Speed limits on Route 9 are consistently enforced by Brookline PD. I'm not sure that you can strictly define it as a "speed trap", which implies that it is not fair, or that the intention is to fill the town coffers over community safety. Many of the postings here list essentially the same segment of route 9 in Brookline. The speed changes a few times, but it's generally reasonable (higher pedestrian and commercial traffic areas should be slower). The cops don't hesitate to enforce, even if they don't have reasonable evidence of speeding. They don't hesitate to use "clocking" rules if they estimate that you appear to be driving fast (i.e., they will ticket you even if they don't get you on radar or LIDAR). It is this point that makes me suspicious of dishonest BPD cops, racist policemen, and financial incentives (as opposed to public safety). Overall, I recommend using high caution on Route 9--- the integrity of the Brookline PD is questionable.