Creating a sense of place using green and blue infrastructure
Grey to Green
Sheffield, England
£9.9m
Sheffield City Council, South Yorkshire Mayoral Combined Authority
European Regional Development Fund, Canal and Rivers Trust, Yorkshire Water
2016 – 2022
City Centre (pop. 555,000)
Economy / Environment
Less affluent
Creation of walking networks linking key trip attractors / Improved connectivity to other sustainable transport modes / New or refurbished open and/or green space / Deprioritisation of vehicles
Castlegate was historically the heart of Sheffield but fewer shops and businesses, industrial decay and the relocation of civic functions led the area into accelerated decline. Vacant buildings, an increasingly careworn character and antisocial behaviour all undermined the remaining businesses and discouraged new investment.
With the opening of a new inner relief road in 2008, traffic on the dual carriageway, which cut through the area, was reduced dramatically. This presented the opportunity to reclaim two traffic lanes and reverse severance, to reconnect Castlegate with the riverside business district, and Victoria Quays canal basin.
Grey to Green was conceived as a transformative environmental project to create a linear park along the redundant carriageways, forming a safe and accessible route through the area and creating a more appealing environment which would attract new footfall, investment and jobs. Critically, the park would be designed with a focus on its function as a Sustainable Drainage System (SuDS), more naturally routing cleaned rainwater slowly back into the River Don. It was created in two phases of works, which took place between 2016 and 2022.
The resulting linear greenspace stretches over 1.3km – giving Castlegate a unique sense of place. Covering 3 hectares, it is a wildlife corridor which is home to 40 semi-mature trees and swathes of low maintenance, high impact perennials and bulbs. The diverse, multi-layered planting is designed to protect pedestrians from air pollution, absorb carbon, cool ambient temperatures and create year-round interest – for both people and wildlife. It provides a habitat for birds, bats and insects, who are encouraged to nest and hibernate using sculptural totems, which include ‘bug hotel’ design features for the likes of ladybirds, lacewings and bees.
Rainwater runs off from the adjacent highway and the walking and cycling paths, flowing over flush kerbs into the planting – diverting it away from the sewer so it can be used within the landscape. The majority of planting areas act as rain gardens, absorbing run-off into the soil. This benefits the plants and allows water to return to the air naturally through plant evapotranspiration. The rain gardens run in sequence, with more intense rain retained on the surface by check dams, which control the water flow. This is passed from one check dam to the next before finally being discharged slowly into the river.
Pollutants such as oils, heavy metals and microplastics are naturally filtered from the rainwater by a layer of sandstone, aggregate mulch and soil, where they are broken down by natural processes.
The green and blue functions of the space have been designed alongside provision for bus, pedestrian and cyclist movements. For example, a wide pavement with regular resting places makes traversing the park more amenable for pedestrians. The totems and elements of the engineering deliberately left on display provide focal points and celebrate Sheffield’s history as a city of makers.
Since Phase 1 of Grey to Green was completed in 2016, a number of businesses have relocated to previously vacant office buildings and warehouses in the area. The improvement to the area has created at least 540 jobs and is projected to create more than 1,600 in total. These include nearly 200 in Castle House, an empty listed building re-developed to accommodate start-up and scale-up businesses and the National Videogame Museum. It is also home to the Kommune food hall, which is part of the area’s expanding food and drink offer, serving workers and people from newly opened residential developments.
The environmental benefits of the scheme are the subject of long-term monitoring by the University of Sheffield. Early indicators of success are heartening:
24,000 bathtubs worth of water diverted from sewage treatment annually.
561% increase in biodiversity in just one part of the scheme.
Positive reductions in ambient temperatures potentially already reducing the urban heat island effect.
Locally, it has also made the case for more investment in transforming tarmacked areas into green public spaces that encourage walking and cycling, with one local survey showing that 98% of people want to see more green streets in the city.