Planned changes to tolls at the Dartford River Crossing between Essex and Kent are being looked at by the East of England Regional Assembly.
The bridge and tunnels take M25 traffic over and under the Thames
The government is proposing an increase in daytime charges, but at a reduced rate for electronic DART-Tag users. Night charges would be removed.
The Assembly's regional planning panel will look at how the changes would affect transport in the eastern region.
A report calls for more of the crossing revenue to help local transport plans.
The report to the panel said that an average of 150,000 vehicles used the crossing each day in 2005 and this figure is expected to rise to between 170,000 and 190,000 by 2016.
It added that the Assembly agrees that action is needed to address the increasing demand on the crossing, but believes the increase in charges from £1 to £1.50 during the day (0600 to 2200 GMT) will have a "marginal" effect on traffic flow.
At present local councils in Essex and Kent only receive about 3% of the total £69m revenue from charges, it added.
This sum should be "increased substantially", said the report.
The Assembly will also discuss concerns that the widening of the M25 coupled with the increased use of the crossing will have a knock-on effect on the amount of traffic using roads in the East.
The report said: "It is essential for the Highways Agency to complement the widening of the M25 and the proposed changes in charges [with new transport initiatives]."
Last year Essex MPs Bob Russell (Lib Dem) and Bob Spink (Tory), and Hertfordshire MP Mike Penning (Tory), called for all tolls to be completely scrapped.
They have pointed out that the charges were set to be withdrawn when the crossing had paid for itself, which happened in 2003.
But the government said the tolls were continuing as a safety measure, in order to control the flow of traffic.