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Comment by valiant-comma | Hacker News Reader

When these articles show up now and again, it’s not clear to me why the various impacted cities don’t choose to ban through traffic. Some articles have implied that this is not possible. Los Altos did this a while back[1]. Is there a legal issue the communities surrounding Los Angeles want to avoid, that Los Altos simply took the risk on?

[1] https://slate.com/business/2017/06/suburbs-finally-figured-o...

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It turns out than bans on through traffic aren't legally enforceable. The signs are merely advisory.

Yep, that seems to be supported by this article[1].

https://padailypost.com/2017/11/17/traffic-complaints-to-res...

A "no thru traffic" sign may not be legally enforceable, and it's certainly difficult to enforce just from a practical perspective.

But physically making the street not be a through street is possible. Just plop down a couple of Jersey walls and you're done.

Check out how Vancouver made semlin, grant, and gravely forcibly "no thru traffic" here: https://maps.app.goo.gl/DFVJNDF2DftbFzpv9

Aren't you then trapping the residents who live on that street in?

My hometown did this in the late 90's, added three barriers across intersections to cut a neighborhood in half. Here's someone recently suggesting removing them to alleviate traffic on the main north/south road (under construction for the last two years or so), but I doubt anything would happen to them:

https://www.centredaily.com/news/local/community/state-colle...

Traffic bound for North Atherton (bottom left of map) has to go down to the intersection with Park instead of taking Allen.

Easy enough to take a bike through them, I used to ride that way regularly in to campus. But I think it's worked well to not have cars shortcutting through the neighborhood at high speeds.

On the street near me there are just chikanes every 100 metres or so, that massively discourages people from using it for using it as a shortcut, because at rush hours the chikanes become a massive pain in the ass:

https://www.google.com/maps/@55.101503,-1.584329,3a,75y,42.5...

Woah.

Can state law change this, or is this a federal funding requirement? (I can't imagine it's a constitutional requirement. Plenty of publicly-funded services from food stamps to the restrooms at Area 51 have restrictions on which members of the general public can use them.)

In some areas governments put up signs like this without stopping to complete the triviality of actually passing a law allowing them to do so.

Whereas there might be nothing whatsoever wrong with such a law you can't legally fine or arrest people for not following instructions you were never legally authorized to give. Essentially anything you put on a sign doesn't gain the force of law.

Example GA went through some drama regarding that notably their local chief of police publicly stated

http://dunwoodynorth.blogspot.com/2017/12/dunwoody-homeowner...

residents in my neighborhood were looking for relief from this cut thru issue along with more enforcement of speeding, stop sign violations and trucks also cutting thru. I reached out to Chief Grogan to share the neighbors concerns and asked that he have the Dunwoody legal staff research the legality of enforcing the "No thru Traffic" on public streets as I personally see the issue as unenforceable.

I wouldn't be surprised if some neighborhoods or property owners also put up fake signs. Wouldn't be the first time.

Occasionally with less selfish motives

https://www.vice.com/en_us/article/kbnzvw/fake-street-sign-i...

I see a lot of streets where I live that have signs saying no trucks except local delivery. I wonder at what level that is instituted and enforced.

> it’s not clear to me why the various impacted cities don’t choose to ban through traffic

Can you physically turn the streets into cul-de-sacs? Where I live a lot of domestic streets are cul-de-sacs presumably to prevent too many people driving past.

There’s one in Los Gatos, I believe, where they did this partially. Cars can empty on to the larger street, but can’t enter from the that direction.

Speed bumps go a long way too by dropping the effective speed.

Speed is a huge problem. I make sure I don't go more than 25 through one of the shortcuts I take through a residential area and when Waze starts sending people down these roads they are extremely aggressive behind me. I'm guessing they'd be driving 40 to 50 if I wasn't in their way which is pointless because the route ends in a long line of car's trying to make a turn. When I was young I used to ride my bike through these neighborhoods - I'd be surprised if parents felt comfortable letting there kids do the same today.

My city seems to do this with more unorthodox methods: cheap out on road maintenance and engineering.

Oh sure, take that side street with all of the sunken sewer grates.

My mom’s street was riddled with potholes. We were happy when they repaved it, but blew it when they put up speed bumps.

This is partly because drivers aren't actually paying there way, and are subsidised by others a ridiculous amount.

And by raising the aggravation and discomfort levels. Some people will avoid streets with speed bumps if they can find an alternate route because they dislike them so much.

Getting a speed bump added to your street is nearly impossible in LA. I lived on a street that badly needed one. It was a double length block paralleling Wilshire, so frequently used as a bypass with many speeding drivers. I looked up the process for requesting a speed bump. They only take so many requests per year, so I had to wait a few months for the request form to open up. I marked my calendar and when the date came it required that you get signatures from 50% of the residents on your street. Since my street was almost entirely apartment buildings and a double length block, this would have been hundreds of people. I gave up. I no longer live there.

Yes, just add a barrier only allowing bikes and pedestrians through.

My small town did this 20 or 30 years ago with a number of residential streets that were commonly [ab]used for shortcuts. They erected barriers that consist of a curb across the roadway and a series of three or four "no entry" and "dead end" signs. Inconvenient, but it stops through traffic.

Tucson and Phoenix have another alternative. The cities are built with the main roads being a large grid. Subdivision roads are twisty and higgledy-piggledy. It's almost always too inefficient to cut through a subdivision to bother trying.

You can install what’s called “Modal Filters”: A series of barriers that lets pedestrians and cycles pass, but blocks cars. This slightly inconveniences local traffic, but blocks through traffic.

Near my downtown side-streets there are temporary barriers that you can actually drive around (but you know you're going against what the sign says).

I presume enforcement is always an option.

Another point, on my street there used to be horrible backup right in front of my house, but once the light near the school nearby went to a half-duplex mode, apps stopped recommending it as a sure bet shortcut. Once that happened traffic lowered considerably.

If the signs prohibit passage, Waze wouldn't be able to use that (legally invalid) route, would it?

Waze and Google Maps tend to have bad/outdated data and tell people to make illegal turns. The roads near my apartment changed over a year ago and I still see people make illegal left turns (including Lyft drivers unless I warn them about it in advance).

Actually can you just put traffic-triggered off-by-default red lights, similar to the ones used on highway on-ramps to trickle cars in during rush hour?

If only one or two cars are seen on the road, turn the light off. If more than that, turn it on and allow one car per green every several seconds. It will reduce throughput enough that Waze will automatically route away from it (and eventually Waze editors will have to figure out how to encode it) without affecting normal residential traffic.

For whatever reason, people don't always care about speed limits but they usually don't run red lights.

That is interesting... metered off ramps. I could see them putting one at the Eastbound 101 exit for Haskell. I see very few people exit there while I'm stuck in traffic waiting to get on the 405. I'm sure a significant number of people are following waze (it often suggests I go that way to save 4 minutes).

I don't understand why "on-ramp" metered lights aren't used in many more places.

Like enforcing easy zipper merging. Put lights on both lanes that need to merge together, out there in the middle of the freeway. Turn them off when there's no traffic.

Yes, in my neck of the woods they cut off some roads used as rat runs by installing bollards. Pedestrians and bikes can still go through but car no longer can.

Around my area in Sydney a few new street signs have been popping up banning traffic from driving through at certain times of the day, without actually changing the roads. The signs say for example 'No right turn 7am-10am' which is when morning traffic sneaks into the side street to get to the CBD faster.

Then I got to sit on my balcony for 6 weeks watching the traffic cops ticket one car after the other until they stopped catching people.

Yes, Portland added diverters to some of its neighborhood Greenway routes, that forcibly divert car traffic (walking and biking can still get through). It was done for basically what's talked about in the article, too many cars using local residential roads for commuting.

Really, this is a design problem with the streets and lack of effective public transportation. LA brought this onto itself.

They made a decision not to make the roads objectively worse to thwart abusers. I think calling that a design problem they brought on themselves is unfair.

It's not objectively worse, any more than road diets make streets objectively worse, or sidewalks, or protected bike lanes, or speed limits. Making roads worse for through traffic makes them better for other uses. It comes down to what your priorities are, and right now, through design, they're choosing to prioritize the very through traffic they're complaining about.

It's not unfair, and it's accurate. The design decisions the area chose as a whole, like handicapping public transportation, led to this situation. With robust public transit, you wouldn't have a huge flood of desperate car commuters driven to find any possible shortcut.

Road diets, sidewalks, bike lanes, and (correctly done) speed limits all have very nice features.

Blocking exits does not in any way improve the road itself.

It just inconveniences people that are improperly cutting through more than normal drivers.

The fact that through traffic is technically possible does not mean it is 'prioritized'.

> Blocking exits does not in any way improve the road itself.

Incorrect. It improves the conditions of the road for local drivers, as well cyclists and pedestrians. Which is exactly why Portland did it. Unless you have an alternative explanation?

> The fact that through traffic is technically possible does not mean it is 'prioritized'.

It shows that they've prioritized enabling through traffic over other concerns.

It's not all that different from road diets. Road diets usually reduce the carrying capacity of the road, making it "objectively worse", in your parlance, in the service of other goals. Diverters accomplish a similar function.

Road diets arguably make the road nicer to be on.

Blocking exits only fixes things through second order effects. The direct effect is negative. If we could stop through traffic via other means, we wouldn't want to block exits, but we would still want bike lanes and speed limits and road diets in residential areas.

It can be controversial. It can pit the wealthy against the working class: a well-off hillside neighborhood may demand that its streets be off-limits to through traffic. But this would mean that another, poorer neighborhood's residents are denied an important route to work. And the question comes up: aren't these public streets? Don't the streets belong to everyone?

Menlo Park has a few streets labeled local traffic only as well.

Palo Alto has quite a few as well. Some are just marked with signs, many have physical barriers allowing only bikes and large trash collection vehicles to easily pass.

A fair stretch of Bryant St. is bike-limited, with narrow barriers every few blocks.

I used it in my bike commute from Sunnyvale to Menlo (which also used pedestrian/bike bridges that cross the creeks that define the Mtn View / Palo Alto and Palo / Menlo borders).

Is there an example of these? I'm having a hard time picturing how a barrier can allow bikes and large traffic to pass whilst blocking other traffic.

There are barriers that restrict traffic based on dimensions - such as the 'bus trap' [1] that only allows wide vehicles, and the 'sump buster' [2] that only allows high-ground-clearance vehicles through.

Of course, these have the disadvantage that (a) they damage the cars of confused motorists [6] (b) cars stuck in traps obstruct busses anyway[5], and (c) large SUVs and pick-up trucks can drive over them anyway [4].

Another option is a powered rising bollard [3] or barrier together with some mechanism (tag, ANPR, keypad) for recognising authorised vehicles. Which avoids a lot of those weaknesses - at the cost of power and maintenance.

[1] https://en.wikipedia.org/wiki/Bus_trap [2] https://en.wikipedia.org/wiki/Sump_buster [3] https://goo.gl/maps/epSrQ2641m6ccf6cA [4] https://www.bbc.co.uk/news/uk-england-northamptonshire-22352... [5] https://www.manchestereveningnews.co.uk/news/greater-manches... [6] https://www.abc.net.au/news/2018-08-22/car-blocks-o-bahn-for...

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