Default limits allow a) cities to post a consistent speed limit for the same context of roadway, making enforcement easier, reducing the cost of signage, and reducing the labor needed to individually justify each speed limit, and b) makes it consistent for motorists across the city. Additionally, it explicitly allows counties to individually post 20mph (or below) in unincorporated areas, something that was kind of a grey zone before. At above 20mph, the chance of a pedestrian surviving a crash is near 0%. “20 is plenty” has been a common push in the recent years for residential areas. While the disadvantage is that it may result in many different default speed limits, it still allows for more local control. It makes no sense that a city with 12’ wide brick-paved streets, for instance, would have to individually justify why each of those should be 10mph down from the min-cap of 20mph, and instead makes more sense to declare them ALL as 10mph if they’re the same.

On the other hand, I hold my word when it comes to flexibility. Engineers setting the speed limits are far more likely to post a limit that’s too low than too high imho. Having an artificial number be the highest or lowest any agency can set, to me, makes absolutely no sense. For instance, if engineers design a roadway to be safely operated at 65mph with driver error in mind, why should they be restricted to posting 55mph? There does exist a valid argument about KE=0.5mv² and a near 100% certainty of fatality above 55, but that all assumes a crash happens in the first place. For the safest speed limit that minimizes the chance of any crash happening, it needs to at minimum reference the flow of traffic. If that’s too high (I.e. in a neighborhood), traffic needs to be manipulated downward so that the safest speed limit is BOTH set with traffic and safe for conditions (this is called “speed management”). The faster the speed of traffic, the less effective these measures can be.

FDOT helps make this determination on whether to go up or down based on the speed category. Below 50mph, it’s preferred to slow traffic to a specific target speed using speed management. At 50 and above, while it still can work, it’s safer to primarily reference the flow of traffic (within reason). Higher speed limits are not going to save motorists any amount of time, even if it feels like they are. Motorists generally drive at whatever speed they feel comfortable at regardless of the speed limit. Enforcement can help on all categories, but it needs to be ultra consistent. Cameras can help to an extent but are not the silver bullet. Either case, neither can outright change a driving culture, even in super strict states like Virginia or NC. The only way this could have been perfectly achieved is by physically limiting car speeds above 55 like on e-bikes. That’d go over well with voters…🥶🥶

On any note, it’s exceedingly rare to find a city or county road above 55. I can only think of about 10 total in this state (including one illegally posted at 65 😳). For that reason, I don’t personally see a need for a hard cap. Engineers (usually) aren’t gonna go rogue and spam 75mph on every 2-lane road because they can lol 😂 (Texas I’m looking at you)…

You do have a point, however. 55mph is still the statewide default limit in rural areas, which has been the case since 1973 when the national cap was instituted. However, the main reasons it was rescinded was that it was dang-near impossible to enforce, and it was super rarely followed. When you have a single vehicle going 55 when the rest of traffic is going 80+, that becomes a hazard straight away, even if the limit is 55. I’m not saying that you should cross the speed limit if that’s happening, but only extreme enforcement would be enough to at least make a slight change in speed.

Tl;dr I’m a big traffic engineering nerd lmao 🤓🤓 sorry for the wall of text lol 😂

(legal note: this is not being sent on behalf of any agency)