Buildings can be razed and replaced. Single-family homes can become multi-story apartment complexes. As Seattle adapts to its status as the fastest growing city in America, residential density has strained to keep up with the influx of newcomers. But building new homes is a far simpler proposition than building new roads, as the city’s daily gridlock demonstrates.

In the next fifteen years, the Seattle area – already among the worst cities in America for traffic – is expected to grow by at least 110,000 people. The thriving tech industry has been pegged as the prime instigator of this population boom. This past weekend, the question was whether the sector could also offer solutions to the city’s growing pains.

Between Friday and Sunday evenings, a group of over 70 computer engineers, data scientists, designers and others hunkered down at the offices of marketing software company Moz in downtown Seattle. Some worked for tech monoliths like Amazon and Microsoft, others at single-staffer startups. Their shared weekend project was Hack the Commute, aimed at crunching the reams of civic data the city has made public, and using it to devise fixes for Seattle’s road congestion.

“This was a big step toward creating a community around civic tech,” said Candace Faber, the event’s project manager and organizer. “The relationship between civic hackers and government needs strengthening. … There are no cash prizes, we’re not offering a $10,000 check. Everyone who came here showed up because they wanted to work together and solve problems… This is about trying to take the lean startup approach, and apply it to the city’s issues.”

At the closing event Sunday evening, participants enjoyed free keg beers and sushi as they prepared to premiere their weekend pursuits. Seattle Chief Technology Officer Michael Mattmiller praised the “3248 hours [participants] collectively spent on one of the toughest challenges we face.” Councilmember and chair of the city’s transportation committee Tom Rasmussen popped in for an appearance.

And then it was off to the races, as each of the 14 Hack the Commute teams took to the stage to pitch their transportation fixes.

From mobile apps that take the headache out of carpool planning, to interactive data visualizations that identify road collision hotspots, the ideas presented ran the gamut.