Archdaily had the chance to speak to SOM regarding the Transit-oriented development (TOD) projects. SOM has extensive engagement in planning, design and engineering on various means of conveyance, and TOD is definitely one of the speciality the SOM team has to offer. Through the interview, we will walk through the design strategies and their changes over the years of TOD Development, the challenges and new area of focus of TOD development, and most importantly, the interview will focus on the design strategy in developing TOD in China, where SOM has participated in many TOD projects, including the South Gateway of Guangzhou Central Axis, Guangzhou Nansha Pearl Bay and Xiong'an District Planing.
ArchDaily (Han Shuangyu): How does SOM define TOD (Transit-oriented development)? What design scope does TOD design include?
SOM (Derek Moore, Thomas Hussey): All development should be “transit-oriented” in the sense that access and mobility must be planned for any development, Greenfield or Brownfield, new city, or existing urban fabric. “TOD” is commonly understood to be intensive mixed-use development in close proximity to similarly concentrated nodes of public transit - rail, light rail, bus, etc. This proximity promotes pedestrian mobility and limits LOV (low-occupancy vehicle) use of private cars, taxis, and app services. It also lowers energy usage for both transit and development.
This more intensive development around transit nodes is understood to be mixed-use, including commercial, hospitality, retail, food, and beverage, and even residential and entertainment. This concentration of uses further reduces energy usage. The core scope of TOD is the coordination of the comprehensive planning and design. Architects are best suited for this role, at the right hand of developers.
TOD project development
ArchDaily: Since the Canary Wharf masterplan and the entrance design of the Jubilee Line subway, SOM has completed many TOD projects. What are the changes, or the shifts in focus in terms of the design direction of TOD over the years?
SOM: Much has changed and yet very little – the overarching objectives of TOD planning and design are present, even as the size and complexity have increased, and new programmatic elements have been added. That objective is to realize the benefits of proximity to transit to improve people’s lives, bolster the economy and enhance energy efficiency. That said, there have been subtle shifts in focus. Transit planning and mixed-use development can be more richly mixed. Public open space has become even more important and more challenging to provide for all parts of the development. But the greater size of the developments has allowed a wonderful diversity of open space and its design. Retail, F&B, entertainment for 24/7/365 liveliness have assumed a greater role in making TOD a destination in the city, even for people who do not transit through or work there. Residential can be an important complement to TOD development, especially in making the Retail, F&B and Entertainment successful financially.
One of the most significant developments in Europe and the US has been the revitalization of older and historic rail stations and terminals for contemporary TOD. At about the same time as Canary Wharf, SOM was engaged at the Broadgate development over the tracks at Liverpool Street Station in London, a crucial early project for TOD. Since then, other stations in London and other European cities have been redeveloped for HSR and other rail, metro, and surface modes, while also retaining the historic structures. In the US, SOM has developed a significant portfolio of TOD projects, beginning with the Northeast Corridor revitalization project, and continuing with Denver Union Station, the masterplan for 30th Street Station in Philadelphia, and the recently opened Moynihan Train Hall in New York. These projects combine the sense of place of historic structures with contemporary transit engineering and design.
TOD in China
ArchDaily: SOM has completed several TOD projects, both in the early years abroad and in recent years China. Tell us about the experiences that are applicable for current projects. What are some of the design strategies designated to Chinese projects?
SOM: One of the biggest differentiators in China's approach to TOD is the massive investment in high-speed rail. In just 13 years since its inception, China boasts the world's largest HSR network with 37,900 km operational track through 2020. Coupled with China's ongoing urbanization, HSR investment offers the opportunity to drive development to zones around new stations within existing metropolitan areas or establish urban development in altogether new places. While China's HSR is a national connectivity strategy, a subset of HSR--called intercity HSR--offers the concept of TOD at a regional scale. Strategies such as "Jing-Jin-Ji", the regional cooperation of the provinces surrounding Beijing/Tianjin, or "Greater Bay Area", the term used for collective urban strategy of the Pearl River Delta, are reinforced through intercity HSR networks.
Along with these networks come opportunities to define satellite districts and new sub centers for cities. Examples include Tongzhou, a new subcenter of Beijing that will be anchored by Beijing East HSR terminal and a four-metro line interchange, or Nansha, a new sub center for Guangzhou at the heart of the PRD. Xiong'an, China's new “model city of the future” is made possible by the insistence on early phase HSR connections to Beijing and Tianjin. Many of China's first generation HSR stations were built at the periphery of cities, designed much in the fashion of airports, with a focus on vehicular access through grade-separated arrivals and departures. This auto-focused approach led to stations that are predisposed to having challenges in anchoring pedestrian-oriented districts.
In recent years there has been a notable effort to integrate HSR stations more smartly within urban environments through underground rail infrastructure and increased TOD capacity. Tianjin Yujiapu brings trains underground right to the heart of the emergent Tianjin Binhai core area. Similarly, below-grade tracks and platforms at Beijing East railway station and Xiong'an's intercity station allow for intensive pedestrian-focused district centers that maximize opportunities for compact development and establish an attractive urban character much more in tune with today's desire for sustainable, healthy, people-focused places.
China has moved TOD to a different level. Some techniques appropriate in Europe and the US are less applicable in China. The greater size and faster speed implementation of TOD developments in China have altered the internal dynamic that prevailed in most TOD planning and design. Previously, development around transit was expected to take place at a slower pace, over years or decades (for example, Canary Wharf, London). Likewise, it was assumed that a more limited set of facilities would be put in place at the outset and a framework established within which new buildings and public spaces would be added over time.
That is, it was expected that TOD districts would mature over time and have a variety of building designs. Likewise, it was assumed that the mix of uses could change according to emerging needs. By the same token, TOD in China has changed the approach to transit planning requirements. The greater size and complexity of the transit components of TOD in China not only means larger sites, more underground rail types (metro, HSR, airport rail), but important and varied rubber-tire modes of mobility - from taxis and app services to shuttles, city buses and inter-city coaches. As the modes have grown and multiplied, so the number of intermodal connections for riders. This has presented challenges to convenience (level changes, diverse fare-control conditions, and commercial opportunities. Likewise, the connections to the street and at the street, as well as to vertical development, have multiplied and become potentially more complex.
But the core objective remains - realize the convenient connections of TOD. Those earlier assumptions about TOD development entailed a more limited opportunity to influence the specifics of design, because the initial design team would not necessarily be the “design guardian” of the district 10, 20 or 30 years hence. The larger initial construction campaigns of TOD in China today presents an important opportunity to determine not only building design, but streetscapes, landscape and open spaces, and amenities. At the same time, this greater ability to establish the look and feel of entire TOD districts from the beginning challenges developers and designers to make sure that there is diversity, variety and texture to the design and programming.
The massive growth in transit nodes means more complex pedestrian movements to be accounted for. Also, given the cost of underground construction, the sizing of concourses and transport areas is critical, not just for the modes of transport, but for pedestrians - riders, visitors, office workers, and residents.
One of the most significant developments in recent years has been the sophistication of modeling and simulation software. Before, we had different software for vehicles and for people. Now, more complex models can be built to simulate different scenarios and mode mixes, not to mention architectural configurations of pedestrian spaces. That said, inputs must be high-quality, and we must always consider the human factor and apply our practical experience. One of the positive aspects of some of the HSR development in China is the location of HSR stations in or closer to the CBD. Major European cities have also made this choice – usually at major existing rail termini.
However, for secondary cities where the HSR is “passing by” the new stations are located on the periphery. In cities with less development momentum the peripheral location forces a host of other connections, including into the CBD. Or it could spawn a satellite district. In this case the urban design dimension of TOD is especially important, to create a livable new mixed-use district. The concentration of transport will ultimately drive development. The overall balance within a metropolitan area must be considered carefully when selecting the site of HSR – and of all transport.
TOD and scales
ArchDaily: A TOD project is large in scale. How do you organize the rail transit, architecture, urban surrounding, and large flow of users? What is the design logic behind such projects?
SOM: Design Logic for the General Arrangement of Transport, Development and People: We begin by acknowledging that rail, surface vehicles and buildings have less flexibility than pedestrian circulation, but we are designing for people! We start developing the optimal layout and spatial organization of each single component of TOD - HSR, other rail and metro, surface vehicles, car parks, vertical development building types - but ultimately, we look to arrange these according to use by people, whether they are transit users, office workers, visitors, residents, or others. We look to make the clearest, most convenient, and most enjoyable paths of movement for all those people. The pedestrian paths become the real armature of the project, even as the needs of the other elements are satisfied.
ArchDaily: In the multiple levels of TOD projects (from underground, ground floor to high-rise areas), what is the design focus of each separate level?
SOM: We have noted the exponential expansion of underground pedestrian levels called for in the concept planning for large TOD developments in China and elsewhere. Certainly at least one level is required for efficient intermodal transfers between underground rail modes - HSR, intercity, metro, airport rail. But there is a tendency to call for several underground levels and to add massive amounts of commercial space to these levels. The danger is that not only transit users, but employees of the TOD development above will be forced to use these underground spaces and that the street level will languish or be dominated by vehicles. People need light and air, views to open space, gardens and landscape for their health and well-being. We would suggest that these levels be limited to access to and connections between modes of transit, and that the street level be privileged.
This is the critical level. Upper levels are determined by building use and other design consideration. Underground levels are driven by transport modes and access. The ground level must be pedestrian-friendly, full of active uses and offerings, and be designed with a distinctive sense of place. It must organize vehicle traffic while not letting them take over the site. People are primary. Let us not forget the importance of the station building itself. It must be internally efficient and function, while also externally identifiable and identifying - in the sense that it is a gateway to the city. The upper levels of the development have three principal drivers - the nature of the use of the building, the imperative to allow light and air to the ground level, and to add to the skyline of the city as a distinctive and important place. TOD development can create a suite of structures that are more than the sum of their parts.
TOD regeneration
ArchDaily: From your current research structure, what are some of the aspects that can be optimized or updated?
SOM: Overbuild refers to high- or mid-rise construction directly over transit elements. The structural supports of the buildings over transit are either integrated with the structural system of the transit or coordinated with it. In recent years SOM has developed special expertise in this important aspect of TOD, allowing more development in closer proximity to transit, especially existing transit where TOD had not been planned for originally. But overbuild techniques are also applicable for new TOD projects.
Two examples illustrate this:
- The structural system for Manhattan West in New York City over the existing rail lines of Penn Station.
- Commercial and residential overbuild fully integrated with the transit structure of the Brightline Miami Terminus in Miami, Florida.
ArchDaily: What strategies have been adopted in the design of rapidly expanding cities to meet changing design requirements and to achieve sustainability?
SOM: The intensiveness of mixed-use development and the opportunity to build new energy-efficient transit makes TOD inherently more sustainable than other forms of development. But from this high base the projects should strive for net-zero.
Of course, the two most comprehensive and impactful changes that can be made are
- to have clean electrical power for all transit modes, including electric vehicles, both LOV and HOV,
- to design the rest of the project with the low embodied carbon for the initial construction and net zero operational carbon. Easier said than done.
Having a clean electrical grid and EVs is a matter almost entirety for government policy. Net-zero buildings involves both government policy, developers and designers working together. Some specific measures that we recommend for TOD and transport development are: Adopt a district-wide strategy for energy - TOD lends itself to this approach. Maximized daylighting for stations, termini, and any enclosed public areas. Likewise, use natural ventilation where feasible in the project and to the degree feasible in the climate. Deploy vegetation and water features in combination with the above measures not only for well-being but for enhanced mechanical performance.
TOD and the future
ArchDaily: What advice can SOM give to TOD developers from a design perspective?
SOM: Take the long view with respect to street traffic, especially LOV: low-occupancy vehicles (taxis, private cars, app services). Assume there will be fewer and that they will be electric. Secure policy commitments. This will reduce traffic demand on the street network of the development and the on-site parking demand. Privilege the ground level, public streets, and open spaces. Avoid creating vast underground areas except for access to transit. Bring your commercial, retail, F&B and entertainment uses to the street level for improved quality of experience. Embrace humane density. TOD is all about the benefits of proximity. But guide designers to allow light and air to the streets and open spaces.
ArchDaily: What other innovations do you foresee in future TOD design?
SOM: Cities and tech companies throughout the world continue to grapple with the introduction of autonomous vehicles and their potential impact on urban infrastructure and development. On one hand, if adopted in a largely single-occupancy manner, the potential exists for increased sprawl and increased vehicular miles driven. Smart transit policies will embrace and guide the technology in a way that is conducive to a greener, low carbon, quality of life agenda. Higher occupancy, shared and localized systems can offer point-to-point accessibility in a way that improves connectivity, reduces traffic congestion, and improves energy efficiency and overall consumption.
The challenge ahead for TOD is to humanistically design the interface of these systems with urban development and transfers to higher capacity regional systems. While many people say, “we don’t know what form air mobility will take,” we would respond: government, developers, designers, and industry should co-guide the outcome so that air mobility is a complement to TOD and not a force that drives obsolescence. There are significant “traffic management” challengers to airspace, even more than surface traffic. Flight paths will have to be carefully managed.
China has a few notable examples of TOD at the intersection of land and air. Shanghai's Hongqiao Terminal seamlessly combines airport terminal, high speed rail terminal and metro stations, with a new mixed-use district. In similar fashion to Hong Kong's airport express rail line, the Beijing Daxing International Airport is developing an express rail system with in-city check-in facilities in the Beijing Lize District and Xiong'an's new core area. These express rail hubs connect with multiple modes of rail and bus transport and create the opportunity for "gateway" districts comprising new office, housing, and retail/entertainment.
