"That increased by 25 percent," says Schenk. "Over an eight-week period we were able to shave down the average time it takes to find a critical violation by over a week."
Such testing is essential to ensure that the plans built on predictive analytics are effective.
"We fail every single time the first time around," admits Schenk. "Inevitably we misunderstand something and our experiment doesn't go well, so we go back we tweak it, we understand what the miscommunication was and we go back to it."
The system has also been used to mitigate public health risks. In summer mosquitoes arrive in Chicago keen to spread West Nile Virus, a disease that can cause headaches, vomiting, diarrhoea, and even death. WindyGrit was used to see which of the 189 mosquito traps in the city caught the most mosquitoes on a bubble map and used that to prepare a plan on to how to limit their spread.
The idea of WindyGrit emerged when Chicago was slated to host both the NATO and G8 summits in 2012. The incumbent Mayor Rahm Emanuel needed to ensure the city's high profile guests were taken care of by fully understanding what was happening in the city. WindyGrit was developed to provide this information in a single central location.
MongoDB offered a database that let the government easily add new data without spending too much time on data modelling and capture it on a map using latitude and longitude GPS coordinates.
The option of using a relational database was rejected due to the extra data modelling that would multiply the time spent adding additional data sources.
"It's very important for us to be very lightweight, to be able to iterate and experiment," says Schenk. "We're able to play around with MongoDB without having to go through a procurement process, which of course is a killer.
"It allows us to experiment with open source technology, and if it works - as it has - we're able to scale it out."
The first iteration took six months to implement and they've since built a second version. There have been bumps along the way, but Schenk has been able to count on the support of the MongoDB development team to deal with them.
"At one point Mongo actually released a Chicago-specific patch," he says. "We discovered a bug very early on and they released a patch just for us to be able to get past a bit of a hitch that we had. They later incorporated that into future releases and it's part of our environment now."
The City of Chicago also collects information on every single taxi, Uber and Lyft ride in the city. Schenk next wants to add that transit data to WindyGrit to understand where trips begin and end and manage the transport infrastructure around them. Privacy concerns are mitigated through authentication and user control levels and avoiding collecting information about the individual citizens.
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