The old “adding capacity doesn’t work” argument well yes it does. What wouldn’t work is not doing anything. Making I-15 10-12 lanes is a good start. I see that project happening. I am worried the 710 won’t see the expansion happen. Traffic will still increase regardless and travel times will be worse off due to the expansion not happening.
There's ample documented evidence that adding capacity induces more people to drive and fills the available space, sometimes within months but usually within a few years. This is more true as you move further from city centers as more open land becomes developed.
The "evidence" that I've seen is often flawed by not taking into account several variables that could prove that the widenings did in fact improve traffic flow by showing not just the freeway section that was widened but traffic in the area such as local traffic or regional traffic. If induced demand real, why isn't the section of I-40 that was widened and opened to traffic here in OKC to the tune of 10 lanes around 7 years ago not bumper to bumper? I am sure that would have magically created new trips for people to go eat hot dogs at some store they wouldn't have otherwise, right? Or could it be the demand was already there? I'm not buying into the induced demand theory especially since it is only applied to road construction and no other industry. I never see people using that argument against transit expansion. People want to drive. Most people live in the suburbs. No one if forcing it. Blame good schools all you want, but it comes down the suburbs offer a superior choice of living and you aren't serving the low density(one of the main selling points of the suburbs and equates to more privacy)nature of suburbs with transit. Likewise, you have to build massive freeways through urban centers to give those people access to the city like anyone else. They and I haven every right to drive our cars into the city(I make it sound like I live in the suburbs but unfortunately I live in the heart of Hollywood) and have the adequate infrastructure to keep up with the demand to move at a reasonable pace.
Who are you or I to say that enough is enough because more people want this lifestyle? Saying a freeway has enough lanes? No. You keep adding lanes to keep up with demand. Build freeways smarter. Build expanded transit lines to give people an alternative. Great and I support it. But what I don't, is blocking expansion of freeways like the recent crap going on with the 710. Traffic will continue to get worse and air pollution will do the same. If the rail alternative will help with freight, than great. But let's not act like if the trucks were reduced through this area this freeway wouldn't need to be widened. It's like every other freeway in SoCal, it needs to be widened. I can't think of a single freeway in LA that doesn't need at least 3 additional lanes in each direction added other than maybe parts of SR-2 and the 210 freeway between Pasadena and Glendale. That section tends to keep flowing somewhat decent for the most part.
Then there are tons of extremely deficient interchanges like the 101 interchanges of the 405, 134, and the 170. Awful interchanges that if fixed could do wonders for traffic. Sprawl isn't going anywhere and most people don't want to live stacked over each other in concrete jungles. That is a fact of life you need to accept. Unless some law is made that goes against the will of the people, freeways and sprawl will likely continue to expand indefinitely and it's nothing more complex than growth. Call it induced demand all you want, but at the end of the day the freeway lacks capacity and simple math can determine the proper number of lanes needed to stop traffic back ups. Forcing, or if you want to put it nicely, 'encouraging' people to use transit isn't the way to go. Giving them the option to, I can get behind. There is a huge difference between the two. It isn't hard to figure out which category Portland, OR falls into.
You've seen what happened after the 405 widening was finished a few years ago. That's a textbook example of induced demand. Freeway widening only improves traffic if traffic volume doesn't increase, otherwise it's a Sisyphean game of catch-up. Los Angeles has reached a combination of sprawl, density, and political opposition that has made freeway widening mostly pointless. Even if they could double the capacity of all freeways, traffic would still just back up onto the major off-ramps near job centers. Adding extra lanes to the Santa Monica Freeway, for example, wouldn't make the 4th Street exit any less of a pain in the ass.
That being said, there are a few chokepoints, particularly at interchanges, that could stand to be improved. The Diamond Bar interchange is pretty high on that list. The multiple weird interchanges along the Ventura Freeway are also poorly designed given current traffic patterns.
There are several factors why the 405 hasn't seen much traffic relief, but that project did a lot of good. Removed over 25 percent of congested local traffic back onto the freeway or otherwise, shortened the rush hour window by 3+ hours or much more, I can't remember. If you want I'll go find the stats for that.
There are other things if you read my post I pointed out. Didn't factor or study any other corridor that would serve as a relief to the 405 for seeing a reduction in traffic. Didn't look at how many new potential cars would have been added as the the LA area saw a population increase from the time the project started to when it ended. They didn't use mathematics to determine the proper number of lanes that should be added. Simple math will give you that answer which obviously more lanes were needed than what was added and hopefully down the road we will see more lanes added here.
A subway will help and give people another option but won't do much to reduce traffic and doing nothing is not the answer, which telling people driving is bad and trying to encourage them to use alternative transportation by letting congestion reach nightmarish levels is doing nothing. But hey, it's cheaper for cities, so until drivers have enough and this bullshit, which I think will be soon, you'll have your way of freeway expansions slowing down around SoCal.
If they doubled the capacity of all freeways it do a world of good. Though you make good points that solutions are needed on the local level, but removing car lanes and adding bike lanes that few people use doesn't help. They need to get serious about building subways. This would be a rare situation where I'd agree with using funds produced from tolls on freeways or HOT/Express lanes provided that traffic flows are maintained to proper target levels which would include getting commuters to and from their entry and exit points traveling at least 50MPH on freeways at the worst traffic flow. Capacity can be increased at ramps and a new system of 6 lane elevated freeways over existing ones to accommodate that along with a minimum of 2 GP in each direction added every freeway.
Get the freeways flowing again and let people figure out the horrid traffic on local streets and then let them figure out a solution which most will realize new grade separated rail is best. However, that does not include neglecting needed car infrastructure like parking and added lanes where possible. As for bike infrastructure, again, I support it as long as it doesn't interfere with traffic flow much or any at all and needs to be kept to separated paths as much as possible.
Induced demand is such bullshit and no reason to not expand freeways. If any such thing exists, go tell the business owners who see new money due to widened freeways how bad they are. Shall I scream induced demand when new rail lines or expansions for rail are proposed?
I am sure we can at least agree that interchanges need to be replaced/modernized and rather quickly at that as widening freeways surely won't do a bit of good if there are continued bottlenecks along the routes. I think with bad driver habits along the stretch of the 405 Sepulveda pass that plague that freeway like drivers slowing down for seemingly no reason at all but in reality limited sight due to the hills, the 101 interchange is another big culprit. I don't know what can be done about the driver habits, but the 101 interchange needs a billion dollar overhaul and I don't see it happening anytime soon or just stupid improvements like adding lanes through it which, ironically enough, I DON'T think will help here.