Call it planners versus algorithms.

Smartphone apps like Waze, a godsend for some road warriors because they shave minutes and even hours off their commutes with their creative detours off main highways, are causing headaches for city planners.

Using crosswalks, wider sidewalks and traffic lights, these transportation engineers aim to make neighborhood traffic slow, safe, and friendly for pedestrians — not send frustrated commuters barreling down side roads.

But the GPS-enabled computer programs often don't know that, or care. Their creators, such as Waze (owned by Google), are sympathetic, to a degree. They may give cities tips on how to effectively game the program so a neighborhood detour doesn't seem that appealing. But at the end of the day, the purpose of the bots is to make use of all available road space, main thoroughfare or country lane.

The upshot is mounting frustration from cities, which are trying to thwart computer systems that are savvier than ever.

"Don't trust your apps!" reads one road sign in Fremont, a city of 225,000 people just north of San Jose. Located off the heavily congested 880 and 680 freeways, it's situated between major San Jose-area employers like Intel, Cisco Systems and eBay, and the more affordable housing suburbs in California's Central Valley.

With highways frequently congested, navigation apps like Google Maps and Waze started telling drivers to hop off the freeway at Fremont's Mission Boulevard, cut through residential streets and then hop back on the highway where things were clearer — much to the distress of the people who lived there.

“The commuters didn’t live or work in Fremont and didn’t care about our residential neighborhoods,” said Noe Veloso, Fremont’s principal transportation engineer.

When he contacted the navigation apps, he was told the apps attempt to prevent congestion by distributing traffic on all public streets, even to quiet residential roadways. The only way to stop the drivers was to change the street routing so these shortcuts were no longer that.

So Fremont instituted commute-hour turn restrictions on the most heavily used residential cut-through routes. The city also partnered with Waze through its Connected Citizens Program in order to share data and information, such as the turn restrictions, so that the app takes them into account. The result has been effective, but Veloso is worried the changes may simply reroute commuters into other neighborhoods.

"We’re just trying to find a balance, to eliminate some of the time savings that's sending people into our streets," Veloso said.

Fremont's situation is playing out in towns and cities across the U.S., with municipal planners just starting to grasp the scope of the challenge.

“Waze and Uber hit transportation planners so fast that we didn’t know what to do,” says Sam Schwartz, a former traffic coordinator for New York City. His 1992 book New York Shortcuts and Traffic Tips was a popular precursor to the systems and apps that have been downloaded by hundreds of millions of users.

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