The fourth and last part of The Death and Life Of Great American Cities discusses possible tactics to solve some of the problems she discusses. She opens by noting that city planning does not lack for tactics that are “aimed at carrying out strategic lunacies. Unfortunately, they are quite effective.” 
In many cases, the tactics are so simple, and so obvious, that they’re hardly worth discussing. Subsidize the kind of housing that people need, rather than luxury housing. Spend money supporting worthwhile neighborhoods instead of tearing them down and replacing them with boondoggle projects. The naivete of the book is charming in that she discusses these proposals in detail, as if the main obstacle to their implementation were a lack of understanding.
She makes some interesting points, for instance that limiting public-housing tenants to those below a certain income makes for an unpleasant place, because you remove everyone who’s successful from the environment. She suggests instead that when income is large enough, the apartment be deeded over to the tenant and the rent payment converted into a mortage (note that unlike a simple sliding rent scale this does not punish you for earning more money).
The chapter on the destruction of cities by automobiles is instructive, beginning with the question,
How much of the destruction wrought by automobiles on cities is really a response to transportation and traffic needs, and how much of it is owing to sheer disrespect for other city needs, uses and functions.
Surprisingly, she ridicules the idea of separating automobile and pedestrian traffic, saying that pedestrian-only zones are, of necessity, surrounded by dead zones of parking and access roads, and that limiting vehicular access is bad for businesses who need deliveries and such. Instead, she proposes balancing the uses so that streets “are not overwhelmed and dominated by floods of cars.”
The more you make cities amenable to cars, she says, the more you need cars. The more parking lots you build, the harder and longer you have to walk. The more Moses-style expressways you build, the more cars will come in, and the more places you’ll need for them to park. And you’ll need to widen streets until pedestrians find them threatening and hard to cross. Businesses will spread out as parking lots intervene. You’ll spend more money on cars, and less on public transportation, so usage of the latter will fall off. Buses will run more slowly because of increased traffic, and therefore more people will drive in.
What’s stunning is that in all these years of building bridges and highways and roads, we never learned the lessons that Robert Moses’ opponents were pointing out in the 1940s: building more roads does not solve traffic problems, it causes them. Instead, she proposes a process of vehicular attrition: of making cities more difficult for cars to use, and instead easier for public transit and pedestrians. This will reduce automobile use and make the city more liveable. The “traffic calming” proposals — making streets narrower and harder for cars to drive fast on — of recent years are a belated and too-small attempt at this glaringly obvious solution.
There’s a good example of how this works in her own neighborhood. Fifth Avenue once went through Washington Square Park. Moses in the mid-1950s proposed a highway cutting through the park, connecting his planned midtown expressway with the (also thankfully unbuilt) lower Manhattan expressway. The neighborhood not only objected to the highway, they actually proposed eliminating the road through the park all together! How insane! Closing a road without making any accommodation for the diverted traffic!
Moses ridiculed them, predicting that the neighborhood would come back and beg him to reopen the road, once traffic in the surrounding streets got bad enough. Of course, it didn’t; instead, cars avoided the area and traffic actually dropped, especially on lower Fifth Avenue.
(Not to keep harping on this point, but here, yet again, is the answer to the question of what New York would be like if Moses had not been around to build his roads. He was blocked from building all of these ridiculous expressways, and can anyone possibly believe that lower Manhattan would be better with highways running through it???)
She also ridicules Moses’ “parkways,” high-speed roads that ban trucks, forcing them onto local streets. Instead she suggests that expressways and other roadways into cities should be only open to the commercial traffic that provides a city’s lifeblood, rather than to passenger vehicles. With London’s congestion-charge working so well, when will New York City finally start charging prohibitively high fees to private cars entering Manhattan?
She spends another chapter discussing the problems of treating cities like artwork, and in particular, regarding neighborhoods as chaotic problems in need of orderly solutions. “The results of such profound confusion between art and life are neither life nor art,” she says. “They are taxidermy.” The stiffened corpses can be seen all around New York. This leads to her final point: that cities are works of chaos, not meaning disorder, but meaning complex interdependent order. City planners approach cities as an engineering problem, rather than the much more complicated biological problem that cities actually resemble: the intricate interaction of multiple complex systems, most of which are not well understood, and certainly not by city planners.
In the end, she finally has to concede the point she’s resisted for much of the book: That the destruction of cities, and what she calls the “Great Blight” of suburban sprawl, are not the result of chance, but of deliberate malice. This misunderstanding and simplification, she says, “could hardly have ocurred, and certainly would not have been perpetuated…without great disrespect for … cities.”  It’s the working of “an all too familiar kind of mind … a mind seeing only disorder where a most intricate and unique order exists.”  And she concludes with a prophetic point, which fails only in that she does not go far enough:
Thirty years from now, we shall have accumulated new problems of blight and decay over acreages so immense that in comparison the present problems of the great cities’ gray belts will look piddling. Nor, however destructive, is this something which happens accidentally or without the use of will. This is exactly what we, as a society, have willed to happen.