Minnesota Zoo Treetop Trail

Minnesota Zoo Treetop Trail

Minnesota Zoo Treetop Trail

TABLE OF CONTENTS

SNOW KREILICH ARCHITECTS

FEASIBILITY & DESIGN CONCEPT

2019

2

4

EXECUTIVE SUMMARY

6

SITE DESCRIPTION & ANALYSIS

24 DESIGN SUMMARY

a. User Experience

b. Gateway Entry

c. Aerial Views & Renderings d. Materiality 68 FAQs a. Safety

b. Accessibility & Touch-down Locations c. Amenities d. Programming 78 STRUCTURAL & CONSTRUCTION STRATEGIES

a. Existing Foundations, Track, & Supports

b. Structural Strategy c. Utilities

d. Potential Staging Areas & Animal Safety

e. Possible Phasing Strategies 96 CONCLUSION

EXECUTIVE SUMMARY

SNOW KREILICH ARCHITECTS

FEASIBILITY & DESIGN CONCEPT

2019

4

The mission of the Minnesota Zoo is to connect people, animals and the natural world to save wildlife. In our efforts to deliver upon our mission, it is our practice to continually and critically assess how our mission remains relevant and our success is measured on how we best meet the needs of the people, state, and wildlife we serve.

We are inspired by and in alignment with the State of Minnesota’s top priorities of thriving communities, family & children, and the Minnesota environment. And with the leadership of the Governor of Minnesota and our board of trustees, we have recently completed a formal master planning process focused on the heart of our mission— connecting people to the natural world.

After two years of research, design, and review, the Minnesota Zoo has unveiled a new master plan: The Pathway to Nature. Serving as the guide to transforming the Zoo experience once again, the master plan invites guests to rediscover the natural world and will reveal over 200 untouched acres of our managed grounds and repurpose existing infrastructure to introduce new incomparable products and programming. And standing above all is the signature project—the Treetop Trail.

Inspired by the High Line in New York City, the Treetop Trail will be a 1.25-mile elevated boardwalk system built on the decommissioned monorail track. As the world’s longest elevated canopy loop, it will be the centerpiece of the Zoo’s bold vision to reconnect its guests with nature. The Trail will add unparalleled beauty in every season and expose Minnesotans to nature in a way that is only possible at the Zoo. Integrating into the track’s existing footprint, the Trail will be the ultimate reuse construction project. It will honor the monorail’s trailblazing legacy, granting access to the farthest stretches of the Zoo’s campus. From getting in your steps to taking in the view, Treetop Trail will offer unique outdoor experiences and programming focused on Connecting to Nature, Health & Wellness, Art & Creative Expression, and Recreation & Leisure. Treetop Trail will bring our guests a new perspective of the Zoo, all from a thrilling height 40 feet above the ground.

Every journey begins with a first step. Let’s take this first step together and build an extraordinary gift for Minnesotans—a Pathway to Nature.

Sincerely,

John Frawley Director/Minnesota Zoo President/Minnesota Zoo Foundation

SITE DESCRIPTION & ANALYSIS

SNOW KREILICH ARCHITECTS

FEASIBILITY & DESIGN CONCEPT

2019

6

Opening on May 22, 1978, the Minnesota Zoo was one of the first to organize exhibits not by species but by their living environment.

This follows and enhances the mission of the Zoo—to connect people, animals, and the natural world to save wildlife.

Thus the Minnesota Zoo is currently organized into 8 trails and attractions: Tropics Trail, Northern Trail, Medtronic Minnesota Trail, Russia’s Grizzly Coast, Discovery Bay, Wings Financial World of Birds Show, & Wells Fargo Family Farm.

The Minnesota Zoo is located south of Minneapolis and Saint Paul in the suburb of Apple Valley, Minnesota, in Dakota County.

The site is just north of County Road 38 and sits just east of Highway 77, which is easily accessed via Interstate 35 from Minneapolis or St. Paul. There are public transportation options from the Mall of America, serviced by the Minnesota Valley Transit Authority.

MINNEAPOLIS

SAINT PAUL

MINNESOTA ZOO

8

The property is made up of 485 acres of land, including small lakes, wetlands, and wooded areas. West and south of the Zoo are residential neighborhoods, while to the north and east is Lebanon Hills Regional Park. This 2,000 acre park contains hiking, biking, and equestrian trails, as well as campgrounds, a lake, and a beach.

The monorail opened in 1979, allowing visitors to view the extents of the Zoo and these living environments by moving around the property in a slow loop. This provided a unique view of not only the living environments of the outdoor animals, but also the surrounding wooded landscape.

10

1.25

MIL

ES

However, due to decreased ridership and expensive maintenance, the monorail train ceased operation in 2013. The monorail infrastructure remains intact in the full 1.25 mile loop and is visible from the several trails and exhibits of the Zoo.

12

The monorail passes through both public and restricted parts of the Zoo. The original entry point for the monorail is still intact just opposite from the Lakeside Terrace, right before visitors on the ground arrive at the Central Plaza.

Original ramped entry to the Monorail

Cafe pavilion adjacent to the Central Plaza

14

RESTRICTED PUBLIC

CENTRAL PLAZA EXISTING ENTRY

Moving south from the entry, the monorail track passes Russia’s Grizzly Coast and over a service road, looping west to align over the Northern Trail. While many exhibits are visible from the monorail, it passes directly over only one habitat, the Black-Tailed Prairie Dogs on the Northern Trail.

Russia’s Grizzly Coast exhibit from the monorail

Northern Trail alongside the monorail

Prairie dog habitat below the monorail

16

RESTRICTED PUBLIC

RUSSIA’S GRIZZLY COAST

NORTHERN TRAIL BLACK-TAILED PRAIRIE DOGS

The monorail continues north from here and passes over the Hanifl Family Wild Woods before slipping past the Wells Fargo Family Farm Grain Elevator.

Hanifl Family Wild Woods Play Area

Wells Fargo Family Farm Grain Elevator

18

RESTRICTED PUBLIC

GRAIN ELEVATOR HANIFL FAMILY WILD WOODS PLAY AREA

Passing the musk ox habitat, the monorail continues over the lake. The track enters a wooded portion of the site and loops back towards the south; this area is not open to the public and is only accessible by service roads. The landscape varies from wooded forest to wetland.

Monorail extending over the lake

Monorail in the woods

Monorail overlooking wetland in the woods

20

RESTRICTED FOREST & WETLAND AREA

MUSK OX

PUBLIC

Finally, the monorail meets back with the Northern Trail with views of the caribou habitat while approaching the Weesner Family Amphitheater. From here it passes by the Tiger Lair and makes its way back towards the Central Plaza and the original entry point.

Caribou visible from the monorail

Monorail loops around the Weesner Family Amphitheater

Monorail passes by the Tiger Lair

22

RESTRICTED PUBLIC

CARIBOU WEESNER FAMILY AMPHITHEATER

TIGER LAIR

DESIGN SUMMARY

SNOW KREILICH ARCHITECTS

The transformation of the existing monorail structure into a pedestrian walkway presents numerous opportunities for visitors to engage with the offerings of the Minnesota Zoo in new and exciting ways, as the scale and breadth of the rail infrastructure is adjacent to so many parts of the Zoo. Developing an opportunity for guests to experience the Zoo from different perspectives, at their own pace and direction, is not to be missed. This is not limited to the Zoo exhibits, but also to the natural habitats of other animals that live in the forests and wetlands in the northern part of the loop.

FEASIBILITY & DESIGN CONCEPT

2019

24

WOODS & WETLANDS

MUSK OX

CARIBOU

MOOSE DHOLE

TIGER

CAMEL ASIAN WILD HORSE BROWN BEAR

PRONGHORN & GAZELLE

TAKIN

BISON

USER EXPERIENCE The first and clearest experience is one that simply results from being up on the monorail: the act of walking and viewing. This is already an experience that visitors to the Zoo have on the ground, but would be amplified by the different vantage point that viewers can get of the animals and habitats adjacent to the monorail.

1 0

5 2

Viewing animals / landscape

26

Pause

Interaction

Suspension

Specific programmatic experiences have been identified and will be designed and curated by the Minnesota Zoo. Programming will vary by season and audience interests. The size and variety of the monorail through the 485 acres of the Zoo allows for this specific programming.

Performance

28

Outdoor classroom

Active programming

Wildlife hides (birdwatching, etc)

GATEWAY ENTRY The existing ramped entry will be “re-skinned” with wood and steel to align with the materials of the Heart of the Zoo and the elevated walkway. The entry allows for areas of rest as well as vegetation that hints at the “Treetop Trail” the visitor is about to embark on.

30

Existing ramp entry

TREETOP TRAIL GATEWAY ENTRY AT CENTRAL PLAZA

32

TREETOP TRAIL GATEWAY ENTRY AT CENTRAL PLAZA

34

TREETOP TRAIL GATEWAY ENTRY STAIR

36

TRAIL AERIAL VIEWS & RENDERINGS Several viewpoints of the Treetop Trail were considered and conceptually rendered. These following images include aerials that show the extent of the trail in the landscape, perspective experiences on the trail, and views from below or at an access point. Seasonality was also considered since the Treetop Trail is intended to be utilized year-round.

TREETOP TRAIL OVER THE NORTHERN TRAIL

38

TREETOP TRAIL OVER THE NORTHERN TRAIL IN THE FALL

40

TREETOP TRAIL OVER THE NORTHERN TRAIL IN THE SUMMER

42

TREETOP TRAIL OVERLOOK AT THE BISON EXHIBIT

44

TREETOP TRAIL OVER THE LAKE

46

TREETOP TRAIL OVER HANIFL FAMILY WILD WOODS NATURE PLAY AREA

48

TREETOP TRAIL IN THE WOODS IN THE FALL

50

TREETOP TRAIL IN THE WOODS IN THE SPRING

52

TREETOP TRAIL AT REFLECTION POND IN THE FALL

54

TREETOP TRAIL AT REFLECTION POND

56

TREETOP TRAIL AT REFLECTION POND WITH INTERPRETIVE PROGRAMMING

58

3D VIEW OF TREETOP TRAIL ACCESS POINT NEAR THE AMPHITHEATER

60

TREETOP TRAIL ACCESS POINT NEAR THE AMPHITHEATER

62

TREETOP TRAIL IN THE WINTER

64

MATERIALITY While the structural components of the elevated walkway are to be concrete and some steel, the decking and all visible portions of the walkway are recommended to be durable sustainable wood decking. Ideally the wood, handrail, and metal guardrail will align visually with the Heart of the Zoo project, as seen to the right.

The surrounding landscape and vegetation will provide the majority of the materiality. We can take advantage of the natural on-site foliage since the elevated walkway will focus on experiencing the surroundings.

66

Durable wood decking

Steel

Wire guardrails, wood handrails

Surrounding greenery as material

Heart of the Zoo entry building

FAQS

SNOW KREILICH ARCHITECTS

FEASIBILITY & DESIGN CONCEPT

2019

68

While the experiential opportunities of the Treetop Trail design are considerable and transformative for the Minnesota Zoo, it is also imperative to consider logistical uses and implications of the elevated pathway. The Minnesota Zoo is committed to providing a safe, accessible, and pleasant new way to view animal exhibits and the surrounding landscape, supported by necessary amenities and programming.

SAFETY The Treetop Trail will consider placement of emergency phone and first aid stations as well as service vehicle access. The elevated walkway will be compliant with all applicable code requirements, with continuous handrails and guardrails. Due to the unique nature of the design, there are no set existing guidelines for an elevated walkway of this length, so local code officials will be involved to determine the exact recommendations, which will be strictly followed.

GRAY WOLF

WOLVERINE

MEDTRONIC MINNESOTA TRAIL

BEAVER

z z

TROPICAL REEF

PUMA

z

z

z

LAKESIDE TERRACE

GUEST & MEMBER SERVICES

RAMP TO UPPER PLAZA

D CO

FOO

zzz

z

z

z

z

z

FOOD COURT

z

(SEASONAL)

WOODLAND ADVENTURE

z

z

(SEASONAL)

z BACTRIAN CAMEL

TIGER BASE CAMP

RUSSIA’S GRIZZLY COAST z AMUR

z

STAIRS

z

LEOPARD

GAZELLE

z

z PRAIRIE DOG

ATM

WILD BOAR TAKIN

BROWN BEAR

z

z

T

EAST ENTRANCE (SEASONAL)

3M PENGUINS OF TIGER THE AFRICAN COASTPARKING LOT

CENTRAL PLAZA

BEE HIVE PLAY SPACE

JELLYFISH SHARK SEA OTTER

UR

UPPER PLAZA INSET

TROPICS TRAIL, MEDTRONIC MN TRAIL & ® TARGET LEARNING CENTER (SEE INSET)

MONK SEAL

IMAX THEATRE

CARGILL ENVIRONMENTAL EDUCATION CENTER

TOUCAN PARKING LOT

DISCOVERY BAY: UNITEDHEALTH GROUP MARINE EDUCATION CENTER EDUCATION EVENT CENTER

zz

z

GIFTS AND SOUVENIRS

z z

PRONGHORN

zz

SNOW MONKEY

z z z

AMUR TIGER

z z

z

NORTHERN TRAIL

RESTROOMS

ASIAN WILD HORSE

zz

TRUMPETER SWAN

GRIZZLY COAST CAFÉ

FOOD

z

zz

(SEASONAL)

z ail z z zzzz zzzz z z

z z

TIGER LAIR

WATER FOUNTAIN

z z

z

($)

DHOLE

ELEVATOR

z

zz

(SEASONAL)

MOOSE

INFORMATION

TIGER PARKING LOT

UPPER SOUTH ENTRANCE

MUSSEL CABIN

WORLD TACOS

zCONSERVATION CAROUSEL (SEASONAL)

(SEASONAL)

EAST ENTRANCE (SEASONAL)

Tropic s Tr

HANIFL FAMILY WILD WOODS PLAY AREA

z

z

z

z

z

HORSE

TROPICS TRAIL GIBBON

CARIBOU

(SEASONAL)

z

GRAIN ELEVATOR

COW

zz

TAMARIN

TAPIR

LEMUR

SNOW MONKEY

CROSSROADS PARK PICNIC AREA

z

z

(SEASONAL)

z z

(SEASONAL)

NURSING AREA

UPPER PLAZA

z z

z

WELLS FARGO FAMILY FARM

GOAT & SHEEP

WEESNER FAMILY AMPHITHEATER

MUSK OX

z

PIG

DAIRY BARN

RAMP TO LOWER LEVEL

z

FARM HOUSE

z

INDOOR THEATER WINGS FINANCIAL WORLD OF BIRD SHOW

GRANARY

z

® BLACK

TARGET BEAR LEARNING CENTER

CHICKEN

SOUTH ENTRANCE

WATER’S EDGE PICNIC AREA

PLAY AREA PICNIC

SMOKE-FREE CAMPUS

Direction of Incline

SHADY OAKS PICNIC AREA

z Steep Slope - Assistance Available If Needed

Tropics Bird Containment Vestibule - Bamboo Curtain & Heavy Wooden Double Doors TO CEDAR AVENUE / HIGHWAY 77

Minnesota Zoo Accessibility Map

70

GIBBON PARKING LOT

ZOO BLVD

AUTOMATED EXTERNAL DEFIBRILLATORS (AED)

CAMEL PARKING LOT

BISON

z

FIRST AID

McANDREWS ROAD (COUNTY ROAD 38)

TO JOHNNY CAKE RIDGE ROAD

ACCESSIBILITY The “Trails & Walkways” guidelines of the NRCS of Minnesota outlines accessibility needs as follows:

Accessibility for Recreation. The Americans with Disabilities

Act of 1990 (ADA) requires outdoor recreation access routes

and some hiker/pedestrian trails to be accessible to people

with disabilities. Address accessibility requirements for new

construction and when existing facilities are being altered.

Compliance with the ADA outdoor recreation guidelines is

not required where:

• compliance would cause harm to cultural, historic,

religious, or significant natural features;

• compliance would substantially alter the nature of the setting;

• compliance would require construction methods or

materials that are prohibited by Federal, State or

local regulations; or

• compliance would not be feasible due to terrain or

the prevailing construction practices.

Make an accessibility evaluation to determine the required level of accessibility for a trail/walkway design.

The Minnesota Zoo welcomes everyone to enjoy the exhibits it has to offer, providing assistance as needed. Therefore, the monorail walkway will be fully accessible to everyone. Accessible entry and exit points with ramps and elevators will be provided wherever possible. The existing entry will require some modification to make it ADA compliant, but the existing slope allows for this. It is recommended that the other accessible points of entry/exit are located at the areas of the existing rail infrastructure that are already almost at grade. These are outlined in the potential “touchdown” locations on the following page.

.25 mi

G

F .17 m i

.20 mi

E

A

.16

.13 m i

mi

B

.16 m 72

mi

D .19

i

C

ACCESS LOCATIONS The potential touch-down locations (where visitors can enter or exit the Treetop Trail) are outlined here. Locations A, B, C, D, & E are in the public and already-visible areas of the Zoo. These are points that people already pass by on their way to something else, whether that is an exhibit or programming. Locations F & G are in the northern, more private part of the Zoo. Visitors are not currently able to access this part of the property, and these points of entry/ exit could encourage the development of hiking trails on the ground to allow for further exploration of the wooded area.

Touch-downs A, B, D, & F are accessible entries (ADA), designed with a ramp, elevator, or both. The aerial images below show all of the points of entry, and lists the height of the existing rail infrastructure at that point.

A

At grade, ADA

D

Elevated 14’-0”, ADA

G

Elevated 14’-0”

B

Existing ramped entry, ADA

E

Elevated 10’-0”

C

Elevated 18’-0”

F

At grade, ADA

AMENITIES The trail itself will be a generous width to accommodate wheelchairs, strollers, and Zoo service vehicles. A variety of seating options will be provided for moments of rest, and amenity stations will be clearly marked and visible through consistent signage.

Access points will be located near existing restrooms, food, and ground paths. Drinking fountains, water misters, shade elements, wayfinding signage, security cameras, a PA system, and trash bins are also to be incorporated onto the Treetop Trail.

Amenity Stations

INTERPRETATION

DISTANCE MARKERS

REFUSE & WATER

74

PROGRAMMING The Treetop Trail will support the current programming of the Minnesota Zoo and serve as a unique setting for new programming.

As the walkway will provide previously unseen views of nature at the Zoo, programming will be paired with it to enhance education, engagement, and interpretation opportunities. The Treetop Trail will also be a one-of-a-kind event space.

Learn

Animal Overlook

EXHIBIT VIEWING

Animal Overlook

EXHIBIT “BUMP-OUTS”

Play

OPPORTUNITIES FOR “PLAY”

76

Pause

INDIVIDUAL SEATING

Pause

GROUP SEATING

Enclosure

ENCLOSURE & SHADE

STRUCTURAL & CONSTRUCTION STRATEGIES

SNOW KREILICH ARCHITECTS

FEASIBILITY & DESIGN CONCEPT

2019

78

The first step in considering the feasibility of the Treetop Trail was to complete a structural analysis of the existing infrastructure.

Through a preliminary evaluation conducted by Meyer Borgman Johnson (MBJ) on site and through existing documentation, the structural capacity of the foundations, tracks, and supports were deemed sufficient for the use of a walking trail.

EXISTING FOUNDATIONS, TRACKS, & SUPPORTS The summary of existing structural systems is based on the review of the existing construction documents and a brief on-site general visual observation of the monorail track. A thorough, in-depth observation will be conducted and testing will be completed to determine material properties of the steel or concrete, and to quantify any corrosion or other damage to structural members. The following describes the existing structural components: FOUNDATIONS Foundations for the monorail columns are only partially described in the existing documents (see footing section on page 24), and are not visible on site as they exist primarily below grade. The foundations appear, based on the available partial documentation, to be concrete drilled piers with a minimum diameter of 36”. The steel columns are embedded in each pier to an unknown depth, although the approximate depths of the “hole” into which the steel column is placed are summarized on documents we have reviewed.

Pier reinforcement is indicated only within the top 3’-0” of each pier. Pier capacity is not described in the documents.

TRACKS The existing monorail beam is a built-up tube section spanning a typical maximum span of 70’-0”. The existing beam is comprised of several continuous plates, transverse wide flange beams and plates, and a pair of continuous HSS sections welded together; refer to detail A on page 24. Monorail beam sections are continuous and fully welded, with slip connections at column supports along curves. We assume these slip connections are adequate to allow for seasonal temperature movements.

SUPPORTS The monorail beam is supported by 27” deep, steel W-shape columns of varying heights.

80

Typical Rail Section

Drilled Footing Section

Track & Support

STRUCTURAL STRATEGY The typical existing, tube-shaped, primary monorail beam has been analyzed for a variety of loading conditions and configurations.

Under consideration was its previous use for support of enclosed trains and several options for the proposed use as an elevated, exterior pedestrian bridge. The analysis considered strength, stiffness (deflection) and a preliminary look at vibration.

The assumed design condition is a typical, straight (not curved in plan or elevation) 70 foot span between columns. Analysis of the curved (in plan or elevation) sections of the monorail are significantly more complex and should be undertaken only after there is a clear understanding of the performance issues and design requirements related to the straight beam spans. For the purpose of this analysis, the connections between beams and columns are assumed fully fixed. The existing drawings identify typical connections consistent with this assumption. However, field verification of individual column and foundation elements with respect to their structural condition and connection details is required.

The analysis confirmed the existing built-up steel tube beams and supporting columns (W27) have sufficient strength and stiffness for support of the monorail trains. The monorail train (including occupants) represents a superimposed load of approximately 70,000 pounds per train. Accordingly, the original, superimposed total load may be represented (for simplicity and for comparison with subsequent design conditions) as approximately 1,000 pounds (1 kip) per lineal foot (plf) along the typical 70 foot span.

82

TYPICAL AREA OF STUDY (70’-0” STRAIGHT SPAN)

A 12’-0” wide cast-in-place concrete deck is proposed, where the concrete deck surface is centered on the existing rail tube. The new 5” structural slab acts compositely with the existing steel structure through the field-welded connection of shear studs to the existing tube. The concrete slab will allow the pedestrian bridge to maintain the curvature of the existing monorail system at a width suitable for pedestrian use. An average 3” thick concrete topping slab is assumed part of the system to provide protection for waterproofing, slope as required for local drainage, and as a replaceable wearing surface to protect the structural slab. This deck surface may be replaced by a lighter system (including wood or composite decking) as subsequent decisions may dictate.

The total superimposed load of this system (dead plus live) is approximately 2,600 plf (approximately 3 times greater than the assumed original superimposed design load). The analysis indicates the existing monorail tube and supporting columns do not have sufficient strength or stiffness to safely support this heavier load without significant supplemental reinforcing. With appropriate reinforcing for total loads, sufficient non-composite capacity does exist within the resulting beam section to carry the wet weight of the structural slab during placement (without need of supplemental shoring to grade). However, suspended formwork hung from the reinforced monorail beam will be required to carry the plastic concrete weight during placement if the slab is not shored to grade.

An option for reinforcing the existing tube structure for this option is shown in Detail C.

84

The horizontal structural system described in Detail C has adequate deflection and vibration performance due to the significant dead load and stiffness generated by composite action. Vertical acceleration caused by both walking and running are within recommended criteria for an exterior pedestrian bridge. The columns will be overstressed and will need to be reinforced to support the increased load, and this can be accomplished by coverplating the flanges to enhance axial capacity (see Detail F for a typical column reinforcing schematic).

The existing foundations will also be significantly overstressed due to the substantial load increases and may require installation of new columns and foundations. It is possible that existing columns may still require reinforcing in conjunction with the addition of new columns and foundations.

Typical column reinforcing schematic

12’-0� wide cast-in-place concrete typical section

WALKING SURFACE, GUARDRAILS, & HANDRAILS

CAST-IN-PLACE CONCRETE

STABILIZING BEAM

REINFORCED EXISTING RAIL & COLUMN

86

Once a thorough evaluation of the geotechnical conditions is completed and the determination made whether to reinforce existing foundations, add new columns and foundations, or undertake a combination of the two, the following additional structural design tasks will be undertaken: •

Conduct a detailed analysis of each individual existing span and supporting conditions for appropriate strength and stiffness (considering both deflection and vibration). This analysis must include actual horizontal and vertical curves and all unique supports not described or specifically evaluated herein (this report is based primarily on typical, straight, 70 foot beam spans).

•

Conduct a detailed vibration analysis for individual components and the system as a whole.

•

Conduct a detailed review of existing piers and other cast-inplace concrete foundation elements for damage due to corrosion or unforeseen conditions.

• Conduct a detailed review of existing steel elements (beams

and columns) for damage due to corrosion or unforeseen conditions.

UTILITIES It appears that the existing infrastructure contains conduit for electrical along the length of the monorail. Additionally, the beam was originally designed to incorporate systems within the beam through cut-outs in the steel. The design options would call for lighting along the length of the monorail, but no other additional systems.

88

POTENTIAL STAGING AREAS The nature of the cast-in-place system allows the construction of the elevated walkway to take place directly along the path of the existing structure rather than below or around it. While the unknown foundation conditions will likely require work on the ground/underground, the construction of the walkway itself can be staged in the service area by the existing train shed or in other offlimits areas that visitors do not interact with.

ANIMAL SAFETY As previously mentioned, the monorail goes directly over one exhibit, the Black-tailed Prairie Dogs, which will require temporarily moving the animals during construction as necessary. Precautions should be taken to protect and minimize disturbance of all animals at the Minnesota Zoo, depending on the species and their sensitivities to noise and their proximity to the construction areas.

90

POTENTIAL STAGING AREAS

.25 mi

G

F .17 m i

.20 mi

E

A

.16

.13 m i

mi

B

.16 m 92

mi

D .19

i

C

PHASING STRATEGY Construction phasing was explored and it was determined that a series of seven phases could be followed to construct the Treetop Trail, as it may not be possible to complete the entire 1.25 mile length of the trail at once. Using the access locations as a guide, the monorail track can be split into these seven segments of construction. The order of these phases will be considered in relation to other improvement projects at the Minnesota Zoo and in terms of visibility to the public. It is recommended to first construct the four phases in the more public, visible areas. The three segments in the more private, northern part of the Zoo could be completed after, while the Zoo is forging new trails to connect to those drop down locations.

The first phase of the Treetop Trail could be from point A to B, connecting the existing Central Plaza to the access point by the amphitheater.

A

B

.16 miles Amphitheater Touch-down (A) to Central Plaza (B)

Segment B to C

Segment C to D

Segment D to E

E

B C .19 miles Central Plaza (B) to Bison Exhibit (C)

94

D

D C .16 miles Bison Exhibit (C) to Northern Trail Overlook (D)

.13 miles Northern Trail Overlook (D) to Grain Elevator and Nature Play Area (E)

Segment E to F

F

Segment F to G

F

G

E

.17 miles Grain Elevator & Nature Play Area (E) to Woods Touch-down (F)

Segment G to A

G

A

.25 miles Woods Touch-down (F) to Woods Overlook (G)

.20 miles Woods Overlook (G) to Amphitheater Touch-down (A)

CONCLUSION

SNOW KREILICH ARCHITECTS

FEASIBILITY & DESIGN CONCEPT

2019

96

This study explored the programmatic, structural, and construction implications of converting the existing monorail at the Minnesota Zoo into an elevated pedestrian walkway. The Minnesota Zoo concludes that the monorail is well suited for conversion to a pedestrian walkway.

Programmatically, the existing monorail has the potential to provide a one-of-a-kind visitor experience for the Zoo’s guests. The elevated structure would offer a unique and varied vantage point from which to view the Zoo’s habitats and surrounding landscape.

This conversion would be an ambitious yet pragmatic way to reuse infrastructure to provide an experience to visitors that is memorable, immersive, and educational.

Structurally, the typical monorail beams have the strength and stiffness required to safely support installation of a new pedestrian bridge. Engineers have proposed the construction of a cast-in-place concrete deck on top of the monorail’s existing steel beam. The slab and beam’s composite design would result in a highly efficient and economical structure that would significantly increase the capacity of the existing structure. Existing columns and foundations may need to be reinforced. Due to the limited available data on the existing beam, columns, foundations and soils, further study will be required.

In terms of constructibility, the proposed design will allow the monorail to be built with minimal disruption to animal habitats and the existing pedestrian circulation of the Zoo. The multiple access points will allow the monorail walkway to be constructed in seven distinct phases over time, permitting the exhibits, habitats, and amenities to remain open during construction of the walkway.