Most people don’t consider the work that goes into designing and building a safe road, but did you know everything is done with precision, and based on best practice studies?

Road signs are sized based on the speed limit of the road to ensure that drivers have adequate time and distance to read the critical information they provide. On interstates with curves, the road is required to have a certain angle to keep vehicles from pitching off the curve by their own inertia. There must also be signage indicating the risk at excessive speeds or for high-profile vehicles. Lane markers must have a specific amount of reflective material; there are even requirements for how often these things are maintained and replaced.

Even the naming of our roads is as methodical as your home address. There are three kinds of major roads: state highways, US highways, and interstate highways. Each is numbered independently from the other but in relation to their own kind, much like you might see county addressing and city addressing in the same relative area. Odd-numbered roads travel north and south. Even numbered roads go east and west. Interstate and state highway numbers increase “left to right” (west to east) and “down to up” (south to north) on the map. US highways increase the other way around.

This can be helpful if you know where one highway is and need to make an educated guess for which direction to look for another. The numbering system gets even more complex but very logical with regard to three-digit interstates around metro areas. Knowing these rules before travel can help you navigate a big city more smoothly.

There is one more trick that may help motorists. On every interstate in the country, a white dashed line divides each lane; that line is ten feet long and separated by thirty feet of paint-free asphalt. In other words, from the beginning of one line to the beginning of the next is forty feet. The next time you travel 75 mph on the interstate and look at those lines, you’ll think I’m steering you wrong, but it’s true. This can give you an idea of how fast you are moving and how impossible it is to slow down on time and avoid a dangerous collision if you are not providing adequate following distances.

Keep your eyes on the road, but when you can safely look, become familiar with estimating distances at 75 mph by using the lane line and the forty-foot measurement you can see.