As I wrote yesterday, we have trucks and buses for highways, feet and pushcarts for streets, and pickup trucks for country roads. A lot of the problems we have come from people using trucks and buses on streets.
One common workaround is to create hybrid vehicles that can operate on some combination of highways, streets and country roads. Panel trucks, sedans, sport-utility vehicles and pretty much any vehicle that I didn't mention in the previous paragraphs are examples. Even bicycles. Versatility is good, right? Well, most of these vehicles aren't actually all that versatile. Cars and trucks of all sizes still disrupt street life. Fast cars and trucks disrupt country roads. Bicycles, compact cars and pushcarts can disrupt highways.
Some of this comes from my Law of Transportation Mode Inertia: people in cars tend to stay in cars. Beyond that, there's another widely observed law of inertia: that people driving at high speeds tend to want to keep driving at high speeds. As long as we have connections between highways, streets and country roads, people are going to keep driving big trucks, buses and other dangerous vehicles on the streets. They will slow down, but not as much as they should. They will keep pushing and pushing the envelope, and it will take all our efforts to beat them back. Is that really what we want to do with our time?
Another workaround is to build hybrid ways that have some of the features of streets, highways and country roads. Chuck Marohn calls these "stroads," and he's talked a lot about how wasteful and dangerous they are. They're all over America, and they satisfy no one. In fact, the Strong Towns approach is to undo those hybrid stroads, by examining each one and deciding whether we want it to be a road or a street (or maybe a country road). If we want it to be a road, we close off the driveways and intersections and make it into a limited-access highway, as proposed by New Jersey Future for Route 1. If we want it to be a street, we add intersections and pedestrian infrastructure, institute traffic calming measures and encourage walkable businesses. If we want it to be a country road, we depave it to gravel or dirt - as many governments are doing anyway, for financial reasons.
Depaving country roads to gravel also helps with the problems of hybrid vehicles. It's a big help in getting cars and trucks to slow down, and it saves money too. On streets, some have tried or suggested restoring cobblestone or Belgian block surfaces for the same reasons; Hoboken is planning this.
The best solution is one that Chuck only hints at in his critique of "forgiving design": roads can be railroads. What if we had no bus bigger than a 30-passenger cutaway, and no truck bigger than a pickup? Everything else has to go by train.
One of the biggest safety features of railroads is their predictability: trains very rarely leave their tracks, unlike steered vehicles. If we keep the big loads and fast trips on trains, then they can't come barreling down our streets and country roads when we least expect them.
Trains also take care of the problem of driver inertia. Instead of an amateur driver rushing off the Interstate with his or her head full of speed, or a stroad driver enraged by stop-and-go traffic, the average pedestrian would encounter nothing but country drivers on gravel roads and local drivers on Belgian blocks. With no highways to drive on, people would buy cars for durability and efficiency, not speed - and probably less people would even buy cars.
Obviously, this is a long way from what we have now, but we have to keep imagining a better world.