Traffic jams at the new Tyne Tunnel tolling system were caused by drivers stopping or changing lanes, tunnel operators have said.
Since midnight on Monday 8 November, motorists have been able to drive through the Tyne Tunnel without stopping to pay as 'Tyne Pass' replaces the existing toll system.
Barriers and traffic lights are no longer in use with cameras installed to automatically register journeys.
Tunnel users either have to pay their fee via a pre-paid account with tunnel operator TT2 or do so before midnight the day after their journey using an online pay later service, an automated telephone line, or at PayPoint tills found in shops.
The toll plazas are still in place but are due to be dismantled in the coming weeks. Only two lanes will be open around the tolling area under the new system to avoid the need for merging, ITV News Tyne Tees has been told.
A 1960s VW campervan becomes the first vehicle to try out the new, fully cashless system.
But motorists have taken to social media to complain about congestion and duplicated payments.
One described the situation as a "carnage" while another called being stuck in a "38 minute" queue a "nightmare".
Responding to the complaints of traffic jams, TT2 issued a statement saying the delays were caused by a "small number of drivers" struggling to adjust to the new system.
"Changing a tolling-system that has been in operation for many decades, will naturally take drivers some time to get used to," a TT2 spokesperson said.
"The majority of travellers adjusted to the new system without any problems and congestion had eased before 10am. However, prior to that, a small number of drivers were stopping or changing lane which created some traffic congestion," they continued.
"This is the first day of open-road-tolling and we expect with each passing day, the number of drivers stopping will reduce and journeys will be further speeded-up. We have made some adjustments to our coning system and we will make other changes to signage to improve understanding by drivers of which lane they should be using.”
It also emerged that some passengers were made to pay twice for using the tunnels.
TT2 acknowledged "minor technical issues" with their payment system and are "re-crediting [affected accounts] with immediate effect".
"There was a glitch with our TT2 payment app. This seemed to particularly affect one version of the operating systems on iPhones and is being rectified," the spokesperson said.
"However, until we roll out the new app over the next few days, we are asking customers to use the website http://tt2.co.uk to access their account. Our new app will be available soon, please keep an eye on our news page for further updates.
Why the change?
Bosses have promised that people will experience faster journeys as nobody will have to stop at a toll booth.
They claim it will save 1,944 hours a week in queuing time, and a 90 oer cent reduction in CO2 emissions around the tunnel thanks to traffic no longer being brought to a standstill.
How does it work?
The new system will work using an Automatic Number Plate Recognition cameras in the tunnels which will recognise vehicle registrations and deduct the toll from the associated acccount.
What are the concerns?
There have been worries raised by some users over how people without access to the internet will cope with the new payment requirements.
There have also been many complaints since the tunnels first introduced a 'pay later' ticket option last year, which has seen drivers hit with heavy fines if they are unable to pay their toll by midnight the next day.
At one stage, almost one in five of the drivers taking a pay later ticket were issued with a penalty notice - which can rise to up to £100, plus the original £1.90 fee.
But TT2 said that around 70% of tunnel users already use a pre-paid account and below 20% pay with cash.
"A positive step"
Gateshead Council leader Martin Gannon, who chairs the North East Joint Transport Committee, said the scheme would "deliver major environmental benefits for our region".
He added: "The investment in a more modern operation will provide major journey time savings, alongside the significant environmental benefits of the scheme.
"This is a positive step towards the decarbonisation of the transport network and achieving our vision of moving to a green, health, dynamic and thriving North East as outlined in the North East Transport Plan."