Milton Madison Bridge Preference Results

April 2009

Executive Summary

On February 12, 2009, approximately 165 citizens of Milton, Kentucky and Madison, Indiana attended a bridge location and design public meeting held in the Brown Gymnasium in Madison, Indiana. Included in the attendees was the Public Advisory Group and the Section 106 Historic Advisory Panel. After other meeting items were attended to, all participants were invited to view, discuss, and rate the suitability of a set of 18 bridge design concepts. Their task was to rate each concept for its suitability in the context of replacement for the existing 1929-era bridge. Meeting organizers contracted with the U. of Kentucky Transportation Center to provide a Structured Public Involvement protocol for purposes of identifying the level and type of preferences of the attendees for various combinations of bridge design properties.

Attendees rated 6 arch designs + 1 truss-arch+ 5 trusses + 6 cable stay concepts. These concepts varied in their visual complexity, color value (lightness to darkness), type of enclosure created by the superstructure, and the overall profile of the structure. This data, together with the preferences gathered from the general audience and the data gathered from the 106 panel, was modeled, so that designers could better understand the interplay between cost, constructability, maintenance, and visual preference by citizens.

Executive Summary (2)A few general observations. •The average preference scores were highest for cable-stay designs, although the variability across the participants was the highest. That is to say, all of the cable stay designs were generally preferred, but none of them, indeed none of the 18 concepts, was a single, clear ‘winner.’•While the public and Sec. 106 average scores were often significantly different in value, rarely were they different in direction: Sec. 106 participant scores tended to be higher and lower than those of the general public.•Low to moderate complexity + light color arches preferred.•Twin arches preferred to single.•Single or twin “H” arches, or twin “A” or “Mod” arches with light color+low complexity a likely preference. •Truss concepts were generally not preferred, with the exception of concepts that mimicked the existing bridge in terms of shape and style. •Lighter colors preferred for multiple-haunch trusses. •Twin arches were generally preferred to single, and light arches preferred to dark. •“A” Shaped cable stays preferred to “Mod” preferred to “H” shapes.•Light arch colors preferred to darker.•Cable complexity not a strong influence.

Citizen’s Preferences

• Citizens + PAG + “PAG+106”

• Parameters Modeled

– Color Value

– Enclosure Level

– Bridge Structural Type

– Profile

– Visual Complexity

Model Coding From FKB

NumericCode

250 500 750

Bridge Type Arch Cable Stay Truss

Complexity Low Medium High

Color Value Light Med Dark

Profile 0 1 2+

Enclosure “A” or Truss Low

Med “H” or Truss High

Scoring Summary and Standard Deviation by Groups

General Observations

• Highest Averages: Cable Stays• Lowest Averages: Trusses• Lower Scores More Uniform (Less Variability)• 106 Means Have Wider Range than Citizen/PAG• Statistically Significant Differences between Citizen/PAG

and Sec. 106 on Majority of Samples• Only Two Samples Differ on Directionality, Rest Differ on

Degree of Preference• For Modeling Purposes, Scoring Ranges for Each Model

Equalized into 7 Categories: VL, L, Below, OK, Above, H, VH• Absolute Values for Categories Unique to That Model Due

to Differences in Range

Observations About Sample Set

• Some Parameters Tested Unevenly: “Profile”

– CS: Two Towers Only

– Arches: One or Two Arches Only

– Trusses: 0,1,2,3 Haunches

• Slight Uneven Distribution of Types: 7 Arches, 5 Trusses, 6 Cable Stays

• Cable Stay Towers = Light Color Value Only

Coding Sheet and Results

Design Citizens and PAG 106 + 106andPAG

Mean Class Mean Class Type Profile ComplexityEnclosure Color

A1 4.65 OK 2.84 L 1 2 3 3 3

A2 4.05 BEL 2.50 VL 1 2 1 3 2

A3 5.36 H 4.16 ABO 1 3 2 3 1

A4 4.46 OK 3.65 OK 1 3 2 2 3

A5 3.67 L 2.74 L 1 2 2 1 2

A6 4.36 BEL 3.20 BEL 1 2 1 1 1

T1 3.77 L 3.20 BEL 1 2 3 3 1

T2 2.52 VL 4.20 ABO 3 2 3 2 2

T3 1.99 VL 2.40 VL 3 1 2 3 3

T4 3.36 L 5.25 VH 3 3 2 1 3

T5 1.59 VL 1.90 VL 3 1 1 3 2

T6 4.90 ABO 6.80 VH 3 3 2 1 1

C1 5.33 H 4.35 ABO 2 3 2 3 3

C2 5.82 VH 4.65 H 2 3 2 1 2

C3 5.50 H 5.00 VH 2 3 1 1 1

C4 6.11 VH 4.65 H 2 3 3 1 1

C5 4.91 ABO 3.75 OK 2 3 1 3 3

C6 6.45 VH 4.95 H 2 3 2 2 1

Arch 01

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

4.65 OK

Sec. 106 2.84 L

Arch 02

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

4.05 BEL

Sec. 106 2.50 VL

Arch 03

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

5.36 H

Sec. 106 4.16 ABO

-- It is simple− Like the color− It is transparent− Like the two spans− It has fewer piers− Like the historic (arch) and modern feel

− It is curvilinear and unobstructed− It fits the space nicely− It looks low maintenance− It matches the bicentennial theme (two arches)

Arch 04

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

4.46 OK

Sec. 106 3.65 OK

Arch 05

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

3.67 L

Sec. 106 2.74 L

− It looks insignificant− There is no inspiration− It looks disproportionate to the space

− It is not as clean− Do not like the darker color− It is too minimal for the space (valley)− It is boring

Arch 06

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

4.36 BEL

Sec. 106 3.20 BEL

Truss 01/Arch07

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

3.77 L

Sec. 106 3.20 BEL

Truss 02

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

2.52 VL

Sec. 106 4.20 ABO

Truss 03

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

1.99 VL

Sec. 106 2.40 VL

Truss 04

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

3.36 L

Sec. 106 5.25 VH

Truss 05

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

1.55 VL

Sec. 106 1.90 VL

− It is boring− It looks like a railroad bridge (bad)− This could be for the centennial

Truss 06

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

4.90 ABO

Sec. 106 6.80 VH

− Like the light color− It resembles the current bridge which is good (2 comments)− It looks historically appropriate− Like the design that goes all the way across the river− The superstructure may interfere with the views looking through it

− The shape compliments the hills− This could be for the “tri-centennial” (three peaks)− It looks less expensive with fewer piers− Fewer piers mean less obstruction for river traffic

CS 01

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

5.33 H

Sec. 106 4.35 ABO

CS 02

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

5.82 VH

Sec. 106 4.65 H

CS 03

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

5.50 H

Sec. 106 5.00 VH

− It has good visibility− It looks fun to drive on− It does not look stable (not sure how the cable stays stand up)− It does not look like an H or a wishbone (good)

− The median post looks like it would cause accidents− This limits your maximum width with the towers in the median− Would there be a concrete barrier at the median along the length of the bridge?

CS 04

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

6.11 VH

Sec. 106 4.65 H

CS 05

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

4.91 ABO

Sec. 106 3.75 OK

− The straight piers are appealing− The dark color may have a negative influence on the rating of the style− It looks like rabbit ears

− It is too geometric for the topography− The cable-stays emphasize the future− The radial cables are better than the harped (parallel) ones

CS 06

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Citizens + PAG

6.45 VH

Sec. 106 4.95 H

− It is very open− It does not take up the river view− It looks like it would take less maintenance− It is a modern looking bridge (good)− This would look better outside of downtown

− Not having structure overhead is a plus (bird droppings, painting, etc…)− There is no place for the pigeons (good)− It leaves the water more open

Pub. Arches: “H” Shape, Two Arch

Light

Dark

Low

HighA3 H

106. Arches: “H” Shape, Two Arch

Light

Dark

Low

HighA3 ABO

Pub. Arches: “Mod” Shape, Two Arch

Light

Dark

Low

High

A4 OK

106. Arches: “Mod” Shape, Two Arch

Light

Dark

Low

High

A4 OK

Pub. Arches: “A” Shape, Two Arch

Light

Dark

Low

High

106. Arches: “A” Shape, Two Arch

Light

Dark

Low

High

Pub. Arches: “A” Shape, One Arch

Light

Dark

Low

High

A5 L

A6 BEL

106. Arches: “A” Shape, One Arch

Light

Dark

Low

High

A5 L

A6 BEL

Pub. Arches: “H” Shape, One Arch

Light

Dark

Low

High

T1 L

A1 OK

A2 BEL

106. Arches: “H” Shape, One Arch

Light

Dark

Low

High

T1 BEL

A1 L

A2 VL

Arches Summary: Pub and 106

• Twin Arches Generally Preferred Over Singles

• Single or Twin “H” Arches of Light Color and Low to Moderate Complexity a Possibility

• Twin “A” or “Mod” Arches of Light Color and Low Complexity a Possibility

Pub. Trusses: 2+ Haunches, Low Enclosure (Tall Structure)

Light

Dark

Low

HighT6 ABO

T4 L

106. Trusses: 2+ Haunches, Low Enclosure (Tall Structure)

Light

Dark

Low

HighT6 VH

T4 VH

Pub. Trusses: 0 Haunches, High Enclosure (Low Structure)

Light

Dark

Low

High

T5 VL

T3 VL

106. Trusses: 0 Haunches, High Enclosure (Low Structure)

Light

Dark

Low

High

T5 VL

T3 VL

Pub. Trusses: 0 Haunches, Low Enclosure (High Structure)

Light

Dark

Low

High

106. Trusses: 0 Haunches, Low Enclosure (High Structure)

Light

Dark

Low

High

Pub. Trusses: 1 Haunches, Low Enclosure (High Structure)

Light

Dark

Low

High

106. Trusses: 1 Haunches, Low Enclosure (High Structure)

Light

Dark

Low

High

Pub. Trusses: 1 Haunch, High Enclosure (Low Structure)

Light

Dark

Low

High

106. Trusses: 1 Haunch, High Enclosure (Low Structure)

Light

Dark

Low

High

Pub. Trusses: Mod. Complex, Low Enclosure (High Structure)

Light

Dark

Low

High

106. Trusses: Mod. Complex, Low Enclosure (High Structure)

Light

Dark

Low

High

Trusses Summary: Public and 106

• More Haunches Preferred Generally

• Taller Structures Preferred (Low Enclosure)

• Lighter Color Values Preferred for Multiple Haunches

• Slight Preference Toward Mod-High Complexity

• 106 Generally Stronger Preference for Trusses, More Tolerant of Dark Colors

Pub. Cable Stay: 2 Towers, “A” Enclosure

Light

Dark

Low

HighCS4 VH

CS3 H

CS2 VH

106. Cable Stay: 2 Towers, “A” Enclosure

Light

Dark

Low

HighCS4 H

CS3 VH

CS2 H

Pub. Cable Stay: 2 Towers, “Mod” Enclosure

Light

Dark

Low

High

CS6 VH

106. Cable Stay: 2 Towers, “Mod” Enclosure

Light

Dark

Low

High

CS6 H

Pub. Cable Stay: 2 Towers, “H” Enclosure

Light

Dark

Low

High

CS1 H

CS5 ABO

106. Cable Stay: 2 Towers, “H” Enclosure

Light

Dark

Low

High

CS1 ABO

CS5 OK

Cable Stay Summary: Public and 106

• “A” Shapes Generally Preferred to “Mod” Preferred to “H”

• Light to Moderate Color Values Preferred

• Cable Complexity Generally Unimportant

Public Acceptance of Process

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%