Vancouver’s Millennium Line
One of the consequences of globalization is that most of the world’s transit infrastructure projects are now led by a handful of international engineering consortia and implemented with only token involvement of local architects and little consideration of community issues. Against this prevailing trend, Vancouver’s Rapid Transit Project 2000 has chosen a different route–one that looks set to yield positive results.
Some 30 years ago, Vancouver area residents successfully overturned proposals for new highway connectors that would have carved up the city and destroyed long-established neighbourhoods. Since then, there has been a heightened awareness of the urban implications of major infrastructure projects, a sensitivity to community involvement and an understanding of the contribution that architects can make to the planning process.
Still without elevated freeways, Vancouver has continued to rely on its established grid of major and minor roads and a regional transit system based on trolley and diesel buses. In the last decade, with the area population nearing two million, increased traffic congestion has highlighted the growing need to develop transportation alternatives.
Consequently, enhancement of the transit system is now a cornerstone of the Greater Vancouver Regional District’s (GVRD) Liveable Region Strategy. Various options have been explored including rapid buses, streetcars and expansion of the city’s single line Advanced Light Rapid Transit (ALRT) system, known as SkyTrain. The original line, now known as the Expo Line, was a legacy of the 1986 World’s Fair.
After much debate, SkyTrain has won out, in spite of vocal opposition to its high capital cost. Expensive it may be, but SkyTrain’s overriding virtue, given the GVRD’s long-term strategy, is its ability to support regional land-use goals. This was clearly demonstrated by the original line, which catalyzed urban densification or revitalization around station locations.
The construction of the Millennium Line, stretching 17 kilometres through the city’s eastern suburbs and linking at two points into the existing Expo Line, is the first phase in the proposed expansion. The line will incorporate 11 new stations, the first two of which are due to open in December 2001. With stations typically representing less than 10% of the overall system budget, few transit authorities consider it appropriate to elevate architects to a lead role. However, in the 1980s Vancouver tried this approach for the Expo Line with a measure of success. This time the Rapid Transit Project Office (RTPO) has gone even further, naming Alan Hart as Chief Architect early in the planning process. Hart worked on Phase 1 of SkyTrain, and his firm, Baker McGarva Hart Architects, has a wealth of experience gained on transit infrastructure projects throughout the Americas.
Much credit for this approach is due to RTPO’s chief executive Leisha Stewart, who viewed the SkyTrain project as an exercise in urban and community design as much as in engineering. Stewart disliked the engineering-driven process used for Phase 1 and its kit-of-parts approach to station design. For the Millennium Line, Stewart wanted to ensure that the guideway alignment and station designs would respond to the needs of the communities they served.
Adding credence to this position were the social problems that had recently emerged around several of the Phase 1 stations and the consequent safety and security concerns expressed by SkyTrain users. Instead of being simple conduits into and out of communities, the new stations were envisaged as multi-functional focal points, making a positive contribution to their neighbourhoods. The realization of this goal was seen as critical if commuters were to be convinced to give up their cars in favour of SkyTrain.
Alan Hart’s first tasks as Chief Architect were to design a public process that would effectively deal with issues of guideway alignment, station location and design, and to establish criteria and terms of reference for the selection and appointment of consultants. The principal concerns were value for money, transparency and public accountability throughout the process.
The public consultation and design process was divided into three stages, each of which was initiated by a proposal call and carried through a series of information gathering sessions, displays and public meetings.
Stage 1 was an Ideas Forum in which four architectural firms developed concepts for enhancing prototypical stations on the existing line, with a view to making them more responsive to community needs. The results were displayed in communities along the proposed new line, and public feedback collected.
Stage 2 was a planning exercise in each of the three municipalities served by the Millennium Line (Vancouver, Burnaby and New Westminster) to establish the optimal alignment for the guideway as well as locations and design criteria for stations. In this way, the alignment of the guideway (compared conceptually to the aqueducts of antiquity) was as much directed by urban design concerns as by engineering imperatives. Where the guideway was to cut through existing communities, its alignment followed what were identified as existing seams or boundaries between neighbourhoods. While RTPO was not obliged to consult with the municipalities, it nonetheless tried to respect their standard approval procedures. This ultimately proved unworkable because of SkyTrain’s fast-track schedule, and at times relations between the parties were severely strained. In the circumstances the degree of fit with municipal planning goals is remarkable, with station designs integrated into local plans for bicycle paths, bus loops and so on.
The final stage was a proposal call to pre-qualify architects for the design of stations. Of the 30 submissions, 13 were selected. The work was broken down into packages of two or three stations, either consecutive or related by context. Three or four of the prequalified firms were asked to submit proposals for each of the six station packages.
While each station location offered specific challenges and opportunities for contextual expression, all were designed to a standard functional template developed by Baker McGarva Hart. This template addressed issues of passenger capacity and crowd dynamics and the accompanying guideline booklet identified common design elements such as elevators, escalators, platform edge lighting and signage. These guidelines and standards were intended to reinforce system identity and to take advantage of economies of scale in purchasing.
Each station then became the subject of an extensive public consultation process with the local community. A variety of contextual approaches emerged from this process, the diversity of architectural expressions being strongly encouraged both by Alan Hart and RTPO. The public process also confirmed the three key design issues common to all stations:
The need for improved safety and security.
The need to create a warmer and more welcoming atmosphere.
The need for a greater range of amenities to be incorporated into stations.
To develop a common strategy in response to these issues, architects for each of the stations met on a regular basis. Working within an intense, highly compressed schedule, the six firms collaborated in an atmosphere of camaraderie and co-operation, sharing ideas and expertise that would benefit the overall project.
The architectural team also chose to share the work of certain basic materials and product research and specification writing. In the case of items such as safety lighting, washroom fixtures, tiles and roofing, this helped to ensure a consistency of appearance for common elements of the stations and to offer RTPO purchasing economies and simplicity of routine maintenance.
With regard to larger issues, surveillance was seen as the key to addressing the security concerns. Fully glazed walls could be used to provide clear sight lines into and out of stations, thereby discouraging criminal activity. In addition, retail a
nd customer service operations could provide surveillance over an extended period.
The main opportunity for architectural expression in the stations lay in the design of platform canopies. It was decided to eliminate the suspended ceilings used in the Phase 1 stations and to encourage exposed and expressive roof structures. Public art would be integrated into the architecture. To address issues of visual warmth and local context, it was decided to investigate the possibility of incorporating exposed heavy timber in the roof structures.
The team quickly discovered there was no North American precedent for the use of heavy timber in buildings of this type. NFPA standards had always been interpreted as requiring transit stations to be of non-combustible construction. However, code consultants Locke McKinnon Domingo Gibson contended that, because transit stations are not specifically identified in the relevant codes, they could be designated as Special Structures and the appropriate safety provisions established from first principles. Given the open-ended structures, under which neither heat nor smoke could build up, it was possible to demonstrate that the required life safety standards could be met with heavy timber.
In turn, Alan Hart and the architectural team established parameters for the use of timber:
To prevent vandalism timber should be kept above a three metre datum level.
Structural timber or engineered wood products used should be dimensionally stable.
All timber should be weather protected for durability.
Given this opportunity, several architects chose to incorporate substantial amounts of timber into their stations, achieving a notable first in North America.
The architecture that has resulted from this process is both contextual and individual, each station making a strong statement about the surrounding community, whether existing or incipient. The community approach and the collaborative design process have set important precedents for infrastructure projects in North America. With the close attention paid to community issues, RTPO feels it is reasonable to anticipate that the Millennium Line will be free from many of the social problems associated with transit systems worldwide. Should this optimism prove justified, it will undoubtedly be the most important precedent of all.
Jim Taggart is an Associate of the Architectural Institute of British Columbia. All photographs by Colin Jewall.
Chief Architect: Alan Hart
Stage 1: Ideas Forum
Boldwing Architecture Inc.
Downs/Archambault & Partners
Peter Cardew Architect
Walter Francl Architect Inc.
Stage 2: Planning exercise
Baker McGarva Hart Incorporated
James K.M. Cheng Architects Inc.
Civitas Architecture Inc.
Hotson Bakker Architects
Paul Merrick Architects Limited
Stage 3: Station Design
Architectura and Walter Francl
Architect (Joint Venture)
Baker McGarva Hart Incorporated
Busby + Associates Architects Ltd.
Hancock Bruckner Eng & Wright
Hotson Bakker Architects
Paul Merrick Architects
Construction of the Guideway
Vancouver’s original SkyTrain line, constructed in the mid-1980s, comprises continuous 30-metre long pre-cast concrete beams spanning between concrete columns. The length of the beams exceeded the maximum permitted for normal road transportation, so special trucks were needed, and transportation was restricted to nighttime hours. Because of the oversize loads, there was considerable damage to roads and sidewalks during construction.
The Millennium Line is being constructed by a different method that overcomes these difficulties. Instead of continuous beams, the guideway is made up of pre-cast segments that are lifted into place by giant bridge trusses and then post-tensioned to form continuous beams. The system is similar to that used to construct the Confederation bridge between New Brunswick and PEI. The contractor for that project, SAR, was part of the joint venture company that won the contract for the Millennium Line.
Typically, the guideway segments are 2.7 metres in length and wide enough to support both the eastbound and westbound tracks. Most segments weigh about 25 tonnes (although some are as much as 60 tonnes) and are small enough to be transported by conventional flat-bed trucks without need for special permits or time restrictions.
The bridge trusses are crane-like assemblies that creep like giant insects along the guideway as each section is completed. There are two types of bridge truss, the span-by-span truss that erects a conventional beam section before moving to the next column bay, and the balanced cantilever truss that sits on top of a column and erects cantilever beams on either side of it simultaneously.
Using this technology, the erection becomes a fast, reliable and repetitive process. Each segment is uniquely designed for a specific location, according to the radius of curvature and slope of the track. It is brought to the site and then lifted into place on cables suspended from the bridge trusses. Once a complete span has been accurately positioned, steel cables are threaded through the segments and then tensioned with a force of 15,750 kilonewtons, creating a continuous beam. The cables are completely encased in concrete to prevent corrosion. Once a span is complete, the bridge truss crawls along the completed section to the next open span, and the process begins again.