Plus there is no such thing as a highway trust fund in Matyland. Thy money in there was raided by the politicians and put in the general fund to help MD to keep a balanced budget, as required by law.
What funny is that, as far as I know, the MTA account (for the toll facilities) has not been raided by the politicians. It is actually all spent on projects, salaries and so on.
They are raising tolls, it seems, due to the actual need to preserve and improve a bunch of aging facilities. As far raising the gas tax, forget about it until they stop raiding the trust fund and spending a lot of it on choo-choos and buses.