Cars as far as the eye can see, you roll forward 10 feet and stop right on the car’s bumper in front of you. As you approach 15 minutes straight with various degrees of pressure on your brakes, you finally snap – “F@RT!” We have all been there. No one likes traffic, some people just deal with it better than others – for the 58% of Americans that live in large cities, it is a real problem. In my lifetime it seems like not much has been done to fix it – maybe make a new lane here, add a stoplight there, but nothing game changing. Is this all we can do?
Back in high school my friend Tony and I sat in traffic a lot as we had over an hour drive to the other side of LA for our club volleyball practice. He pondered “what if everyone who is sitting in traffic only thought about ways to solve traffic? Would we find a solution?” I’m not sure, but I do know it is a problem worth solving – millions of productive person-hours are wasted in cities across the world by needlessly sitting in cars that aren’t moving.
The hillbillies will say “how about you just move out of the city? If we just make smaller cities we don’t have this problem.” Bad solution – cities lower pollution, raise production, result in higher pay, have more culture, and encourage ambition. So back to the drawing board.
One of the biggest contributors are traffic signals – they make you sit and wait for your turn. How can this be improved? Let me present some of the thinking that has been done over the years. The biggest improvement that can be made is to eliminate left turns. This would allow us to go from a 4 cycle stop light to only 2. San Francisco chooses to annoy people by simply not allowing left turns in some parts of the city – you have to take three rights! I hope we can do better than this.
Over 50 years ago the Jughandle was introduced in New Jersey. On the West Coast this is commonly seen on freeway overpasses – rather than taking a left turn to get on the freeway, you take a right and go around a big banked 270 degree turn, passing under the road you were originally on (or stopping at the traffic light if there is not a bridge). Kind of confusing taking a right instead of a left, takes up a lot of space, but sometimes it is an improvement!
Around the same time in another part of the country the Michigan Left was introduced. Just like the Jersey Jughandle, you go past the intersection to make a left turn. Except this time you make it from the left lane (which is intuitive) and make a U-turn followed by a right turn when you get back to the intersection. I like this approach and Wikipedia indicates that it is starting to gain a little traction in various parts of the world. However, this requires significant space in the median, which is not always available.
Within the last 10 years an engineering student wrote a paper about a new kind of intersection: the Diverging Diamond Interchange. Is this going to finally be the answer? It looks pretty sweet, watch the video below for a simulation:
There are dozens of other possibilities, ranging from the absurd to a simple roundabout, but I’ll spare you the detailed analysis. From learning about all of these it is apparent we should standardize on a couple of approaches, lest we end up needing to watch dozens of videos like this one explaining a “continuous flow intersection”:
In conclusion, there is no one answer to this problem. There are dozens of possibilities, all with their pros and cons. The approach with the least congestion is to add another dimension to the equation – a bridge or tunnel. However this is not cost effective. Alternatively if we had unlimited space around the intersection, there are some very interesting things that can be designed. Or we could just take the UPS approach and optimize our driving by taking as many right turns as possible!
Main source: Don’t Turn Left!