Until March 2011 Finsbury Circus was an attractive enclave of greenery in the centre of the City of London. It was the largest public open space within the City’s boundaries and was home to an immaculately maintained Lawn Bowls club, which had existed in the gardens since 1925. Unfortunately its location was its downfall: until 2016 the park will be a key part of the Crossrail construction project, providing essential access to the Liverpool Street and Moorgate tunnel dig. All that is left is a circumference of ancient trees, a small path with benches and the bandstand.
As part of its commitment to excellence in the environmental management of construction, Crossrail was looking for solutions to enhance the greenery of the site at Finsbury Circus as well as providing additional control of the noise and dust pollution in the area. Treebox was able to use its experience at similar construction sites to offer environmental benefits using a range of products.
Treebox suggested the use of pre-grown ivy green screens as a quick and effective solution for the hoarding around the construction site, with an additional green wall system to provide a feature wall on the hoarding that cut the park in half by the bandstand. This system uses uniquely designed planters with moulded hooks that attach to wire mesh frames. Each planter holds 550cc of substrate material separated from a 50ml water reservoir by a water absorbent membrane. A separate irrigation system with pressure regulated drippers was used to ensure each pot (and associated plant) received the correct amount of water on a daily basis.
A big challenge during the installation of both systems was to maintain the security of the hoardings. Though the park was closed to the public overnight it was important to ensure no-one could use the screens or green wall to gain access to the construction site due to the potential for injury. A review of the designs highlighted potential risks that were mitigated through subtle design changes to the attachment systems used on the installations.
The green screens were installed using an efficient procedure of cutting slots in the wooden hoardings, then using the displaced wooden panels fixed temporarily over the slots to maintain security. Screens were positioned and secured when required without the need to complete the whole operation as one task. Irrigation for the screens was achieved using pressure-regulated drip lines placed along each ivy trough and automatically controlled using a timer.
The feature wall was more easily managed, with the wire mesh support being installed as part of the preparation and the potted plants hung when they were delivered on site. All potting of the containers was carried out off-site at our nursery to maximise efficiency and minimise the impact on the public space around the installation site. Irrigation of the green wall was achieved by attaching irrigation lines to the wire mesh with pressure-regulated drippers above each pot. The overall green wall was split into two irrigation zones, each controlled by a separate valve to ensure water pressure was maintained.
Experiments have yet to be carried out to measure the exact technical impact of installing the green solutions around the construction site, but general feedback from the public using the park has been positive.
Whilst unlikely to compare with the original green space, at least the green screens and feature wall provide a more attractive vista than wooden hoarding. City workers can also sit and eat their lunch in front of the greenery in the knowledge that in addition to the aesthetics the plants are also providing site security and enhanced air quality.