BOSTON – One-fifth of major Massachusetts roads and highways are deficient and the combined gridlock, safety hazards and poor road conditions add up to $8.3 billion in additional costs to motorists, according to a report released Tuesday.

The costs stem from vehicle depreciation and repair costs, increased tire wear associated with poor pavement conditions, the financial cost of traffic accidents, and the cost of time spent in traffic and fuel wasted during tie-ups, according to the report by the Washington, D.C.-based TRIP research company.



The report arrives two weeks before election day when activists seeking to limit increases on the 24-cent-per-gallon gasoline tax are working to pass a ballot referendum that is opposed by major construction firms and business interests. Question 1 would repeal a 2013 law that links future gas tax increases to inflation, which was part of a larger tax law aimed at funding transportation repairs and improvements.



Tank the Gas Tax argues that lawmakers should be required to vote before any increase in the gas tax. Between state and federal taxes and fees, consumers pay the government $6.73 for 15 gallons of gas, according to the campaign. Opponents of the repeal effort say that before a 3 cent-per-gallon increase last year, the gas tax hadn’t been increased in more than two decades.



TRIP Director of Policy and Research Rocky Moretti said the group, which is funded by insurance companies, labor unions and transportation businesses, does not have a position on the ballot question, but was aware of it and wanted to educate the public.



“We believe that when people have information on their transportation system they’re in better position to decide how they wish to proceed,” said Moretti, who said it is an “organizational policy” not to take a stance.



Massachusetts Taxpayers Foundation President Michael Widmer and AAA Southern New England Director of Public and Legislative Affairs Mary Maguire, who are both vocal opponents of Question 1, spoke at TRIP’s press conference held in a Beacon Hill office building.



Widmer said indexing is a “standard form of tax policy so that we don’t see our revenues depleted,” and Maguire said the current condition of Bay State roads is unsafe.



“It threatens the safety of all of those who use our roads and bridges,” said Maguire, who said U.S. Sen. Chris Murphy, D-Conn., has proposed raising the federal gas tax.



The TRIP report registers a variety of costs associated with the current state of road conditions, including accidents, vehicle maintenance and time spent sitting in traffic.



The average Boston-area driver loses 53 hours each year to traffic. Worcester drivers lose 33 hours per year, Springfield motorists lose 28 hours and South Coast drivers lose 22 hours annually.



Between 2008 and 2012, 1,697 people were killed in crashes, an average of 339 per year. The rate of fatalities on rural roads was 3.5 times greater per mile traveled than other roads and highways, according to the report, which found wider roads, medians, improved lighting and other upgrades can improve safety. Based on other research, TRIP estimated roadway features were a “contributing factor” in about one-third of the fatal accidents.



“We want people to be in as forgiving an environment as possible,” said Moretti.



Accidents cost South Coast drivers an average $754 annually, cost Springfield drivers an average of $553, Worcester drivers $515 and Boston drivers $298, according to Moretti, who said the study was “just looking at economic costs.”



The report credits the Legislature with adding $600 million in annual transportation spending through the 2013 law that upped tobacco taxes and raised the gas tax 3 cents while linking it to inflation. TRIP also argues that the funding increase falls $400 million short of the $1 billion annual shortfall identified in transportation spending.



TRIP found that bad road conditions contributed to more vehicle repairs, faster depreciation and more gas consumption, which added up to $2.3 million in increased operating costs caused by the roads.



Two years ago there were 4.7 million licensed drivers in Massachusetts, according to TRIP.



