of . Rush hour bus headways on the M23 are supposed to be 4.5 to 5.5 minutes. A 2015 report found that half of the average M23 bus's time is spent either at a bus stop or stopped in traffic; that 28% of the duration of the average M23 trip is spent waiting at bus stops due to passengers boarding; and that the M23 only moves at over for an average of 10% of each trip. This was exacerbated by 23rd Street's varying width of , causing buses to need to change lanes frequently; as well as the fact that bus stops were frequently blocked by other traffic, and by double parked cars. The street was designated as a "Vision Zero Corridor" due to the high rate of injuries along the street (714 traffic-related injuries, 75 of them serious, as well as 5 deaths due to traffic incidents between 2009 and 2013). In 2009, the Metropolitan Transportation Authority and the New York City Department of Transportation (NYCDOT) identified the M14A/D, on parallel 14th Street, as a potential corridor for Phase II of SBS, the city's bus rapid transit system, as well as finalized plans to implement SBS on the M16/M34 along the also-parallel 34th Street. The crosstown bus corridors were noted for slow travel speeds. The M23 was originally not planned to be an SBS route, but in 2008, it had been part of a pilot program in which 30 articulated, redesigned SBS buses were rolled out on the M23 for some time. After lengthy consultation, the M23 was converted to SBS on November 6, 2016, with all-door boarding, off-board fare payment, dedicated New York City bus lanes, and BusTime-equipped countdown clocks at some stops. This is keeping in line with other SBS routes with the same upgrades, which have seen their average speeds increase between 10% and 25% after implementation. It replaced M23 local service at the cost of $1.7 million. The M23 SBS keeps the same route as the M23 local, with one redundant westbound stop on 5th Avenue and a bidirectional stop on Lexington Avenue being eliminated. Another bus stop, at the intersection of 20th Street and the western portion of the 20th Street Loop, was planned for elimination, but was retained after community members objected; their objections included that removing the bus stop would make it harder for the elderly residents of Peter Cooper Village to