Why the I-15/U.S. 95 freeway interchange is called the ‘Spaghetti Bowl’

Freeway interchanges with nicknames including “bowl” are a regular part of many Las Vegas Valley motorists daily commutes.

From the Spaghetti Bowl where Interstate 15 and U.S. Highway 95 converges downtown, to the Henderson Interchange, also known as the Henderson Spaghetti Bowl, where the 215 Beltway, Lake Mead Parkway and Interstate 11 intersect to the Centennial Bowl in the northwest, where the 215, U.S. 95 and surface streets meet; there are no shortage of traffic bowls in Southern Nevada.

The term “bowl” might catch some who are new to the valley off-guard, arriving from places that may not have intricate freeway interchanges and leaving many to ask, “Why are these interchanges commonly referred to as bowls?”

The first use of “Spaghetti Bowl” in the state dates back to January 1973, when an article in the Reno Evening Gazette called the Interstate 80/U.S. Highway 395 interchange by the name, according to the Nevada Department of Transportation.

At the time the Northern Nevada interchange was newly constructed, but NDOT spokesman Justin Hopkins said, “The origin of the term remains unclear, beyond the obvious visual resemblance of the interchange structure to a bowl of spaghetti.”

Around that same construction on the I-15/U.S. 95 interchange was underway in Las Vegas.

“While we cannot definitively determine if one project influenced the naming of the other, there’s a possibility of mutual influence,” Hopkins said.

An interchange is a system of interconnection roadways in conjunction with at least one grade separation, that allows for movement between two or more roads or highways, according to the American Association of State Highway and Transportation Officials.

An interchange that is referred to as a “Spaghetti Bowl” is usually categorized as a system interchange, according to NDOT.

“This type of interchange connects multiple controlled-access highways without involving at-grade signalized intersections,” Hopkins said. “More specifically, the configuration of a Spaghetti Bowl interchange aligns with what is known as a stack interchange.”

A stack interchange comprises roads on four levels, including the two perpendicular highways, with an additional level for each pair of left turn ramps, Hopkins said.

When stack interchanges are particularly large and complex, they “May bear resemblance to a mixing bowl, mixmaster, or indeed, a bowl of spaghetti, hence the colloquial terms “Mixing Bowls,” “Mixmasters,” or “Spaghetti Junctions,” Hopkins said.

“These terms stem from the intricate appearance of the interchange, reminiscent of tangled strands of boiled spaghetti.”

Contact Mick Akers at makers@reviewjournal.com or 702-387-2920. Follow @mickakers on X.