Flexible working hours: an end to the ordeal of rush hour?

In the Paris region, more and more workers have working hours that are no longer explicitly fixed by their employer. Instead, they have what we call flexible working hours. According to theories in transportation economics, this greater freedom granted to employees ought to spread out people’s starting hours and therefore help to improve travel conditions at rush hour. But is this actually the case? Are more flexible working hours really the right solution to end the problems of rush-hour congestion? Do employees with flexible schedules actually avoid the morning rush hour? And, more generally, how do they choose to set their own working hours?