Most use signing and flashing yellow lights during school times, but there is debate surrounding the efficacy of these measures. Massachusetts has set their default speed limit at in the vicinity of a mobile vendor with flashing yellow lights (such as an Ice Cream Truck) and at in a school zone when children are present. In North Carolina, the Central Business Districts (CBDs) have a statutory speed limit of unless otherwise posted. They use "Reduce Speed Ahead" signage instead of the more common "Reduced Speed Ahead" signage. In Oregon, rather than having a “when children are present” speed limit, they have a speed limit with a time-of-day system, usually school days, 7 a.m. to 5 p.m. The speed limit is for school roads with posted speeds of or below. Pennsylvania generally uses speed limits for school zones during arrival and departure times. In Rhode Island the default speed limit is within of a school, which starts to emulate a zone but is not an area-wide speed limit. In West Virginia school zones have a statutory speed limit of , except for roads with a speed limit of or higher, which have an advisory speed of in school zones when children are present. A school zone includes adjacent to the school (or school road) in both directions. Wisconsin has a default speed limit of in school zones, near parks with children, and in alleyways. Mexico Mexican cities which have established zones (Zonas 30): Monterrey, Nuevo León: in Barrio Antiguo Guadalajara, Jalisco: in Historic Downtown Zapopan, Jalisco: in Historic Downtown Los Mochis, Sinaloa: in Downtown Oceania Australia Residential streets of Melbourne suburbs Fitzroy and Collingwood are zoned 30 km/h. Leibig Street in Warrnambool is zoned 30 km/h Sydney CBD's only 30 km/h street is Druitt Street, next to Town Hall station. Other 30 km/h zones in Sydney include in the Centennial Park, Bi-centennial Park and in the Botanic Gardens. On 11 July 2020, Northern Beaches Council reduced the speed limit of Manly's town centre to 30 km/h. Liverpool city centre in Sydney's south west followed suit on 17 July. New Zealand A number of suburban shopping areas around Wellington have had 30 km/h limits since ca. 2010. In the Wellington Central Business District, 30 km/h limits will be put in place from the end of July 2020. The central area of New Plymouth was converted to 30 km/h in Jul 2012. The