Why should we put the whole responsibility on the individual road user, when we know they will talk on their phones, they will do lots of things that we might not be happy about? So let’s try to build a more human-friendly system instead. And we have the knowledge to do that.

But to do that we need to have those who build this to actually accept this philosophy. Even in our country context, it still has been a struggle to get our road engineers to understand that they are responsible, it starts with them. Then the individual road user also has a responsibility. But if something goes wrong it goes back to the designer of the system.

There’s a little bit of engineer-bashing there. We engineers are great at solving the problems that are put in front of us. We aren’t always great at framing the problem in new and better ways – for example, an objective of safe streets for all users and not just maximum flow rate of cars. But if you frame the problem in that new and better way and give it to the engineers, we will solve it for you.

Speaking of engineer bashing:

“If there was honest predicting, some percentage of them would under-predict traffic,” he said. “There would be a bell curve. Instead… what we have is these projections that are always immensely above what the actual traffic is.”

There is ample incentive for these firms to inflate numbers. Firms that predict high levels of traffic attract investment dollars and regulatory approvals, which lead to construction projects, and the same firms often end up directly cashing in.

The article is about some anecdotal cases where future traffic was overestimated, toll road companies went bankrupt, and taxpayers were left paying at least part of the bill. This is unfortunate, but it is a pretty serious charge to accuse an engineer of purposely enriching private parties at the expense of the public. (Full disclosure: I have professional ties to organizations mentioned in this article, although I don’t have direct involvement or knowledge of any projects mentioned.) I think the correct conclusion here is that it is time for some of the tools and assumptions and methods used in transportation engineering and planning in the United States to be seriously reexamined and brought up to date.

 

more trees!

This article in Landscape and Urban Planning is all about street trees. You would think this topic would have been exhausted, that is the technology would have been perfected, by now. And it has, in a few places. I am convinced it is not that leading edge knowledge about trees needs to be advanced all that much, but most cities are completely ignorant of what the best practices are. People in charge don’t know what they don’t know and have zero interest in finding out.

Street trees are an integral element of urban life. They provide a vast range of benefits in residential and commercial precincts, and they support healthy communities by providing environmental, economic and social benefits. However, increasing areas of impermeable surface can increase the stresses placed upon urban ecosystems and urban forests. These stresses often lead tree roots to proliferate in sites that provide more-favourable conditions for growth, but where they cause infrastructure damage and pavement uplift. This damage is costly and a variety of preventative measures has been tested to sustain tree health and reduce pavement damage. This review explores a wide range of literature spanning 30 years that demonstrates the benefits provided by street trees, the perceptions of street trees conveyed by urban residents, the costs of pavement damage by tree roots, and some tried and tested measures for preventing pavement damage and improving tree growth.

walkability matters – duh

For people still looking for an answer to the question “does walkability matter?”, here is some more solid evidence from Cities to add to the mountain.

In this study, researchers examined 170 neighborhoods in a medium-sized city to see whether walkability influences neighborhood sustainability. Until 2008, there had not been a reliable measure of the social, health, and economic impact of walkable neighborhoods. This dramatically changed when scholars were able to quantify walkability with tools such as Walkscore™; which measures how accessible daily living activities are by foot. The researchers investigated how walkability impacts the quality and sustainability of a neighborhood. They developed models that evaluated the correlation between an area’s Walkscore™ and four broad measures of urban sustainability: neighborhood housing valuation; foreclosures; and crime. Our analysis shows a positive impact not only on neighborhood housing valuation but also on neighborhood crime and foreclosure. These results provide policy opportunities for planners and citizen groups to pursue strategies to encourage the development of more walkable and sustainable neighborhoods.

I know I’m a broken record, but getting around under our own muscle power for most trips most of the time is the key to (in no particular order):

  • reducing carbon emissions
  • reducing air pollution from vehicle emissions, especially particulates which cause asthma and heart disease – this will add quality years to all our lives
  • solving drunk driving
  • saving lots and lots of money that we used to spend on cars
  • saving enormous amounts of space in cities that used to be used for car maneuvering and parking – space that can now be used for relaxing, recreating, habitat, housing, economic or commercial activity
  • creating space for people – yes, you can increase density and reduce crowding at the same time
  • increasing physical health through more physical activity, decreasing obesity, diabetes and heart disease, adding years to peoples’ lives
  • improving psychological health through physical activity
  • increasing social interaction
  • increasing business activity and profits
  • creating an ecosystem of innovative, creative people, businesses, nonprofit and government agencies

protected bike lanes

Continuing on my recent transportation theme, this article on Alternet has some really good statistics on protected bike lanes. I am convinced that biking (a.k.a. cycling) is just a more practical way to get around urban areas than cars – it gets more people from point A to point B with less infrastructure, less cost, less wasted space, and no pollution. Plus, it promotes a more healthful, active lifestyle and urban design that supports that.

But for all this to happen, we have to build cycling infrastructure that is truly safe, and the U.S. just hasn’t fully committed to that. There are signs of hope, however – here are some of the statistics I’m talking about:

  • 27% of all trips in the Netherlands are made on bicycles. The Dutch designs are not secret but are available here (although their manual costs 90 Euros and it is not clear to me whether an English version is available).
  • The “pioneering” American city in protected bike lanes is…Montreal with over 30 miles (I just remembered, Canada shares our North American continent). But New York City has caught up and surpassed them with 43 miles. Other cities are Chicago (23 miles), San Francisco (12 miles), Austin (9 miles), and D.C. (7 miles). (Here in my native Philadelphia, we have not built protected bike lanes but have closed some lanes to traffic and painted some new stripes on the streets that would allow us to eventually separate them. Philadelphia has a burgeoning cycling culture and I think eventually it will happen. We don’t like to do anything first, we always sit back and watch what New York is doing for a few years before we build up the courage to try something new.)
  • Studies are finding that bike infrastructure boosts retail sales – 49% for a street in New York, 24% in Portland – and 65% of merchants surveyed reporting positive effects in San Francisco. (I’m not surprised by this – there is less space wasted on car travel lanes and parking, less time wasted circling around looking for parking, less money spent on parking, more room for trees and fountains and sidewalk cafes – you have more people in a given space, yet less crowding, with more time and money on their hands and a nicer environment where they want to hang around.)
  • And…duh…protected bike lanes are safer for everyone, and add more capacity to move more people at much lower cost compared to new traffic lanes.

The article also links to this fantastic collection of articles and data on protected bike lanes from “peopleforbikes“.