Drivers could face 90 minutes of delays in traffic this bank holiday weekend, according to traffic data firm Inrix.

With a high volume of holidaymakers set to take to the UK’s roads and National Rail delivering over 30 engineering projects during the bank holiday weekend, drivers can expect delays of up to 90 minutes on peak routes, increasing by an average of 27% across the country, based on the latest Inrix data.

Commuters in London and the South East of England will experience the most congestion, with traffic almost 50% higher than usual. The M25 between junctions 9 and 21 (both directions) tops the list of expected delays with an anticipated 90 minutes of gridlock, meaning travellers planning to fly from Heathrow Airport, which carried almost 75 million passengers in 2015, or Gatwick Airport, should seek alternative routes or factor in additional time to catch their flight.

Those heading to less far flung destinations in and around Bristol and Weston-super-Mare should also plan for delays on the M5 of up to one hour. Drivers visiting Manchester face delays of up to 45 minutes on the M6 between Keele and Knutsford and between junction 19 and 22, as do those using the M6 to travel to Liverpool. Londoners should be prepared for closures on rail lines in and out of the capital, as well as a reduced service on a number of TfL lines.

The busiest period over the entire bank holiday weekend will be on the Friday rush hour, with peak congestion expected around 5 p.m. as travellers start their journeys to take advantage of the long weekend. Traffic levels are expected to peak on Friday 29th April between 4pm and 6pm.

Greg Hallsworth, UK traffic analyst at Inrix said: “Drivers in the UK are no strangers to traffic, spending an average of 30 hours in gridlock last year. At peak times like the bank holidays – particularly this bank holiday as it coincides with the UK half term – roads that are already stretched have the added pressure of holidaymakers and railway engineering works. Our advice to drivers is to check before starting your journey, travel at smarter times and take alternative routes to avoid delays hampering plans.

“If you must travel at the busiest times check the Inrix traffic website for real time traffic information, use the Transport for London website (www.tfl.gov.uk/traffic/status) for updates in the capital, or tune into local radio and TV to help steer clear of delays.”

Edmund King, AA president, added: “Spring bank holiday and the start of the summer half term are on a collision course on Friday and drivers will have to expect delays. With temperatures picking up, travellers will have to make sure their cars don’t overheat and also carry water for themselves should they get stuck in a traffic jam. Delaying departure until later in the evening is often a shrewd move as the combination of work exit and holiday exodus traffic tends to ease after the rush-hour. Using mobile phone services, like the AA App, gives drivers the heads-up on levels of traffic and hold-ups ahead, with the option to avoid them.”