How could we slow local traffic and still speed commutes?

A mobility quandary: we want to speed painfully slow commutes from home to work yet we strive to slow commuter cut-through traffic near those homes.

Yes, you can slow neighborhood traffic and still speed commutes, but they’re seldom discussed in the same breath. It’s a quest for one or the other, not both. 

Yet traffic countywide is interconnected – if some areas slow down, other roadways jam up. Just think Waze or Google Maps. Or the butterfly effect, where a tiny change can trigger an enormous chain reaction.

The Miami-Dade Transportation Committee last week probed how to let local areas cut speed limits to 20 without having to coordinate with the county’s transportation team. The concept had unanimous support, with no talk of ramifications of such independent changes. The aim was just to cut the red tape to get it done.

Commissioner Micky Steinberg said 20 miles per hour is more appropriate in “an interior residential road, not a collector road, not a main artery – an area where it’s just truly for a community to be able near a school or just an urbanized town center” to cut speed limits.

“My interest is trying to beat technology at its game” by reducing the speed limit showing on Google Maps so that mobility apps direct cut-through traffic elsewhere, said Commissioner Raquel Regalado.

Commissioner Eileen Higgins offered a motion so “the county will just do this automatically” when an area seeks to lower the speed limit to 20 rather than going through a study.

“I see no reason on residential streets that some department that manages thousands of streets around the county, if the municipality is saying we need to slow down traffic on a street they should be able to slow down traffic on that street, particularly if they’re enforcing it.”

But “the requirement for a study is actually a state law,” noted Chief Operations Officer Jimmy Morales. “So I think the policy can certainly be the direction … that we should be OK approving 20 miles per hour speed limits in internal city roads, but the city, or in our case if it’s [the Unincorporated Municipal Services Area of the county], we still have to do a study under state law.”

Studies can indeed slow the process of slowing the traffic. Commissioner Juan Carlos Bermudez recollected that in March 2024 then-Commissioner Kevin Marino Cabrera sought a study from Mayor Daniella Levine Cava on lowering speed limits to 25 in unincorporated areas on all residential roads and near all county parks. He asked where that report went.

The study is done and has been sitting in the office of Commissioner Natalie Milian Orbis, who recently replaced Mr. Cabrera, Mr. Morales said. The commissioners who voted for it can’t find out what the study shows until she releases it – and she may not even know it’s there for her review. Slow traffic indeed.

For that study, the mayor was told to list existing speed limits on all county-maintained residential roads in unincorporated areas. She was also to offer a plan to put the lower speed limits into effect, including the costs and available funding.

Without the study – or a new one covering the same ground for lowering limits to 20 instead of 25 – a move to lower speed limits would be like driving blindfolded.

But even with the 2024 study, or a new one for 20 miles per hour, two other vital considerations would be missing from any directive to facilitate the lowering of speed limits around the county.

First, what would eliminating cut-through traffic mean to the broader aim of adding to and speeding mobility? It’s fine to say just add mass transit to increase mobility as lower speed limits reduce it, but adding transit takes decades while traffic speeds could be lowered in months.

What’s the impact in the interim? How much slower would commutes be as more cut-through drivers return to main roadways?

Second, how do we ensure that a lower speed limit equates to slower driving? Rushed drivers may ignore slower posted limits without a missing deterrent in the equation: more local policing. 

Adding police cost money, a cost to be calculated in a countywide ability to lower speed limits. Without teeth, lowering speed limits is just a wish.

Other methods of trying to slow or deter neighborhood traffic like adding roundabouts and speed bumps have been spreading. They do force most drivers to slow down – though Ms. Regalado told the Transportation Committee that Google Maps doesn’t consider those devices in recommending neighborhood cut-throughs.

The solution to driving too fast, or too frequently, in residential neighborhoods is complex and can’t be taken in isolation via a quick vote to let all residential areas just lower speeds to 20 at will.

We’d all like to solve transportation dilemmas with a simple vote to let every area do what it wants to do. But in the end, that’s likely to be self-defeating as we try to add vital mobility.