Bad concept, imho. It would be much better to use these detectors to sync up the green lights with the flow of traffic, to keep everything running smoothly. Instead, they are going to do the opposite and clog up their streets even more.
Also, the proposed stopping of traffic will increase the emission of CO2.
I live in an area with limited traffic and the most congested area is getting on and off one of the freeway exits. Every so often I see the traffic engineers messing with the timing and when they get it wrong, it is amazing what a bad result they can get.
Worse, this punishes those not speeding
The speeders and non speeders alike are caught at the light.
A few good speed bumps carefully designed to look like pothole would be a better alternative
That said the only time I have been to Philly I was speeding as fast as I could out of town