Traffic engineering: does it really exist?

Why am I sitting at red lights at 3 in the morning? Why are there streets where I’m guaranteed to hit every red light for 7-8 blocks? Why do I watch extended left-turn signals with no turnees while streets in both directions back up with traffic?

Are cities working hard to maximize traffic flow? Is traffic engineering really making a difference? How widespread are their contributions? Is this a real science or a figment of my imagination?

Yes, hapaXL, there is a traffic engineer.

Traffic engineering is a subject I studied in engineering school, and though I didn’t go into it, I have worked with a number of professional traffic engineers.

Cities definately work hard to improve traffic flow, particularly where traffic flow affects air quality. New roads and intersections are designed only after careful traffic projection and modelling of traffic flow. The difference between a modern road design and an older road design can be significant.

One difficulty in optimizing traffic flow is cost, particularly in cities that have an existing road system. For each intersection, the municipality has to decide what traffic control devices to use. In a lower traffic area, it may simply not be cost-efficient to install traffic signals with sensors that provide a protected left-turn only when cars are waiting.

Moreover, traffic engineering is usually primarily concerned with traffic flow at peak periods, rather than at times of minimal traffic flow like 3 am.

Sometimes, you’ll hit red lights every block because the lights are poorly timed. On the other hand, sometimes you’ll hit a lot of lights in one direction because the traffic lights are optimized for traffic flow in the other direction. If there is a lot of peak-direction traffic one way at certain times (e.g. heading to downtown in the morning and away from downtown in the evening), traffic engineers will often set up a traffic light progression that will allow the heavier traffic to flow smoothly while burdening the lighter traffic in the other direction.

Traffic engineering can make a large difference, though because of limited resources it cannot make everything perfect for everyone.

Seattle is currently undergoing a transportation initiative by the mayor to synchronize and update traffic lights in the city. Apparently there hasn’t been funding for the last several years to update the traffic signals for current flow levels, and the mayor is trying to get re-elected, so he’s pledged a lot of funding to update the lights and move traffic along quicker.

Here’s a site giving info about the city’s program:

Also sometimes a route is intentionally slowed down to either limit traffic on it or to ease traffic on another road (the one that your’s feeds into)

Also, sometimes the traffic is intentially slowed in order for more and more cars to waste gasoline, thus requiring you to purchase more fuel more often, thus increasing state revenues via fuel taxes.

And late at night, the city’s special pot hole patrol sneaks around side streets making huge, gaping holes in the pavement in order to generate more tire & hubcap sales. :rolleyes: