The Flood of School Traffic

My kids are back in school this week after a very long winter break. As I dropped them off Monday morning, traffic felt especially bad after not having to do dropoff for the past three weeks. As I sat there in a long line of cars, I reflected on this flood of traffic we crate every school day.

We’ve designed our roads to be a giant floodplain for cars. Our local roads act as headwater streams, feeding into the larger streams of our collector roads, and onto the rivers of our arterials. The start of the school day act like a predictable but sudden downpour. Cars leave their garages and parking spaces to arrive at the same place all at once. The result of this flood of traffic is that the roads in our residential communities are most impacted in the twenty minutes before and after the start of school.

When it comes to flooding caused by rainfall, we’ve developed a number of ways to reduce flooding beyond just building bigger storm drains and wider rivers that can be applied to the flood created by school traffic. In general, floods can be mitigated by holding water where it falls and lengthening the time it takes to reach downstream.

Many new developments include stormwater basins to capture the first few inches of rainfall on-site and let it infiltrate into the soil where soil conditions allow it. This ensures that the water that falls on that site doesn’t contribute to the downstream water that could become a flood.

Applying this to schools, cities and school districts should be building more neighborhood schools. Neighborhood schools keep cars further upstream in the local roadway network, instead of congregating on the collector and arterial roads. This has the added benefit of allowing more kids to walk and roll to school, keeping some cars off the road entirely.

In flood management where the soil is not conducive to percolation in a storm water basin, basins are still a useful tool to retain water and discharge it slowly over time. By slowing the discharge of water, it allows downstream rivers to handle all of the water over a longer period of time instead of being inundated with it all at once.

Schools, of course, are a little different since the objective is to get kids to school at the same time when school starts. That is, unless the school were to adjust the start time of each grade to spread out when kids arrive. If a K-6 school offset the start time for each grade by ten minutes, the school rush would last over an hour but be only one-seventh as bad at any one time. (And yes, there would be more cars for the earlier starting grades due to kids having siblings, but the basic principle works.)

Much of the discourse around city building resolves around how to accommodate more cars during times of peak demand, whether that is providing enough parking or widening our roads, while most of the time we have far more capacity for cars than is good for our cities. As with floodwaters, we need to do a better job of shifting demand for these facilities to places and times where we have excess capacity. For schools, this can be done through building neighborhood schools and drawing out the start of the school day. With a bit of thought, these same principles can apply throughout our cities.