A cool, wet start to last year kept many motorcyclists off the road, making 2013 only the second year since 1997 that fatal bike crashes have declined, according to a report scheduled to be released Tuesday.

The report by the Governors Highway Safety Association projected a 7 percent decrease in the number of motorcyclists killed last year. The final fatality total is expected to be 4,610, fewer than the 4,957 in 2012 and nearly identical to the 4,612 in 2011.

“It’s heartening that motorcyclist fatalities didn’t increase over the past couple of years, but they’re not decreasing either,” Kendell Poole, GHSA chairman, said in a statement. “Long-term gains in motorcyclist safety won’t occur because riders are deterred by bad weather, but from consistent use of proven countermeasures.”

The GHSA report comes in advance of federal data for 2013, which are expected to be released later in the year. The GHSA collects statistics directly from the state safety officers who make up its membership.

Comparing year-to-year numbers for the first nine months of 2012 with 2013, the GHSA said fatalities decreased in the District and 35 states, increased in 13 states and remained the same in two. The District had three fatalities in 2013, down one from the previous year, Maryland had 54, a decrease of 15, and Virginia reported 60, a drop of 11.

The National Highway Traffic Safety Administration said motorcycle deaths accounted for 15 percent of highway fatalities in 2011 , though motorcycles amount to just 3 percent of vehicle registrations. NHTSA said motorcycle crash injuries increased from 81,000 in 2011 to 93,000 in 2012. Motorcyclists are more than 26 times more likely to die in a crash than occupants of cars, and five times more likely to be injured, NHTSA said.

Alcohol is a bigger factor in motorcycle crashes than it is for cars, with 27 percent of riders intoxicated, compared with 23 percent of drivers. Motorcyclists killed at night are three times more likely than other drivers to have been drunk, NHTSA aid.

Advances in car and truck safety have created a relatively steady decline in the overall national highway fatality rate, but many new features, such as air bags, are not available on motorcycles.

The GHSA said data show that people in passenger vehicles were twice as safe in 2011 compared with 1997, but with motorcyclists there was no improvement over the same time span.

One reason cited by the group and echoed by NHTSA is the declining use of motorcycle helmets. Head injury is the leading cause of death in motorcycle crashes, NHTSA said, and the federal agency said the use of helmets dropped from 66 percent in 2011 to 60 percent in 2012. It estimated that 1,699 lives were saved by helmets in 2012, and that another 781 riders would have survived had they been wearing them.

The District and 19 states — including Virginia and Maryland — require helmets for all riders. Thirty-one states have repealed mandatory helmet laws, though some require them for younger riders.

“Wearing a helmet on every ride is an important way for a motorcyclist to stay safe, but we all play a part. It’s up to all motorists and motorcyclists to make our roads safer,” NHTSA’s acting administrator, David Friedman, said in a statement. “All road users need to share the responsibility of keeping the roadways safe.”

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