Cohabitation/Composite Structure

An intervention for the Lower Don Trail
with Grace Yang.

First Prize – 8th International Landscape Bienalle
part of a submission of 10 projects representing the University of Toronto Master of Landscape Architecture program.
Runner-up – Vectorworks Design Scholarship 

Abstract
This project seeks to engage people with the dual spectacles of bird migration and flood inundation in the Lower Don Trail’s role as migration flyway corridor and flood-plain for the Don River, respectively. 

By creating and improving a pathway system that connects the site to it’s valley walls in a landmark fashion, the ravine is monumentalized through the dual structure of flood adaptive pathway & habitat protection system.

Through expansion and study of indicator species of vegetative and aviary typologies appropriate to the watershed, this project aims to rehabilitate and exhibit the natural temporal qualities of water and air while simultaneously offering an alternative opportunity to recreate. One can connect unconventionally with Toronto’s natural landscape with the backdrop of sensory realities of the valley highway, viaduct infrastructure, and graffiti art.

Early conceptual collages of precedents and the relationship of Toronto to her landscape systems

Early conceptual collages of precedents and the relationship of Toronto to her landscape systems

TORONTONIAN LANDSCAPE

Toronto, as place, has preserved a watershed ravine system of naturalized habitats in the midst of rapid urbanization.
This ravine relies, not on views to the mountains like our cities to the west, but on the courage to run or walk downhill, descending into an often moist and soggy landscape wild with trees and underbrush. When looking to experience the city within a park, we need look no further than to the main trunk stream of the most urbanized watershed in the GTA.

05_cohabitcomposite.jpg04_cohabitcomposite.jpg

Site Boundaries & Layers

We chose our site along the Don based on its location as a transition zone between the rejuvenated and natural habitats north at the Evergreen Brickworks and the extreme engineered and channelized condition south of Gerrard street.

Projects & Policies

Currently, it is home to the Chester Springs Marsh – a demonstration project by Friends of the Don – to illustrate the restorative potential of wetland landscapes along the don river. It also falls in the centre of the lower don trails master plan art and access project, which identified ways in which the Lower Don Trail could be improved through art and accessibility.

Social Context & Visitors

Surrounded on all sides by tower and single family residential development, and currently mostly services people from that area. In good weather conditions, people might bike down from far up the valley or throughout Toronto, and it looks beautiful from fleeting glance of a car. But accessibility is a huge issue because..

Physical Conditions: Edges & Access

The Don Valley is hemmed by highway traffic; namely the Don Valley Parkway, which currently supports three times as much traffic as it was designed to contain. One can subway to either side of the viaduct but can only enter the river valley from winchester street bridge or from the Evergreen Brick works at Bayview Avenue to the north. It is an extremely unsafe environment in terms of exits – one every 2km. However, once descended into the site, it is an oasis of spray painted steel, eroded river bank trails, unkempt grasses, active hydro corridor and gas line. amidst the sound of birds and highways, it inspired in us a unique sense of place where the blending of naturalized habitat with an active urban lifestyle. PROCESS & DESIGN
Our project can be broken down into four major steps: zoning to sensitivity, creating habitat for birds, improving access for people, and the weaving and knotting of a pathway that ties together all the the components of our project.

Zone to Sensitivity

Based on ecological and functional assessments, we zoned the site into three sections: the “enhancement zone”, “mitigation zone”, and “program area”  that offer varying degrees of recreational use and protected habitat areas. The enhancement area is defined by a coniferous forest edge, and trees and understory vegetation to buffer against impacts from the highway. Vegetation in this area connects to the surrounding urban tree canopy. The section shows how the gradients of vegetation type, height and density promote diverse micro-climates and habitats. The mitigation area is where human program is integrated with restored habitat.The program area, situated at the most engineered part of the river is most intensely used section by people as shown by the winding interchanges directing cyclist and pedestrian movement.

BIRDS & VEGETATION

Toronto is part of the Atlantic flyway, and plays an important role for migratory songbirds. Most stop at the Leslie street spit, and then fly around the GTA. A bird needs a certain distance before it has to land again, which is where our site comes in. We propose the expansion of wetland and meadow and forest in these areas, as underrepresented and current small patch existing landscape types in our site and the Don River Valley.

Vegetation is habitat zone specific to biotic communities and also chosen for specific spatial qualities provided along the path. Key species of birds were chosen for their representative qualities and their unique niches according to biotic habitat type.

Vegetation is habitat zone specific to biotic communities and also chosen for specific spatial qualities provided along the path. Key species of birds were chosen for their representative qualities and their unique niches according to biotic habitat type.

Access for People

Our site is 900m long from north to south. We introduced new exit and entry points every 300m (shown in this section cut through the length of the valley ) to allow the path system to thread back and connect directly to the bordering neighbourhoods. Two ramps zig zag down the valley wall from the streets of adjacent schools on the two sides of the river so people can experience the valley which is now visually and physically inaccessible.
Once they cross over the highway, each path twists into a perch-like observation deck. Pathways and perches such as these are elevated 7 meters from lowest elevation point in order to be accessible during frequent floods.
North of the site, a ramp reminiscent of highway infrastructure spirals down from prince edward viaduct, allowing for a spectacular 360 degree view of the river valley. Our last linkage is a bridge to carry cyclists from rosedale valley road and Bayview avenue to our trail.

The new Lower Don Trail we propose is a continuous and composite structure that allows pedestrians and cyclists access in and out of the valley, even during and after frequent flood events. Additionally, it serves to protect enhancement areas, while providing intentional nesting grounds for some urban adapted species. Pathways are different widths to emphasize spatial compression and expansion with the help of vegetation.

A 4m wide boardwalk preserves small dark habitats underneath in the lowest lying vegetated meadow area. Tall trees will line the ravine entrances at each bookend, with narrow 2m gravel path to create sense of movement and compression, encouraging people to move through the space. A walled structure in the north has dual purpose to protect sensitive wetland and constructed habitat from entry while still allowing views. Weathered steel lends a materiality capable of accruing patina of constant flood, spray paint, and spray wash over time.

Substructure of the observatories provide an exciting moment for at grade visitors to spot nests in the underbellies of bridges, and a common way-finding device – the chimney swift tower, marks decision points in the path.


Details

We chose certain species, such as bats and blue birds, and looked at their preferred nesting dimensions to create suitable habitats that are integrated under the bridge structure and in the habitat walls along the path.  The resultant composite structure doubles as protective wall to keep humans and wetland separate, while also providing nest-able habitat for urban adaptive species. Boardwalks rise where frequent floods inundate the site, leaving users of actual dirt paths with the stark realization that they are travelling on solid and dry ground.

To conclude, our project exhibits how a downtrodden river valley, indicative and symbolic of the ravine legacy of Toronto’s urban landscape, can be revitalized to encourage the co-habitation of people, plants, animals, and subsequently, place.

Further Projects