We demand and expect our transport systems to to get us where we want, when we want to be there, and as fast as possible. We are, however, human beings. And as with any other built system, we have to ask whether our fast and efficient modes of travel are necessarily always good for us.
Some of the indications are not good. As the World Health Organisation (WHO) reported, almost 1.3 million people die each year on the world's roads. Road accidents are the ninth leading cause of death globally and the leading killer of young people aged 15 to 29 years. Annually, road crashes also cause between 20 million and 50 million non-fatal injuries. Trends have been downward, fortunately. But this toll is the rough equivalent of French battle deaths during World War I being lost every year and equals all battle injuries during that war.
Cars in particular also emit numerous chemicals, including carbon monoxide, benzene, formaldehyde, and tiny suspended particles called "particulate matter". Health effects of such emissions include lung disease, cancer and especially respiratory diseases such as asthma.
One estimate is that air pollution, to which auto emissions are a major contributor, leads to 24,000 premature deaths in the United Kingdom alone every year.
A 1999 study in Australia estimated carcinogens from auto emissions cost ten to 18 lives per year (not including particulates, whose effects could not be determined). Still, this is not a trivial number for those ten to 18 individuals. And other estimates of Australian health emission impacts are far higher than this conservative estimate.
Transport modes have more subtle effects on the human body as well.
Prolonged exposure to transport noise, whether from traffic, airports or other modes such as trains, has been shown to affect cardiovascular health, sleep, and to reduce performance in concentration and analytical skills, especially in children.
Additionally, vibrations created by vehicles have real, if diffuse and complex, effects on humans, including the potential for long-term muscle damage and psychological and cognitive impairment.
Some impacts are especially hard on operators of particular types of vehicles, especially motorcycle, bus and truck drivers, where there is often sustained long-term exposure to vehicle vibrations.
In terms of broader behavioural effects, it is now recognised that the way people travel affects the amount of physical activity they undertake.
One literature review notes that cardiovascular and other health risks are lower among groups who use active transportation (such as walking and cycling and, to a lesser degree, mass transit).
In particular, people who commute to work by car are less healthy than those who commute by healthier modes.
The review notes predictions that premature deaths in London could decrease by 528 per million people annually by 2030 if more people realised the health benefits of increased use of active transportation.
Of course, transport professionals are by no means unaware of these physical effects. The well-established field of human factors research studies the way in which human beings affect and are affected by the design of transport infrastructure, vehicles, and operations such as signage. And there is substantial knowledge of the broader effects of transport on the environment and earth ecosystems in which human beings and all other species live.
For all the human health impacts of the modern transport system, there are obviously substantial benefits in the form of greater economic productivity, vastly increased spatial access and mobility, and even health gains, such as increased ability to get preventive and other medical care.
All technology imposes health risks of some sort. So a purely negative focus on these is unhelpful. Nonetheless, it's useful to ask whether our transport technologies, policies and investments are good for us. If not, we need to adjust and redesign our transport accordingly.
Positive changes, many of which are currently underway, include:
A greater focus on redesigning congested urban spaces to encourage walking and social interaction and to lower automobile use and speeds. This could achieve many health and safety outcomes simultaneously.
Traffic calming - a range of techniques ranging from speed humps to pedestrian malls which create attractive active transport environments.
Road pricing and increasing parking fees, or eliminating parking altogether to encourage public transport use and walking.
The expansion of bike-share schemes, where public bicycles can be rented and dropped off from multiple locations.
Further safety improvements to automobile safety design for new car models.
Prioritising action on "black spots" on roads and highway "geometrics", which includes improving lines of sight at intersections and around curves.
These reforms need not involve costly or radical overhaul. Road safety used to be a neglected policy; small but significant changes there have saved millions of lives. A broader incorporation of the human body into transport design and planning could save millions more.