Seventy-seven percent of all fatal traffic accidents occur on two-lane roads, a nonprofit transportation research group reported in 1995.

The Road Information Program (TRIP) also reported that fatal accidents are more than twice as likely to take place on two-lane roads than on highways with four lanes or more.

TRIP analyzed data on traffic fatalities and accidents published by the National Highway Traffic Safety Administration (NHTSA).

“While much of our nation is debating the effects of higher speed limits on traffic fatalities, there is another important traffic safety factor that is being ignored,” said William M. Wilkins, executive director of The Road Information Program (TRIP). “Road improvements such as wider lanes and widening shoulders and paving existing shoulders, adding a median and upgrading roads from two lanes to four lanes can significantly reduce traffic accidents, fatalities and injuries. Other road safety factors include providing crash barriers, better signage and lighting.”

“What hasn’t been reported is that the NHS will provide $5.2 billion a year to the states to make needed road safety improvements,” Wilkins said. “But this only scratches the surface because a new U.S. Department of Transportation report estimates that the United States is spending only about half of the money necessary to make needed road improvements.”

TRIP’s analysis of the data found:

  • Roads that were upgraded from two lanes to four lanes with a median experienced a 71 percent reduction in fatal accidents.
  • Widening a lane has been found to reduce fatalities by 21 percent.
  • In 1994, 77 percent of fatal accidents occurred on two-lane roads that carried just 51 percent of total vehicle miles traveled.
  • In 1994, roads with four lanes or more had 13.8 percent of fatal accidents while carrying 41.7 percent of travel.
  • The fatal accident rate per hundred million miles traveled on two-lane roads was 2.03, while the fatal accident rate on roads with four or more lanes averaged 0.95.
  • The same pattern holds true regarding the total number of traffic accidents. There were more than 2.7 million traffic accidents on two- lane roads in 1994, compared to about 1.4 million accidents on roads with four or more lanes.

In addition to the number of lanes and the presence of a median, another important traffic safety factor is the width of the road and shoulders. Wilkins said the nationally recommended width for a lane to be considered safe is 12 feet. Excluding interstate highways (which have at least four lanes), TRIP estimates that about three-quarters of the nation’s 159,000 miles of major roads are two-lane, and 15 percent of those are less than 12-feet in width.

“It simply stands to reason that if drivers have more room to operate and additional space to return a vehicle to the road, then traffic accidents can be reduced,” Wilkins said. “This is especially true when you consider how going from a two-lane road to a four-lane road can help reduce head-on collisions, which often result in more serious or fatal accidents.”

Wilkins said states considering an increase in their speed limits also should consider making needed upgrades to their roads and highways and bridges to reduce congestion and increase safety. “We’re not saying that every two-lane road should be made into a four-land road,” Wilkins explained. “What we are saying is that these factors should be considered from a safety standpoint and that these upgrades should be given serious consideration when they are practical. This is especially true if automobiles are going to be traveling on those roads at higher speeds due to increased speed limits.”