By definition the travel times for motorized traffic are longer in a 30 km/h zone than in an area with 50 km/h roads: the speeds driven are lower. The larger a 30 km/h zone, the longer the response times of the emergency services (ambulance, fire, police). In a 30 km/h zone of 25 hectares an auxiliary vehicle requires 11 seconds extra response time, in an area of 200 hectares, this extra response time increases to 31 seconds; both in comparison with a 50 km/h area of equal size .
In principle buses do not belong in a 30 km/h zone, but for pragmatic reasons a bus route is often present in the larger areas. For a bus the extra driving time in a 30 km/h zone of 70 hectares is about 1 minute .
In addition to extra travel time driving comfort also plays a role. Especially road humps and plateaus, but also road narrowings and chicanes make it less comfortable for occupants of motorized vehicles. For ambulance personnel and patients and for bus passengers this can be a disadvantage .