<story><title>The Lowdown on Lidar</title><url>https://docs.google.com/file/d/0B941PmRjYRpnX3ZqLWlQMGdGXzQ/edit</url></story><parent_chain><item><author>ihaveajob</author><text>Speed radars are good for speed traps, but not so great to prevent speed related incidents. They share the same fatal flaw with all other single-point speed meters: You can just slow down for a minute, while you pass by the speed trap, and then speed up for the rest of your trip. Instead, a 2-point speed meter (i.e. license plate readers every few miles, measuring time between matching reads) system is superior because a) their margin of error is negligible and b) they measure sustained speed over a long distance rather than at a single hot spot, thus making roads safer. I can&amp;#x27;t believe it&amp;#x27;s not implanted at least in all interstate freeways.</text></item></parent_chain><comment><author>growse</author><text>Possibly because the cost&amp;#x2F;benefit just isn&amp;#x27;t there.&lt;p&gt;In the UK, the data shows that speeding (excessive speed for the conditions above the speed limit) is the primary cause in single digit percentage of accidents. I believe there&amp;#x27;s data from 1996 and 2007 for this, will dig it out when I&amp;#x27;m not on mobile.&lt;p&gt;If you want to spend money on accident prevention, there&amp;#x27;s much better things to target than speeding.</text></comment>
<story><title>The Lowdown on Lidar</title><url>https://docs.google.com/file/d/0B941PmRjYRpnX3ZqLWlQMGdGXzQ/edit</url></story><parent_chain><item><author>ihaveajob</author><text>Speed radars are good for speed traps, but not so great to prevent speed related incidents. They share the same fatal flaw with all other single-point speed meters: You can just slow down for a minute, while you pass by the speed trap, and then speed up for the rest of your trip. Instead, a 2-point speed meter (i.e. license plate readers every few miles, measuring time between matching reads) system is superior because a) their margin of error is negligible and b) they measure sustained speed over a long distance rather than at a single hot spot, thus making roads safer. I can&amp;#x27;t believe it&amp;#x27;s not implanted at least in all interstate freeways.</text></item></parent_chain><comment><author>malchow</author><text>&amp;quot;I can&amp;#x27;t believe [average speed camera systems are] not implanted at least in all interstate freeways.&amp;quot;&lt;p&gt;Possibly because a civil society, favoring the preservation of a measure of basic autonomy, does not implement &lt;i&gt;every&lt;/i&gt; measure for tracking, enforcing, circumscribing, and monitoring the people.</text></comment>