A longstanding goal of the neighborhood has been to get the speed limit on Sycamore Drive lowered from the current 35 mph (preferrably to 25mph).
Years ago, certain Georgia counties and towns were notorious for setting ridiculously low speed limits (which sometimes changed dramatically upon entering the county or city limits, even though the driving conditions had not changed).
In an effort to curb speed traps, which were giving the State a bad reputation, the Georgia Department of Transportation ruled counties and municipalities could not enforce speed limits set below that determined by the 85% rule, which assumes 85% of drivers will not drive at an unsafe speed.
Wikipedia provides much more about setting speed limits.
While it would seem reasonable that 85% of drivers would drive at or below a safe speed on a residential street, not many residential streets appear like wide thoroughfares, as Sycamore Drive does.
While the speed limit on Sycamore St. from Church St. to Ponce de Leon is 25 mph, it is a narrow street with considerable on-street parking and also has speed bumps (something we cannot have on Sycamore Drive because it is sometimes used by ambulances, even though Winn Way is the official ambulance route from the South). Sycamore Drive is VERY wide from Hilcrest to Pinehurst (wide enough for two 11-ft traffic lanes and parking on each side, but not much parking on the east side. From Pinehurst to DeKalb Medical, it is wide enough for two lanes and parking on one side (or, as is actually done, random parking on either side and weaving by cars). The wider the roadway, the faster cars tend to go.
There are actually very few examples of residential streets in Decatur with 35 mph speed limits. They can probably be counted without the thumb on one hand.
The City can post 25 mph signs, but it cannot enforce that speed. In fact, it does not give tickets until a vehicle is going considerably over the posted speed limit, so vehicles can FLY down Sycamore and only get a warning ticket.
Our best chance at slowing traffic is to use "traffic calming" meaures. The City could mark two 11-foot traffic lanes, with parking lanes on each side from Hillcrest to Pinehurst, and a single parking lane on one side from Pinehurst to the City limit (DeKalb Co. would have to do it northward from there). "Bulb outs" (using concrete raised curbs or plastic "bots") could be installed at intersections. The bulb outs prevent vehicles from driving wide of the marked lanes. If it is allowed (and I'd have to check that), thin trees or scrubs planted in the bulbouts would add to the narrow-street appearance.
Here's an example of a more elaborate bulb out:
Examples of low-cost bulb outs in Decatur, using 8 inch high white plastic markers (aka "bots") can be seen on Church St. and W. Ponce (assuming the bike lane is finished by now - I haven't driven by lately). Later, more permanent bulb outs can be installed, as is the plan for W. Ponce, according to this Decatur Metro post:
When the street appears narrower, even when the marked lanes are the required 11 feet, cars naturally slow down. Some might even elect to take Winn Way, if navigating Sycamore becomes too much of an inconvenience. This has been well illustrated on Ponce near the Post Office.
The City is already looking at a possible median at Grove.
If you have any ideas, the rest of us would love to hear them.
All that said, it appears municipalities can set lower speed limits basic on engineering studies, per Georgia Code 40-6-183 as shown in the continuation
If you'd like to search GA law, use this.