Transportation Connectivity

American Planning Association - Washington Chapter

2009 Conference – Vancouver, Washington

What is RDI?

RDI is the Route Directness Index and is calculated by dividing crow’s flight travel distances A by actual travel distances B.

RDI is a superior and meaningful measure of transportation connectivity.

Why is RDI Important?

The Route Directness Index (RDI) can be used to quantify how well a street network connects destinations.

The RDI can be measured separately for motorized and non-motorized travel, taking into account non-motorized shortcuts, such as paths that connect cul-de-sacs, and barriers such as highways and streets that lack sidewalks.

A high RDI may indicate that streets are well connected with good sidewalks and blocks are likely relatively small so that people can travel more directly to destinations.

A low RDI may indicate that the street network has many unconnected dead-ends and blocks are large so people must travel farther to reach destinations.

How Can RDI be Applied? - Examples

Neighborhood Design Growth Management Non-Motorized Concurrency and Quality of Service

How Can RDI Be Applied? - Examples

Bike Access to LRT Station

How Can RDI Be Applied? - Examples

Access to Commuter Rail Station

How Can RDI Be Applied? - Examples

Pedestrian Access to LRT Station

Why Is RDI Relevant to Planning?

Cities are exploring many transportation, land use, energy, environmental and sustainability policy issues and considering new measurement techniques:

Complete Streets Policy Concurrency Program Refinements VMT and GHG per Capita Reduction Multi-Modal Level-of-Service (LOS) Street Connectivity Policies

Why The Need For A Software Solution?

RDI is a simple calculation, however when applied to larger area with multiple origins and destinations, performing the calculations manually is nearly impossible.

Evaluating the benefits and effects of proposed pathways and sidewalk improvements is also impractical without software.

Existing proxy measures are inherently flawed and do not provide the accuracy and validity of an RDI analysis.

What Is The Value of RDIdesktop?

Our RDI solutions and services provide cities, counties, transit agencies and MPO’s superior methods and measurements to make better policy decisions.

Making Better Decisions

Based on the results of an RDI analysis you can identify areas of poor connectivity and test the effect of proposed improvements quantitatively in a fast and easy manner.

Existing Conditions

Shared-Use Path Connections

Average RDI Score: Poor / Fair .58

New Shared-Use Paths

Shared-Use Path Connections

Average RDI Score: Fair / Good .66 14 % improvement

RDI – “Before & After” Delta

Shared-Use Path Connections

More Information

Contact:

Andy Mortensen: 503.313.6946

Hicham Chatila: 206.499.8618

Brent Turley: 208.585.1895

Patrick Lynch: 206.979.3040