Congestion eases - but Portsmouth remains a traffic jam blackspot

However the research – conducted by TomTom Traffic Index and released today – also shows that the city is one of the top 25 most congested towns and cities in the UK.

The study found that congestion across the UK was four per cent worse last year than in 2014, with the problem increasing in 17 of the 25 towns and cities in the report.

Only Portsmouth, Nottingham, Middlesbrough and Preston have shown slight decreases in congestion.

Cllr Ken Ellcome, cabinet member for traffic and transportation at Portsmouth City Council, said: ‘These figures are quite encouraging.

‘Considering that we are the most densely populated city in the UK except London, to be as far down as we are, especially compared to cities like Southampton, Bournemouth and Brighton, means we are doing reasonably well.’

He said that work done by the council to encourage cycling, building bus lanes, installing a park-and-ride service and sequencing traffic lights, had helped to reduce congestion.

Cllr Ellcome added: ‘We have had a lot of big events in the city too, like Victorious, people going to the Isle of Wight, America’s Cup, the Great South Run and the Summer Show.

‘So for a city that has put on that number of events on a small island with only three roads in, we are not doing too badly.’

Cllr Ellcome said the authority would continue to work on solving the traffic problem, and said that £900,000 had been set aside for this in the council’s local transport plan.

The research showed congestion across the UK has grown 14 per cent over the past five years, while in the rest of Europe the problem has eased by three per cent.

Belfast was the UK city with the most serious hold-ups – and the 14th worst in the world. London was the 20th most congested city in the world – and the second worst in the UK.

Ralf-Peter Schaefer of TomTom Traffic said: ‘Building new motorways and ring roads doesn’t eliminate congestion. More must be done to better manage existing road space and to spread demand.

‘People simply aren’t doing enough to change their travel habits – such as working flexible hours, avoiding peak commuting times, making use of real-time traffic information and trying alternative travel modes.

‘If only five per cent of us changed our travel plans we could improve traffic congestion on our main roads by up to 30 per cent.’

WHERE THE SNARL-UPS ARE

Here are the 25 most congested cities in the UK in 2015 and their average increase in journey times compared to if traffic flowed freely, according to the TomTom Traffic Survey:

1. Belfast 40%

2. London 38%

3. Manchester 37%

4. Edinburgh 37%

5. Brighton 34%

6. Hull 33%

7. Bournemouth 32%

8. Newcastle 31%

9. Bristol 31%

10. Sheffield 30%

11. Leicester 29%

12. Liverpool 29%

13. Swansea 28%

14. Birmingham 27%

15. Leeds-Bradford 27%

16. Nottingham 27%

17. Glasgow 26%

18. Cardiff 26%

19. Coventry 25%

20. Southampton 24%

21. Reading 24%

22. Portsmouth 23%

23. Middlesbrough 21%

24. Stoke-on-Trent 20%

25. Preston 19%