Street layout and connectivity - how is that related to sustainability and obesity prevention?

This week’s post discusses connectivity - how easy is it for you to get from point A to be B on foot or by bicycle in your community? This follows nicely from last week’s post on compactness and diversity and will sum up the series on sustainability and obesity prevention.  Now equipped with this bit of background info, we will be better able to determine which community design options, like the Fused Grid, are better for sustainability, and possibly for our waistlines and overall health.  

As I highlighted before, suburban loop and lollipop neighbourhoods are confusing and time-consuming to navigate. They often preclude walking anywhere because of their design; there is never a short, straight line route to where you want to go. In these types of designs there are very few intersections, which are said to increase <driver> safety. However, as the number of intersections increases, the shorter the distance there is to walk from point A to B (motivating people to actively commute), and the more routes you have to choose from, making the walk/ride more interesting (also motivating). 

Walking distances for the loop/lollipop design versus traditional grid

To increase the connectivity of subdivisions, some features discussed in the post on safety could be added, such as way-finding signage for ‘cat-walks,’ as well as adding pedestrian and bike trails through green space, which link different areas within the neighbourhood or the wider community.

Adding biking infrastructure can increase the connectivity over larger areas. I find this especially important for me as I strive to actively commute to work from Aylmer to Ottawa. The National Capital Region is better than many places; we have separate pedestrian/biking pathways and some shared road bike lanes. The City of Ottawa is even planning to pilot a segregated bike lane on Laurier street. Overall, though I find though that the infrastructure is discontinuous and more geared to the leisure walker/biker, not the commuter. For example, you take a bike pathway and suddenly find yourself on the road going the wrong way on a one-way street. Or you have to decide between taking a separate, safer bike pathway that follows the meandering river, or take a direct, much faster, but less safe route that uses the roadway.    

The relationship between physical activity/obesity and measurements of street connectivity, such as intersection density and block size, has not been clearly demonstrated in the scientific literature (1-3). However when these measures are incorporated into an overall walkability index that generally includes land-use mix and residential density, more walkable neighbourhoods (with higher intersection density, more mixed land-use, and higher residential density) have been found to relate to decreased obesity among adults (2).

Few studies have been conducted on children, although one study in Alberta found that girls living in highly walkable neighbourhoods were less likely to be overweight than girls in less walkable neighbourhoods, with no difference found among boys (4). Another study in the U.S. did not find a significant relationship between obesity and street connectivity, but did find that children living in neighbourhoods built after 1969 (curvilinear, suburban design) were more likely to be obese than children living in neighbourhoods built before 1970 (traditional, grid iron design with small blocks and lots of intersections)(5).

There is some evidence, as has been discussed in previous posts, that changing the design of the built environment (specifically with regard to increasing safety and mixed land-use) can increase physical activity (this is akin to an experiment)(6). Interestingly, there is also some evidence that improving cycling networks in cities and towns modestly increases cycling (7). However, it is difficult to determine if this results in more new riders or more trips taken by existing riders; the former being much better from a public health perspective. Unfortunately, there are very few studies that examine how changes in neighbourhood/street layout can lead to later changes in physical activity or obesity. Perhaps because randomizing people and telling them where to live is a difficult thing to do. Nonetheless, some researchers are getting around this problem with novel study designs - hopefully with results coming soon.   

On-street marking and separating bike lanes in Manhattan, picture from Active Design Guidelines, NYC

     
As I discussed in a previous post, the Centers for Disease Control and Prevention in the U.S. conducted a comprehensive review with the goal of developing recommendations for childhood obesity prevention at the community-level (8).  Related to increasing street connectivity, the report recommended that communities should:

1. Enhance infrastructure supporting bicycling and walking;
2. Enhance personal safety in areas where persons are or could be physically active;
3. Enhance traffic safety in areas where persons are or could be physically active.

Increasing connectivity at the street, neighbourhood, and town/city level may get people out walking or biking for transport or pleasure, especially if the area is compact and diverse. Overall, though, I would argue, that if our spaces are aesthetically pleasing, safe, compact, diverse AND connected, we would be most likely to be active for transport or pleasure, which  increases the sustainability of the area and can help to keep excess weight in check. A great new resource that I stumbled upon from NYC highlights exactly what I have been talking about over these last 4 posts + the introductory post on sustainability. It also goes a whole lot further, showing how to design buildings to increase physical activity, where to build, and increasing access to public transit and healthy food options, to name a few. It's free to download.

References

1. Saelens BE & Handy SL. Built environment correlates of walking: A review. Medicine & Science in Sport Exercise. 2008; 40(7S): S550-66 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2921187/
2. Feng J et al. The built environment and obesity: A systematic review of the epidemiologic evidence. Health&Place. 2010; 16: 175-90 
3. Carter MA & Dubois L. Neighbourhoods and child adiposity: A critical appraisal of the literature. Health&Place. 2010; 16: 616-28 
4. Spence, J. C. et al. Influence of neighbourhood design and access to facilities on overweight among preschool children. International Journal of Pediatric Obesity. 2008; 3: 109-116.
5. Grafova, I. B. Overweight children: assessing the contribution of the built environment. Prev Med. 2008; 47: 304-308.
6. Heath GW et al. The effectiveness of urban design and land use and transport policies and practices to increase physical activity: A systematic review. Journal of Physical Activity and Health. 2006; 3 Suppl 1; S55-76 http://www.aapca3.org/resources/archival/060306/jpah.pdf
7. Yang L et al. Interventions to promote cycling: systematic review. BMJ. 2010; 341:c5293 http://www.bmj.com/content/341/bmj.c5293.full
8. Khan LK et al. Recommended Community Strategies and Measurements to Prevent Obesity in the United States. Morbidity and Mortality Weekly Report. 2009; 58(RR-7) http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5807a1.htm

Compact and diverse communities: sustainable and obesity preventive?

This is the third post in the series – ‘Sustainable community design and obesity prevention;’ only one more to go. Today I will obviously be discussing how compact and diverse areas can influence our waistlines. 

It makes sense that for neighbourhoods to be liveable (enjoyable, sustainable, useable, etc.) there must be interesting and necessary amenities accessible within easy walking distance.  Although there are differing views as to the meaning of ‘easy walking distance,’ I am referring here to destinations that are accessible in about 10 minutes or so – about 1 km, or the distance of a traditional city block.

These amenities should include banks, schools, restaurants/pubs, cafes, shopping, grocery and corner stores, parks and open spaces, and meeting places such as courtyards and piazzas.  The term ‘mixed land-use’ refers to the mixing of residential, commercial, and institutional uses. This makes neighbourhoods and the broader community more compact, as well as diverse. 

In an ideal world, I would live in an area where I could access all amenities, as well as my job, on foot.  Right now, according to www.walkscore.com, I live in a ‘car-dependent’ neighbourhood – scoring an abysmal 27/100. Curiously downtown Hull, QC (close to my home) seems to do pretty well, although I’m not convinced the site takes into account whether anyone actually lives there (e.g. downtown Hull is mostly government buildings).  In the better weather, I have to ‘force’ myself to bike the 12 km into work and back home.  Although I am no marathon runner, I consider myself to be in fairly decent shape, so assuming the average person would commute 24 km round trip by bike each day is not feasible (and I don’t even actively commute each and every day); obviously the walk is impossible and public transportation is a bit annoying.

Among adults, the general finding in the scientific literature is that mixed land-use, high density, and low sprawl (different measures that take into account density, degree of mixed land-use, block size, etc) are associated with increased walking (1), and a decreased probability of obesity (2) and high blood pressure among area residents (3). Mixed-use zoning alone can dramatically increase physical activity; a review of 12 studies showed that the median improvement in the level of physical activity was 161% (4).  In children, the association between compactness and weight is less clear and reflects, at least partly, a lack of similar studies with which to compare results (5).

The Centers for Disease Control and Prevention in the U.S. conducted a comprehensive review with the goal of developing recommendations for childhood obesity prevention at the community-level (6).  Included in the recommendations were:

• Support for locating schools within easy walking distance of residential areas 
• Zoning for mixed-use development

Compact, diverse neighbourhoods and communities are more liveable and likely more healthy, but can we afford to live in these places?  More people living in one area make amenities viable but that also increases land value.  How do we build or retrofit these communities, simultaneously making them profitable for developers/cities and equitable for all residents?  

References

1. Saelens BE & Handy SL. Built environment correlates of walking: A review. Medicine & Science in Sport Exercise. 2008; 40(7S): S550-66 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2921187/ 
2. Feng J et al. The built environment and obesity: A systematic review of the epidemiologic evidence. Health&Place. 2010; 16: 175-90 
3. Leal C & Chaix B. The influence of geographic life environments on cardiometabolic risk factors: A systematic review, a methodological assessment and a research agenda. Obesity Reviews. 2010; March 1. 
4. Heath GW et al. The effectiveness of urban design and land use and transport policies and practices to increase physical activity: A systematic review. Journal of Physical Activity and Health. 2006; 3 Suppl 1; S55-76  http://www.aapca3.org/resources/archival/060306/jpah.pdf 
5. Carter MA & Dubois L. Neighbourhoods and child adiposity: A critical appraisal of the literature. Health&Place. 2010; 16: 616-28 
6. Khan LK et al. Recommended Community Strategies and Measurements to Prevent Obesity in the United States. Morbidity and Mortality Weekly Report. 2009; 58(RR-7)  http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5807a1.htm

Sustainable community design and obesity prevention: Implications for increasing safety

Today’s post, discusses the implications of neighbourhood safety, which was briefly touched on in the previous post on aesthetics. I should highlight here that when I refer to safety, I am including both objective (measured, say with crime or traffic accident statistics) and subjective forms (as perceived by residents themselves). 

In order for communities (neighbourhoods or whatever synonym you would like to use) to be sustainable, they should not be environments in which residents are unable to experience all that the community has to offer, either because they live in fear of getting injured or killed, or are actually more likely to get injured or killed when out and about.

Some studies in the scientific literature have found that unsafe neighbourhoods discourage adult residents from walking – specifically lack of sidewalks (1).  This is a huge problem in my neighbourhood where only main arterial roads have sidewalks on each side. Among children, a Canadian study (Nova Scotia) linked increased parental perceived neighbourhood safety to increased participation in unorganized sports (2). Another study in Australia that followed the same children over time (a ‘longitudinal’ or ‘cohort’ study), found that parental concerns with traffic deterred moderate-to-vigorous physical activity among boys, but not girls (3). However, girls' own concerns with road safety was cross-sectionally related to decreased physical activity levels (4).

A pedestrian dashes across a huge intersection in Denver (Photo credit: 'Complete Streets')

In terms of obesity, few studies focusing specifically on neighbourhood safety have been conducted. One longitudinal study on children uncovered an influence of parental perceived neighbourhood safety on BMI that appeared to be mediated by increased TV watching. In other words, the results indicate that parents may restrict their children's outdoor physical activity if they perceive the neighbourhood to be unsafe, which translates into increased sedentary behaviours (TV watching in this case) and then increased BMI (5). 

   

Based on a review by Heath et al, changing urban design and land-use policies may be effective at increasing the physical activity levels of neighbourhood residents (6). The six intervention studies that they reviewed generally centred on redesigning the environment at the street-scale to make walking and biking more enjoyable and safe (examples include improved street lighting, traffic calming, and enhancement of street aesthetics). The median increase in physical activity across the studies was 35% (inter-quartile range of 16% - 62%).  

The list below highlights ways communities can potentially increase real or perceived safety. It is a compilation from various sources in the research, public health, and urban planning sectors (1,6-8)  . Hopefully more rigorous studies of their effects on residents, in terms of increasing physical activity and decreasing obesity, are soon to come:

○    Traffic calming techniques (to slow down and/or discourage automobile traffic):

·         Widening sidewalks and narrowing width of streets 

·         Adding landscaping – i.e. trees lining the road, placed in between the sidewalk and the road (this can increase perception of safety by pedestrians). At the same time, landscaping should not obscure line of sight by both pedestrian and driver

·         Installation of speed humps

·         Altering road alignments

·         Adding traffic circles or pavement treatments

·         Removing vehicular rights of way (i.e. make dead end streets) but keeping pedestrian rights of way

○    Ensuring adequate lighting along roadways and walkways (wherever pedestrians are likely to walk)

○    Ensuring clear way-finding signage for pedestrians

·         Pedestrian crossing signs and marked crossing areas

·         Street names at the start/end of pedestrian walkways (i.e. ‘catwalks’ in subdivisions)

○    Plowing of bike lanes and sidewalks in the winter time

·         This is especially problematic in Canada (see picture below and an interesting post on cycling in the winter by a fellow colleague - in French)

                         There is supposed to be a bike lane here - see the green sign? It's hardly ever
plowed in the winter (Stewart and Cumberland Streets, Ottawa Canada)

○    Allowing adequate time for pedestrians to cross at traffic lights    

○    Ensuring that at minimum, streets have sidewalks and a paved shoulder for cyclists. Although I'm sure cyclists would much prefer the establishment and maintenance of separate bike trails and more bike lanes on roadways 

○    Creating ‘eyes upon the street’

·         Layout of residential areas

·         Building height and form

Certainly more research is needed on this topic, to relate changes in design, crime levels and overall perceptions of safety to changes in physical activity and obesity. Intuitively though, increasing the level of safety in areas where we live makes our spaces more enjoyable and useful, regardless if they have measurable impacts on our waistlines. 

References

1. Saelens BE & Handy SL. Built environment correlates of walking: A review. Medicine & Science in Sport Exercise. 2008; 40(7S): S550-66 
2. Veugelers P et al. Neighbourhood characteristics in relation to diet, physical activity, and overweight of Canadian children. International Journal of Pediatric Obesity. 2008; 3(3): 152-9 
3. Crawford D et al. The longitudinal influence of home and neighbourhood environments on children's body mass index and physical activity over 5 years: The CLAN Study. International Journal of Pediatric Obesity. 2010; 34: 1177-87
4. Carver A et al. Perceptions of neighbourhood safety and physical activity among youth: The CLAN Study. Journal of Physical Activity & Health. 2008; 5(3): 430-44
5. Cecil-Karb R & Grogan-Kaylor A. Childhood body mass index in community context: Neighborhood safety, television viewing, and growth trajectories of BMI. Health & Social Work. 2009;34(3):169-77
6. Heath GW et al. The effectiveness of urban design and land use and transport policies and practices to increase physical activity: A systematic review. Journal of Physical Activity and Health. 2006; 3 Suppl 1; S55-76
7. Institut National de Santé Publique du Québec. Indicateurs géographiques de l'environnement bâti et de l'environnement des services influant sur l'activité physique, l'alimentation et le poids corporel. 2009. Available at: http://www.inspq.qc.ca/pdf/publications/1001_IndGeoEnvBati.pdf
8. Dempsey N. Quality of the built environment in urban neighbourhoods. Planning, Practice & Research. 2008; 23 (2): 249-64