Description of the condition
Physical activity has many benefits for health including a reduced risk of cardiovascular disease (Schnohr 2006; Oja 2011), cancer (Inoue 2008; Schnohr 2006), type 2 diabetes (Hu 1999) and other causes of mortality (Andersen 2000; Matthews 2007; Savela 2010). A lack of physical activity is a dominant factor in the rise in obesity levels (Prentice 1995); yet data from England suggests that fewer than half of all adults and less than a third of children meet the recommended guidelines of physical activity levels (DH 2011). Inequalities exist in terms of the amount of physical activity undertaken, resulting in inequity in the consequent health benefits attained. For both sexes, participation in exercise decreases with increasing age, with women and girls being less likely to be active than men and boys (DH 2011). People from ethnic minorities and low income families are less likely to take part in exercise than other ethnic and socioeconomic groups (NHS 2006).
Previous and current UK governments have stated their commitment to increasing the nation’s physical activity levels, and thus its health, evidenced by the number of published consultation documents and action plans over the last decade (for example, “Choosing activity: a physical activity action plan" (DH 2005); “Be active, be healthy” (DH 2009); “Healthy weight. Healthy lives” (DH 2008); and “Start Active, Stay Active” (DH 2011)). This commitment is no doubt fuelled by the estimated annual costs to the National Health System (NHS) for treating obesity-related diseases, which are expected to rise to £10 billion by 2050, while the costs to the wider society are expected to rise to £49.9 billion per year (McCormack 2007). The economic benefit of decreased morbidity and mortality from a 1% unit reduction in the percentage of sedentary people in the UK is estimated at £1.44 billion (mean of £2423 per additional active person per year) (CJC 2005).
Cycling is a physical activity that confers multiple benefits. It is a readily accessible form of physical activity that can fit more readily into an individual’s daily routine than other activities (Hillsdon 1996; Cavill 2008). It has additional wider public health benefits gained as a result of fewer car journeys in terms of reducing emissions (Lindsay 2011) and improving the local environment through reduced congestion and community severance (McClintock 2002). Cycling also offers a cheaper form of transport for those who are socially disadvantaged and who are less likely to have access to a car than the socially advantaged. Thus, the benefits from increased cycling rates are clearly wide ranging.
The physical environment is known to play a key role in impacting physical activity such as cycling (NICE 2008; Fraser 2010). A barrier to increased cycling rates is the fear of injury (TfL 2008; Rivara 2011). Cyclists are vulnerable road users who are frequently in close proximity to larger and faster motorized vehicles which offer the occupants some protection if an accident occurs, unlike the cyclist. Cyclists report fear of injury from lack of segregated cycling routes, the volume and speed of traffic and driver behaviour (TfL 2008). In 2008, in England there were 115 pedal cyclist fatalities and 2450 reported seriously injured casualties (DfT 2010). There are many more cycle related injuries that are not reported to the police and thus do not appear on the police databases but which nevertheless require medical attention (Cross 1977; Amoros 2011). Indeed, it is estimated that two thirds of cycle-motor collisions are unreported to the police (Cross 1977; Amoros 2011) and half of these result in injury (Cross 1977). Inequalities exist in cyclist injuries with a risk of cyclist injury being 20% to 30% higher in lower socioeconomic groups than higher socioeconomic groups (Hasselberg 2001; Engström 2002). In 2008, cyclist casualty rates were around 29 per 100,000 in the most deprived 10% of areas of England compared to 20 per 100,000 in the least deprived (DfT 2010). Thus to maximise the public health benefits of increased cycling rates it is necessary to minimize the risk of cycling injuries and people’s fear of cycling.
Description of the intervention
One key approach to reducing the fear and risk of injury for vulnerable road users such as cyclists is through engineering and, in particular, through transport infrastructure. Transport infrastructure refers to those physical measures within the built environment which are in place to enable traffic to flow safely and thus allow society to function fully. Transportation infrastructure generally develops over time and is frequently designed with the needs of the motorized vehicle user being of most importance (WHO 2004). Within this, infrastructure specific to cycling includes measures to manage cycle traffic and motorized traffic, to varying degrees, in mixed traffic conditions. It generally takes one of three main forms. Firstly, there is cycling infrastructure that manages the road space for shared use by both motor vehicles and cyclists and includes cycle lanes. Secondly, there is cycling infrastructure which separates cycle traffic from motorized traffic. This may include special routes for use exclusively by cyclists but which may also be shared with pedestrians. Thirdly, management of the traffic network represents a third form of cycling infrastructure and includes traffic regulations that ban certain types of traffic from making particular turns and speed management.
How the intervention might work
The role of infrastructure in reducing the fear of cycling is evidenced by research that has found that changes in infrastructure can positively influence cycling rates (Garrard 2008; Winters 2010; Yang 2010) with cyclists choosing to use routes serviced by bicycle facilities. In terms of injury prevention, research also indicates that infrastructure is effective at reducing injuries (Rodgers 1997; Moritz 1998; Lusk 2011). Reducing the risk of cycling injury may also reduce the social inequalities seen in cycle injuries. As an injury prevention strategy, cycling infrastructure is particularly potent for several reasons. Firstly, it is population based and thus can reach large numbers of the population, secondly its passive mode requires no actions from individuals and thirdly, changes are made only once, thus requiring no reinforcement (Reynolds 2009).
Why it is important to do this review
There has been one previous review of cycling infrastructure and its impact on cycling crashes and injuries. This review identified a number of features that alter the risk of a crash and injury (Reynolds 2009), with on-road 'clearly-marked, bike-specific facilities' providing greater protection to cyclists than on-road cycling with traffic or off-road cycling with pedestrians. The promotion of cycling and walking is highly topical with recently published reports on schemes to promote cycling in the UK (TfL 2008; Sloman 2009). With much on-going research in this area new results are frequently being published. There is no Cochrane review of this topic as previous cycling-related Cochrane reviews have focused on the use of cycle helmets (Thompson 1999; Macpherson 2008) and cyclist visibility (Kwan 2006) to reduce cyclist injuries. The current review of measures to promote cycling and walking by NICE will not assess infrastructure (NICE 2011). There is, therefore, an urgent public health need for a Cochrane review to assess the effectiveness of cycling infrastructure on cycling injuries and to identify those structures which are most effective at reducing injuries.