85 on the Interstate

State Sen. Don Gustavson, R-Sparks, wants to give state highway officials the option of raising the top speed limit on Nevada’s limited-access, four-lane highways to 85 mph.

Nevada would become the third state, with Utah and Texas, to allow speeds faster than 75 mph.

“People are driving 80 or 85 anyway,” Sen. Gustavson said.

Mr. Gustavson acknowledges his bill wouldn’t do anything to make the trip between Southern and Northern Nevada any quicker, since it wouldn’t apply to U.S. 95 between Las Vegas and Reno, too much of which is an open-access, two-lane road.

There are only two stretches of road in Nevada, both of them interstates, likely to be affected. One runs for about 70 miles, from North Las Vegas to Mesquite on Interstate 15. The other runs for more than 300 miles — Interstate 80 from Fernley almost to Utah.

Pushkin Kachroo, director of the Transportation Research Center at UNLV, says higher speed limits can be safe.

For one thing, just because drivers often do 60 in a 50 mph zone doesn’t mean they exceed higher speed limits by the same ratio. In fact, drivers tend to drive at the speed they consider safe. When limits are raised to approximate the speed at which 85 percent of the traffic is moving, engineers have discovered frustrations drop and safety improves.

A study done in 2008 shows that 85 percent of drivers, during clear weather and visibility, drive 76 to 77 mph — not 90 — in the 75 mph zone on I-80.

That’s why the 85 percent threshold is commonly used.

A nationwide study conducted by the Federal Highway Administration found that when speed limits were raised to the 85th-percentile consensus speed, accidents and fatalities dropped, according to Chad Dornsife, formerly of the National Motorists Association and now head of the Oregon-based Best Highway Safety Practices Institute.

However, “When they lowered limits below the prevailing speed they saw an increase in accident rates.”

Sen. Gustavson’s bill has a good chance of passing. It has numerous co-sponsors, including Senate leaders from both parties.

No one is proposing that traffic go 85 mph in your local school zone.

But the National Highway Traffic Safety Administration says drowsy driving is a factor in more than 100,000 crashes, resulting in 1,550 deaths, each year.

For long lonely stretches of interstate — where at least 16 percent of accidents are attributed to motorists falling asleep due to the lengthy trip times between Western cities — giving state engineers this leeway makes sense.