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Comment by yabones | Hacker News Reader

Waze is good, but it does have some very weird over-optimizations.

Anecdote: A couple years ago, while driving into Toronto on the 401, we hit some traffic as always. Waze told me to get off at the next exit which I was fortunately right beside, so I assumed it was going to route me around the accident and back onto the highway after it cleared up. What it really did was take me up the off ramp, do a U-turn, and get back onto the on ramp to gain about 700m of distance from where I was before. It theoretically saved me 5 minutes of travel time, but it only really moved me a few dozen car lengths ahead.

Their wealth of real-time and historical data is certainly beneficial, but it also causes some truly bizarre navigation now and then.

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Waze seemed to not understand the express/collector system in Toronto for the longest time, and would have you merge back and forth between the two unnecessarily. It seems to have become better over the last year or two, however.

https://en.wikipedia.org/wiki/Local–express_lanes

Every GPS I've ever used seems confused by the express/collector system on the 401. Google Maps, the one built into my Toyota, and the old Garmin all had trouble with it.

Waze used to do the same thing to me on my morning commute. The worst thing was that the backup I was "avoiding" was itself caused by the merging traffic from that onramp, so Waze was perpetuating the vicious cycle.

Any time I try to use waze it gives the most insane route recommendations. Would they shave 1 or 2 minutes off my commute? Sure! But will I be tasked with crossing several 5 or 6 lane stroads in doing so? You bet! It's like what do you value more, saving like 4 or 5 minutes of driving a day or your life?

For me it’s depended on where I am at the time. In LA it would do exactly that, having me cross many lanes in heavy traffic, but elsewhere it was fine.

My theory is that Waze must model what maneuvers are possible/easy based on other drivers in the area. So if you live in an area with more aggressive drivers it assumes those maneuvers are easier to do.

Yeah Waze needs a "UPS" setting where it doesn't take you straight across stroads and heavily favors turning right, while not routing you straight through everyone's residential neighborhoods.

Google does this to me too, sends me on some really annoying route because it's slightly faster.

I also wonder if they kind of "round robin" routes so not to cause traffic?

I can imagine a future where map routes are optimized to give subscribers to Google services priority while allocating free users to alternate ones to free up traffic.

I think it pays to learn how to drive and ride without Google maps, it's amazing how many people I know who are completely dependent on Google maps for navigation.

Once upon a time, I was trying to cross from VA into MD via the Woodrow Wilson Bridge. The bridge was closed due to an accident. Waze happily directed off the highway and onto side streets, where it had me do circles in and out of parking lots and strip malls until I gave up and went home. It was really weird - literally couldn't go anywhere, so instead of telling me to stay put, it just ran me around in bumper-bumper traffic for 90 minutes.

Did it really take you 90 minutes to realize you were going in circles?

No, that was the time it took me to give up and go home (vs waiting for the bridge to re-open). It wasn't literal circles, but looping in and out of feeder roads, neighborhood streets, etc. Completely silly - nobody with a destination in MD was going to get there, why would Waze take us off the interstate at all?

Clarification for those not familiar with the area: if that bridge is out, your options are a 20-mile detour that involves driving through downtown DC, or a detour of over 100 miles to the next crossing downstream.

Yeah that happens to me sometimes, to the point where I just ignore it and stay in traffic instead of going down exits and B-roads, which are more effort / more tiring than just creeping forward.

It has sent me down some interesting roads though.

I sometimes feel that Google Maps goes into what I call its "I feel like a country drive today" mode. I'm pretty sure it's usually slower because half the time I miss one of the 20 turns it's telling me to make--especially at night or if there's some multi-road intersection where the roads aren't at right angles. It's particularly annoying if there has been recent snow because the back roads tend to have snowdrifts or are otherwise just slow.

I use extensively when in LATAM. It sometimes feels as if the route chosen was for the algo to "probe" an alternative.

It is a technique commonly used in gaming, StarCraft for example. It is called “send a drone” or “send a probe”.

But do drivers earn points for taking these side missions? Like if you accept multiple probing missions, do you earn a badge that the algo uses to find drivers known to be willing to accept these new assignments which should increase the likelihood of the missing being accepted?

It’s like in StartCraft, no? Do drones earn points ;) ?

I know some human drives do that without Waze. It is a faster and legal route, why wouldn't the algorithm send you down that path?

It seems like it would mess up traffic more? I have heard that Waze sends drivers through residential areas as shortcuts, which, you know, kills kids.

My two cents: weaving through dense traffic is stressful and probably puts you at a higher risk of an accident than remaining in the same lane for an extra 5 minutes. I prefer to ignore those kind of shortcuts.

It's arguably an asshole move, even if legal. You really just gain the same time as the other people collectively lose between the off ramp and on ramp. In addition you cause additional traffic on the ramps, which might hold up other road users using these ramps normally.

I imagine the Nash-equilibrium of this pattern if more people does this is that there is blocked traffic on the highway between the ramps and also on the ramps.

Not arguably. It's objectively selfish. Why is your time worth more than those that you're passing?

This seems like over-optimizing for time. For the individual there are trade offs in wear and tear, fuel consumption, stress, accident risk, and as a sibling comment indicates, a social component.

For traffic in general this increases the number of lane changes and merges, increasing risk and slowing traffic further. Depending on location it may benefit by using more of the road surface (and alleviate problems further back) or may cause problems off the freeway at the local exit either due to greater traffic at the intersection or the freeway queue backing up into surface streets. (Or both.)

It should also be noted that this is an illegal maneuver in some US states. I presume Waze doesn’t suggest it in those states.

I'm not totally averse to taking shortcuts on routes I know well. But excessive shortcuts through suburban developments to save a few minutes are sort of obnoxious even if they're legal.

My experience has been that map apps are overly reliant on average times when traversing city streets. A shortcut thought LA might save you 10 minutes if the traffic light gods are in your favor or might add 30 minutes if you hit a red light at every intersection.

There are two parallel roads between my home and office and google likes to tell me that they will take the same time. One goes though about 10 stoplights in busy retail areas, one goes though about 5 stoplights in quiet industrial areas.

On average both roads might get me there at the same time, but on a unlucky day the busier road may cost me 20 minutes. I always take the other path

Traffic flows better if played as a collective game, where the objective is to help the others get through it along with helping yourself.

This strategy, if followed by enough people, massively reduces traffic stress. It may also reduce travel time, but honestly the difference is likely just a few minutes each way.

Yes, I've driven in cities that play by the "we are in it together, let's work together to get us all out", and cities that play by "any advantage I can get regardless of the cost to others".

Problem is, once enough people start playing the selfish game, the equilibrium breaks and everyone has to go selfish.

that's how you kill a society. Kill the social contract, the care for your fellows, one form of interaction at a time.

There should be a way to adjust how aggressively it optimizes.

I'd like the option to add small positive or negative weights to intersections / roads I know to be problematic.

Generally I also prefer to stick to more major roads unless there's a major time savings (E.G. >= 5 min, this is part of 'how aggressive' you propose) or accident.

The other aspect of aggressive would be the relative cost for 'unusual movement', such as (legal) U turns, cutting across on small side street connections rather than a major intersection, etc.

What it really did was take me up the off ramp, do a U-turn, and get back onto the on ramp to gain about 700m of distance from where I was before.

I'm pretty sure that isn't even legal, at least in the state of Washington. I rarely go that way, so help me out here Seattle-area Eastsiders, but a lot of folks used to do this on eastbound WA520 at 108th in Bellevue, to the point that there at least used to be a sign at the bottom of the exit ramp saying (in much fewer words) no, you can't get back on the freeway by going up the entrance ramp. (Sorry, street view doesn't show the sign that said, IIRC, "no reentry", so I could be imagining it.)

There is a similar sign next exit 17 on 405N prohibiting existing and re-entering back.

This actually works in some cases. There is a section of I95 near me with an exit "shunt" that's divided from the main highway. The main highway has a merge where another interstate joins, and that "shunt", where you can enter/exit is protected from the merge traffic. So taking the shunt can save you 5-10 minutes when the merge point is at a standstill.

I have a very similar experience. Truth be told, it is what I have on my car's navigation whenever I know exactly where I'm going: the warnings about traffic jams, stationary radars, police and all that is all I care about. But whenever I need directions, I quickly switch back to the big G.

So you saved 5 mins? Seems like an overall ok experience?

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