The Oregon Department of Transportation (ODOT) plans to use new technology to update curve advisory speed signs over the next three years.

According to the department, around 50-75% of all the curve speed advisory signs in the state will change, with most seeing an increase in the advisory speed of 5 to 10 mph.

ODOT stated that there are three reasons for implementing this programme. The first reason being that updated Federal Highway Administration (FHWA) procedures require consistency of curve advisory speeds on all public roads.

"Special software processes the data after each trip so engineers can set the correct advisory speed."

Further, use of new technology allows ODOT to determine advisory speeds for curves with greater certainty. Current speeds were set using analog tools that have now been replaced with GPS-aided digital tools.

The third reason is that vehicles, road design and pavements have advanced, with newer vehicles able to corner with increased speeds, while maintaining a comfortable ride.

According to the agency, 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.

However, ODOT now employs GPS technology, which 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.

Updation of the curve advisory speed signs will continue through 2019.