Photograph of a waiting shelter on the carpool lane in Rennes

Carpooling and public transit: A winning combination in Rennes, France

Waiting shelter on the carpool lane in Rennes
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PostedNOV. 9, 2023
Words byKeolis
Instead of pitting personal cars and public transit against each other, Keolis Rennes (France) has decided to combine their strengths. To this end, the company has opened a carpooling route along a departmental highway in the northern section of the urban area with five “stations”, an adapted roadway and a carpooling application to connect users, all without the need for a reservation. Now people in Rennes can “carpool” just like they take the bus!

Context: Carpooling, a lever for reducing pollution 

Like many other cities, elected officials in Rennes have adopted incentivizing policies to respond to two challenges: reducing car traffic in saturated urban areas and limiting pollution and greenhouse gas emissions.

Carpooling represents one of the key levers of this policy, helping to cut down on solo commuting, in which a single person travels alone by car. In Rennes, carpooling is already included in the local version of the regional climate-air-energy plan (PCAET), covering all 450,000 residents of the area.

Rennes Métropole has entrusted Keolis Rennes to manage the operational roll-out of this new carpooling service, known as “Star’t”. The goal is to offer the same flexibility of use and service quality as public transit.

A new and innovative shared transportation offer based on carpooling

In February 2021, Keolis created its first carpooling line along a departmental highway in northern Rennes to serve four suburban towns. Designed like a bus route, the carpool route includes five stops with sheltered waiting areas and passenger information panels to help drivers pick up and drop off passengers.

The system is based on a mobile application to facilitate short-distance carpooling, known as Star’t, which connects drivers and passengers in real time. Drivers can stay informed of requests by a notification on their phone or by checking the information panels located at each stop.

"STAR à votre rencontre" animation stand
"STAR à votre rencontre" animation stand
Discussion between a driver and a passenger

The solution features several key innovations:

- A new dynamic for carpooling 
Traditionally, carpooling often refers to journeys with a planned schedule at set times. In Rennes, this solution makes it possible to expand carpooling to all types of trips, even unplanned outings, by connecting users in real time without the need for a reservation. 

- A relatively cost-effective solution  
This new shared transportation service does not require any major structural investments (about a third of the costs have been recovered in the first 10 months of operation in 2021), making it a relatively cost-effective solution. Alongside the two project leaders, Keolis Rennes and Rennes Métropole, the partner Ecov, an expert in rolling out carpooling lines, is working to expand the daily use of carpooling.

Yann Besnard

Yann Besnard

Head of the Urban Carpooling project at Keolis

"Quite often, communities have met their mobility needs with public transport and by purchasing their own vehicles. With this carpooling line, we have created a new transit offer together with users and their own vehicles."

Benefits: An extended mobility offer with carpooling

In Rennes, the carpooling route enriches the mobility offer by covering routes not currently served by the urban area’s existing public transit network, which is organized in the form of a star around Rennes. The carpooling route follows a departmental highway that encircles the city and offers a transit capacity that is both flexible and efficient for suburban residents: the average wait time for a vehicle is seven minutes.

In September 2023, about 30 passengers a day used this service, which is free of charge for passengers. Drivers, on the other hand, receive €0.50 per trip and an additional €1 for each passenger.

Star't carpool stop
Star't carpool stop
Yann Besnard

Yann Besnard

Head of the Urban Carpooling project at Keolis

"A resident of a suburban town outside Rennes can travel to a neighboring town by car, sometimes with a wait time of just three minutes, all at no charge and without having to pass through downtown Rennes."

Next steps: Creating new carpooling routes

A second carpooling route is scheduled to be launched in 2024. Operated by Keolis, it will have the distinction of extending beyond the scope of the urban area managed by Keolis. This expansion responds to Rennes Métropole’s request to work on carpooling across a wider scale than the metropolitan area alone.

STAR carpool poster


passengers a year (2023 estimate for the first line in service)


minutes average wait time for a vehicle

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