A transportation group is proposing a plan to change the way Illinois pays for road construction, including an increase in gas taxes.  The Transportation for Illinois Coalition unveiled the proposal Tuesday in Springfield.  They say it provides stability and $1.8 billion annually for construction on roads, bridges, railways and airports.  Funding from the state’s five-year capital construction program is set to run out this year.  The plan would come at an increased cost to drivers.  It calls for a 4 cents increase in the gas tax and higher vehicle registration fees.  It would end ethanol credit for gasoline.  Coalition chairman Doug Whitley says the tax increase is necessary for more revenue because cars get better gas mileage than 20 years ago.  The state gas tax hasn’t been increased since 1990.