FINDING THE WAY BACK: variables in asymmetric route choice Margarita Greene_Rodrigo Mora_Hernán...

FINDING THE

WAY BACK:

variables in asymmetric

route choice

Margarita Greene_Rodrigo Mora_Hernán Kirsten_Daniel Wurman SSS6

__________________the initial question______________some relevant literature________________________five cases______________________final remarks

FINDING THE WAY

BACK:

variables in asymmetric

route choice

recursive asymmetric trips as an opportunity to reveal relevant aspects in route choice

ROUTE CHOICE_cost (time, money)_perception of risk_environmental factor_aesthetics

spatial variables_decision places during the trip_

importance of visual fields_perception of distance_

PERCEPTION OF DISTANCE:

_Canter and Kragg (1975)…shorter routes are overestimated, while larger are underestimated

_Sadalla and Staplin (1980), Sadalla and Magel (1980)…perception of distance is affected by turns and intersection

_Montello (1992)…distance assessment can also be affected by memory loading

_Golledge (1995) asymmetric paths in a university campus • individuals paths vary in paper and real-world• individuals generally do not retrace routes, especially in orthogonal environments• they assign a “cost” to turns, preferring paths that demand fewer turns• individuals adapt their navigation decisions constantly

SPACE SYNTAX

and within SPACE SYNTAX:

_Hillier and Iida (2005)

topological and angular properties of urban grids are better predictors of movement patterns than metric properties

_Conroy-Dalton (2003) longest leg and angular deviation play a significant role in route choice

(the British Library theorem)

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Enquiry Desk

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24º

66º

• Spatial decision-making is a negotiation process

• In metric and topological equal conditions, the

longest leg route will be chosen providing that the path offers the minimum

angle of deviation.

MINIMISINGANGLES OF DEVIATION

THE BRITISH LIBRARY THEOREM Conroy-Dalton (2003)

FIVE CASES

30 students of the MSc Programme, Pontificia Universidad Católica de Chilewere asked to recall a frequent asymmetric route from personal experience

five cases were selected.

Felipe Lanuza

1_Visual Assessment of Metric Distance

• Trip between office and University Campus.

• Trip involves 8 turns and several street crossings.

• It also involves crossing the Mapocho river.

• Two Decision Points were identified: A and B.

• Longest leg versus distance assessment are being negotiated at A and B. Due to street crossing a different balance results in the way to and fro.

O-DD-O

2_First Leg Theorem and Preservation of Linearity

Daniel Martínez

O

O

x

y

O

D

O

D

38

9

3614 76

9

1242

y

x

• During path OD, the student somehow negotiates between continuing his path _maintaining his inertia_ or saving metric distance, though increasing the trip’s topological cost

• During the return trip, the student faces the same negotiation.

Both O-D trip and D-O trip involve two routes, each of them with one decision point: x and y respectively

3_Enrique Gonzalez

3_Assessing Angles in a Multiple Choice Trip

O

DO

D

xy

wz

2666

4244 63

25

7523

7031

60

21

O

DO

D

xy

wz

• Both O-D and D-O trips involve three possible routes. • Two decision points at each of these trips: x,y and w,z

As the student approximates the destination the angle of deviation changes reducing the “cost” of turning.

Again, as he reaches the origin the angle of deviation changes.

Jose Pablo Flores

4_Environmental Factors in Route Selection

O

D

O

D

3917

O

D74

16

85.5 98.4

the OD route is clearly shorter , nevertheless the student chooses a longer route in the way back

The return trip is longer (98.4 vs 85.5 metres) yet simpler in topological terms.

The student reports choosing the second trip because of its attractiveness.

5_Hernan Kirsten

5_Avoid Backtracking

The OD trip starts with the longest leg and minimum angle deviation, yet is longer in metric terms.The choice of the return trip involves a small deviation _to the bakery_ and stop. This allows a reassessment of the trip, where the minimum angle deviation theorem again encourages the s2 route, specially considering that the backtracking is at the end of the journey and not visible form the Decision Point.

Theme/Name Backtrac

king

Topologi

cal vs.

Metric

Compass

Orienta

tion

Inertia

Unstable

Environ

ments

To and

Fro

Program

Visibility

Fields

Longest

Leg

Order

and

Priority

Visual assessment of

metric distance

First leg and

preservation of linearity

Assessing angles in a

multiple choice Trip

Avoiding backtracking

Environmental factors in

route selection

• Backtracking: a natural instinct to avoid retracing steps.

• Angular, topological and metric: negotiating process that individuals undergo negotiating distance against route complexity.

• Compass orientation: a natural instinct towards the orientation of the destination.

• Route inertia: routes have an inertia that has to be broken by an external stimulus

• Unstable environments: urban space changes during the day and so offers a different choice during the day or season (for example car parks or traffic)

• To and fro programs: the way towards a destination is less liable to be affected by secondary programmes, while the return trip looses urgency and is easily diverted

• Visibility fields: length and area of visual fields affect the decision making process in route choice, although they can affect it in opposing ways (attracting or detracting alternatives)

• Longest leg: the visible longest leg in direct route is more attractive in the route choice

• Order and priority: perception of metric or topological costs vary according to the position in a path: a metric gain is perceived as more valuable at the beginning or a topological cost is perceived as less important at the end of the trip.

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FINAL REMARKS:

FINDING THE WAY BACK: variables in asymmetric route choice Margarita Greene_Rodrigo Mora_Hernán...

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