Flexible working has no effect on traffic jams, research by the mobility institute KiM for the environment ministry shows.

Although the number of people choosing flexible working has risen from 27% to 32% over the past five years, the choice of flexi-time is mainly outside of the busy morning and evening rush hours, the research shows.

This is mainly because most flexible working is actually overtime, the KiM says.

Nor is the number of flexi-workers growing as fast as expected. The ministry forecast that by 2010 43% of people would choose flexible working.

The researchers say a change in working culture is needed and this can only be achieved with financial stimuli such as tax breaks.