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Commentary: Why do people on bikes run red lights and stop signs?

This article first appeared in the St. Louis Beacon, Feb. 26, 2013 - One of the most common complaints car drivers have about people riding bicycles in traffic is that they often run red lights and stop signs. Yet many Missouri residents are unaware of what is commonly referred to as the “dead red law.” This law permits people on bicycles to advance through a red light, after coming to a complete stop and ascertaining safety, if the “traffic control signal continues to show a red light for an unreasonable time.”

At certain intersections, this law is essential for bicycles to continue on their path; many lights remain red until sensors are activated that prompt the light to change. It can be difficult or impossible for a bicycle to trip these sensors, thus the red light remains until a car arrives. While the dead red law obviously benefits those who ride bicycles, it is in the best interests of car drivers as well. If someone on a bicycle is at the front of the line at a red light that does not detect him or her, everyone will be held up for a very long time.

When it comes to stop signs, we can probably all agree that St. Louis has plenty. With stop signs on most neighborhood corners, it unfortunately becomes easy to take them a little less seriously, no matter your mode of transportation. We are known in the region for the “St. Louis stop,” which is not a full stop at all, but rather a roll-through. Yet the truth is that while stop signs in St. Louis may be inconveniently abundant for all roadway users — it is illegal to disregard them, cyclists included.

Frequent stop signs are especially cumbersome to people on bicycles. To understand why, it helps to think of the energy involved. The average cyclist produces 100 watts of energy while riding 12.5 miles per hour, a comfortable speed for city riding. To maintain this speed on a roadway with stop signs every 300 feet, a cyclist must increase his or her energy production to 500 watts — a challenging feat even for elite athletes. Since most people riding bicycles cannot produce this much energy, stopping at all stop signs means reducing speed by about 40 percent (click here for an interesting, plain-language case study).

Abundant stop signs present a unique challenge to efficiency for people on bicycles. However, adjustments in laws can be made to remedy this, and make streets function better for all users. A prime example of policy reflecting the real needs of roadway users can be found in Idaho. A law was passed in 1982 that allows people on bicycles to yield at stop signs, instead of requiring them to come to a full stop (commonly referred to as the “Idaho Stop”). Yielding does entail slowing down and looking both ways, but also allows for maintaining enough momentum to prevent energy depletion.

Here is where the differences between travelling by bike and car must be considered: an individual on a bicycle not only travels more slowly than someone driving a car, but he or she also has a greater field of vision and can stop more quickly. These factors allow people on bicycles to yield safely at stop signs when there is no other traffic, and stop when a full stop is warranted.

Traffic engineers have found that it is difficult to get people using any mode of travel to comply with regulations and signs that feel unwarranted. For example, when a road is designed for people to drive 55 mph, a sign that says 25 mph will not be enough to slow traffic down, leading to unpredictable travel speeds. The Idaho Stop addresses the problem of unpredictability, and allows all roadway users to know what to expect from one another, decreasing dangerous encounters.

Many argue that if bicycles are to be considered vehicles, they need to be held to the same standards as motor vehicles. However, vehicles without motors have unique operating characteristics. People using bicycles are far more vulnerable than those driving cars, yet still fall under the “vehicle” umbrella. A car is made of about 2,000 pounds of metal, moves between 20 and 40 miles an hour or more, and surrounds and protects the driver. A bike, on the other hand, weighs an average of 30 pounds, moves at about 12 miles an hour, and leaves the biker exposed. It’s imperative to bear in mind these differences in mass and speed when considering how all vehicles share the road, especially at intersections.