2009 gulf traffic rdi discussion

Applying Principles of the

Plan Abu Dhabi 2030

Urban Street Design Manual

Toolbox of Connectivity

Using

An Abu Dhabi Emirate Demonstration

* Trademarks provided under license from ESRI.

*

North Wathba DemonstrationUsing RDI Desktop to

demonstrate functional

implementation of the Abu

Dhabi Urban Street Design

Manual for North Wathba

Master Plan area

connectivity:

(1) Comparing North Wathba

Neighborhood Plan to

existing Abu Dhabi

neighborhood

(2) Measuring connectivity to

LRT station and the

importance of sikkas

2

1

What is the RDI?

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.

The RDI is calculated by dividing direct travel distances by actual travel distances. For example, if streets are connected, have good sidewalks, and blocks are relatively small, people can travel nearly directly to destinations, resulting in a high index. If the street network has many unconnected dead-ends and blocks are large, people must travel farther to reach destinations, resulting in a low index.

RDI DesktopTM includes RDI scoring, one of four sub-models to measure non-motorized system.

Abu Dhabi Urban Street Design Manual

Abu Dhabi

Urban Street

Design Manual

defines Direct

Route Index

Same theory

and similar

measure to RDI

DesktopTM

(only numerator

& denominator

flipped)

The Modern Sikka

Traditional

Arab

pedestrian

access routes

Historically

sized at about

3.2 meters

wide –

sufficient for

passage of two

laden camels

Developed Under-developed

Existing Neighborhood

Comparative

Assessment of

RDI DesktopTM

Existing Abu

Dhabi

Neighborhood

Airport Road

23

rdS

tree

t

25

thS

tree

t

Poor-Fair RDI

scores

reflecting

limited internal

routes and

external

boulevard

crossings

Neighborhood RDI Score

Poor

Fair

Parcel

RDI DesktopTM Metric

ParcelExcellent

Average RDI Score: Fair .65

Existing Sikkas

are typically

underdeveloped

Underdeveloped Sikka

North Wathba Neighborhood

Neighborhood design:Mixture of villa plot

size

Neighborhood centers

Maximized public realm for non-motorized connectivity through: Quality street

pedestrian zone

Connecting Sikkas, park/open space and fareej


Measured

without Sikka

connections

Good-Excellent

RDI scores

Poor

Fair

ExcellentParcel


Parcel

Average RDI Score: Fair .65


Measured with

Sikka

connections

Good-Excellent

to excellent RDI

scores

Poor

Fair

Excellent

Parcel


Parcel

Average RDI Score: Good .73

Comparative RDI Scoring

RDI Score

Difference: With

and Without

Sikkas

Parcel


Parcel

Plots that benefit significantly

by Sikka connectivity

Access to LRT Station

RDI one of

several

models

helpful in

LRT station

area access

and

connectivity

planning


RDI “Before”

Street

Sidewalks Only

Poor

Fair

Parcel


LRT StationExcellent

Average RDI Score: .77Excellent


RDI “After”

Street

Sidewalk and

Sikka Network

Poor

Fair

Parcel


LRT StationExcellent

Average RDI Score: .79Excellent


RDI

“Difference”

Plots benefiting

from planned

Sikkas

Plots that benefit significantly

by Sikka connectivity

Distance Decay

Distance Decay

is an important

model to

consider

walking and

cycling travel

demand

Non-motorized

network without

planned Sikkas

Distance Decay

Distance Decay

is an important

model to

consider

walking and

cycling travel

demand

Non-motorized

network with

planned Sikkas

Measuring Sila’a Connectivity

Emirati Neighborhood Concept

Planned Street Layout

Sila’a Base Street And Plot Map

Converted to GIS for RDI analysis

RDI is calculated by dividing direct (“crow flight”)

travel distances by actual travel distances on a scale

of 0.1 – 1.0.

Streets that are well connected are patterned in small

blocks, and have good sidewalks - where people can

travel nearly directly to destinations thereby resulting

in a higher index value.

Street networks with many unconnected dead-ends

and large blocks – where people must travel farther to

reach destinations thereby resulting in a lower index

value.

An RDI of 1.0 is the best possible rating, indicating

that pedestrians can walk directly to all destinations.

An average RDI value of 0.65* is considered

acceptable

Parcel


Parcel

RDI Without Sikkas

314 lots > 0.65 (62%)

Parcel


Parcel

Average RDI Score: Fair

.67

RDI – With Sikkas

465 lots > 0.65 (92%)

Parcel


Parcel

Average RDI Score: Good

.72

RDI Delta - With and Without Sikkas

Parcel


Parcel

Shade Route Assessment

Walk times based on

street / sikka network

Walking time baseline

assumption:

1.1 meter / second

Shade Route Assessment - Baseline

Baseline assumes no

shaded routes.

Walking time baseline

assumptions:

1.1 meter / second

Travel time to nearest

Mosque

Challenge: Identifying

shade routes to better

connect outlying plots

with neighborhood

Mosques

Shade Route Assessment – Draft Plan

Walking time with newly

designated shade routes

assumes:

“Walking threshold

increases 50% with

shade” or effective

travel time cut in half

on shaded links.

(So “5 minutes” gets you

farther with shade)

Shade Route Assessment – The Difference

Shade versus no

shade difference

Parcels most

benefited by shade

route are noted in

dark blue

Sikka Planning/Design Principles

Width – Limit width to about 3.2 meters. Wider

sikkas are more difficult it is to shade for cooler

micro-climates and costly to maintain

Shade sikkas by a combination use of building

face, planted trees and awnings

Stagger sikka corridor alignment to enhance

safety perception by avoiding a long 'tunneling'

effect

Emphasize private ownership or sponsorship of

adjoining sikkas - helps prevent disutility

Design sikka systems for

varied users, (a) sometimes separated use for Arab

women and servants, and (b) multiple and mixed use

for expatriates, school children, and transit users; and,

daily temporal change in use (morning and evening

pedestrian/transit commuter, walk-to-school, mid-day

shopping, mosque attendance, etc)

Establish street/settlement and sikka

alignments, to the extent possible, to take

advantage of sun positioning (summer vs winter)

and prevailing winds

How Can RDI DesktopTM Help?

UPC Street Design Manual Implementation – measurable

guidelines

Help Establish Non-motorized Neighborhood Connectivity

Standards - design guide thresholds for neighborhood planning

site plan review

Non-Motorized Plan Strategic Prioritization

Measure current networks - target critical non-motorized connections

Minimizing expensive and unnecessary data collection

Help expedite Draft Plan project identification and prioritization

Critical Plan Priority Analysis and Ranking – consistent and

robust technique (with other sub-models) to measure important:

Neighborhood Connectors

Transit Access Connectors

Urban Boulevard Crossings

2009 gulf traffic rdi discussion

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