De-Congesting Arizona’s Chino Valley Highway

Stanley Consultants was hired by the Arizona Department of Transportation (ADOT) to design a solution for traffic flow problems on State Route 89 (SR 89).

Since 1992, State Route 89, which runs from Interstate 40 south to US Highway 93, has been an important thoroughfare for travelers in central Arizona.  The Town of Chino Valley sits near the center of this highly traveled road and accommodates over 24,000 vehicles daily – a substantial number for any two-lane road to transport.

The ADOT evaluated a three-mile section of SR 89 when accidents became more prevalent and complaints of congestion became more frequent.  Chino Valley residents and businesses were concerned because the constant stream of traffic on the single-lane highway made merging and turning hazardous.

Stanley Consultants served as prime design consultant to develop a solution to this congestion and safety problem.  The highway was expanded to two lanes in each direction.  An innovative "inside out" design approach allows for future expansion to three lanes in each direction simply by removing the road's wide internal median.  The roadway features numerous right and left turn lanes, a superior drainage system, and the state's largest roundabout.  The roundabout two-lane configuration is capable of accommodating two semi trucks side-by-side – a first of its kind in Arizona.  The roundabout has also been designed to accommodate an additional third lane for the ultimate configuration.