Louisiana’s highway conditions plummeted to 40th in the nation and pavements on urban interstates are better than only two other states, according to a report released Thursday.

The state also ranks 44th in its highway fatality rate, 41st in the condition of rural interstate pavements and 39th in the number of deficient bridges.

The findings are included in the 21st Annual Highway Report by the Reason Foundation, which calls itself a libertarian think tank in Los Angeles that issues policy papers on a wide range of topics.

David T. Hartgen, the author of the study, said Wednesday the state’s rating was also hurt by a drop in its spending for highway maintenance. “So a bigger problem and less money to work with yields a drop in the ratings,” Hartgen said in an interview.

The state was ranked 24th in highway conditions and spending effectiveness by the same group in 2011.

The latest review covers 2012.

Hartgen said the ranking dropped in part because urban interstate mileage rated as poor rose from 8.7 percent to 15.3 percent, which is three times the national average.

The only states whose urban interstate pavements were rated as worse than Louisiana are California and Hawaii.

Rural interstate mileage classified as poor shot up from less than 1 percent to 4 percent, which is about double the national average.

“In just one year the backbone, if you will, of the Louisiana highway system registered a very significant uptick in the percent of poor mileage,” he said.

“It is easily a yellow flag and maybe a red flag,” Hartgen said of the drop in interstate pavement conditions.

Rodney Mallett, a spokesman for the state Department of Transportation and Development, said the state has invested $6.4 billion in highway improvements since 2008, including over $1.8 billion to improve key interstate corridors.

Mallett also said the state has nearly doubled spending on highway safety projects, to nearly $50 million, and highway fatalities have dropped almost 30 percent.

The report was issued just a week after a special committee began hearings on how to boost state aid for roads and bridges amid a $12 billion backlog of improvements.

Senate Transportation Committee Chairman Robert Adley, R-Benton and a member of the panel, has repeatedly complained that the state is spending too little on highway maintenance.

“That is our problem,” Adley said Wednesday of the report’s linkage of maintenance and deteriorating pavements.

He said the state needs to spend at least $70 million per year for road upkeep.

“I am going to introduce several bills to ensure that happens,” Adley said.

Louisiana was one of six states that accounted nearly half of the pot holed urban intestate pavement mileage.

Wyoming was rated No. 1 for highway conditions and how well its dollars are spent.

Hawaii is listed as 50th.

Longshot attempts in the Legislature to increase transportation spending have died in recent years over how to pay for any improvements.

Adley and others have insisted that this time will be different, and he and other transportation leaders will be spending their final year in the Legislature in 2015 because of term limits.

Louisiana is among a handful of states that showed a boost in the number of troubled bridges in recent years, according to data released in July by Governing Magazine.

That tally showed that 14 percent of bridges statewide are structurally deficient — some of the elements are deteriorated or damaged — under a scoring system used by the federal government.

Another 15 percent are listed as functionally obsolete, which means they no longer meet modern safety design standards.

The state is also in the midst of a $425 million plan to resurface and repair about 1,100 miles of rural roads through a bond program approved by the Legislature in 2012.

Louisiana is rated 19th for urban interstate congestion, 8th for maintenance spending per mile and 19th for administrative spending per mile, according to the report.

Follow Will Sentell on Twitter @WillSentell. For more coverage of Louisiana government and politics, follow our Politics blog at http://blogs.theadvocate.com/politicsblog/.