Mersey Gateway is 3rd most expensive toll in country - and makes whopping £39m a year THE Mersey Gateway is the third most expensive toll route in the country and makes almost £39m a year, a new survey has found. Figures compiled by comparison website GoCompare show the controversial bridge’s £2 is one of the most expensive in the UK, with only the Dartford Crossing in London and the M6 Toll Road costing more. The survey also found that the £1.80 toll on the Mersey Tunnels was the fifth most expensive in the UK, but generated even more income than the Mersey Gateway.