Network, Placemaking and Sustainability

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Network, Placemaking and Sustainability

• Norman W. Garrick
• Wesley E. Marshall

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Vehicle Miles Traveled1945 to 2005
3
Annual vehicle miles traveled per year in USA
3,000,000,000,000 miles or ½ Light Year
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Miles per day per capita1945 and 2008
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The Transportation Sustainability Gap
USA
Sustainability Gap
Norway
Daily Miles Traveled For every man, woman and
child
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Traffic Fatality(per 100,000)
USA
The Netherlands
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Davis, California
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California Cities Study
Street network, safety and sustainability in
24 medium sized California cities Cities
selected to represent a range of traffic safety
level
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24 California Cities

• Antioch
• Apple Valley
• Carlsbad
• Madera
• Morgan Hill
• Perris
• Redding
• Rialto
• Temecula
• Turlock
• Victorville
• West Sacramento

• Alameda
• Berkeley
• Chico
• Cupertino
• Danville
• Davis
• La Habra
• Palo Alto
• San Luis Obispo
• San Mateo
• Santa Barbara
• Santa Cruz

Safer Cities
Less Safe Cities
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Davis
1940
1950
1960
1970
1980
1990
2000
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Turlock
1940
1950
1960
1970
1980
1990
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CALIFORNIA CITY COMPARISON
SaferCities
Less SafeCities
Population
65,719
59,845
PopulationDensity
5,736 per sq. mi.
2,673 per sq. mi.
Real IntersectionDensity(does not include dead
ends)
106 per sq. mi.
63 per sq. mi.
Mode Share
84.1
95.8
Driving
5.4
1.7
Walking
4.1
0.7
Biking
6.6
1.7
Transit
TotalRoad Fatalitiesper 100,000 pop.
3.2 per year
10.5 per year
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How Do we Characterize Street Networks?
Intersection Density
Gridded
Hierarchical
Street Length
Sparse
Connected
Dense
Connected Nodes
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Characterizing Street Networks

• Street Network Configuration
• Street Network Scale

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(No Transcript)
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MACRO NETWORK
Tree
Linear
Grid
MICRO NETWORK
Tributary
Radial
Tree
Grid

• MACRO

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PALO ALTO
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NETWORK COMPARISON
Tree
Linear
Grid
Tributary
Radial
Tree
Avg. Year of Development
1974
1966
1965
1966
Grid
Avg. Year of Development
Pre 1940
1950
Pre 1940
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NETWORK COMPARISON
Tree
Linear
Grid
Tributary
Radial
Tree
Safer Cities
5
2
40
21
Less Safe Cities
6
15
30
34
Grid
Safer Cities
N/A
3
4
25
Less Safe Cities
N/A
1
5
9
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NODE COMPARISON
SaferCities
Less SafeCities
RealNode Density(does not include dead ends)
106 per sq. mi.
63 per sq. mi.
Macro IntermediateNode Density
6.9 per sq. mi.
5.2 per sq. mi.
6.3
8.2
Major Nodes
Dead End Node Density
32 per sq. mi.
23 per sq mi.
30.2
36.5
Dead Ends
LEED-NDNode Density
74
40
Non-MicroNode Density
39 per sq. mi.
23 per sq. mi.
Non-MicroNodes
36.8
36.5
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SAFETY COMPARISON
SaferCities
Less SafeCities
Total Fatal or Severe Crashes
12.7 per year
17.0 per year
Macro IntermediateFatal or Severe
9.1 per year
13.7 per year
1.8
3.3
Fatal or Severe
Micro RoadFatal or Severe
2.0 per year
1.7 per year
Fatal or Severe
1.7
2.7
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SAFER CITIES - NETWORK TYPE COMPARISON
LT
GT
RT
TT
Node Density
105
155
185
195
Dead End Density
42
42
33
39
Vehicle Mode Share
87.8
86.1
88.9
87.5
Fatal or Severe
2.9
2.8
1.7
2.0
(Non-HW Crashes)
GG
RG
TG
LG
Node Density
N/A
279
250
256
Dead End Density
N/A
16
26
13
Vehicle Mode Share
N/A
79.4
84.9
70.8
Fatal or Severe
N/A
1.6
2.0
1.5
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LESS SAFE CITIES - NETWORK TYPE COMPARISON
LT
GT
RT
TT
Node Density
65
88
111
116
Dead End Density
28
31
41
25
Vehicle Mode Share
95.5
94.5
95.5
94.9
Fatal or Severe
11.9
4.4
3.9
3.8
(Non-HW Crashes)
GG
RG
TG
LG
Node Density
N/A
N/A
158
201
Dead End Density
N/A
N/A
12
10
Vehicle Mode Share
N/A
N/A
90.2
89.2
Fatal or Severe
N/A
N/A
2.6
2.4
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SAFER CITIES NETWORK DENSITY
NetworkDensityComparison
1 Sq. MileGrid Size
9x9
12x12
15x15
660
480
375
Block Length
IntersectionDensity
81
144
225
lt 81
81-144
144-225
225
Mode Share
88.1
86.7
82.9
76.2
Driving
5.3
3.9
5.3
8.1
Walking
2.4
3.8
4.0
4.2
Biking
3.0
4.5
6.8
10.4
Transit
Fatal orSevere(non-highway)
4.9
2.3
1.8
2.0
Macro or Int. Fatal or Severe
5.1
2.4
1.8
2.0
Micro Roads Fatal or Severe
3.0
1.7
2.2
1.8
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LESS SAFE CITIES NETWORK DENSITY
NetworkDensityComparison
1 Sq. MileGrid Size
9x9
12x12
15x15
660
480
375
Block Length
IntersectionDensity
81
144
225
lt 81
81-144
144-225
225
Mode Share
94.9
95.0
93.6
89.4
Driving
2.1
1.6
2.1
4.9
Walking
0.4
0.6
0.6
1.0
Biking
1.4
2.0
2.3
2.8
Transit
Fatal orSevere(non-highway)
5.8
3.3
3.4
4.0
Macro or Int. Fatal or Severe
6.2
3.4
3.6
4.2
Micro Roads Fatal or Severe
5.0
2.6
2.6
1.6
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Radburn, New Jersey

• American version of English Garden City
• Superblock design each block between 30 and 50
  acres
• One of the earliest American road hierarchies
  including cul-de-sacs

(Southworth Ben-Joseph, 1997)
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Radburn Cul-de-sacs
The flood of motors had already made the
gridiron pattern, which had formed the framework
for urban real estate for over a century, as
obsolete as a fortified town wall.
Charles Stein, Radburn Designer
(www.columbia.edu/cu/gsapp/projs/call-it-home/htm
l/chapter8.1.html)
(www.radburn.org/map3n.html)
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Government Policies

• Federal Housing Administration (FHA) created
  publications recommending specific street
  patterns
• Endorsed hierarchical street layouts with
  cul-de-sacs that minimize through traffic on
  residential streets

(www.columbia.edu/cu/gsapp/projs/call-it-home/html
/chapter8.2.html)
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Government Policies

• FHA called the grid layout
• monotonous,
• with little character,
• uneconomical,
• and a safety issue

(www.columbia.edu/cu/gsapp/projs/call-it-home/html
/chapter8.2.html)
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1938 - FHA Technical Bulletin No. 7 Planning
Profitable Neighborhoods
We should discourage through traffic
short blocks not economical
(www.columbia.edu/cu/gsapp/projs/call-it-home/html
/chapter8.2.html)