A call for redesigning American streets

{***Pause/Music***}
{***Noah***}

Coming up on Harvard Chan: This Week in Health…

Redesigning how American streets function.

{***Anne Lusk Soundbite***}
(Everything we have designed in the U.S. is based on the convenience for the car driver. How do you change that and incorporate the bike? To me, you do so not just putting in a sharrow or painted bike lane, which is not as safe, you give them treed corridors that lead to key destinations and you redesign how cities function.)

In this week’s podcast we’ll explore how America’s streets can be redesigned to benefit bicyclists and pedestrians—and we’ll explain why doing so may even help mitigate the effects of climate change.

{***Pause/Music***}
{***Noah***}

Hello and welcome to Harvard Chan: This Week in Health. I’m Noah Leavitt.

In our last episode we explored the need to design our buildings and cities in ways that can mitigate the effects of climate change—including extreme heat.

And we’re continuing that theme with this week’s episodes. But instead of buildings, we’re taking things down to the street level—to focus on bicyclists and pedestrians.

A new study from Anne Lusk, a research scientist here at the Harvard Chan School, analyzed how bicyclists and pedestrians responded to various placements of trees along cycle tracks—barrier-protected bicycle-exclusive paths between the road and the sidewalk.

And while trees along a cycle track may seem like a minor issue, the research shows that the placement of these can play an important role in how people walking and biking perceive traffic, pollution, heat, and even safety.

But the benefits extend beyond just those using the street—and could even be a factor in mitigating the effects of climate change. These trees may make it more likely that people will bike—helping to reduce pollution.

And increased greenery can also help cool cities, which often suffer from a heat island effect—they’re significantly warmer than more rural areas.

Lusk says all of this highlights the need to re-think how we’re designing streets to encourage more people to walk and bike instead of drive.

We’ll get into that later in our interview, but I began the conversation by asking Lusk what cycle tracks are and why they are the gold standard for bike infrastructure.

{***Anne Lusk Interview***}

ANNE LUSK: Traditionally in the US, we have had the bicyclist bicycle in the road and operate their bicycle as a vehicle. Our study in Montreal showed that bicyclists have a 28% lower injury rate– and there are 2.5 as many bicyclists– if you provide a cycle track. A cycle track is a protected bike lane that separates the bicyclists from the vehicles. That means that you have some sort of separation, such as a delineator post, or a low island, unlike a bike lane, in which you only have a painted line, and many drivers then park on a bike lane.

NOAH LEAVITT: And just to expand on that a little bit more, what does the data show in terms of when I guess encouraging people to bike when they have a cycle track, versus just maybe even just a bike lane, or the sharrow, those painted arrows on the road?

ANNE LUSK: So there are cycle tracks, protected bike lanes, that are separated from the vehicles. There are bike lanes, in which there’s a painted line. But as we know in Boston, many people double park on a bike lane. Or they swerve and they use the bike lane as a passing lane or a turning lane. And then there’s a sharrow, which is a double chevron and a bicycle symbol. And it’s to indicate to the car drivers that the bicyclists have the right of way to be in the road.

But a lot of times, the bicyclists don’t want to be in the center of the lane. They don’t want to what’s called take a lane. And then also, the drivers are impatient because a bicyclist is going to go more slowly than the driver. So the driver wants to pass the bicyclist following the sharrow.

So more people prefer the cycle track. It’s new to the US. It does take up road width, because you have to have the barrier space, and you have to have ideally enough room for the bicyclist to travel one direction and other bicyclists to pass. Because some bicyclists will be slower than others, and we want the faster bicyclists to be able to pass the slower bicyclists.

NOAH LEAVITT: And so in this study, you were looking at a design of cycle tracks, specifically with regard to trees. So can you explain a little bit about what you’re looking at and maybe why you decided to examine this particular design aspect?

ANNE LUSK: We know with climate change, that there are many seeded cities that suffer from heat island effect. There is so much hardscape in a city that the heat is retained in all of that asphalt. The asphalt from the roadway, the asphalt even from the BRT, Bus Rapid Transit corridor, the asphalt from underneath the parking, and the asphalt from the sidewalks. And there are fewer ways then to cool the city or to address pollution. Or to even address the perception of safety from the traffic.

So because we recently introduced cycle tracks into the US, and there are now many of them being built in cities, we thought it was also time to look again at the design of the right of way from building front to building front, and determine, where do we put a tree if we want a tree.

NOAH LEAVITT: And so what did you find, I guess, in terms of Boston? How often are trees being used, and then what effect does that have when trees are used?

ANNE LUSK: Trees are planted in cities. Boston is behind New York City in planting street trees. Many cities have goals of planting street trees. The problem is the only design guidelines that we have in the US for planting street trees are to either have the street trees planted in the front yards, meaning that’s difficult in an urban setting because you don’t have front yards with houses, or to plant the trees in the sidewalk.

If you plant trees in the sidewalk, they sometimes only live three to 10 years because they’re planted in a very small tree pit. And the tree roots can’t then communicate with the tree roots from other trees to better ward off diseases. The trees can’t stabilize an equal balance of tree roots in all directions to then be more solid in the event of a tornado coming through. So the trees that are toppled. And because the trees don’t get enough nutrients in that small tree pit, they have a short lifespan.

So we don’t have the healthy crown that we did once have when the Dutch elm was introduced into the American street. But of course, the Dutch elm then suffered from Dutch elm disease.

NOAH LEAVITT: And so I thought one thing that was interesting– that when there were trees between the cycle track in the streets, cyclists had a lesson perception of traffic and pollution. So can you talk a little bit more about that? I guess when cyclists see these trees, how does that affect their perception of riding a bike in a city?

ANNE LUSK: This study was using photo montages because obviously, we can’t move trees and plant them, get 100-year-old trees in the ideal location. So we studied five cycle tracks in the Boston area. Some of them had trees, some of them had trees between the sidewalk and the cycle track, others had a few trees between the cycle track and the street.

So we took the actual picture of that sidewalk and cycle track. And first of all, took out the trees. No one liked not having trees. So that was sort of understood. A few people were happy without trees, but most people liked having trees. There was less perception of preference about the trees between the sidewalk and the cycle track, and that’s the typical location in urban streets, because we’re always continuing to plant trees in the sidewalk.

There was a higher preference for the trees and bushes between the cycle track and the street. And the second was for trees in between the cycle track in the street. And there also was some preference for trees in between the parallel parked cars.

In asking people’s perceptions about the tree locations, we also learned that if the trees were in between the cycle track and the street, pedestrians and bicyclists, of the 836 interviewed, felt that the tree location between the cycle track and the street lessened their perception of traffic. They were less fearful of traffic because they sort of had a tree barrier. Lessened their perception of exposure to mobile source air pollution, because again, it sort of cooled the environment, it had a tree barrier between the smog in the road.

And finally, it gave them the perception of being cooler. Now whether they were cooler or not– and this was only from a picture, we don’t know. But we do know that their perceptions changed if we put the trees in between the cycle track and the street.

NOAH LEAVITT: And you talked a few minutes ago about kind of climate change with the concern around heat islands in these cities. So I mean, it sounds like in addition to potentially improving the experience for bicyclists, has that kind of benefit of kind of improving life for kind of all users of the city.

ANNE LUSK: That’s an excellent point. What we would like would be to have a climate street design guideline that is written by landscape architects in addition to the highway engineers. Because now in a community, a tree warden might be an individual person. There might be an arborist committee, a small number of volunteer people looking at the trees in the community. And then there all the highway engineers, and the state highway engineers, the city highway engineers, and the federal highway engineers. And they’re all looking at level of service, wanting to have high volumes of cars go through a corridor fast.

So how do you help defend that small tree warden or that arborists committee in deciding that placement of trees is important. The growth of the trees to 100 years is important. And cooling the heat island of the city is important. We believe if there was eventually a climate street guideline that would fully focus on the placement of trees, that this guideline would be helpful in designing bus rapid transit corridors. Where again, you might find there a few token trees planted in the sidewalk, but there’s a large expanse of heat island asphalt in the eventual the design.

And urban landscapes can last 50 to 100 years. So if we design properly now for cooling, for water retention, and also, for water runoff, then we could have mature trees. And we could have cooled the city and provided an excellent environment for the bicyclist and the pedestrians.

NOAH LEAVITT: I mean, it seems like one of the key points is probably that it’s easier to build the trees into the initial design of a cycle track them to retroactively plant them.

ANNE LUSK: Much easier to think in advance because if for example, trees were planted in the island that is the waiting area for bus stop passengers, as on a bus rapid transit, then underneath that island for the bus passengers, the landscape architects could have designed a complete system with gel, with water retention areas, with storm water management to then fully nourish the trees over their 100 year lifespan. And that could be a hardscape corridor that is softened with the trees. And the planting then could extend for years and years. And the trees would be able to mature.

If we look at some of the old cities in the south, we can find mature trees, but they’re in sidewalks. And there’s a parallel parked car beside that tree. And then the bicyclist only have the option of biking in the road.

NOAH LEAVITT: Is there evidence basically showing that on cycle tracks where there are trees between the cycle track and the road, maybe in other cities, that people are more likely to bike? To bike to work? I mean, is there a connection there?

ANNE LUSK: We do know that our study in Hangzhou, China showed that people preferred to bike because of the beauty of the city. And Hangzhou has staggering numbers of trees in between the cycle track and the street. And the trees are very large caliber– the tree diameter is very large. So they’re very mature. So the crown extends all the way over the sidewalk and the cycle track and into the street.

And it is such a comfortable environment and an inviting environment to bike, that you have far higher levels of bicyclists. And you could say, well, that was a dated time in China, and they’re now doing away with those street trees and those wide cycle tracks. But China now is planning even more wide cycle tracks with the tree component, because they know that they have mobile source air pollution, that don’t want to have this many people in cars. And to get more people to bike, you can’t give them a bike environment in which they’re biking in the road and their only distance is a plastic linear post that looks like a cigarette standing on edge and white diagonal lines, that doesn’t shade them, doesn’t lessen their pollution exposure, and doesn’t cool them.

NOAH LEAVITT: I mean, how can cycling advocates, how can public health people I guess kind of make the case for cycle tracks? Because it seems like– I mean, I guess there are some of the potential benefits to them. The climate change effects you talked about, just getting more people biking can reduce emissions. It’s healthier for people to bike to work, for example. So I guess what’s the strategy in terms of encouraging cities, towns to install more cycle tracks?

ANNE LUSK: The issue involves looking at all of the complexities in how you design that streetscape from building front to building front. And now, we have policies in which we let people park cars and store them on the side of the road 24/7 because they are given a free parking permit or essentially, a free parking permit that only cost $25 a year.

We should be looking at where do we put the cars. Could we instead store the cars in tall buildings. And to incentivize people putting their car in a tall building, could we then, in each stall, put an electric outlet, so they could then be motivated to buy an electric vehicle, knowing they have a designated space, that is indeed a space that goes along with their property, and increases their property values. And they’re always able to recharge their electric vehicle in that space, because that can’t happen on the side of the road.

And then if they know that outside of their house, they maybe don’t have their parallel parking space, but they have a handsome tree corridor that also increases the property values and adds to their quality of life, allows them to bike with their kids to the store to schools, then those residents might feel that it’s to their advantage. Because we know now with Uber and Lyft, even though we thought that would lessen the number of cars, because parking is so difficult in the Boston area many people are leaving their parked car in front of their house, getting an Uber or a Lyft that takes them to their destination. And drops them off. And we have 2 times as many cars on the road.

So backing up and looking at the complexities, we need to figure out where do we put the cars. We know people want to have cars. How do we accommodate that. And once we’ve done that, we can look then again at the street design and decide we want cycle tracks, we want street trees. We’ve now eliminated the parallel parked car. Let’s plant the trees so that they live to be 100 years old.

NOAH LEAVITT: And when it comes to encouraging biking, I guess how much of this is infrastructure, but how much of it is culture change. Because I was struck when I was in Denmark at not just the infrastructure, but also, in the morning, the mother and the father and the kids– they all bike to school, and then the parents bike to work. I mean, biking is just a regular form of transportation. So what’s the balance between investing in the infrastructure, the design, but also try to maybe push changing cultural norms around transportation?

ANNE LUSK: We know in Helsinki, they have been pushing the bike. But they have been doing so by eliminating car parking and having cars on the outer perimeter. And by providing safe bicycle environments in the inner city, then more people are biking.

The reason the Dutch bike– they know it’s healthy. They know that it’s more pleasurable to go out with their children, but they also know that it’s much more convenient, because it’s harder for them to get their car. And everything we have designed in the US is based on the convenience for the car driver, and that’s a major shift.

So it’s so easy to go out and get in the car because you have it beside your kitchen door. It’s easy to open the garage door because you have an automatic garage door opener. It’s easier to drop your kids off because you’re headed to work. It’s easier to get to work because you have a paid parking space at work. It’s easier to pick your kids up because they’re going to soccer practice after work. You pick up your dry cleaning on the way, you’re grocery shopping, and then you pull back into that driveway with the automatic garage door opener. How do you change that and incorporate the bike?

To me, you do so not just by putting in a sharrow or a painted bike lane, which is not as safe. You give them tree corridors that lead to key destinations, and you redesign how cities function by looking also at the cars, the parking. That automatic garage door opener is so appealing, so how do you change that?

NOAH LEAVITT: I mean, it’s been interesting seeing just in Boston over the last five years how the infrastructure has grown and changed. I mean, are you optimistic that US cities will be able to make that kind of transition in the decades ahead?

ANNE LUSK: We’re finding that the US cities are being led by the citizens because they want to have the cycle tracks. What is a shame to me is the policy now is to wait until a bicyclist is hurt or killed, and then we finally put in the safer cycle track.

And recently, on the Longwood Medical area, we did a survey to ask people which bike routes they are choosing. And out of that– it’s a four foot by six foot, what I call a bike patterns map, in which I took all the responses from the 219 bicyclists, who had indicated safe, less safe, and unsafe sections, and I marked all of those lines in those respective colors on the map. And it showed patterns. And all of the information from all of the 219 bicyclists was on that map and it spoke volumes.

And it did not involve hurting or killing a bicyclist, because the bicyclist, able from their cognitive map, to say, this corner is unsafe. This location is unsafe, this area needs improvement. And I think if we move in the direction of really picking people’s brains apart and saying, tell me what you know, because you’d like on this route all the time, then we’re more responsive to the needs of the bicyclists, because we shouldn’t have a surge in die to put in a cycle track.

NOAH LEAVITT: Just a last question to try to bring it back to the specific study. I guess, what are some of the next steps here? I mean, would you be looking at other cities? I mean, you touched on the example of China. So what are some of your next steps for this particular research?

ANNE LUSK: I think the next steps involve looking at all the opportunities to plant trees. We’re putting it in bus rapid transit corridors. But in a recent review of all the bus rapid transit corridors throughout the US, there’s a token tree in the sidewalk, and the opportunity is missed to put that in the wide island that is the bus stop area for the buses.

I think that we could revisit streets and decide where we’re going to put the parallel parked cars. Do we need them on the street if we want to have a divider between the cycle track and the street, can it be with trees. Can we plant the trees so that we have tree roots that are healthy.

And the major push for me is to eventually have someone or us develop that climate street design guideline that is written by the landscape architects and the highway engineers that fully embraces the trees. Not just as a scenic byway corridor, but as a safe climate street for bicyclists and cars and pedestrians.

{***Noah***}

That was my conversation with Anne Lusk about bicycle infrastructure in the United States.

If you want to learn more about her work and see photos of cycle tracks from the around the world just visit our website, hsph.me/thisweekinhealth.

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