There
is a common misconception in the design of large infrastructure
projects like transit systems that the inclusion of sustainable design
strategies is an “add-on” that increases project cost. In
our experience, sustainable design strategies are actually an effective
means of: 1) Bringing Value to the project; and 2) Reducing Risk to the
transit agency.
Good
sustainable design is actually a form of radical common sense that can
challenge some of the assumptions that accompany current transit design
principles. Using a combination
of critical thinking and creativity, the integrated design process
examines each component of a transit system to determine if each is
necessary (rather than expected), and if each is able to serve more than
one function. In Permaculture
terminology, this is known as “stacking”, and is the way that natural
systems find high levels of efficiency by having each element serve many
needs simultaneously. This often means that more can be accomplished by actually building less.
In
terms of Risk Reduction, current approaches to risk management tend to
focus on issues that may occur in the period from Design through
Commencement of Service – cost escalation, time escalation, and
disruptions to the delivery process. However,
unlike other types of commercial development, transit agencies build
their facilities to have an ultimate design life of 100 years or more,
with capability for 50 years of continuous operation before
refurbishment is necessary. Far
greater risks exist that are associated with the lifetime of the
system, many of which can be mitigated using sustainable design
strategies:
Lifetime risk
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Sustainable design response
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Cost and availability of electric power in the region
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Design for reduced energy consumption and energy recovery
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Wear and tear on transit facilities
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Specifying for durability
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Climate change impacts
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Design for extreme weather events
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Ridership meeting projected levels
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Creating appealing, people-oriented facilities
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Sustainable design therefore brings long-term Value on three levels: to the Project, to the System, and to the Community. To the Project, this means potential reductions in capital cost by finding synergies through the integrated design process. To
the System, it means bringing long-term value through energy savings,
reducing life cycle cost, and using good design to attract ridership. And
to the Community, it means supporting public health by encouraging
transit ridership, enhancing environmental quality, and providing
mobility options that are integrated with public spaces.
In our transit design work, we have explored many opportunities to find “stacking” synergies. Here are some examples of this philosophical approach:
For
underground or elevated stations, it is common practice in transit
design to include a combination of stairs, elevators, and escalators to
provide vertical access to street level. Elevators are essential for those with disabilities, or for the convenience of travellers with strollers or luggage. Stairs are also essential, but escalators are worth reconsideration in some situations where lower ridership is anticipated.
From
a functional perspective, escalators have the advantage of moving large
numbers of passengers quickly and efficiently, but strictly speaking
their function is redundant to that of stairs and elevators. When
provided the option of stairs or escalators, human nature is for people
to take the escalator, even if they are capable of taking the stairs. Escalators however have a high capital cost, a high level of
required maintenance, and high ongoing energy costs as they generally
run continuously whether they are carrying people or not.
Some systems have addressed this issue from a variety of perspectives. At
the Copenhagen Metro, a deliberate choice was made to eliminate
escalators from underground mezzanine levels to the surface in order to
promote public health through the use of stairs. On
Sound Transit’s U-Link project, escalators were selectively deleted at
some station entrances for cost reasons, where lower anticipated
passenger volume did not warrant the high level of associated
investment. When eliminating
escalators, it is advisable to increase the capacity of stairs in order
to compensate for the reduced efficiency of moving large numbers of
passengers quickly.
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| Photo Credit: VIA Architecture |
Some transit designers have also found whimsical solutions to vertical circulation– as demonstrated by the ProRail Transfer Accelerator at the recently renovated Overvecht Rail Station in Utrecht, Holland and the musical stairs installed at Odenplan, Sweden. Both are playful means of encouraging passengers to exercise while taking transit.
Lighting Strategies:
Lighting strategies can be a significant contributor to reducing long-term energy consumption at transit stations. Key principles include:
Use high efficiency fixtures with long lamp life
Use high light-reflectance materials to reduce the quantity of lighting required
Use controlled integration of daylight and electric light
Waterfront station, Canada Line, Vancouver: The
Canada Line lighting design achieved energy savings by means such as
avoiding over-lighting, integrating daylight sensors, and scheduling the
lights to turn off during non-revenue hours.
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| Photo Credit: Ed White |
Landscape and Structural Synergies:
Good
integrated transit design includes an ongoing dialogue between
structural design, urban design, and landscape teams to develop
solutions that solve many issues simultaneously. Some good examples of this type of “stacking” are as follows:
Commercial Station, Millennium Line, Vancouver – this station platform was sited in the former Grandview railway cut, which is located several meters below street level. During
the public consultation process for the station design, local residents
were concerned about the loss of habitat in the cut and about
preserving the green space that it provided in the highly urban
neighborhood. VIA’s design
solution was to line the east side of the cut using a stacking, precast
‘green wall ‘system that not only retained the soil but also provided
space for planting and associated habitat.
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| Photo Credit: Ed White |
Canada Line, Vancouver – one of the common issues associated with transit infrastructure is vandalism and anti-graffiti strategies. On the Canada Line, the design team used a series of trellis structures around guideway columns to act as ‘green screens’. These not only discouraged graffiti but also provided enhanced opportunities for landscape in the surrounding urban environment. Green
screens of this nature can also be used on bridge abutments, and the
screens can be made hinged or demountable to allow for structural
inspections as required.
Materials Strategies:
Many creative strategies are available to the design team that relate to the use of materials. These fall into several general categories – Reuse and Salvage, Local materials, and Design for Durability. Some examples are as follows:
Reuse and Salvage
– Transit agencies that have been constructing systems for many decades
often have a “boneyard” or similar source of materials that have been
salvaged from previous projects, for use in current project design. The
re-envisioning and re-purposing of these materials can provide a
creative design challenge to architects and urban designers, saving
embodied energy and capital cost.
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| Photo Credit: Waterleaf Architecture |
Where
new transit projects require building demolition, it has become
increasingly common to have salvage goals written into demolition
contracts. These materials can either be repurposed within the transit project, or accounted for as credit within the demolition contract.
Local Materials
– The Millennium Line SkyTrain extension in Vancouver pioneered the use
of wood in modern transit structures, a material not used for transit
design for many decades. On
very old systems such as the London Underground and the Chicago “El”, it
is still possible to see wood used in escalators and station platforms,
but wood had generally been eliminated from transit design due to
concerns about fire hazard, durability, and other technical
considerations.
Three
of the Millennium Line stations designed by VIA – Rupert, Renfrew, and
Commercial – featured wood beams as prominently visible structural
members. This choice was made for a variety of reasons: to
honor the historical context of the timber industry in British
Columbia, to promote the use of new wood technologies, and to add warmth
and richness to the visual environment of the station platforms. In
order to address the technical concerns associated with wood, three
‘rules of engagement’ were established to govern the appropriate use of
wood: 1) that it be located out of the ‘touch zone’, or minimum 3 meters
above the platform surface, to prevent vandalism; 2) that it be
completely weather protected; and 3) that it be dimensionally stable, in
this case through the use of glu-lam technology.
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| Photo Credit: Ed White |
Design for Durability
– Often the most underrated form of sustainable design, the
specification of materials that are durable is essential to successful
transit design. Not only does
this save long-term cost associated with ongoing replacement or
refinishing but it also avoids the indirect costs associated with
station closures and down-time due to maintenance activities. The
use of stainless steel for transit handrails, as well as precast
concrete or stone stair treads, and porcelain tiles for platform and
concourse pavers, are essential strategies in durable transit station
design.
In summary, good sustainable design directly supports good transit design. A
robust integrated design process will reveal the opportunities for
efficiencies and synergies between disciplines, resulting in both short
and long term cost savings and economies of effort during design and
construction.
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