tag:blogger.com,1999:blog-1883551996126668365.post5251950072829501803..comments2024-01-11T21:24:44.379-07:00Comments on A Blog of Tom: Fair Warning and Photo RadarTom Cantinehttp://www.blogger.com/profile/06234109728445439457noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-1883551996126668365.post-39513319245013061302014-10-09T12:36:27.474-06:002014-10-09T12:36:27.474-06:00I will defer to your expertise, although I'm n...I will defer to your expertise, although I'm not sure we've understood each other correctly with regard to the 85 figure. I understood from my reading that number to mean the 85th percentILE of traffic, not 85% of some "desired speed", for which the question "desired by whom?" arises. <br /><br />I agree that ultimately the setting of speed limits is a political question. However, so too is the question of policy on how to administer those limits. <br /><br />Whenever you're making rules, the key question is always: "How do we want people to behave in response to this legislation?" In the case of speed limits, we can take a very narrow approach to this question and just say we want people to drive slower. But I think we should also look at the overall policy objectives as well, which in this case means traffic safety and the efficiency of our roadways generally. It wouldn't be helpful, after all, to adopt enforcement strategies to bring speed down if those strategies created bigger problems elsewhere. And, as the principal objective of speed limits is to maximize the efficient movement of traffic, simply slowing everyone down isn't necessarily a desirable objective anyway.<br /><br />My suggestion for a buffer doesn't need to be anchored with the speed limit at the bottom. We COULD have photo radar issue warnings to people when they are clocked at any point within 5 km/h of the speed limit. "Hey, you came really close to speeding there, dude!", which could be effective if we decided, politically, that we wanted traffic speeds to average somewhere under, rather than at, the posted limit.<br /><br />Personally, I don't think that's very practical, because in my experience a posted limit of 60 km/h means most people will be doing their best to go at least that fast, and usually a little over. The intuition is a natural one: if it says 60, I can go 60, so don't hassle me for going over 55. So it'd be a difficult intuition to dislodge, which is why I think it would be more useful to have the warning buffer kick in AT the limit rather than just below it.Tom Cantinehttps://www.blogger.com/profile/06234109728445439457noreply@blogger.comtag:blogger.com,1999:blog-1883551996126668365.post-38765604128669752812014-10-09T07:19:28.143-06:002014-10-09T07:19:28.143-06:00You are correct that recommended speed limits are ...You are correct that recommended speed limits are usually recommended as 85% of desired speed. So if the average speed of free flow travel is 105 km/h, then recommended speed would be approximately 90 km/h. This is regardless of weather any cars are uncomfortable driving below that speed. There's no statistical spread consideration on which drivers are more or less comfortable on what speed, just the average desired speed. This speed is calculated based on road factors (how wide the lanes are, how big the shoulders are, how far away light standards are, etc.) and not studied for any individual road. This stuff is mostly considered for highway speeds.<br /><br />The posting of any speed limit, however, is a political choice. Most communities have speed limits for certain types of roads (50km/h for local roads, 60 km/h for access roads, etc.) regardless of the design speeds of the roads. Some engineering these days goes into reducing the design speed for roads by narrowing them, having parking lanes, speed bumps, etc. so that desired speed matches the local political choice in road speeds. Even if the 85th percent desired speed of a road in Alberta was 130 km/h, the provincial government still wouldn't post it above 110. <br /><br />I say this because pursuing any comment on the engineered speed or design speed of the road is not a valid point of debate. Your local or provincial government sets the speed, and the road is designed accordingly. Even if it is designed for faster travel than the local government allows, it's the politics which need to change to actually change the posted limits.<br /><br />Once you get to that point in the discussion, any talk of buffers and whatnot is irrelevant. There's a limit, follow it or risk breaking the law and suffering the penalty for it. It's a moral choice. <br /><br />I would also argue that it's a moral choice for politicians setting the limits to ignore whatever desired speed that the road has and enforce a lower limit. This will tempt more people into breaking speed limits. Governments are not, in my opinion, moral entities.James Tipmannoreply@blogger.com