TomTom, a supplier of in-car location and navigation products and services, has named the Polish capital of Warsaw as the most congested city in Europe in its latest quarterly traffic congestion report.

The congestion index study, carried out in 31 European cities, identifies and analyses traffic conditions based on real-time travel data, captured by vehicles driving the entire road network, including local roads, arterials and highways.

Overall congestion levels for all of the cities analysed in Europe is 24%, which means that travel takes 24% longer than when traffic is flowing freely.

The congestion index report revealed that journey times in Warsaw are 42% longer when compared to the non-congested periods, while its travel times are 89% higher during the mornings and 86% in the evening peak hours.

TomTom chief executive officer Harold Goddijn said when the company combines the travel database with its detailed real-time traffic information and routing technology, it can not only pin point congestion, but can also guide drivers away from congested areas on to faster routes.

"Even when only a percentage of drivers use a different and faster route, the available capacity on the entire road network increases, which benefits all drivers," Goddijn added.

According to the study, the Bradford-Leeds area is the most congested in UK and seventh most congested amongst the 31 cities studied.

Bradford-Leeds’ overall congestion level is reported at 28%, while it spends up to 63% more time in traffic during the morning rush hour and 60% during the evening peak time.

The top ten congested cities in Europe according to the congestion index report between January and March 2012 include Warsaw with a 42% congestion level, Marseille (41%), Rome (34%), Brussels (34%), Paris (32%), Dublin (30%), Bradford-Leeds (28%), London (27%), Stockholm (27%) and Hamburg (27%).

The congestion index study compared the travel time during the non-congested period with peak hours to calculate the difference in percentage. Higher percentage indicates more time taken to travel the same distance during the peak hour.