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free floating car sharing

Crunching Bumpers: A Large Scale Data Analysis of Free Floating Car Sharing by Ella Rebalski

Dec 14, 2017

What is it about certain cities that encourages free floating car sharing? Why would people use the service as opposed to public transportation or a personal vehicle? And what do we know about the ‘lucky’ people, who find a nearby car, a direct route, and an easy parking spot so that their trip is faster than usual?

These questions are being studied by researchers in Sweden, who are looking at data from three different free floating car sharing (FFCS) operators in 35 different cities in North America and Europe. The Swedish Energy Agency is funding the project, and the research is being done collaboratively between RISE Viktoria, a part of the government-owned Research Institutes of Sweden network, and Chalmers University. The project sets out to determine what makes cities places where free floating car sharing is successful.

The Lucky Index: Free Floating Car SHaring

One result that can be taken from the data is how the speed of the quickest trips varies over the day. When plotting all trips in a city in a time-distance diagram, a borderline is clearly visible, representing the quickest trips: those that have travelled without any trouble in terms of finding the car, driving or parking, i.e. the speed for the “lucky” users, here called the lucky speed.

The lucky speed typically varies with time of day, due to congestion but also the number of available cars and parking places in relation to demand.  A Lucky Index can then be calculated as the minimum lucky speed divided by the maximum lucky speed. A lower Lucky Index could indicate some problem in the city or operation.

What is so interesting about the Lucky Index? On its own, it simply represents what is already common knowledge: some trips are faster than others. But when used as a metric to compare between cities, it can show which cities have more issues with traffic that cause trips to take longer – for example, parking or congestion issues.

Is FFCS faster then other transportation modes?

The answer is, of course, that it depends. The graphs below are result of statistical analysis of data from the city of Madrid. They show the general idea of what might be faster or slower when car sharing trips are organised into neat, mathematically defined increments. Unfortunately, real life is not usually organised like this, so while these graphs give us an idea of how FFCS relates to other modes of transport, there are many variables that they can’t take into account.

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If we look at the graphs above, we can see that most of the trips show that cycling is faster, and walking is slower, but there are also some (though fewer) trips that show the opposite.

So if users want to get from one place to another faster, they (most of the time) could ditch the car and take a bike. Maybe the people using FFCS just don’t cycle, but there could also be other reasons for the slower choice: weather, the number of people in the car, or the reason for the trip could all be factors.

shared mobility city index

From the graph above we can see that in Madrid, on average, using FFCS is a bit faster than making the same trip with public transportation.

There are, however, many trips that are faster with public transportation, so some users are using the slower option when they use car sharing. We can’t know why they do this, but speculation could suggest the ‘luxury’ of having a semi-private vehicle compared to a public one, the need to transport something heavy or otherwise cumbersome that would be inconvenient on public transportation, or maybe the need to stop and do errands on the way.

Questions for the future

Why do people choose FFCS when it is not the fastest option? If we look at movmi’s Shared Mobility Index, we can see that often cities which have bike sharing also have a high success rate for other forms of shared mobility. But are the same people who use bike sharing also using free floating car sharing? And why would they choose one or the other?

Then, of course, there is the issue of car shedding  – when people get rid of a car and use car sharing instead, thus (theoretically) freeing up more space on streets. While this study could make comparisons between car ownership rates and utilisation rates of FFCS in the same cities, it is impossible to know if one affects the other without doing a survey of FFCS users.

In cities where there is free and/or designated parking available for electric or car sharing vehicles, or in cities where parking is particularly expensive or hard to find, FFCS seems to be more successful. If we take the Madrid example again, the city allows electric vehicles to park for free in certain spaces, and since all the FFCS cars there are electric this means there many parking options. But the results from this research are still not conclusive enough to prove anything about the link between parking policy and FFCS success.

The Shared Mobility Index looks at the daily rate for unreserved garage parking in the cities it ranks, which is a fantastic start to further examining this area. More information on street parking regulations and availability in different cities could help to answer questions about usage patterns that may or may not be encouraging car shedding.

Do you want to understand how attractive your city is for free-floating? Download the Shared Mobility City Index report.

Biography: Ella Rebalski is originally from Vancouver. She has worked and lived in many different cities in Canada, France, and Sweden, and is currently a Researcher in the Electromobility group at RISE Viktoria in Gothenburg.


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