Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

How UPS trucks saved millions of dollars by eliminating left turns

gadgets.ndtv.com

Post reply on HN
Print view View original

81–90 of 101 posts

Re: How UPS trucks saved millions of dollars by eliminating left turns

#81

Post by technofiend »

camiller wrote: post #68
helipad wrote: post #19

Earlier quoted context omitted.

My brother came to Michigan to visit from the UK. After a few days he said: "So, I can go on a red light for a right turn, but sometimes I have to wait at a green light for a left turn?" It was then I realised how peculiar the signals in the US can be.

Flip side, having driven in England 20+ years ago. In England, when stopped at a red they politely blink a yellow light when your stop light is about to turn green. In the US not only do we not do that, but many localities put extended shields around the lights, polarized lenses, etc. To prevent you from knowing when your light is about to turn by observing the lights for the perpendicular street. In other words... E…

It's apocryphal but my history professor stated US stoplights used to actually have the red to green warning in order to assist large trucks which need a few seconds to build momentum. It caused more wrecks because of red light runners not clearing the intersection in time and people with a fresh green light trying to immediately enter the same intersection.

Re: How UPS trucks saved millions of dollars by eliminating left turns

#82

Post by jrnichols »

capnrefsmmat wrote: post #66
dorfsmay wrote: post #21

Earlier quoted context omitted.

Turning right on red is one of those idea that once you've been exposed to it you wonder why isn't everybody adopting it... A similar idea is the train system in Munich where they built their platforms such that they can open doors on both sides, making one side of the train the exit, and the other side the entrance. Ever since I saw that, every single time I wait for people getting off a crowded train, I wonder "Why…

> Turning right on red is one of those idea that once you've been exposed to it you wonder why isn't everybody adopting it... It was first introduced in the 70s in the US in response to high oil prices, and only after road safety tests apparently demonstrated its safety. But since then there's been a fair amount of research indicating it increases accidents and pedestrian fatalities, amounting to somewhere under 100…

And now, turning right on a red light is just a cash cow for the slimy red light camera companies. Some areas report that upwards of 95% of the tickets issued by red light cameras were for not stopping for 6 seconds before turning right on a red light.

("In a two-month period in 2010 in South San Francisco, 98 percent of the 672 red-light violations recorded at El Camino Real and Westborough Boulevard were for right turns. Other cities say 4 in 5 tickets go to people turning right at intersections."

http://www.mercurynews.com/2016/01/06/roadshow-right-on-red-...

Re: How UPS trucks saved millions of dollars by eliminating left turns

#83

Post by lorenzhs »

euyyn wrote: post #80
lorenzhs wrote: post #52

Earlier quoted context omitted.

Since you need turn restrictions if you want to compute routes that users can actually follow, adding different costs for different kinds of turns (left, right, U-turn) is easy. See my other comment in this thread on the challenges associated with incorporating turn costs and restrictions in gerenal: https://news.ycombinator.com/item?id=13616676

> Incorporating turn costs into route planning is actually not that easy! [I]t doesn't play well with many speed-up techniques. + > Since you need turn restrictions if you want to compute routes that users can actually follow, adding different costs for different kinds of turns (left, right, U-turn) is easy. Does this mean all those speed-up techniques don't produce routes that are actually allowed? What's the point…

Nah, it's just that it took work to integrate turn restrictions, and that that results in a bit of a slowdown.

It's easier to do research on a more limited version of the problem (shortest path in a road graph with a suitably chosen edge weight function) and then generalise than start out with the most general formulation. The results are wild: these techniques are millions of times faster than Dijkstra's algorithms and provably produce the exact same result. It's what makes Google Maps possible.

Re: How UPS trucks saved millions of dollars by eliminating left turns

#84

Post by snrplfth »

jrnichols wrote: post #82
capnrefsmmat wrote: post #66

Earlier quoted context omitted.

> Turning right on red is one of those idea that once you've been exposed to it you wonder why isn't everybody adopting it... It was first introduced in the 70s in the US in response to high oil prices, and only after road safety tests apparently demonstrated its safety. But since then there's been a fair amount of research indicating it increases accidents and pedestrian fatalities, amounting to somewhere under 100…

And now, turning right on a red light is just a cash cow for the slimy red light camera companies. Some areas report that upwards of 95% of the tickets issued by red light cameras were for not stopping for 6 seconds before turning right on a red light. ("In a two-month period in 2010 in South San Francisco, 98 percent of the 672 red-light violations recorded at El Camino Real and Westborough Boulevard were for right…

> "And now, turning right on a red light is just a cash cow for the slimy red light camera companies."

Hm? I'm pretty sure that revenues from red light camera tickets generally go to municipalities, not the companies that make the cameras themselves.

Re: How UPS trucks saved millions of dollars by eliminating left turns

#85

Post by ksenzee »

snrplfth wrote: post #84
jrnichols wrote: post #82

Earlier quoted context omitted.

And now, turning right on a red light is just a cash cow for the slimy red light camera companies. Some areas report that upwards of 95% of the tickets issued by red light cameras were for not stopping for 6 seconds before turning right on a red light. ("In a two-month period in 2010 in South San Francisco, 98 percent of the 672 red-light violations recorded at El Camino Real and Westborough Boulevard were for right…

> "And now, turning right on a red light is just a cash cow for the slimy red light camera companies." Hm? I'm pretty sure that revenues from red light camera tickets generally go to municipalities, not the companies that make the cameras themselves.

The cameras are sold as a service, so the companies only make money if there are enough tickets for the municipality to justify the expense.

Re: How UPS trucks saved millions of dollars by eliminating left turns

#86

Post by snrplfth »

ksenzee wrote: post #85
snrplfth wrote: post #84

Earlier quoted context omitted.

> "And now, turning right on a red light is just a cash cow for the slimy red light camera companies." Hm? I'm pretty sure that revenues from red light camera tickets generally go to municipalities, not the companies that make the cameras themselves.

The cameras are sold as a service, so the companies only make money if there are enough tickets for the municipality to justify the expense.

Sure, but the vast majority of the funds from tickets go to the city - that's who it's really a "cash cow" for. And the municipalities are the ones actually making the rules that govern the tickets themselves. Why "slimy companies", and not "slimy City Halls"?

Re: How UPS trucks saved millions of dollars by eliminating left turns

#87

Post by DerekL »

lorenzhs wrote: post #54
Theodores wrote: post #38

This optimisation must exist at a basic level in all satnav software because journey time must be longer for the route with more left turns, as fed back into the system from previous journeys by other users. It would be an interesting experiment to see how different consumer grade satnav systems compare on this pure travelling salesman problem.

It's not TSP. In TSP, you have a graph and want to visit every node exactly once . Here you have a (road) graph and want to visit some set of nodes (the delivery addresses) at least once (it's okay to drive past a house where you dropped off a parcel earlier if that somehow makes the journey shorter). Also, consumer satnav systems don't support this kind of query. You can't plug in a list of dozens of destinations an…

It reduces to a special case called the metric TSP. If going through node C is shorter than going from A to B directly, then just replace the A-to-B distance with the length of A-to-C-to-B. It's just as hard to solve as regular TSP, but easier to approximate.

Re: How UPS trucks saved millions of dollars by eliminating left turns

#88

Post by serge2k »

mstade wrote: post #8

> In the US, and other countries where you drive on the right side of the road, right turns are free, but for a left turn you need to wait for a green light. I don't know of any other country than the US where turning right on red is allowed, unless there's specific signage or additional traffic lights to allow it. Indeed, the turn-on-red rule in the US seems to work inverse to how I've seen it elsewhere – i.e. it's…

Canada for starters.

Re: How UPS trucks saved millions of dollars by eliminating left turns

#89

Post by pimlottc »

stevedt wrote: post #39
poulsbohemian wrote: post #33

Earlier quoted context omitted.

It gets even better -- you can also make an "Oregon left" - in Oregon it is legal to turn left on red if you are turning onto a one way street. http://www.oregonlive.com/commuting/index.ssf/2015/10/turn_l...

In California you can turn left on red from a one-way to a one-way street.

Same in Ohio. Never heard it called an "Oregon left" before.

Re: How UPS trucks saved millions of dollars by eliminating left turns

#90

Post by serge2k »

poulsbohemian wrote: post #33
mstade wrote: post #8

> In the US, and other countries where you drive on the right side of the road, right turns are free, but for a left turn you need to wait for a green light. I don't know of any other country than the US where turning right on red is allowed, unless there's specific signage or additional traffic lights to allow it. Indeed, the turn-on-red rule in the US seems to work inverse to how I've seen it elsewhere – i.e. it's…

It gets even better -- you can also make an "Oregon left" - in Oregon it is legal to turn left on red if you are turning onto a one way street. http://www.oregonlive.com/commuting/index.ssf/2015/10/turn_l...

Washington too.

and one way to one way is legal on red.

Post reply on HN