Boardwalks : General Guidance
General Guidance | Design List | Evaluation Summary
Boardwalks can be a valuable management tool on countryside recreation sites in providing a method of balancing the needs and interests of visitors with the protection of important wildlife habitats. In particular, boardwalks can be used:
- to accommodate public access to, or over, sensitive areas;
- to provide visitors with the opportunity to experience, enjoy and learn about wetland and other habitats that might otherwise be inaccessible;
- to prevent and/or reverse damage to sensitive wildlife habitats caused by public access;
- to avoid impacts on the hydrology of a site that might arise from the construction of ground level paths.
Boardwalks can, however, be relatively obtrusive in the landscape and expensive to construct and should therefore be used selectively and only where necessary, with lengths of run being kept to a minimum. The minimum clear width of boardwalks should be 1200mm to permit convenient use by pedestrians, people with prams and pushchairs and wheelchair users. A width of 1700mm will accommodate two way traffic; alternatively, where use is low, passing places can be provided on a 1200mm wide boardwalk. A decision on the appropriate width of a section of boardwalk will be determined by the expected level and types of use, the width of approach paths, structural requirements and economy.
Where a boardwalk is likely to be used by people in wheelchairs or by people with mobility difficulties, it is advisable to install edge boards/edging strips or handrails. Such measures may also be necessary, for reasons of public safety, where a boardwalk is elevated or passes over water. Ease of access onto the boardwalk can also be improved by making sure that it is level or ramped to a gradient of not greater than 1:12 . Edging strips should be a minimum of 75mm high, whilst edge boards should be at least 100mm in height, with a gap of no more than 75mm between the lower edge and the boardwalk. (See Information Sheet 6. 2 for details).
Handrails normally have a minimum of three rails with the top rail at a height of 1000mm, the middle rail at about 750mm (to assist wheelchair users and children) and the bottom rail with a gap below of no more than 75mm. Assuming that the rails are approximately 100mm deep, this will leave a gap between the lower and middle rails of approximately 475mm. An extra rail can be added if there are concerns about the danger that this might pose for young children. (See Information Sheet 6. 3 for details). The cross section of each handrail should be such that the grip is between 40mm and 50mm in diameter. When designed specifically for children, a grip of 25mm to 32mm in diameter is more suitable. In countryside locations, handrails will normally be constructed from timber (preferably hardwood) which, if well smoothed, will minimise the risk of splinters.
On boardwalks with timber decking, boards should be laid at right angles to the direction of pedestrian flow. The 'BT Countryside for All : Good Practice Guide to Disabled Peoples' Access in the Countryside' recommends a maximum gap between boards of 12mm. Whilst this measurement may be appropriate for boardwalks being used by disabled people, a larger gap of up to 25 - 30mm can be used on those installed in remoter and more inaccessible locations. For example, the boardwalks installed on upland sections of the Pennine Way use a gap width of 25mm (see Information Sheet 6. 1 for details). Algal growth can make timber decking slippery in wet conditions. This can be reduced by regular applications of a water based wood preservative 1 and good ventilation around the boards.
A non-slip surface can be provided by epoxy tar sprays 1 spread with grit. The main weakness of this technique is that the tar may not form a secure and long lasting bond to the wood: this can be strengthened by applying the tar to new timber, before it has had time to weather. Grooving the decking boards prior to installation can improve grip. Galvanised rabbit netting or plastic mesh can also be stapled to the boards to improve the level of grip for pedestrians and wheelchair users. However, care should be exercised in the use of this technique in that, in time, holes often develop and, if these are not repaired, there is a serious risk of people being tripped. It can also make the boardwalk more dangerous in icy conditions. Care should be exercised in the use of such chemicals and they should be avoided on sites of high conservation value