A new tunnel under the Thames could help relieve the congested A12 Blackwall Tunnel in the next nine years, City Hall transport bosses believe.

A second phase of public consultations is being opened by Transport for London this week on two new river crossing proposals in east London, a road tunnel at Silvertown and vehicle ferry further east at Beckton.

A tunnel between the Royal Docks and the Greenwich Peninsula would relieve pressure on the A12 Blackwall Tunnel through Poplar and Bromley-by-Bow, say planners.

It would also help prevent closures caused by over-height vehicles attempting to use the narrow, 114-year-old northbound Blackwall Tunnel, already the worst of the Thames crossing bottlenecks with northbound delays averaging 20 minutes during the morning rush-hour.

The Transport Secretary in June designated the proposed Silvertown tunnel a ‘Nationally Significant Infrastructure Project’ after pressure from London mayor Boris Johnson, which means it could be open as early as 2021.

Further east, the proposed vehicle ferry at Gallions Reach linking Beckton and Thamesmead could replace the ageing Woolwich Ferry carrying North Circular Road traffic.

It would take just 10 minutes to cross, including boarding time, with more space for vehicles waiting to board which would prevent ferry traffic causing congestion on surrounding roads. Earliest opening date once planning permission and funding is secure would be 2017.

Both the Blackwall Tunnel and Woolwich Ferry are also vulnerable to closure because of their age and design. The new river crossings would overcome these problems.

The public consultations will also look at how the schemes would be paid for, including Community Infrastructure levies and even the possibility toll charges. The consultations close February 1 and can be done online at www.tfl.gov.uk/rivercrossings