Motorcycle Rider Training and Skill Development
 

Special Report

 

ODOT has announced a major highway project that will affect the motorcycling community: Curve advisory speeds across the state will be increasing from 2016-2019.

This is important to motorcyclists because curve entry speed is critical to safe cornering. Riders accustomed to the older, more conservative Oregon advisory speeds may be in for a surprise when the 25, 35, 45 mph corners they approach are sharper than they anticipate!

For more information contact Tom Fuller, ODOT at 503-986-3455 or Thomas.fuller@odot.state.or.us

 

Road Sign

That curve you know you can take at 40 because 
the sign says 30? Well, maybe now it really means 30.

Driver Alert: ODOT Is Updating Curve 'Advisory Speed' Signs Around The State 

ODOT, SALEM – You do it multiple times every day and probably aren’t even aware of it: Adjust your speed going around a curve to 5 to 10 miles per hour above the number on those yellow curve advisory speed signs.

But here’s a heads up: Those signs and speeds are probably going to be changing – and they will better match the curve, so you’ll want to pay attention, everywhere you go in the state.

In fact, some 50 to 75 percent of all curve speed advisory signs will change over the next three to four years, most seeing an increase in the advisory speed of 5 to 10 mph. Why is Oregon doing this? There are three main reasons:

New federal requirements improve safety and create consistency. Updated federal procedures require consistency of curve advisory speeds on all public roads. Consistency in curve signing means a curve with an advisory speed of 40 mph in the Willamette Valley will feel similar to a 40 mph curve in Baker County or a 40 mph curve in another state.

New technology allows for more reliable speeds. New technology allows us to determine advisory speeds for curves with greater certainty; current speeds were set using the analog tools that have now been replaced with GPS-aided digital tools.

Vehicles, road design and pavements have advanced. Newer vehicles can corner with increased speeds while maintaining a comfortable ride. Oregon’s roads have also benefited in the past several decades from improved design and advanced pavements, creating safer, smoother roads.

Time for an Update

Current advisory speeds were set by investigators using the ball bank indicator method, which involved driving curves multiple times to figure out how far to the right or left a ball suspended in liquid traveled in its arc. The variability inherent in this method and irregularities in road surfaces contributed to setting inconsistent and conservative advisory speeds – which is why so many drivers are comfortable going faster than the posted advisory speeds.

In addition, roadway crews would sometimes reduce speeds even further on curves where other problems occurred. Today, ODOT employs GPS technology that allows an engineer to drive a curve fewer times and provides more consistent and reliable results. Special software processes the data after each trip so engineers can set the correct advisory speed.

Many Speeds Going Up

Most curve advisory speeds will increase by 5 to 10 mph (though some will increase even more). ODOT crews and contractors have already started replacing or removing signs. The effort will continue through 2019.

ODOT MAP

A map showing curves analyzed as of March 2016. Road-
level detail of highways affected is not yet available. 

All public roads in Oregon that see volumes of more than 1,000 vehicles a day are subject to the new Federal Highway Administration requirements. ODOT is lending GPS curve analysis equipment to local jurisdictions to assist in the process of updating the speed advisory on local and county roads.

Eric Leaming, an ODOT Traffic Devices engineer involved in the curve analysis, said it is going to be very important to watch and follow the new advisories.

“Before, advisory speeds were very conservative and inconsistent,” Leaming said. “Now, these advisory speeds are going to be uniformly closer to the speeds drivers are comfortable traveling at through a curve. You won’t want to go faster than the advisory speed.”

Leaming said greater uniformity and accuracy of the advisory speeds will improve safety and the driving experience for people on the road. 

Further Reading

For expert tips and techniques for negotiating curves, visit TEAM OREGON Resources.

For more information and frequently-asked questions about the curve advisory speed changes, click here.

You can read a comprehensive assessment of the ODOT Curve Advisory Speeds Program performed by Oregon State University researchers here.

For more than you ever thought you wanted to know, you can review the Federal Highway Administration’s procedures on setting curve advisory speeds, click here.  

About Us

TEAM OREGON is a cooperative partnership with the Oregon Department of Transportation and Oregon State University, providing statewide training, education and outreach for riders of all levels of experience and riding ability. Since 1984, the program has trained more than 180,000 riders.

 

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