Road design, safety and Vision Zero - Printable Version +- Waterloo Region Connected (https://www.waterlooregionconnected.com) +-- Forum: Waterloo Region Works (https://www.waterlooregionconnected.com/forumdisplay.php?fid=14) +--- Forum: Transportation and Infrastructure (https://www.waterlooregionconnected.com/forumdisplay.php?fid=25) +--- Thread: Road design, safety and Vision Zero (/showthread.php?tid=1409) |
Road design and Vision Zero - danbrotherston - 05-11-2019 (05-11-2019, 10:06 AM)SammyOES Wrote: I don’t think those stats actually prove that the 400 series highways are safer than backroads, but it’s definitely closer or more likely than I thought. I've explained numerous times. This is about the fact that engineers design roads that are INTENDED to kill people. Who should those people be? No engineer has ever built a plane, bridge, or building which was INTENDED to crash or collapse. So yes, if you support building roads which are intended to kill people, who should those people be? Which family members would you pick? Because it sure is easier when it's other people who are intended to die... You have made it clear, you refuse to understand this point. RE: General Road and Highway Discussion - creative - 05-11-2019 Another “perfect Dan post”! RE: General Road and Highway Discussion - danbrotherston - 05-11-2019 (05-11-2019, 02:44 PM)creative Wrote: Another “perfect Dan post”! Object all you want, I speak the truth, our roads are intended to kill people. RE: General Road and Highway Discussion - MacBerry - 05-11-2019 (05-11-2019, 01:48 PM)danbrotherston Wrote:(05-11-2019, 10:06 AM)SammyOES Wrote: I don’t think those stats actually prove that the 400 series highways are safer than backroads, but it’s definitely closer or more likely than I thought. Your logic isn't logical ,,, it is weird. RE: General Road and Highway Discussion - SammyOES - 05-12-2019 (05-11-2019, 12:11 PM)neonjoe Wrote: I would guess that based on AADT the 401 is safer than a lot of smaller roads(for fatal collisions) The percentage of cars on the road that get in accidents is lower than on a road that carrier 1/10 of the traffic. All traffic going in same direction is similar to why roundabouts are safer (fatality wise) than standard intersections. I think the measurement that is most relevant is per km driven. I think that’s what the link previous was using and accounts for traffic. My continued skepticism is that typical 4-lane divided highways in the States don’t really compare that well to the 6 to 24(?) lane, heavily trafficked, higher effective speed highways like the 401 in the Waterloo-to-GTA area. But like I said, it’s definitely closer than I realized and it’s quite likely I was wrong. RE: General Road and Highway Discussion - jamincan - 05-12-2019 Rural highways should really be compared separately from urban highways. Over long distances, collisions from crossing the yellow line are probably more of a problem (due to fatigue or unsafe passing) and have high risk of fatalities. On multi-lane urban roads with no median (think Steeles between Milton and Mississauga), the risk is probably significantly lower, and the number of collisions from rear-ending or side-swiping other vehicles is likely significantly higher (with lower fatality rates). The nature of collisions is likely similar on the 401 between the same cities, but the fatality rate is probably higher on the 401 versus Steeles due to higher speeds. RE: General Road and Highway Discussion - jamincan - 05-12-2019 I wonder as well how the higher speed limit may affect highway capacity. Generally speaking the highest throughput per lane is supposed to be at speeds quite a bit lower than this (80kph or so I seem to recall reading?), but I suppose if volumes increase, the speed of traffic would drop down naturally anyway. RE: General Road and Highway Discussion - SammyOES - 05-12-2019 (05-12-2019, 08:52 AM)jamincan Wrote: I wonder as well how the higher speed limit may affect highway capacity. Generally speaking the highest throughput per lane is supposed to be at speeds quite a bit lower than this (80kph or so I seem to recall reading?), but I suppose if volumes increase, the speed of traffic would drop down naturally anyway. I would have assumed that theoretically the higher the speed limit the higher the capacity. And that in practice you’d see increasing the speed limit increase capacity up until some speed that reflects human abilities (but at which point you’d just stay at that capacity figure). I can’t think of why a lower speed limit would have a higher capacity. In practice I don’t imagine anything would change. I find increased congestion increases the average speed people go (I think people are willing to speed up to match the flow of traffic but much less willing to slow down) up until some point where average speed falls because of general congestion. RE: General Road and Highway Discussion - danbrotherston - 05-12-2019 (05-12-2019, 09:31 AM)SammyOES Wrote:(05-12-2019, 08:52 AM)jamincan Wrote: I wonder as well how the higher speed limit may affect highway capacity. Generally speaking the highest throughput per lane is supposed to be at speeds quite a bit lower than this (80kph or so I seem to recall reading?), but I suppose if volumes increase, the speed of traffic would drop down naturally anyway. Higher speeds mean greater separation between vehicles, which counteracts the higher speeds. How does congestion increase average speeds. Isn't congestion by definition when there are too many vehicles to fit in the available capacity, which necessarily reduces speeds because of queuing....if you have lots of cars, but all traveling at the normal speed, you don't have congestion, you just have lots of cars. RE: General Road and Highway Discussion - SammyOES - 05-12-2019 Sure, yes, traffic volume instead of congestion. I agree about higher speeds meaning more separation. But I would be surprised if the average separation doesn’t increase gradually with speed. I guess though it is possible that the rate of change of separation relative to travelled speed increases in such a way that overall capacity decreases. RE: General Road and Highway Discussion - jamincan - 05-12-2019 From the WSDOT: Quote:As congestion increases and traffic begins to move slower than 70% of the posted speed limit, overall productivity declines and the highway supports fewer vehicles, as highways are engineered to move specific volumes of vehicles. In addition, highways do not operate at their maximum efficiency when moving at 60 MPH (the most common highway speed limit in Washington State) because of the need for increased spacing between vehicles. RE: General Road and Highway Discussion - KevinT - 05-12-2019 (05-11-2019, 04:34 PM)danbrotherston Wrote: Object all you want, I speak the truth, our roads are intended to kill people. You're right, the engineers do suck. If I was designing a road to intentionally kill people I could come up with infinitely better designs like spike pits after blind curves or something. RE: General Road and Highway Discussion - danbrotherston - 05-12-2019 (05-12-2019, 08:34 PM)KevinT Wrote:(05-11-2019, 04:34 PM)danbrotherston Wrote: Object all you want, I speak the truth, our roads are intended to kill people. You're right, I misspoke, our roads are intended to kill exactly a specific number of people, in that aspect, our engineers do fine. They can in fact predict the death and destruction a piece of infrastructure will see with a fair bit of precision. Again, this is the ONLY engineering discipline where "fail x% of the time" is acceptable for x > 0. And just in case anyone doesn't want to reread the previous lengthy exchange and is confused, this is not to say that there are no tolerances, no mistakes, that no bridge ever collapses. What it says is that when it happens, we consider it a failure, and we investigate why it happened and we stop it happening again--in traffic engineering, it's part of the design, no need to fix anything. RE: General Road and Highway Discussion - SammyOES - 05-12-2019 It’s such a weird view. Even if we keep narrowing down what you’re talking about, it’s still easy to show that you’re wrong. Bridge designers know that there’s some probability that someone will jump off their bridge and kill themselves. In aggregate, they absolutely know for sure that people are dying from their designs. And yet, we don’t strive to make it impossible* for someone to commit suicide. It’s the same with road designs. Any given stretch of road has some probability of a fatality. In aggregate, it’s a guarantee someone will die. * note: we almost certainly don’t do as much as we should. So I’m not saying we shouldn’t do more - even while still saying we should accept we can never totally prevent bridge suicides. RE: General Road and Highway Discussion - SammyOES - 05-12-2019 And, of course, this idea that road fatalities are just accepted and never investigated is also ridiculous. Just because we don’t have the resources to investigate every accident in detail like we do for major plane accidents doesn’t mean it never happens. Major accidents (like say the Humboldt Broncos accident) are looked at in depth and recommendations are made to try to prevent similar accidents from ever happening again. Wide scale accident statistics are looked at and acted on. For example, we have concrete barriers for most of our divided highways because we found a common cause of death was crossing over through the ditch into oncoming traffic. |