There is a new filter option called, “Travel time” which will allow you to filter schools based on commute times. You can filter schools within 15 minutes, 30 minutes, 1 hour, and 1.5 hours from a specified zip code.
Please note that this implementation is an approximation based on calculated travel times from a zip code to a school address. Because of this, travel times from your specific address to a school may be off by 5-10 minutes.
There are two reasons why this feature was implemented in this fashion:
- This is the fastest and least computationally-intensive way to get travel distances. By pre-calculating times for every school, the system has quick access to travel times without needing to compute time and distance on the fly. There are about 300 zip codes in NYC and about 450 high schools, which means there are approximately 135,000 pre-calculated travel times stored in the database. It helps that most zip codes have easy access to public transportation so zip code approximations should introduce no more than 10 minutes of commute time error.
- Travel time computations cost money. For example, if I were to implement a dynamic computational component that queried Google given a particular address, the cost could be thousands of dollars a day depending on traffic and usage. Instead, I made use of Google’s free $200/month credit to slowly build the commute database over three months. Now that I have all the data, users can make unlimited requests for commute times without any cost.