Silvertown Tunnel: Who pays and why the controversy?
The new £2.2bn Silvertown Tunnel stretches almost a mile (1.4km) under the Thames from Greenwich to Newham next to the Blackwall Tunnel.
First announced in 2012, Mayor of London Sir Sadiq Khan reviewed the scheme when he came into office, saying it would be a vital link across the Thames to east London.
It is now open and both tunnels are subject to tolls - costing £4 in peak times to drive a car through.
Who will have to pay and why is the tunnel still seen as controversial by some?
Why was it built?
The mayor and Transport for London (TfL) think the new tunnel will alleviate congestion and tailbacks at the Victorian-era Blackwall Tunnel, which shuts 700 times a year.
They say the new tolls will control the numbers using the tunnel and stop an increase in congestion and pollution.
PA MediaIt was paid for with private borrowing which will be paid back with the tolls over 25 years.
It is a big change for east London, and will become the first road access charging in London since the congestion charge in 2003.
Does everyone have to pay?
On average, 100,000 vehicles a day use the Blackwall Tunnel.
Not everyone will have to pay the tolls, with some exemptions for Blue Badge holders and black cabs, but most other vehicles will have to pay the charge for using either tunnel.
There is a 50% discount for residents in 12 east London boroughs who are on low incomes, and a £1 reduction to off-peak fares for small businesses, but you need to register for the discounts.
Crucially, off-peak charges only apply to those who have signed up to the TfL Autopay system.
Why is it controversial?
There has been vociferous opposition to the tunnel by those who think increasing road capacity will in turn increase congestion and pollution.
Some residents have raised concerns that as the Silvertown Tunnel is free at night, it will be attractive to HGVs that will drive through Greenwich and Newham - especially because larger HGVs will be able to use the bus lane in the new tunnel, whereas tall HGVs couldn't go through the Blackwall Tunnel.
Councils say the tolls create a "two-tier" London, with the east unfairly having more toll crossings compared with west London.
Critics have also said the tunnel goes against the mayor's own environmental policies, and there are also fears future mayors could scrap the toll completely, leading to an increase in pollution.
However, the mayor has set up free buses, a fully-refundable DLR and a free bus for bikes to try to encourage people to switch to public transport.
TfL said it would monitor pollution levels and stressed the tolls should prevent a big increase in HGVs.
When do I have to pay?
You have to pay three days after you use the tunnel.
Peak times are, in effect, in the morning in the northbound direction and southbound in the afternoon.
You can pay online or on the phone, but it's recommended to sign up for TfL Autopay.
If you don't pay the user charge, you could be fined £180, but you will only get one fine for each day you didn't pay the charge. Tfl has said it "reserves the right" to issue a warning instead of a Penalty Charge Notice initially.
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