This is in the center of town-in Ridgewood,NJ. These poles were the basic model of metal lampost that existed in major cities such as Newark, jersey City, Hoboken and Union City. The mast arms were mostly removed and a tapered arm attached that contained a silverliner fixture. These poles exist today but have modern arms and fixtures. Notice the wide base. You can find these poles and identify them by the matchingwide bases. The town of Haddonfield still lines their main street with them (Kings Hwy.) but has modern fixtures attached to them. they painted them and restored the poles.Princeton ,NJ also has done the same thing.
Not necessarily, most poles today on city streets are not breakaways they are used mostly on the freeways. They can't use breakaway poles on most city streets if sidewalks are around because knockdowns are dangerous to pedestrians.
The ones here either have a breakaway coupling on the pole, a breakaway aluminum base like how Darren described, a set of breakaway bolts or, a breakaway baseplate.
Usually the material in the breakaway parts are either weakened or are very brittle like the aluminum bases which makes them break easily if struck.
The big traffic signals here are not break away. I saw one that stopped a car hijacker, after he clipped a car during a high speed chase. Only damage to the pole was a dent, made by the car crumpling around it. The hijacker did break a window in the shop next door with his head, as funnily the bonnet ( hood in the USA) also did not crumple, but broke off the hinges and went though the car at neck hight.
Usually the material in the breakaway parts are either weakened or are very brittle like the aluminum bases which makes them break easily if struck.