Greenways are linear wildlife corridors that may already exist in the form of woodland belts, overgrown railway lines and waterways, opportunities identified in the context study, or can be designed as new functional landscape elements.

Greenways can be used to link together habitats and form routes from residential areas to larger greenspaces. Waterways can also provide ecological services such as drainage to attenuate flooding. As highlighted in Section 3.1, ‘greenways’ design must adhere to basic principles of urban design.

Woodland Greenways
In order to reduce car dependency urban housing is increasingly likely to incorporate clearly defined pedestrian routes, cycle routes and public transport corridors. This creates the opportunity to integrate these areas within a network of woodland greenways. Warrington New Town was a pioneer of this approach, with the successful establishment of ecologically functional woodland greenways based on experience from the Netherlands and Sweden.

However, an important point to learn from this case study is that if the aim is to maximise their function as linear habitats then pedestrian and cycle routes must be excluded or be well-designed. Recreational routes can be incorporated as long as they are punctuated by links to surrounding areas where housing provides informal surveillance. A good example is the proposed New England Quarter in Brighton (see illustration). An old railway line is to be improved as a recreational route whilst also enhancing its value as a Site of Importance for Nature Conservation.

Wetland Greenways
Greenways can also take the form of waterways with associated wetland and woodland habitats. Germany’s Emscher Park project in the Ruhr valley pioneered the de-culverting of engineered waterways, with the re-introduction of wetlands and buffer strips of ecologically functional meadow and woodland habitats. A similar approach has been taken in the UK by the Environment Agency.

Sealed surfaces can reduce soil moisture and, as is increasingly the case in the UK, leave low lying areas susceptible to flooding from excessive run-off. There may therefore be the opportunity to create Sustainable Urban Drainage Systems (SUDS), which can function as wetland habitats. The Environment Agency and CIRIA (the Construction Industry Research & Information Association) have been actively promoting the use of SUDS.

A good example can be found at Kirchsteigfeld in Berlin. SUDS are common in new German housing schemes for flood alleviation, but they also create buffer strips for habitat creation. Whilst the width of the buffer may be constrained by land use pressure, integration with linear greenspaces of the kind seen at Kirchsteigfeld, and as proposed for New Hall near Harlow in Essex can allow for wider corridors.

Management is required to maximise habitat potential. Intermittant tributaries can be linked up using swales. Contaminants, for example from surface car parking, may need pre-treatment by reedbeds. Tree planting may be required for bank protection and sediment may require periodic removal.