For example, consider curb radius at intersections. The smoother the curve, the nicer the experience for cars. If you can take the turn at 35 mph, then you don't even need to slow down. The car behind you doesn't need to slow down as you turn, and it's altogether more enjoyable to drive. But that means that the intersection is much larger, to accommodate the smoother turn. That means cars are making a right turn at higher speeds, leading to more dangerous collisions with pedestrians.

And this happens for pretty much every tradeoff. That might be why you see it as an impasse between different groups, because either tradeoffs need to be made, or the overall cost goes up significantly (e.g. moving all parking spaces underground).

* Bike lanes are adjacent to car traffic, decreasing usage. We could have separated bike lanes, but that space was already used for more car lanes.

* Bike lanes take circuitous routes, increasing distance. We could have more direct routes, but that space was already used for wide roads.

* There's no walkable area in the city center, because the shops have large set-backs, and are spaced far from each other. We could have storefronts closer together, but that wouldn't allow for as much parking space.

* Bike parking is rare, and typically pretty far from your destination. We could have bike parking at every storefront, but that would require cars to be parked further away. (Though, given that you can fit 10-15 bicycles into a single car spot, the impact even there would be minimal.)

We could stop building suburbs, stop building massive parking lots around big box stores, add more public transportation such as light rails, make some highway lanes dedicated to bus transportation (thereby reducing induced demand for cars which would actually reduce traffic), etc.

The solution is probably zoning. First, create smaller zones, resulting in more diversity. Second, allow some light commercial use inside residential areas. Ideally, stores like small supermarkets should always be within a 20-minute walking distance inside towns or cities. Third, create denser plots: discourage single-story buildings, leave less space empty on the plots, and create narrower roads.

The problem is the conversion, but it's doable over a longer period of time. If the proper laws are in place, this is probably doable over a year or 50-75.

There are some streets that are safer than others, but what would be great is if say Valencia, Cortland, Market, Haight, Cole, Columbus and some other roads through downtown (like minna St. and Stevenson) were dedicated to bikes. Some have main bus lines, so maybe allow those to continue to operate as mixed use with bikes and buses. The intention is to make bike thorough fares which are safe from collisions with cars and especially delivery trucks.

This in my mind is the fastest way to transition from a car gridlocked city to one where alternative things like bikes, and battery assisted bikes, can operate safely. Most travel in cities is under 2 miles, perfect for biking (I have a bike that has seats for both my kids, which makes it great for families too).

Safety is probably the largest reason why more people don't bicycle, and targeting main shopping districts would encourage their use to get to those places, while also increasing the general enjoyment of those areas, with the added benefit of increasing traffic to businesses in those areas.

However, everytime I go there, the street is still full with cars: delivery trucks that bring the retail goods to the stores (which are not easily accessible otherwise), construction trucks for the apparently constant repairs they're doing on the road, ambulances, etc. Even when most of them are not driving you're still constantly surrounded by (mostly big) vehicles.

As you suggested in reply to a sibling comment, more bike lanes make sense. Parking on some roads could be converted to bike lanes. Perhaps it makes sense to lower the speed limits for cars, also.

So it's a nice thought experiment but not at all practical, on top of that 'bike lanes in apartment building hallways' make you wonder just how much experience the designer has riding bicycles, you park your bike at the interface between inside and outside and you don't run around the apartment hallways on a bicycle because of (1) pedestrians, (2) playing kids, (3) the fact that you now have to elevate your bicycle every time you want to go in or out of your house and (4) storing your bike at streetlevel is simply much more practical.

In a suburb, the solution isn't anything except building more and better roads.

People aren't bicycling 10-15 miles to the grocery.

They should be, but, that's a different societal problem.

Ditto for public transit, when public transit is sparsely utilized it tends to be less safe while as dense public transit will certainly have incidents but the increased ridership leads to increased safety funding and just more witnesses making crime less attractive in terms of expected gain.

It is a hard problem even before we get into NIMBYism and other socio-political complications. I definitely disagree with you but I think your comment was quite fair and reasonable.

Heavy car traffic is a stable system that's actively unfriendly to pedestrian and bicycle uses. You need to slowly claw away space for bicycles and increase ridership; and then work to densify and intermix commercial and residential for things to work well.

It takes decades, and the initial steps make things worse even if the new equilibrium is better.

As for pedestrian traffic, my experience with medium US cities is that they are far too spread out for walking to be an option for most things. It's hard to see how this could change without Americans abandoning their beloved individual suburban homes with yards.

I think in most places public transportation is the only effective replacement for cars.

But bikes and walkers should have the advantage of more direct routes that take less time. Steps on roads on Queen Anne Hill being a good example, but there should be more of that type of thing. Grade separate bike lanes, bike tunnels, etc. They can be surprisingly thin and sneaking them in works wonders.