CT has already commissioned a study - you can find the results if you search
if i recall correctly, the study was actually about reducing congestion on i95 and the merritt pkwy- they studied several alternatives, including tolls.., and decided that the best way to reduce traffic is to add lanes - duh.., i guess...
i think they also concluded that tolls would reduce traffic too - just not as much.., but it depends on the tolls - again - duh!
one thing they suggested is congestion pricing - higher tolls during rush hour
i think they suggested that the tolls only be the kind you can drive through at highway speeds - you either use easypass, or they send you a bill. they also looked at where the tolls should be - i forget what they decided.., but i think it's not just at the state borders, but scattered along the highway
this is from memory.., and i may have some of it wrong.
my guess is adding lanes is expensive so it may not get done in the near future unless it is pretty much wholly paid for by the feds - maybe as part of a big infrastructure program.
anyway.., the need for revenue in CT is as great as the need to reduce congestion.., so there will be tolls even if they build new lanes