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Introduction

GO Transit, the Greater Toronto

Areas commuter rail/bus system is

currently undergoing a dramatic

expansion in service. A part of this

expansion is an improvement in rail

service between Hamilton, Ontario

and Toronto in the east. In some cases,

in order to meet the increased trafficdemands, it is necessary to add addi-

tional tracks to accommodate the

existing and future rail traffic. This is

certainly the case in the area of West

Burlington where a third track was

deemed necessary.

Problem

Near the intersection of Highway 403 and Highway 6, the existing twin tracks abut Sunfis

Pond. Sunfish Pond is an environmentally sensitive pond managed by and forming a part oBurlingtons Royal Botanical Gardens. Sunfish pond is the home to many rare aquatic specie

A problem with the new construction was that the existing geometry of the present rail line

did not provide adequate room for the 15m (50 ft) high embankment to be widened to accom

modate a third track. The main concern was stabilizing the embankment as the right of wa

was widened to protect the slope and prevent sediment migration and accumulation in Sunfis

Pond, which in turn could disturb the natural habitat and aquatic wildlife.

Solution

The solution was a combination of geosynthetic and non-geosynthetic solutions to perm

widening of the rail right of way. The non-geosynthetic solution consisted of a sheet pilretaining wall, tied back with a combination of earth anchors and a network of battered pile

The height of this wall was approximately 5 m (16.4 ft) by 180 m (590 ft) long.

Constructed above the sheet piled wall was a geosynthetic-reinforced slope with a vegetate

faade. In order to construct this slope it was necessary to cut into the existing slope. The pr

mary reinforcement specification called for Uniaxial (UX) geogrid which was installed in ho

izontal layers running from the slope face into the embankment. The vertical spacing of th

primary reinforcement layers was 1000 mm (3 ft) center to center. The secondary reinforce

ment consisted of a lighter weight geogrid. This also was installed at 1000mm (3 ft) vertica

CASE

STUDY

Volume 10

Number 2

April 2007

14649 Highway 41 NorthEvansville, Indiana 47725

812-867-66321-800-772-2040FAX 812-867-0247www.nagreen.com

Rail Transit Line Expansion withSC250 Protects Environmentally

Sensitive PondOntario GO Transit works with Burlingtons Royal Botanical Garden in Rail Line Expansion

FAC

TS

The steep railway embankment needed to be stabilized during con-

struction of a third track. Sunfish Pond (foreground) also

required protection from sediment runoff.

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spacing and was vertically offset from the primary grid by

500mm (1.5 ft).

Upon completion of the 10m (32 ft) high granular embank-

ment, the 1:1 slope was covered with 150mm (6 inches) of

topsoil, and hydroseeded with a mix of grasses.

In order to protect the vegetation and topsoil from short-termerosion and also provide long-term reinforcement for the

vegetation root matrix, the decision was made to cover the

entire slope with a turf reinforcement mat (TRM). The pro-

ject engineers with the help of Armtecs Erosion Solutions

Specialists chose North American Greens SC250 because of

its proven performance. The SC250 is a composite turf reinforcement mat comprised of two heavy-duty UV sta-

bilized outer nets, a corrugated center netting incorporated with organic straw/coconut fiber mechanically bond-

ed together. This TRM provides immediate erosion control via the natural (70% straw/30% coconut) matrix,

while the three dimensional netting structure provides permanent reinforcement to the root and stems of the veg-

etation.

To ensure proper installation of the SC250, the installers followed North American Greens DOT System, a

spray-on color-coded dot pattern which indicated exact placement of fasteners. In addition, proper overlapping

of adjacent SC250 panels and trenching the material in at the top of the slope offered optimum erosion control

performance. With the use of North American Greens Erosion Control Materials Design Software (ECMDS )

the project engineers were able to select the proper TRM and offer Go Transit and the Royal Botanical Gardens

a stable, cost effective design.

Results

The selection and installation of the proper products cou-pled with good growing conditions allowed for rapid ger-

mination of the seed mix through the SC250 C-TRM, and

a great start to a fully vegetated slope. Along with provid-

ing GO Transit the means to expand the railway system

and bring more rail traffic into Ontarios Lakeshore west

corridor, the project had additional benefits for

Burlingtons Royal Botanical Gardens. While the removal

of vegetation during construction was unsightly for visi-

tors and had the potential to harm Sunfish Pond, ultimate-

ly the Gardens was pleased to have the opportunity toremove non-native plantings that had established on the

embankment and replace them with native species that

historically would have existed in the area. By re-estab-

lishing native plantings near Sunfish Pond, the Royal

Botanical Gardens was able to improve the natural habitat

surrounding the area. While the rail expansion project at Sunfish Pond was only a small part of the larger billion

dollar railway expansion project funded by the Canadian Government and Ontarios Go Transit, it offered an

example of how green engineering practices could produce a successful result for all parties involved including

Mother Nature.

North American Green SC250 C-TRM was installed as a surface

stabilizer aimed at preventing surface erosion and promoting the

reestablishment of vegetation.

After only a few months, theSC250 reinforced railway

embankment was completely

revegetated, and Sunfish Pond

was well protected from the

potential of slope erosion and

sediment runoff.