Silva Cells’ Star Performance at Wembley: A Case Study

– The world’s most well-known and recognized stadium, which went from seeing 2 million visitors a year to 9 million by 2016, is getting its entryway revamped complete with green infrastructure.

– The sheer scale and complexity of this project required a flexible long-term tree growth solution that accommodated numerous underground utilities.

– Silva Cell was the No. 1 choice to promote healthy tree growth and provide a safe pedestrian walkway and increased accessibility for all patrons.

Wembley Stadium: A Brief History

Just 10 miles west of Central London, a 45-minute drive, or a 25-minute Underground train ride, is Wembley, London. It is home to the largest stadium in the United Kingdom, and one of the most famous stadiums in the world. Its scale, location, range of events (sports, music, entertainment), the icons it has hosted, and its construction history make it renowned. The stadium and surrounding area (Wembley Park) have been reconstructed on several occasions since the 1920s. Every reconstruction led to a new name: Wembley Park, Wembley Stadium, Empire Stadium, Olympic Stadium, Wembley Complex. The Empire Stadium was built by the British Empire in 1922 in time to host the first FA Cup Final in 1923. It would go on to host the Summer Olympics in 1948 and the FIFA World Cup Final in 1966, seating up to 120,000 people.

Pedestrian Walkway Access Evolves with Safety in Mind

The London Underground has had a stop at Wembley Park (.6 kilometer away from the stadium) since 1894. In 1948 it was reconstructed to handle higher volumes of passengers associated with the Olympics. Thereafter, the .6-kilometer walkway between the Underground and the stadium would be referred to as Olympic Way (or colloquially “Wembley Way”).

As the stadium and its popularity grew, hosting millions of people per year, planners and the city council saw an opportunity to prioritize spectator and visitor safety. This culminated in the 1977 redevelopment project that turned Wembley Stadium into “Wembley Complex.”

c. 1948, Wembley Way

c. 1948, Wembley Way

Two pedestrian walkways were developed to allow people entering and leaving the stadium to be segregated from vehicular traffic. The main thoroughfare, Olympic Way, was 18 meters (60 feet) wide. Wembley Complex incorporated buildings outside of the stadium to cater to spectators and tourists. Esso Motor Hotel, a conference center, and shopping areas were just some of the new parts of the complex.

Recent Decades Bring Growth and Green Infrastructure

Pelé, the Brazilian football legend, referred to Wembley Park as: “The capital and the heart of football.” The Rugby League World Cup, boxing, and WrestleMania events are just a few of the sporting events held at Wembley Stadium.

The 1980s and 1990s brought pop icons including The Rolling Stones (12 times), Tina Turner, Madonna, Elton John—and the stadium was the venue for the Live Aid African famine relief concert in 1985 and a 70th birthday celebration for Nelson Mandela in 1988.

Wembley Stadium is a living legend, but as the legend aged and sports popularity grew, the need for a modern national stadium to host football, rugby, and entertainment became apparent. From 2000 to 2007, Wembley was closed for demolition and reconstruction, resulting in a modern structure now able to hold 90,000 people.

By 2010 it was averaging 2 million visitors a year, surrounded by shops, conference centers, and hotels. This massive development would give rise to green infrastructure, in response to the needs of the permanent residents of Wembley, London.

In 2016, a 10-year reconstruction project was proposed that would encompass the entire Wembley Park. . The design team was a joint venture between Populous and Foster + Partners. The £3 billion project included 7,000 new homes, a 7-acre public park, 8,640 new jobs for both construction and permanent retail, and 50 trees along the famous Olympic walkway.

Silva Cells Bolster the Trees at Wembley Way

Silva Cells both support the tree roots and suspend the pavement that receives millions of footsteps from millions of visitors around the world. The first of two installations of Silva Cells occurred in 2017 along Olympic Way. 900 2x Silva Cells were installed in 2017 along Olympic Way to support 36 (18 identical pairs) new trees. With new buildings constructed on both sides of Olympic Way, the original trees and old memorabilia stalls were removed and replaced with the new trees, consisting of 18 (24 eventually) different species on opposite sides of the pedestrian walkway.

Silva Cell installation at Wembley Way

The trees are referred to as the “Avenue of Champions,” and each species is arranged in order of its longitudinal origin. In addition to adding to diversity and mitigating monoculture, Gross Max, the landscape architect, wanted to create an array of different colors that would burst in the autumn season. The trees from the station to the stadium reflect the temperate zones of the Northern Hemisphere. Starting west (being the station end) to east, they are arranged in order of the longitude of their natural habitat. The latitude of each tree is engraved into the tree grill.

Managing stormwater, along with the health and survival of trees throughout this multi-year-development process, was at the forefront of a successful project for the developer, Quintain. To manage the stormwater, a separate attenuation tank was installed down the middle of Wembley Way.

While the Silva Cells were installed in July 2017, it should be noted that the trees were not planted until February 2018. Silva Cells can be installed many months prior to when the trees need to be installed. Silva Cells’ flexibility was ideal for this project.

January 2018

March 2018 May 2019

May 2019, Photo credit: Quintain.

Figure 1. 24 species of trees will be paired opposite each other on Wembley Way. 18 pairs have been planted thus far. Photo credit: Quintain.

Photo taken in May 2018. Additional planting and Silva Cell installation taking place in 2021.

Silva Cells Vital to Ensuring Accessibility for All

Part of the project will add steps and a ramp leading from the end of Wembley Way to the front of the stadium. Silva Cells and a total of 12 trees will be on both sides of the ramps. The Silva Cells are to be installed in January 2021. The “ped-steps” construction began in July 2020 and should be completed by the end of February 2021. These 12 trees will have the support of 600 Silva Cells, creating 35 m3 of soil volume while sharing soil with neighboring trees, creating a continuous positive feedback loop for root growth.

Rendering by Quintain of Wembley Way, from above. Note the different species of trees as well as the ramp and pedsteps.

The steps and the ramp are inclusive for all people. The developer, Quintain, wrote in a press release in July 2020, “the Olympic Steps will improve accessibility for all visitors to the National Stadium. The programme of works will see four large new lifts installed at the National Stadium, each able to carry three wheelchair users at a time. The steps have been designed to meet industry best practice and will be rigorously tested prior to use at major events.”

At Wembley Way, Silva Cells were specified by Gross Max, the landscape architect, and installed by VolkerFitzpatrick. They required a flexible solution that would allow them to easily work around the many utilities and footings at the project. It also provided them with the ability to work in stages and for the stadium to remain open to the public for concerts and events during construction. Furthermore, it allowed the tree planting areas to be completed a couple of months prior to planting, which allowed them to plant at the appropriate time for healthy tree growth and within the project time frame. DeepRoot is thrilled to have been part of such a historic and iconic footpath with Silva Cells. We look forward to attending an event and strolling along the revitalized Wembley Way with high performing green infrastructure of diverse trees from around the world in the near future.

Installation Summary:
Number of Silva Cells: 1, 500 2x (phase 1 and phase 2)
Amount of soil volume per tree: 35 m3 per tree
Number of trees and type: 48 (see species list in Figure 1)
Type of project: Integrated trees, stormwater, stadium, plaza, streetscape
Project designer: Quintain, Populous, Foster + Partners
Project contractor: VolkerFitzpatrick (phase 1 and phase 2)
Installation date of Silva Cells: July 2017, phase 1; January 2021, phase 2
Project timeline: Wembley Way 2016–2021; Wembley Park 2016–2027

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