Ironically traffic speeds in New York are measured using yellow cabs since they drive around constantly and are required to have GPS.
I think one of the biggest impacts has been on the sustainability of the transit services. For all road users, slower speeds require you to maintain more labor and vehicles out to maintain SLAs/frequencies, or to increase waits. For bus users in particular, it starts a vicious cycle because of several additional factors
* some baseline amount of people will just switch to rideshare instead of buses, reducing revenues and decreasing traffic speeds since buses are more space-efficient than cars
* with less revenues and less ridership, there is pressure to cut service to be more "efficient" at spending money
* with poorer services, more people switch to rideshare, further reducing revenues and decreasing traffic speeds
Now what level of congestion is 'acceptable' is mostly based on comparing to other cities, and how the electorate is feeling. That being said, the political pressure was so strong that NYC had already implemented congestion charges on rideshare and taxis, and is currently implementing tolling in Manhattan to try and reduce car numbers. Uber actually came out in support of it. https://www.uber.com/blog/new-york/uber-supports-congestion-...
I think one of the biggest impacts has been on the sustainability of the transit services. For all road users, slower speeds require you to maintain more labor and vehicles out to maintain SLAs/frequencies, or to increase waits. For bus users in particular, it starts a vicious cycle because of several additional factors
* some baseline amount of people will just switch to rideshare instead of buses, reducing revenues and decreasing traffic speeds since buses are more space-efficient than cars
* with less revenues and less ridership, there is pressure to cut service to be more "efficient" at spending money
* with poorer services, more people switch to rideshare, further reducing revenues and decreasing traffic speeds
Manhattan bus ridership entered this negative spiral and fell 23% https://nyc.streetsblog.org/2017/02/21/decline-in-nyc-bus-ri...
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Now what level of congestion is 'acceptable' is mostly based on comparing to other cities, and how the electorate is feeling. That being said, the political pressure was so strong that NYC had already implemented congestion charges on rideshare and taxis, and is currently implementing tolling in Manhattan to try and reduce car numbers. Uber actually came out in support of it. https://www.uber.com/blog/new-york/uber-supports-congestion-...