Norman W. Garrick Lecture 3.2 Basics of Urban Street Networks Norman W. Garrick Lecture 3.2

Impact of Street Network Design Research shows that street network design can impact Traffic safety Choice of Mode Vehicle Miles Travel Health outcomes Character and value of communities

versus

Risk of Severe Injury or Fatality* Chance of being Severely Injured Safety Impact Risk of Severe Injury or Fatality* versus Chance of being Severely Injured 30% Higher Chance of being Killed 50% Higher *Given that an injury occurred

Odds of Dying in a Road Accident based on Intersection Density* Impact on Safety Odds of Dying in a Road Accident based on Intersection Density* 1 in 200 1 in 500 *Given that an injury occurred

Percentage of People Walking, Biking or Taking Transit Impact on Mode Choice Percentage of People Walking, Biking or Taking Transit

Impact on Mode Choice Percentage of People Walking, Biking or Taking Transit Effect of Intersection Density for Cul-de-sac Network

Impact on Mode Choice Percentage of People Walking, Biking or Taking Transit Effect of Intersection Density for Gridded Network

Why sprawl may be bad for your health Their study* looked at 24 medium-sized cities in California, built at different times and with a variety of different street designs. They then examined self-reported health data from the California Health Interview Survey, which sampled 40,000 to 50,000 adults in 2003, 2005, 2007 and 2009. Their analysis controlled for socioeconomic status, commute times, the presence of fast-food restaurants and grocery stores and other land uses. Ultimately, they found that higher intersection densities were significantly linked to reduced rates of obesity at the neighborhood level, and reduced obesity, diabetes, high blood pressure and heart disease at the city level. *Marshall, Garrick and Piatkowski

Cul-de-Fat: How Suburbanization is Contributing to Obesity Do We Look Fat in These Suburbs? Just living close to Walmart makes you Fat

Features of a Good Urban Street Network High Density of Intersections The density can be measured by intersections per square mile or my block size or other related parameters High Connectivity within Neighborhoods Good Porosity Between Adjacent Neighborhoods There should be good connections between neighborhoods. Not all streets should extend beyond neighborhood boundaries but most should. Streets that traverse multiple neighborhoods or even the whole city should be frequent (no more that ½ mile apart). Great Variety in Streets Types The street network should have streets that support a variety of land uses and social contexts. As such they should vary from very busy to very quiet, from mostly commercial to mostly residential. In general, the busier streets should be the more commercial and facilitate regional as well as local travel. While the more residential streets should be shorter and facilitate mostly local travel. No Restrictions on the types of streets that are connected to each other For example, small neighborhood streets should connect to big regional streets with no restrictions. One-way streets are an example of restrictions on how streets are connected The turn ROUTE MODIFICATION is used to describe types of restrictions that are frequently employed All Streets should be walkable and crossable and multipurpose All Streets should have building frontage

Good Porosity Between Adjacent Neighborhoods Less Good Example

Good Porosity Between Adjacent Neighborhoods Good Example

Factors in Creating Diverse Street Type Great Variety in Streets Types Factors in Creating Diverse Street Type What are the factors contributing to difference between streets types? Street cross-section design Continuity of the street in the network Type of intersection connection in the street network Street alignment in the street network Note that these are a combination of Features of the street itself, and Features of the street network. The street design should complement the street network design

All the streets are the same in the network No variation in the street type

Prenzlauer Berg – Regional Context

Prenzlauer Berg – City Context

Prenzlauerberg Berlin

The Streets of Prenzlauer Berg Schoenhauser Allee The main street Prenzlauer Allee The second main street Pappelallee A neighborhood shopping street Raumerstrasse A neighborhood shopping street Goehrener Strasse A residential street

Schoenhauser Allee The main street

Schoenhauser Allee The main street

Schoenhauser Allee The main street

Prenzlauer Allee The second main street

Pappelallee A neighborhood shopping street

Pappelallee A neighborhood shopping street

Raumerstrasse A neighborhood shopping street

Greigenhagener Strasse similar to Goehrener Strasse A residential street