Why do highways, like the West Loop in Houston which I had the "pleasure" of driving in last week (and where I took that picture, because it was slow enough for me to actually snap a picture), back up? It's not uncommon at all for highways to get congested even during non-peak hours, and yet hours, days, are wasted. We build these massive ten lane highways, and they just get backed up, with you being lucky if you can average 30 mph.
Hopefully you're not thinking "It's only because they don't have a mass transit system" because if you're thinking that, well, that's not quite right. (Note that the cities with the highest congestion do have what are considered to be top-notch transit systems)
First, congestion's main problem is people. Until they come out with self-driving (or at least semi-autonomous) cars that don't make human errors like humans do, or you suffer some sort of substantial population loss in the city, there will always be congestion.
Highways really only max out at around five lanes (not counting exiting/entrance lanes, HOV/HOT lanes, or frontage roads) effectively and no amount of mass transit will erase congestion.
However, the popular line of thinking along New Urbanists today is that highways cause congestion somehow. This is a corruption of induced demand theory, the corruption being that new developments will follow highways, fill it up, and making the freeway (or widening of it)'s net gain being zero. The actual ID theory is a little less than that, but this New Urbanist corruption is wrong as all get out, so keep reading.
The reality is of course, highways really are the most effective at reducing congestion, and even in the 1960s, the freeways (urban freeways especially) removed lots of surface street traffic and congestion.
With the same line of thinking, this can reach its logical conclusion that by removing highways, you remove congestion. Obviously this doesn't work this way, but those with tinfoil hats think differently.
The Katy Freeway was one of the most controversial highway widening projects ever, but the growth for the highway remained rather constant over time. Houston was booming in the 1960s and 1970s, and even by the 1960s, there was development (with department stores and hotels) some 12 miles outside of downtown, and further developments into the 2000s brought further development as it slowly became the "Energy Corridor", and the town of Katy began to grow far beyond its original borders (a lot of this rapid growth took place in the 1990s). However, during all this time, the highway hadn't been substantially upgraded in years, save for a reversible HOV lane installed in 1984.
For a different example, in the 1970s and 1980s, bypasses were installed in College Station-Bryan (two cities some 90 miles northwest of Houston) and Navasota (a smaller town south of it). The bypasses were functional four-lane highways and even included frontage roads. However, oddly enough, it didn't "induce demand". I talked about this in an old post over at the other blog, but it's important so it bears repeating.
A mall, a few subdivisions, and even a multi-story office building were added along the new bypass in the early 1980s, but it never sucked any life out of the main stretch (Business 6) of town, where all the businesses were located. New stores in the late 1980s and early 1990s, like Target, H-E-B Pantry, Wal-Mart, and Albertsons ALL went for the main road. It wasn't until the 1990s where some big draws started building (Sam's Club, a large movie theater, Lowe's, Wal-Mart Supercenter). It wasn't even until the mid-2000s where hotels, supermarkets, and freeway-fronted restaurants were finally added, wherein the highway finally started to appear like other highways in the case that sprawl surrounded it, but that's because the growth naturally caught up to it as it was expanding anyway (and not even in the DIRECTION of the freeway).
That sort of thing happened in Navasota, but it's ignored because it blows their theory. In fact, despite some anecdotal evidence and observations, studies have shown that highways really do help congestion.
But since the whole "widening freeways causes sprawl" thing is a corruption of the original concept, the base theory still holds water since new lanes will tend to discourage using alternative transport.
In this case, "alternative transport" doesn't necessarily mean mass transit, it means non-freeway arteries.
Let's look at a Houston example of a congested stretch of highway.
The West Loop and the Destruction of Post Oak Road
The West Loop, in Houston, is constantly congested because 610 functions here as both a major loop highway used for commuting and the north-south artery it was originally. As a result, massive congestion, and it's been like that since the 1980s.
In the beginning, that road was Post Oak Road, a road that went from Hempstead Road (the highway that the Northwest Freeway bypassed, and we'll talk about that later) down to the Meyerland area (and beyond). That road was largely superseded by 610 since the road had a fairly wide median and the area wasn't nearly as developed as today.
Want to follow along Post Oak as it was originally? Well, you can't. It looks okay, even after the southbound starts becoming the 610 frontage road, until you realize that you have to turn right to keep following it (you can even see the wide ROW where it curved west), otherwise, the frontage road will either merge south on 610 or force you back onto Hidalgo, which will intersect with Post Oak. Only then by continuing south you can eventually continue on Post Oak as it was meant to go, but only after several miles of playing the role of the 610 frontage road, which involves dealing with cars constantly exiting and entering at relatively high speeds.
That's best case scenario. Following it north would be a harder problem, because just going north means you'll end up as the 610 frontage road that will completely bypass Post Oak, you'd need to turn left on Richmond (a major east-west road in the Uptown area--the source for the northbound Post Oak is coming from the Westpark Tollway), then continue north on Post Oak, then cross under the freeway again to go north, then go back across at Memorial. That's not at all an acceptable north-south route, and the only other viable north-south viable in the neighborhood is Sage, which is a two-lane road. It can't be widened because it's surrounded by million-dollar homes on both sides.
In fact, the whole thing is an IMPROVEMENT from the way Post Oak was chopped up originally, as prior to the Westpark Tollway c. 2004, the southbound Post Oak went straight into the westbound US-59 frontage road.
The real rub comes in the fact in the years since Uptown started to develop and densify, the neighborhood blocked any attempt to improve traffic, the only thing allowed was rebuilding the exits and entrances. This included widening the freeway, double-decking it, and creating a new north-south arterial, the "Uptown Parkway" (from a defeated late 1980s/early 1990s proposal), which ran into problems because it was to go through the Memorial Park area, though the part of the park in question wasn't really accessible and the park suffered great damage in the 2011 drought anyway.
The West Loop has a great many uses, but a replacement north-south arterial to connect parts of the city it is not.
Parkways and Other Arterials
Likewise, it's the same reason why highways out to the suburbs clog up because that is usually the only effective way to go, and a north-south grid doesn't exist yet. It's not for lack of trying--there's a Kirby Drive in Pearland that would go theoretically go the distance to the 15 miles inside the city where the main Kirby Drive is. Same with Bellaire, such a latitudinal line extends out to the vast sprawl of Katy.
There are some problems with this, even decades after they were conceived, there's still gaps in the system, namely for Kirby and Bellaire.
Holmes Road & Airport Blvd. (~1.8 miles)
North of Orem Road (~500 meters)
Between the "City Park" development and Beltway 8 (~1.6 miles)
So you'd still need around 4 miles of road that hasn't been built yet. That's the first problem. The second problem is that the southern Kirby parts actually built (basically south of Holmes Road) are not meant for major arterials. Sure, there's a pretty nice intersection built up for Kirby at Beltway 8 but the actually built segments were built for funneling people out of subdivisions (which, admittedly, is what they do a good job of doing) but would be a poor arterial that would be a good way up to downtown that would avoid the highways).
Bellaire, likewise, is also missing segments.
As discussed last time, did the Claiborne Expressway kill the neighborhood? No. I'm afraid that accusation is (largely) a bunch of New Urbanist bullshit. However, it did do something wrong by essentially killing the businesses along the road. When you have an elevated highway, you can't see a thing when driving, so the solution is to put up lots of high-mast signs for gas stations, hotels, and other stores. This subjectively looks pretty ugly, but it ensures success (at least longevity) for roadside businesses and by extension, the neighborhood. Unfortunately, that's also the fastest way to kill off buildings you might want to be saved.
In that case, the best thing to do from even a 1960s P.O.V. is to slice through a neighborhood and forget the original highway or "main road". While New Urbanists might like the fact that I agree that the Claiborne shouldn't have been built, they would go bald in horror that I suggest a freeway cut through a neighborhood. Here's why:
First, it's not as controversial as you think. In Houston, Interstate 10 (the central section) cut through neighborhoods. The result isn't pretty (see the "Built Before Freeways" photo), but where that highway actually cut through, 75% polled felt that the positive benefits of the freeway outweighed the negative. Even the controversial Harrisburg Freeway had a surprisingly good approval rating.
That doesn't mean it's not controversial and wouldn't suck for those in the immediate area, but there has to be a corridor created somehow (because land use doesn't stay the same forever), and that would involve demolition.
Secondly, it leaves the original road open as an arterial, and a way for businesses to continue. Hempstead Road allows for a true relief corridor since it was bypassed by Northwest Freeway, and it continues to have shops, restaurants, and other mid-century buildings (many not doing so well, sadly, but that's just natural decline), just as it did before the freeway. Unfortunately, not all of Hempstead Road is open and drivable, the main continuous segment only really starts at the Beltway.
But these arterials have a lot of traffic on them as well, and has more stoplights than you can shake a stick at, only having a real use when congestion would be bad otherwise. That's why any city could use more parkways, another tool in the "alternative transport" toolbox that's not mass transit.
The best types of arterials that would actually help congestion are parkways (see the Uptown Parkway example above), which, in general, have lower speeds, not built to expensive freeway standards, and often no trucks but they also have other features, including being surrounded by parkland (no commercial blight here), no driveways (that's where things get slowed down), and few stoplights. Unfortunately, since parkways have tended to fall out of favor as freeways were put into practice, and they cannot be retrofitted into the urban fabric, that's really not an option anymore. Parkways were also the hallmark of the Robert Moses era and went down with his reputation.
While Robert Moses-type parkways don't exist anymore, examples could be found in non-limited access highways that have high speed limits (60 mph) and just a smattering of turns and stoplights. Care should be taken to preserve them as parkways by limiting the residential and businesses off of them or just convert them to freeways.
The lesson to learn here is that expanding highways doesn't make a whole lot of sense COMPARED TO strengthening major arterials, and dual uses should NEVER be allowed. Don't allow a highway to make up for an arterial that was lost (that's even in 1960s freeway literature. Don't allow a residential collector to become a major arterial, it will just encourage people to use the freeway.
And don't believe the nonsense that adding lanes causes congestion.
Do you get what I'm saying?
Please leave comments/questions/angry accusations that I over-generalized in some parts. Thanks!
EDIT: Made some changes to be less harsh