Traffic congestion in cities across the UK has got significantly worse over the past year, according to a new report by satnav manufacturer TomTom.

The fourth annual Traffic Index shows average journeys in 2013 took 27% longer than they would in free-flowing traffic – up from a 26% delay in 2012.

Traffic jams in ten out of Britain’s 17 biggest cities have become worse over the past 12 months, five have failed to improve, only two - Leeds-Bradford and Bristol - have improved.

The report also suggests that drivers using rat runs may actually be making their journeys slower. The data shows that local roads have twice as much lost travel time (32%) as main roads (15%). 

And British commuters are now spending 10 working days a year stuck in traffic, up from nine days a year ago.

TomTom analysed over ten trillion pieces of data worldwide to compile its traffic index, which showed that Moscow remains the most congested city globally with congestion at 74%, rising to road rage levels of 141% in the evening peak.  Istanbul (62%) is in second place, followed by Rio de Janeiro (55%).

“Traffic congestion is nothing new, and continues to be a global challenge,” said Harold Goddijn, CEO of TomTom.  “The traditional responses to congestion - such as building new roads or widening existing ones - are no longer proving to be effective.”

Picture: 10 most congested cities chart