A cracked bike helmet didn’t save your life

You see these stories in the news all the time. A bicyclist gets hit by a car and suffers a major head injury. It could have been much worse, we are told, but thankfully he was wearing a helmet. A shattered bike helmet is shown, with the implication that this could have happened to his skull:

While pictures like this are scary and dramatic, they are actually further evidence that bike helmets are ineffective. This helmet did not function in the way it was intended. In fact, it failed spectacularly.

Let’s review the physics of a bike helmet. They are constructed out of polystyrene foam (styrofoam) which is supposed to compress in a collision. This compression spreads the force out and reduces the acceleration of the brain as it smashes into the inside of the skull. At least that is how it is supposed to work — under ideal laboratory conditions where the impact force is perpendicular to the helmet. Actual collisions are chaotic events involving complex interactions. When subject to an oblique impact, the styrofoam will typically crack and break off without compressing. This is what appears to have occurred in the helmet shown above. If there is no compression, then it is unlikely the helmet absorbed the impact.

What is unfortunate about these kinds of news stories is that they give false hope about the effectiveness of bike helmets. And rarely do these stories ever mention the dangerous road infrastructure that caused the crash to happen in the first place.

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Even after they’ve been repealed, mandatory helmet laws discourage cycling

We all know that mandatory helmet laws discourage cycling. But even after such laws are repealed, the effects can linger:

The city of Dallas has decided that Edward Adkins doesn’t need a bicycle helmet or a bogus fine and arrest warrant hanging over his head.

Adkins received a $10 ticket for failing to wear a bicycle helmet in September 2014, even though the Dallas City Council had changed the city’s safety ordinance months earlier to only apply to minors. Adkins said he couldn’t afford the ticket, which caused the fine to balloon to $259 and turn into a warrant for his arrest.

Adkins said he didn’t show up to court because he didn’t have the money to pay and thought he was guilty. He didn’t know the law didn’t require him to wear a helmet until a reporter told him.

He ended up giving away his bicycle because he didn’t want to pay for a helmet.

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Self-driving cars are not a solution to housing affordability

Palo Alto Mayor Patrick Burt has come up with the solution for the lack of housing in Silicon Valley: workers living in self-driving cars as they endure 2-hour commutes:

Burt:   Our TMA is moving towards reducing the number of trips 30 percent. We can have shared, autonomous vehicles powered by carbon-free electricity.

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NTSB investigates a bicycle crash

The NTSB has taken the highly unusual step of actually investigating a bicycle crash:

The National Transportation Safety Board is investigating the Kalamazoo bicycle crash that killed five people and injured four.

Officials with the NTSB confirmed Friday the agency is investigating the crash, and said its team already is in Kalamazoo.

NTSB spokesman Eric Weiss said the team will look at all aspects of the incident, including how it happened and how the truck hit the bicyclists. He said the team will reconstruct the crash and find out if there are any safety issues that could be improved, from the vehicles involved to the road.

Weiss said the NTSB is investigating because the agency has taken an interest in the case, and not at the request of local authorities.

“This is such a singular event that we wanted to look at the issues behind it,” said Weiss, who acknowledged it’s unusual for the NTSB to investigate crashes involving bicycles.

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Caltrans loses another crosswalk lawsuit

A jury has just award $9.5 million in damages to the family of a man struck and killed in a crosswalk on El Camino:

Caltrans was aware of studies discouraging the marking of crosswalks in busy uncontrolled intersections and was aware of accidents elsewhere along El Camino. But Caltrans refuses to remedy any particular crosswalk until someone has been killed or injured in that location.

This was not the only lawsuit over the lack of pedestrian safety on El Camino. A court awarded $8 million to the family of Emily Liou, a 17-year-old who was struck in a crosswalk on El Camino in Millbrae.

El Camino is notorious for having a large number pedestrian fatalities and injuries. So if this keeps up, it is going to get prohibitively expensive for Caltrans to continue its inaction on ped safety.

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