Posts Tagged ‘street grid’

Metro Detroit: The walkability factor

Monday, December 5th, 2011

University of Michigan professor and Brookings Institute fellow Chris Leinberger wrote an interesting op-ed in the New York Times, The Death of the Fringe Suburb.

The article reiterates much of Leinberger’s presentation given earlier this year at CCS in Detroit. In summary, there is “great pent-up demand for walkable, centrally located neighborhoods” rather than sprawling outer suburbs.

Given this demand, he calls for increased investment in cities and its surrounding, older suburbs.

The cities and inner-ring suburbs that will be the foundation of the recovery require significant investment at a time of government retrenchment. Bus and light-rail systems, bike lanes and pedestrian improvements — what traffic engineers dismissively call “alternative transportation” — are vital. So is the repair of infrastructure like roads and bridges. Places as diverse as Los Angeles, Phoenix, Salt Lake City, Dallas, Charlotte, Denver and Washington have recently voted to pay for “alternative transportation,” mindful of the dividends to be reaped. As Congress works to reauthorize highway and transit legislation, it must give metropolitan areas greater flexibility for financing transportation, rather than mandating that the vast bulk of the money can be used only for roads.

Lisa Rayle of Data Driven Detroit (D3) wrote this great companion piece that estimates Metro Detroit’s potential walkability based on street patterns. Basically, more dense American street grids promote walkability, while sprawling, cul-de-sac designs do not. It’s something we covered some time ago since street patterns also affect bike friendliness.

D3 analyzed block sizes in Metro Detroit to evaluate street patterns and therefore potential walkability — and created a map.

The map shows average block sizes in the Detroit region. Blue indicates a walkable street grid, or something close to it. Yellow indicates streets too far apart to be walkable. (Because this map is based on Census TIGER files, not street data, it is only an approximate estimate of block size.)

Block size is not all that matters. To be walkable, neighborhoods need destinations (schools, grocery stores, jobs) within walking distance. They need a certain density (usually at least 20-25 dwelling units per acre). They need to be safe, with good sidewalks, lighting, and protection from traffic. The above map does not include any of these factors. But the map does indicate, approximately, which areas have the underlying structure for walkability, upon which more convenient destinations and a better walking environment might be built.

Rayle’s last point is important. Block size determines potential walkability. Your destinations still need to be within walking distance. A quick review of the Michigan city walkability scores brings home the reality that we have much room for improvement.

And finally, it’s no surprise that this map aligns with what we wrote late last month about the varying bike-friendliness of Metro Detroit (Macomb, Oakland and Wayne counties.) Bike-friendliness and walkability are closely related.

UPDATE: Rayle also wrote this interesting look at how the street grid (and walkability) in Downtown Detroit has degraded over time.

Cul-de-sacs are a Dead End

Friday, April 3rd, 2009

cul-de-sac-hellLook at this map from West Bloomfield on the right.

The neighborhood streets are not in a traditional American grid pattern. Instead they are a maze of disconnected cul-de-sacs and roads to nowhere.

This design is embraced by communities where people drive everywhere and rarely walk or bike.

This design forces cyclists as well as motor vehicles to use the more busy arterials (such as Orchard Lake Road in this West Bloomfield example.) That often means less welcoming roads for many cyclists and plenty of traffic congestion.

Some cities (Charlotte, N.C., Portland, Ore., and Austin, Texas) and even states like Virginia are pulling the plug on cul-de-sacs.

According to the Washington Post:

The state has decided that all new subdivisions must have through streets linking them with neighboring subdivisions, schools and shopping areas. State officials say the new regulations will improve safety and accessibility and save money: No more single entrances and exits onto clogged secondary roads. Quicker responses by emergency vehicles. Lower road maintenance costs for governments.

But aren’t cul-de-sacs safer? Not really, according to William Lucy, co-author of the book Tomorrow’s Cities, Tomorrow’s Suburbs. Cul-de-sac communities have some of the highest rates of traffic accidents involving young children.

And these street patterns certainly aren’t safer for cyclists.

That’s one major reason why cycling in older cities like Detroit or Berkley is much more bike-friendly and convenient than places like West Bloomfield.

[There is additional cul-de-sac coverage at National Public Radio.]