Morgan Sindall were awarded the contract for the replacement of Blackhorse Lane bridge. The new bridges were to be made an extra two meters wider to allow for a cycle path. The bridges would also allow road traffic access over the Croydon Tram Line once complete and works were scheduled to be completed in spring 2020.
NBC Environment were contacted by Morgan Sindall to advise and provide a solution to prevent historic issues reoccurring with feral pigeons nesting, roosting, and defecating faeces hazardous to human health beneath the proposed new bridges.
The undercarriage of the replaced bridges provides a perfect location for nesting and roosting pigeons. Pigeons are a community flocking bird and as such will gather within the void areas within the undercarriage of the bridges which provide the perfect harbourage for many feral pigeons, providing them with a safe nesting and roosting location.
If left unprotected there would have been a risk of an extreme build-up of feral pigeon faeces over the highly invested structure and existing brickwork. Feral pigeon faeces are extremely acidic and if left untreated, even for a short period of time will result in unsightly staining on the new structure. This in turn would result in ongoing expensive maintenance costs, with the need to stop the tramline running in order to gain access to the areas to carry out any maintenance works.
Feral pigeon faeces carry several dangerous diseases, such as Histoplasmosis, Ornithosis, Campylobacterosis and Cryptococcosis. This is extremely dangerous as the bacterial spores are hazardous to human health as it can become airborne dust which carries micro-organisms and can be inhaled into the lungs leading to respiratory difficulties and other illnesses. This creates a risk not only to passengers on passing trams with open windows, but members of the general public who are using the public footpath beneath the bridge.
NBC Environment installed 50mm stainless steel weldmesh on both bridges to create a physical barrier in order to prevent feral pigeons from entering the areas that offer them shelter. This in turn provided secure protection without the need for further maintenance, therefore not having to suspend the tram line in the future and would also provide protection from the general public.
The client requested that these works would ideally take place in the early hours of a day when the Croydon Tram line would not be running, this would provide a safe working environment whilst the installation takes place, so the project was completed overnight.