Reading List for 05/17/2025
The “Safe System” of road design, a manufactured “superwood”, concrete sphere batteries, Tesla’s insurance arm, the University of Nebraska’s drought monitor, and more.
Welcome to the reading list, a weekly roundup of news and links related to buildings, infrastructure, and industrial technology. This week we look at the “Safe System” of road design, a manufactured “superwood”, concrete sphere batteries, Tesla’s insurance arm, the University of Nebraska’s drought monitor, and more. Roughly 2/3rds of the reading list is paywalled, so for full access become a paid subscriber.
The “Safe System” of road design
Asterisk has an interesting article on the “Safe System” of road design that’s widely used in other countries to make roads safer and reduce traffic fatalities. The US, which has not widely adopted such a system, ranks 87th in the world in traffic deaths per capita. It does slightly better in traffic deaths per billion vehicle miles, but still not great. The system seems to be a combination of reducing vehicle speeds (either by changing the posted speed limit or via other design changes, like narrowing roadways) and building roads in such a way that “they’re safe when used intuitively”. The article describes a few of these interventions:
The U.S. model typically encourages wide lanes and corners to increase driver visibility, but this has the unintended consequence of encouraging cars to go through intersections faster, and thereby decreasing the peripheral vision they might have retained at a slower speed. Instead, the Safe System intersection is designed to limit car speed and facilitate eye contact between users. It does so by expanding pedestrian areas via curb extensions or bumpouts, narrowing crosswalks, and removing parking within 20-25 feet of an intersection. The crosswalks and narrowing of the lanes encourages cars to slow and to stop well ahead of the crosswalk, while bumpouts shorten the distance pedestrians must be in the road.
A report from Johns Hopkins on the system describes a few more of the interventions:
Specific design changes in a Safe System include:
Lane reductions, on some multi-lane roads where pedestrians and bicyclists are present, that help slow vehicles and give drivers more time to react
Flashing beacons that alert drivers to pedestrian crosswalks
Roundabouts that slow traffic through dangerous intersections and prevent deadly side-impact collisions
Median barriers that, when used on some rural divided highways, reduce head-on collisions
I also thought the design of these “2+1 roads” in Sweden was clever:
Sweden developed 2+1 roads, a three lane road where two lanes run in one direction and one in the other, alternating every few kilometers, separated by a cable barrier. The barrier reduces head-on collisions, but still permits faster drivers to overtake slower ones — without having to clear space for a full highway. Rural highways where 2+1 roads were installed saw a 79% reduction in fatalities between 1998 and 2007 compared to those that did not. Crucially, they were relatively inexpensive to install.
New York congestion pricing
In other roadway news, the New York Times has a good overview of the changes that have resulted since congestion pricing (charging vehicles to enter Manhattan during high-traffic hours) was instituted in January.
Almost immediately after the tolls went into effect Jan. 5 — charging most vehicles $9 to enter Manhattan from 60th Street south to the Battery — they began to alter traffic patterns, commuter behavior, transit service, even the sound of gridlock and the on-time arrival of school buses.
Evidence has mounted that the program so far is achieving its two main goals — reducing congestion and raising revenue for transit improvements — even as the federal government has ramped up pressure to halt it. In March, the tolls raised $45 million in net revenue, putting the program on track to generate roughly $500 million in its first year.
It’s interesting that public opinion is still apparently not great: I had gotten the impression (probably by spending too much time online around urbanist folks) that it was unpopular initially but then became popular once the benefits started appearing. But less than 50% of New Yorkers surveyed want to keep the program.
Superwood
A popular direction for materials-related academic research is to try and make an improved version of wood. Announcements of “breakthroughs” on transparent wood, for instance, are very common. I think in general it’s unlikely for these sorts of academic research announcements to ultimately progress outside of the lab, and it’s especially unlikely for materials-related research: it’s one thing to develop a material with some interesting properties in a lab, it’s another thing entirely to turn that into a competitive product that can be produced cheaply and in large volumes.
But here’s an improved version of wood that has at least developed to the point of trying to compete in the market. Via TechCrunch:
In 2018, Liangbing Hu, a materials scientist at the University of Maryland, devised a way to turn ordinary wood into a material stronger than steel. It seemed like yet another headline-grabbing discovery that wouldn’t make it out of the lab.
“All these people came to him,” said Alex Lau, CEO of InventWood, “He’s like, OK, this is amazing, but I’m a university professor. I don’t know quite what to do about it.”
Rather than give up, Hu spent the next few years refining the technology, reducing the time it took to make the material from more than a week to a few hours. Soon, it was ready to commercialize, and he licensed the technology to InventWood.
Now, the startup’s first batches of Superwood will be produced starting this summer.
Per the article, Superwood is made by treating wood with “food industry” chemicals and then compressing it, increasing its strength by roughly a factor of 10. The company plans to start by making durable facade materials, but eventually make engineered structural lumber elements by chopping the wood into chips and gluing it into the proper shape, like OSB or LSL. Wood this strong would be a genuinely impressive development, especially if they can get its costs down, so I’ll be keeping an eye on this.
Concrete sphere batteries
Here’s an interesting concept for an energy storage system that I hadn’t seen before. Make a hollow concrete sphere with a hole in it, and a turbine mounted in the hole. Drop the sphere into the ocean, and let it fill up with water. To “charge” the battery, use the turbine to pump water out of the sphere, and then close the hole, leaving a vacuum inside. To discharge it, let the water flow back in, driving the turbine in the process. It’s essentially a pumped hydro storage system, but under the water rather than on land.
It’s called the “StEnSea System” (Stored Energy in the Sea), and the Fraunhofer research institute in Germany is developing a prototype of it. Via Water Power magazine:
The StEnSea (Stored Energy in Sea) project has been in development since 2012. Fraunhofer IEE is working with US start-up Sperra, which specialises in 3D concrete printing for applications in the field of renewable energies, along with Pleuger Industries. This German company, headquartered in Miami, manufactures underwater motor pumps, a key component of the StEnSea spherical storage. The partners have selected a coastal area off Long Beach near Los Angeles as the storage site and plan to put it into operation by the end of 2026 at the latest.
The StEnSea project will anchor a hollow, 400-ton concrete sphere with a diameter of 9m at a depth of 500-600m. By emptying the sphere, the storage is charged. When water flows in, electricity is generated, and it is discharged. The power of this prototype is 0.5MW with a capacity of 0.4MWh.
It’s a cool concept, but it’s not clear how realistic it is. Some back of the envelope material cost estimates suggest it’s not obviously infeasible, but the challenge will be cost-effectively installing it and keeping it operational in corrosive sea-water hundreds of meters below the surface.