N.J. Stat. § 39:4-98
Subject to the provisions of R.S. 39:4-96 and R.S. 39:4-97 and except in those instances where a lower speed is specified in this chapter, it shall be prima facie lawful for the driver of a vehicle to drive it at a speed not exceeding the following:
Whenever it shall be determined upon the basis of an engineering and traffic investigation that any speed hereinbefore set forth is greater or less than is reasonable or safe under the conditions found to exist at any intersection or other place or upon any part of a highway, the Commissioner of Transportation, with reference to State highways, may by regulation and municipal or county authorities, with reference to highways under their jurisdiction, may by ordinance, in the case of municipal authorities, or by ordinance or resolution, in the case of county authorities, subject to the approval of the Commissioner of Transportation, except as otherwise provided in R.S. 39:4-8, designate a reasonable and safe speed limit thereat which, subject to the provisions of R.S. 39:4-96 and R.S. 39:4-97, shall be prima facie lawful at all times or at such times as may be determined, when appropriate signs giving notice thereof are erected at such intersection, or other place or part of the highway. Appropriate signs giving notice of the speed limits authorized under the provisions of paragraph (1) of subsection b. and subsection c. of this section may be erected if the commissioner or the municipal or county authorities, as the case may be, so determine they are necessary. Appropriate signs giving notice of the speed limits authorized under the provisions of subsection a. and paragraph (2) of subsection b. of this section shall be erected by the commissioner or the municipal or county authorities, as appropriate.
When designating reasonable and safe speed limits for a street under its jurisdiction pursuant to this subsection, as part of an engineering and traffic investigation, a municipality or county shall consider, but not be limited to, the following criteria: residential density; the presence, or lack, of sidewalks; the prevalence of entry and exit ways for business and commercial establishments; whether school children walk adjacent to the street on their way to and from school; and the proximity of recreational or park areas, schools, community residences, family day care homes, child care centers, assisted living facilities, or senior communities. Nothing in this paragraph shall substitute for traffic count, accident, and speed sampling data as appropriate.
The driver of every vehicle shall, consistent with the requirements of this section, drive at an appropriate reduced speed when approaching and crossing an intersection or railway grade crossing, when approaching and going around a curve, when approaching a hill crest, when traveling upon any narrow or winding roadway, and when special hazard exists with respect to pedestrians or other traffic or by reason of weather or highway conditions.
The Commissioner of Transportation shall cause the erection and maintenance of signs at such points of entrance to the State as are deemed advisable, setting forth the lawful rates of speed, the wording of which shall be within the commissioner's discretion.
N.J.S. § 39:4-98