[takk309]

Traffic engineer here. Generally there is a hierarchy of roads called functional class. It goes local street - collector - minor arterial - major arterial - freeway. From local to freeway the speeds increase and the land access decreases. Good urban design should connect only roads one "step" apart, that is local roads should only connect to collectors and so forth. Reality is clearly different.

I would imagine everyone can think of a local road that is more convenient than another route therefore attracting high traffic volumes. These roads become problematic without improving the proper route. The other side of the coin is an arterial that is built but too many accesses are allowed to connect to it. In my home town this has happened when the city council caved to developers and allowed residential construction on a major arterial because nobody wanted to build commercial developments at the time. Jump ahead 10 years and there is now a strange neighborhood with driveways directly on the busiest street in town.

Changing roads is very tricky due to the funding sources. Usually local roads are only eligible for local funding where as arterials are eligible for federal funding. There are exceptions and it is much more nuanced than can be explained in one paragraph.

[PaulDavisThe1st]

> Generally there is a hierarchy of roads called functional class. It goes local street - collector - minor arterial - major arterial - freeway.

This heirarchy seems to miss the importance distinction that Strong Towns makes between a "street" and a "road", in that "streets" are places where human life takes place, and "roads" are how vehicles move rapidly from place to place. It has only category with the word "street" literally present, and then moves immediately to other things whose relationship to the street/road distinction is unclear. This is a problem because streets include those that are purely residental as well as those with retail etc.

[takk309]

You are correct. The old way of thinking about roads/streets (synonyms in this case) is a place to move cars. The people centric view on transportation is new enough that there isn't much traction among the old guard at state DOTs. Changing something like functional class and what it means is very hard due to decades of history. As the saying goes, old dogs can't learn new tricks. This is especially true for government agencies. I have worked with cities that have a strong desire to make their transportation network people centric but the state won't help pay for it because the concepts don't move enough cars and to them, that is all that matters.

[mcv]

Exactly. Ideally, only the street should have real street functionality (houses and shops directly accessible from the street). Maybe the collector too; it's meant to have many streets connecting to it, so access to car parks for shops makes a lot of sense there too. But anything arterial should just be about getting people from one end to the other as smoothly as possible.

There's one more category that's often ignored in this list: the rural road. There, the functions can mix without any problems, but only because of its very low density and low use; very little traffic means you can still cross the road easily, and have time to turn into drive ways and things like that without hindering anyone.

[TulliusCicero]

> Usually local roads are only eligible for local funding where as arterials are eligible for federal funding.

This is part of the problem. Want to build infrastructure to support walking or biking or transit? Fill out a grant, maaayyyybe the feds will help.

Want to build a highway that'll be used as a local road because the area is super low density? Excellent! *Uncle Sam's wallet instantly flies open*

[Aloha]

Thank you for the informative post!

I'll actually defend the stroad, they work fine so long as you don't allow parking, and you limit the driveways to 2-3 per "block" - anything more than that and they cease to function as an street or a road. Often the stroad is just a section with a bunch of businesses on an otherwise well designed arterial road.

The pictures they post of supposed stroads look like normal arterials to me.

[adgjlsfhk1]

The problem with 3 driveways per block is you've just made a really low density set of stores. This means that you massively increase the average distance someone has to travel to get to the store they want. One of the main reasons to separate streets and roads is that it encourages tightly packed small shops which (especially when combined with mixed zoning) create low average travel distances. Lower travel distances mean fewer cars on the road (cause more stuff is in walking/biking distance) and therefore lower traffic.

[TulliusCicero]

> The pictures they post of supposed stroads look like normal arterials to me.

That's because in America, most arterials are stroads. We've gotten used to bad infrastructure.

And yeah it works on some level, sure. American businesses still manage to function, people still manage to do things. But there are a number of major downsides still.

[aidenn0]

Where I live there's a diamond interchange between two state highways controlled only by stop-signs at the end of the off-ramps towards the smaller of the two.

Near that interchange there is a neighborhood. For whatever reason, both sides of the neighborhood have traffic lights, so when traffic is heavy, if you want to go from the larger to smaller highway (particularly if you want to turn left!), it's far more expedient to cut through the neighborhood.

[throwaway0a5e]

>Changing roads is very tricky due to the funding sources. Usually local roads are only eligible for local funding where as arterials are eligible for federal funding. There are exceptions and it is much more nuanced than can be explained in one paragraph.

Don't get me started on all the perfectly functional things they screw up because some jerk central planner in DC wrote a spec based on national averages.