The warning comes from TomTom as its latest traffic data shows that traffic congestion on secondary roads is worse than main roads, and commuters around the world are spending, on average, eight working days a year stuck in traffic. 

'Traffic congestion is nothing new, and continues to be a global challenge. The traditional responses to congestion, such as building new roads or widening existing ones are no longer proving to be effective. Real-time traffic information can help drivers find the quickest shortcut on their journey, and assist governments to make smarter decisions to improve traffic flow for their cities,' said Harold Goddijn, CEO of TomTom.

TomTom also released its list of the ten most congested cities based on its Traffic Index – said to be the only global measurement of traffic congestion comparing travel times during non-congested hours with travel times in peak hours experienced by passenger vehicles. The Index takes into account both local roads and highways. 

The top ten most congested cities ranked by overall Congestion level in 2013 were:

1.    Moscow: 74%   

2.    Istanbul: 62%

3.    Rio de Janeiro: 55%

4.    Mexico City: 54%

5.    São Paulo: 46%

6.    Palermo: 39%            

7.    Warsaw: 39%

8.    Rome: 37%

9.    Los Angeles: 36%    

10.  Dublin: 35%