Intelligent Transportation System

Ramp meters help to control the flow of traffic entering a freeway.

The ADOT Research Center Library might not carry any best-sellers, but where else are you going to find a title like, “Benefits of high volume fly ash: new concrete mixtures provide financial, environmental and performance gains”?

Much has changed since ADOT got its start in 1927. Back then, the agency was known as the Arizona State Highway Department and roads certainly were built a little differently. Methods, materials and technology have changed so much since then.

If you drive Valley freeways during rush hour, you’re probably pretty familiar with ramp meters … They’re the two-light signals positioned at most Valley on-ramps that tell motorists when it’s okay to head onto the freeway. Ramp meters have been used in the Phoenix-Metro area for about the past 20 years and maybe you think not much about them has changed … but, actually they’ve recently become much more efficient!