Basics of Urban Street Networks

Norman W. GarrickLecture 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

versus

Safety Impact

Risk of Severe Injury or Fatality*

Chance of being Severely Injured

30% HigherChance of being Killed

50% Higher *Given that an injury occurred

Impact on SafetyOdds of Dying in a Road Accident

based on Intersection Density*

1 in 200

1 in 500

*Given that an injury occurred

9%

2%

4%

1%

9%

2%

Impact on Mode ChoicePercentage of People Walking, Biking or Taking Transit

Impact on Mode ChoicePercentage of People Walking, Biking or Taking Transit

Effect of Intersection Density for Cul-de-sac Network

< 81 81-144 144-225 225+0%

5%

10%

Impact on Mode ChoicePercentage of People Walking, Biking or Taking Transit

Effect of Intersection Density for Gridded Network

< 81 81-144 144-225 225+0%

5%

10%

Guidelines for Street Network Design

A good street network should have

1. High DensityThe density can be measured by intersections per square miles or my block size or other related parameters

2. Good Connectivity at all geographic scales (from regional to neighborhood)Not all streets should be connected at all scales but the streets that connect region wide should be frequent (no more that

½ mile apart).

3. Great variety in streets typesThe street network should have streets that vary from very busy to very quiet, from mostly commercial to mostly

residential. In general, the busier streets should be the more commercial and the more regional. While the more residential streets should be shorter/more local.

4. No Restrictions on the types of streets that are connected to each otherFor example, small neighborhood streets should connect to big regional streets with no restrictions.

Prenzlauer Berg – Regional Context

Prenzlauer Berg – City Context

Prenzlauerberg

Berlin

The Streets of Prenzlauer Berg

Schoenhauser AlleeThe main street

Prenzlauer AlleeThe second main

street

PappelalleeA neighborhood shopping

street

RaumerstrasseA neighborhood shopping

street

Goehrener StrasseA residential street

Schoenhauser AlleeThe main street

Schoenhauser AlleeThe main street

Schoenhauser AlleeThe main street

Prenzlauer AlleeThe second main street

PappelalleeA neighborhood shopping

street

PappelalleeA neighborhood shopping

street

RaumerstrasseA neighborhood shopping

street

Greigenhagener Strassesimilar to Goehrener Strasse

A residential street