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yes I'm interested in understanding how what we call urban former effects travel
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behavior so by urban form I mean all sorts of characteristics of the built environment you live in so density is
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the amount of jobs were achieved to residency is a quantity of roads and all of those characteristics and we're
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interested in how this is going to affect the way you travel and how many miles you actually do and how many miles
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you do especially by car why are we concerned by that because there are some social cost associated with using
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personal transportation so we know for each mile that we drive society anchors a caste or three or four cents maybe
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well maybe were slightly more associated with two different forms of pollution one is greenhouse gas emissions I a
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carbon that fosters climate change global warming and all of that and the second one is much more localized small
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particulates which typically give asthma to babies and all people and from time to time they die
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so what we found is that urban density measured by summing the quantity of jobs and residence in whatever five miles
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around where you live was remind someone where you live reduces higher urban when density
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reduces your travel so the elasticity is typically 10% higher well density leads
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to reduction in traveling of about one percent so the conclusions that surprised us
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most is the fact that actually we were expecting the situation and the results to be fairly complicated and fairly
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subtle what we discovered it actually reality was for once very simple in the sense that there's actually one major
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characteristic of cities that matters the moment where we live that matters that's the was that's the density were
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around you everything else is really well secondary and matters far less and what we also found is that those results
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were extremely robust we were also expecting like different groups of residents to react differently depending
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on where they lived because we were also expecting people who like driving to live in places where it's easier to
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drive and these to be really important in the results actually not at all everybody seems to be reacting more or
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less in the same way or at least we could not find very much of a difference across different groups across different
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types of environments so basically again if you were if you bring up what density
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by about well 10% you reduce driving by about 1% even though we do find some effects but
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this 10% higher than CG leading to one percent less driving is actually a very small effect so if you want to see what
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it means or what to understand what it means in reality if you were to take the 30 million Americans that live at the
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lowest weight density in rural areas and bring them to nearly the highest rent density in the country that's a scale of
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displace that's a displacement where the scale of Syria at the moment so it's
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massive it's not something that's going to happen at all but that would lead to
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a reduction in driving by whatever four or five percent some even something that
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is still extremely drastic but slightly less so so taking again 30 million more Americans from northern city areas which
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instead of shootings end up will completely bring them to high density areas but leaving some people into low
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density areas the effect on electric driving would be minimal because who's that who that are broked to high-density
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areas will drive less but those that actually are left in the low density areas will drive lots more
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and this it's nearly what a perfect world offset so as a result you won't be
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able to achieve will very much in terms of global warming using urban policies of that sort what you need to use or to
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go after well pollution you need after well local pollution what you need to tax for congestion ie the concentration
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will the concentration but of course in some areas where the cities so you need to make them pay for that and you need
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to tax well carbon well emissions like for instance the province of British Columbia does in Canada it's a
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resounding with success so I know it's politically a really hard proposition in
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this country but that's the one thing that works everything else will not do
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very much so we have this perception that because indeed the federal government in this
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country is not very effective at doing very many things that's a lot of the solutions have to be local and you are
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whatever Meyers for America and all the solutions have to be coming from City Hall's and from Wheeling Meijer to some
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extent but global problems they require global solutions they require federal interventions we are not going to solve
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all global warming by having cities practicing smart growth that will only achieve very very little and some of it
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like imposing green bells if anything might be just counterproductive so what sets us about what I eat
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scenario where there's been a lot of research so what he's setting us about
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is first we use extensive data for travel instead of looking at the tiny area and the number of cars we actually
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rely on a big survey done by the department of transportation with nearly a million trips so that's a very large
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gauge survey then we use extensive measures of the local environments where people reside so what we've done was
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actually used satellite imagery and grid every seeing on a one kilometer by one kilometer basis both the description of
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the physical environment but also using a vast array of data are coming from the
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census coming from employments and so on and so forth and greeting all that to know exactly what there is around where
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people leave in terms of number of jobs of number of residents how richest residents are how educated they are and
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this and that so we use vastly more data also to describe the environment and the
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last thing we did it's not because you observe a negative correlation between
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how dance and REI is and how little people drive that is that this relationship is causal this relationship
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may may just be completely spurious because again people that like to drive may want to live in low-density
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environment so what we've done was to design a new methodology to address that
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question looking at the fact that people when you in some cases they move what will somewhere where car went mm they
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moved to neighborhoods that were very highly well comparable in terms of all characteristics but some of those
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neighborhoods between 2000 and 2010 got a lot more population and not everybody moved out or move Dean so we look at
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people how they responded to well differences in the amount of population went at the guards for zoos that have
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stayed for a long time so that allows us to go sorry to be with technical here but but dr. Rosen's good to go with
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ruvie selection problem and actually make some causal statements where we can actually claim that the local
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environment has an effect on the amount of driving one that you do but this effect again is more
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so what's next is I want to think more about what congestion because we think
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of congestion as a big problem it's true that to where traffic jams are for everyone to see is everywhere
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particularly in developing countries where people keep well buying cars with economic growth and the situation gets
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worse at the same time we have no serious idea about the economic cost of that congestion and for that I want to
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be able to use new data that's now made available through through web mapping
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with services like Google Maps where you can actually get some travel times from
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anywhere to anywhere else in real time knowing about the number one of travelers you can actually estimate the
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true cost of congestion the other thing I want to look at well more is urban land use because we tend to think about
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land use as a use so it's something that could be one use one day maybe another
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use another day so really key is when we build stuff it's for a very very long
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time and very often that stuff is very pal it's very well tacky weather to the
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needs of a particular user or set of users so when we think about land use we can see land use moving from agriculture
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to residential and VC's for everyone to see but what's happening to all manufacturing it's usually not places we
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go to so some of it gets reconverted whenever it's really really central very
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valuable land but there's a lot of suburban land in declining cities it looks like nothing is happening so we'd
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like to be able to know actually how much changes well there is in land use well over time among the more
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residential slash manufacturing slash with different types of development and we will also like to know if things
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revert back with to nature well from time to time our perception is not but again this is something that we don't
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know