Interesting infrastructure - Tactile paving, triangular slip base and bridge protective assembly

Today I will talking about transportation infrastructure, and I’ve taken some photos of things that you might find interesting. Here they are if you want to take a guess before I say what they are.

This first one is an easy one - these are some photos I took of a sidewalk.

Notice the bumpy bricks on all of the ramps?

These are required on sidewalk ramps in the U.S. by the Americans with Disabilities Act, but they’re not for traction like many people Think.

These are called tactile paving, and their purpose is to help people with visual disabilities delineate the boundary between sidewalk and road, detectable warnings for people who might not otherwise be able to identify a potential Hazard.

Tactile paving isn’t just found in the U.S. Lots of other countries have detectable warnings for all kinds of hazards, including subway lines, steep grades, stairs, and of course, road crossings.


They often have a contrasting color so they’re easy to identify, and many use a very recognizable texture called truncated domes.

This next one is a little bit tougher. This is a road sign I photographed while I was sitting at a red light.

Take a look at the bottom of the post. There’s something interesting going on there. This is a triangular slip base, one of many types of breakaway sign post systems.

In the U.S., signs located near the roadway are required to easily break away if struck by a vehicle. A lot of people think this is a cost saving measure, so a new sign can be easily installed without digging a new hole. But the real reason for the breakaway design is safety. A well-anchored metal pole can be extremely dangerous during a high-speed car accident.

If an errant vehicle hits a sign that doesn’t break away, the narrow pole can pass through most parts of a car like butter.

Engineers have found that it’s much safer for signs to easily break off when hit, getting them out of the way of the accident before they can be a hazard.

This last one is something that may only be in Texas. I’ve never seen it in another state. This is a photo of an overpass bridge, but notice underneath the clearance height sign, there’s some kind of galvanized bracket.

This is called a bridge protective assembly. These are extremely common on bridges in Texas. Their purpose is to protect the first beam from an over-height vehicle impact.

If a truck carrying something too tall tries to drive under a bridge, the impact can cause serious problems. Most concrete bridge beams have almost all of their reinforcing steel at the bottom.

If the reinforcement is damaged, the strength is significantly reduced. So bridges with the highest potential to be impacted by an overweight vehicle usually have some protection.

This bracket actually hangs from above with a layer of energy absorbing material between it and the beam. The goal is to reduce the vibration associated with an impact to hopefully minimize the damage to the structure.

After a little research, I found that Texas is phasing out the bridge protective assembly in favor a protective wrap of carbon fiber, which is apparently much more effective. Do the bridges in your state or country have protection against over-height vehicle impacts. Or do you have some other piece of infrastructure in your hometown that you think is unique or interesting. Maybe you walk by something every day and have just always wondered what it is. I love infrastructure, and I want to show others how interesting it can be.