Driverless cars increase congestion – but could cut massive parking times

January 9, 2017

A new UK government report has cast doubt on the short-term benefits of driverless cars. The Department for Transport study predicts a “decline in network performance” once one in four cars become driverless. It said early models of the vehicles acted more cautiously and the result could be a “potential decrease in effective capacity” on motorways and A roads. The study did, however, note that should driverless vehicles make up between 50% and 75%, they will reduce congestion.

Hopes are high that driverless vehicles using connected car technologies will be able to reduce the time people spend in transit. Regarding time spent finding a parking space, a 2006 French study said parking time would be radically reduced by connected car technology, saving up to €1 billion a year. The latest research suggests that motorists in the UK could be spending up to three days a year searching for a parking space. The survey, by the Privilege car insurance company, said that drivers in Cardiff spend 2.8 days per year looking for a space, while motorists in Glasgow and Birmingham recorded more than 2.5 days (a day is calculated as 16 hours).

Meanwhile, research by the International Transport Forum shows that shared mobility vehicles could entirely replace private cars in medium-sized cities. In the study, which was modelled on Lisbon, private cars were replaced by a fleet of six-seat vehicles (“shared taxis”) that offer on-demand, door-to-door shared rides in conjunction with a fleet of eight-person and 16-person mini-buses (“taxi-buses”) that serve pop-up stops on demand and provide transfer-free rides. In the simulations congestion disappeared, traffic emissions were reduced by one third, and 95% less space was required for public parking. The car fleet needed would be only 3% of the size of today’s fleet. Although each car would be running almost 10 times more kilometres than currently, total vehicle-kilometres would be 37% less even during peak hours.

T&E clean vehicles director Greg Archer said: ‘Cars with no driver represent both a massive opportunity but also a huge threat. The way we establish a framework for them in our towns and cities will determine whether autonomous cars create a traffic heaven or hell. This new research shows there could also be some short-term benefits from connectivity but also negative transitional effects.’ 

‘Our clogged cities don’t need mobile offices, bedrooms or lounges for one, or empty cars polluting our streets looking for parking spaces or driving home. Autonomous cars must be electric, shared and integrated with public transport to be part of a sustainable transport solution and carmakers need to show the same enthusiasm for each of these solutions. It will also take a level of integration between the EU, national and city levels that we are a long way from achieving now.’

In Europe there are currently 239 million private cars. This asset is parked for 95% of the time and, when used, it is often stuck in traffic with an average occupancy level of 1.6 persons per vehicle. Economically, congestion imposes an annual cost of €100 billion, reducing GDP by 1%. 

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