By Jonny Lupsha, Wondrium Staff Writer
There are always potholes, despite the wonders of traffic engineering. Scientists have developed theories of traffic flow and have implemented several types of interchanges to accommodate, but potholes remain. A Florida man planted a tree in one.
The common, everyday pothole in the road has been a point of annoyance for drivers for what seems like forever. Swerving out of their way or aligning a car so the hole passes between its tires is as much a factor of driving as using a blinker. So what happens when a private street, which is business owners’ responsibilities rather than the city’s, keeps getting them?
One business owner in Fort Myers, Florida, got sick of filling potholes with cement. Instead, he planted a banana tree in one to warn other drivers, get a laugh, and maybe point out the ridiculousness of the situation.
It may be the oddest innovation in traffic engineering, but it’s not the only one. In his video series Everyday Engineering: Understanding the Marvels of Daily Life, Dr. Stephen Ressler, Professor Emeritus from the United States Military Academy at West Point, said that despite how chaotic it may seem on the road sometimes, traffic comes down to an exact science.
Traffic Engineers
“Traffic engineers apply the scientific study of traffic flow to the designs of roads, intersections, and traffic control,” Dr. Ressler said. “They’re principally responsible for the geometric design of intersections, sidewalks, crosswalks, and bike paths, as well as traffic control markings, signs, and signals.
“Traffic engineers are also extensively involved in conducting investigations to improve traffic safety.”
According to Dr. Ressler, these investigations often study past automobile crashes to determine if any locations are particularly hazardous. They also involve research on how improving and changing roads can minimize crashes, plus analysis on prioritizing future projects that will fix the most urgent problems at said locations.
What does it all add up to?
“The work of the traffic engineer […] specializes in facilitating the safe and efficient movement of vehicles and pedestrians within a road system,” Dr. Ressler said.
Traffic Terminology
Perhaps not surprisingly, traffic engineering comes with some associated lingo that professionals use to improve traffic safety. Traffic flow, Dr. Ressler said, is the hourly rate at which vehicles pass a specific point on a highway. It’s measured in vehicles per hour.
On the other hand, density refers to the number of vehicles on a certain length of highway at any given time, which is measured in vehicles per mile.
“[A] chart developed by a professional organization called the Transportation Research Board relates average vehicle speed to vehicle flow rate, measured in passenger cars per hour per lane, for six different levels of service,” he said. “The levels of service are defined with level A corresponding to totally free, unconstrained traffic flow and level F to your worst nightmare traffic jam.
“The six levels of service are actually defined in terms of traffic density.”
Service level A equates with a density of 11 vehicles or fewer per mile per lane. Higher density causes greater constraints on traffic flow, which means lower levels of service.
Finally, mean speed is defined as “the average speed of all vehicles passing a point on a highway within a specified period of time, measured in miles per hour,” according to Dr. Ressler.
“All three of these quantities are mathematically related by the equation ‘flow = density x speed.’ Note that the units in this equation work out consistently, as we would hope—vehicles per hour = vehicles per mile times miles per hour.”
The equation does not account, however, for banana trees in the road.