Making Connectivity A Part of Your Smart Growth

APA Washington

October 6, 2010

Why is Connectivity Important?

Street network characteristics influence safety     

• 24 California cities: safer and less safe

• Safer cities have reduced rates of severe and fatal crashes

• Safer cities have greater street and intersection density per sq mile

• Underlying factor may be lower vehicle speeds

 Source: Street network types and road safety: A study of 24 California cities

Wesley Marshall and Norman Garrick, April 2010

Marshall and Garrick California Cities Comparison

Safer Cities

Less Safe Cities

Difference %

Year of Incorporation Average

1895 1932

Population 2000 average

65,719 59,845 -8.0

Fatal crashes not on highwaysAverage per city per year per 100,000 population

3.1 10.1 273.9

Real Intersection Density City average per square mile (not including dead ends)

106.2 62.7 -41.0

Local Road density City average centerline miles per square mile

15.1 11.2 -25.8

Block Size City average in acres

18.2 34.5 89.6

Why Connectivity is Important

Street network patterns influence mode choice

• Street network patterns: connectivity and density

• Connected dense street networks have higher walk, bike and transit

mode-share

• Intersection density associated with greatest increases rates of walking and biking

• Model indicated:

Increased intersections from 81 to 324 per sq mile would lead

Walk/Bike combined mode share increases from 3.2% to 7.8%

  Source: The Effect of Street Network Design on Walking and BikingWesley Marshall and Norman Garrick, November 2009

Why Connectivity is Important

Associated with less driving

CMHC study of Seattle neighborhoods:

• Fused grid increases walking trips by 11.3%

• A 10% increase in network density for pedestrians can be associated with 23% decrease in local vehicle miles travelled

Sources: Canada Mortgage and Housing Corporation

Olympia’s Policies

• Where no street connection, build connector paths • Block sizing good, 1800 feet max

• Street connections = moderate success• Need to make case; data and analysis will help

• 100 non-motorized connectors inventoried• Need to formalize existing connectors

ViaCity RDI Applied to Olympia • Via City Route Directness Index (RDI) Measurement tool

• Transpo Group tests on Olympia

• RDI = tax parcel to all other parcels in specific radius

• Good RDI is 100, “as-the-crow-flies” direct

• Enhance network = RDI improves

• Case for street connections and connector path construction

ViaCity RDI Applied to Olympia

Olympia Test:

• Baseline street centerlines• Add existing trails• Add planned connectors• See RDI improve• Sub area demonstrations

ViaCity RDI Applied to Olympia

1

2 3

4Connectors

Shared-Use Paths

Subarea Connectivity Analysis

Olympia Citywide RDI

Pedestrian Connectors & Pathways

Connectors

Shared-Use Paths

Area 1: Baseline Connectivity

Area 1: Plan Impact

Connectors

Area 1: RDI Statistics

Connectors

Area 2 : Baseline Connectivity

Area 2 : Plan Impact

Connectors

Area 2 : RDI Statistics

Connectors

Area 3 : Baseline Connectivity

Area 3 : Plan Impact

Connectors

Area 3 : RDI Statistics

Connectors

Area 4 : Baseline Connectivity

Area 4 : Plan Impact

Connectors Shared-Use Paths

Area 4 : RDI Statistics

Connectors Shared-Use Paths

Subarea Improved Connectivity

Connectors

Shared-Use Paths