Misconceptions about Mobility Growth

Higher speed is the main cause of mobility growth. When people go faster, they will travel further. This is the shortest summary of the history of passenger mobility .

📌 The Core Development

An illustrative example is the high-speed rail connection between Paris and Lyon. After its opening in 1981, commuters were able to travel daily between these two cities. This was not possible before.

More generally, the rise in both ownership and speed of the car after the second World War, allowed for increasing distances from home to work, to school, shops, hospitals and friends.

🔍 Background & Sector Context

The average distance a person travels per day tripled since 1960: from 10 to 30 (Dutch data). This growth is entirely caused by car use, being from door-to-door faster than both public transport and the bicycle.

Many empirical studies underpin that speed is the main cause of mobility growth. Total travel time is roughly constant : a person in a city or country travels on average 1.1 hour per day. When travel time is constant, higher speed inevitably leads to longer trips.

📊 Industry & Real-World Impact

However, conventional wisdom makes us believe in other causes of mobility growth. Such as, rising income, decreasing costs of car driving, working from home or changing preferences in favour or against cars. The dominance of speed is overlooked in standard views by traffic engineers and politicians alike. Even statistics on average speed in urban and rural areas are scarce. This omission hides important consequences for transport policy. Here are three:.

🔮 Strategic Outlook & What Lies Ahead

Road building in congested areas does not solve congestion. Directly after opening, there is less congestion and car speed increases. However, after only a few years this gain disappears, because extra road capacity attracts extra traffic . One of the empirical studies showing this, is aptly titled “The Fundamental Law of Road Congestion”.

Secondly, when average car speed does not increase anymore, the growth in car mobility will end. This is the reality in rich countries with a mature motorway grid. Average car speed stabilized in the Netherlands since the turn of the century, and consequently car mobility per person even decreased by 3% between 2005 and 2019 (the last year before the Covid lockdowns). The UK, Spain, Belgium, Sweden and Luxemburg also show a drop in car mobility per person over the same period. Other countries will follow. Neglecting car speed as the main driver behind traffic growth results in traffic forecasts that are systematically too high.