That's an excellent and very specific question about urban design! Yes, many modern public benches in cities worldwide are specifically designed with features to prevent skateboarders from grinding on them. This practice falls under the broader category of "hostile architecture" or "defensive design," aimed at discouraging unintended uses of public furniture.
The most common feature is the addition of small, metal studs or knobs along the bench's prominent edges, especially the seat ledge and armrests. These are called "skate deterrents" or "skate stoppers." They are strategically placed to make the surface uneven and impractical for a skateboard truck to slide against, effectively stopping a grind before it starts. You'll often see these as discreet, low-profile attachments.
Another design approach is to eliminate the continuous, smooth ledge altogether. Many contemporary benches use segmented seating—individual seats with gaps or armrests dividing them—which removes the long, inviting rail that skateboarders seek. Benches are also increasingly being bolted directly to a concrete base or platform, leaving no gap underneath for tricks.
The intent from city planners is primarily maintenance and safety. Constant grinding can damage benches, wearing down materials, loosening bolts, and leading to costly repairs. There's also a liability concern regarding collisions between skateboarders and pedestrians. However, this design choice is often debated. Critics argue it makes public spaces less welcoming for everyone, particularly the homeless who might rest on benches, and that it pushes skateboarding—a legitimate sport and form of transportation—out of public view without providing alternative spaces.
So, while the classic, long, smooth marble or concrete bench is becoming rarer in high-traffic urban areas, its modern counterpart is often equipped with subtle features intended to preserve its primary function: providing a place to sit.