The opinion of the Court was delivered by
CLIFFORD, J.These consolidated actions seek recovery on account of the wrongful deaths of plaintiffs’ decedents, resulting from an automobile accident. The collision occurred on a State highway. The issue is whether the State is liable under the New Jersey Tort Claims Act, N.J.S.A. 59:1-1 to 12-3 (the Act). The trial court gave summary judgment in favor of the State, and the Appellate Division reversed. Kolitch v. Lindedahl, 193 N.J.Super. 540 (1984). Because of a dissent in the Appellate Division, the State’s appeal is here as of right. R. 2:2-l(a). We reverse.
I
On October 31, 1978, at approximately 9:30 p.m., Stefan Lindedahl was driving his automobile in the southbound lane of Route 9W in Alpine, New Jersey. As Lindedahl entered a section of the roadway known as Walkers Hollow, his automobile went out of control and collided with another driven by Marilyn Bradley. Riding with Mrs. Bradley were her two sons, David and Philip, and a young neighbor, Alan Koliteh. All of the occupants of the Bradley car were killed.
Stephen Koliteh filed a wrongful death action on behalf of Alan in the Law Division, Bergen County, which was consolidated with a similar suit by John Bradley on behalf of Mrs. Bradley and the two boys. The complainants sought damages for various acts of negligence from Lindedahl, the Borough of *489Alpine, the County of Bergen, and the State of New Jersey, i.e., the State Department of Transportation.1
Plaintiffs claim that certain features of the roadway at the accident site amount to a dangerous condition within the Act’s general liability section, N.J.S.A. 59:4-2. That section reads in full as follows:
A public entity is liable for injury caused by a condition of its property if the plaintiff establishes that the property was in dangerous condition at the time of the injury, that the injury was proximately caused by the dangerous condition, that the dangerous condition created a reasonably foreseeable risk of the kind of injury which was incurred, and that either:
a. a negligent or wrongful act or omission of an employee of the public entity within the scope of his employment created the dangerous condition; or
b. a public entity had actual or constructive notice of the dangerous condition under section 59:4-3 a sufficient time prior to the injury to have taken measures to protect against the dangerous condition.
Nothing in this section shall be construed to impose liability upon a public entity for a dangerous condition of its public property if the action the entity took to protect against the condition or the failure to take such action was not palpably unreasonable.
The asserted “irregularities” of the highway begin with those features that affect the sight distances, such as foliage, poor lighting, and worn curbing, but do not end there.2 At Walkers Hollow the road is characterized by a “vertical sag curve.” This is a technical term for a design in which, as applied to a roadway, a downgrade is followed by an upgrade, and the road surface between the two itself contains a curve along the horizontal plane. Pursuant to N.J.A.C. 16:28-1.123, the speed limit in the area of Walkers Hollow is 50 miles per hour, although when the road was originally built in 1925, the limit was considerably lower, namely, 30 miles per hour. Aside from this increase in the speed limit, the highway is unchanged from the way it appeared when it was first constructed. The core of *490plaintiffs’ argument is that the posting of a 50 miles-per-hour sign within 200 feet of the curve created a dangerous condition of the roadway, or, to use their language, a “death trap” for unwary drivers.3
At the trial level the State asserted its immunity under various provisions of the Act, including plan and design immunity, N.J.S.A. 59:4-6; discretionary immunity, N.J.S.A. 59:2-3; and immunity for failing to provide ordinary traffic signals, N.J.S.A. 59:4-5. It also denied liability for having failed to post emergency signals under N.J.S.A. 59:4-4, and argued that its activities did not result in a dangerous condition of the roadway under N.J.S.A. 59:4-2. More specifically, the State’s position is that it cannot be held liable for the posting of a sign that does nothing more than inform the travelling public of the correct limit. The State also asserts that the setting of the limit in the first instance is a discretionary function and therefore protected under N.J.S.A. 59:2-3(b), which states: “[a] public entity is not liable for legislative or judicial action or inaction, or administrative action or inaction of a legislative or judicial nature.” The gist of the State’s contention, then, is that it cannot be a tort for a public entity or employee to inform the public of a duly promulgated discretionary determination.
*491The trial court concluded that the various immunity provisions of the Act were dispositive of plaintiffs’ claims. 'On appeal the Appellate Division agreed with the State on its plan and design immunity, but reversed, over a dissent by Judge Fritz, on the issue of whether a dangerous condition had been created under the Act’s general liability section, N.J.S.A. 59:4— 2. The court below reasoned that the State would not be immune from liability for a dangerous condition of the roadway were a jury to determine that such a condition existed as the result of an operational (as opposed to a planning-level) decision to post the speed-limit sign within close proximity to the curve itself. Judge Fritz dissented on the limited issue of whether liability could be imposed under N.J.S.A. 59:4-2.
II
Although immunity under the common law has been cut back or in some jurisdictions eliminated completely, this Court made clear in Willis v. Department of Conservation & Economic Dev., 55 N.J. 534 (1970), that actions of a legislative or judicial nature should still be immune from suit.4 As the Court there stated:
It is time for the judiciary to accept * * * responsibility and adjudicate the tort liability of the State itself. * * * [W]e will not attempt to express an ultimate doctrine; the constituent principles will be better evolved out of the realities of specific cases. But we do emphasize that the State will not be liable for legislative or judicial action or inaction, or administrative action or inaction of a legislative or judicial cast, nor generally with respect to decisions calling for the exercise of official judgment or discretion.
lid. at 540.]
*492Following the decision in Willis the Attorney General completed an exhaustive review of the law in this area and made extensive recommendations for change.5 The New Jersey Tort Claims Act, which stems from these recommendations, became effective on July 1, 1972, and carries the following legislative declaration:
[I]t is hereby declared to be the public policy of this State that public entities shall only be liable for their negligence within the limitations of this act and in accordance with the fair and uniform principles established herein. All of the provisions of this act should be construed with a view to carrying out the above legislative declaration.
[N.J.S.A. 59:1-2.]
The statute is therefore unmistakably clear in providing that liability on the part of the State cannot be imposed unless consistent with the entire Act itself. See Bell v. Bell, 83 N.J. 417 (1980); McGowan v. Borough of Eatontown, 151 N.J.Super. 440 (App.Div.1977).
Ill
To recover under N.J.S.A. 59:4-2, the Act’s general liability section, a plaintiff must show that the property was in a dangerous condition at the time of the injury; that the injury was proximately caused by the dangerous condition; that the dangerous condition created a reasonably foreseeable risk of the kind of injury that was incurred; and that a public employee created'the dangerous condition or that the public entity had notice in time to protect against the condition itself. Brown v. Brown, 86 N.J. 565, 575 (1981); N.J.S.A. 59:4-2. Additionally, there can be no recovery unless the action or inaction on the *493part of the public entity in protecting against the condition was “palpably unreasonable,” a term nowhere defined in the Act.
For today’s purposes we accept what was stated in Williams v. Phillipsburg, 171 N.J.Super. 278, 286 (App.Div. 1979), in which the court differentiated the term “palpably unreasonable” from ordinary negligence:
We have no doubt that the duty of ordinary care, the breach of which is termed negligence, differs in degree from the duty to refrain from palpably unreasonable conduct. The latter standard implies a more obvious and manifest breach of duty and imposes a more onerous burden on the plaintiff.
We conclude that the term implies behavior that is patently unacceptable under any given circumstance. As one trial court has suggested, for a public entity to have acted or failed to act in a manner that is palpably unreasonable, “it must be manifest and obvious that no prudent person would approve of its course of action or inaction.” Polyard v. Terry, 148 N.J.Super. 202, 216 (Law Div.1977), rev’d on other grounds, 160 N.J.Super. 497 (App.Div.1978), aff'd o.b., 79 N.J. 547 (1979); see also H. Margolis and R. Novack, Tort Claims Against Public Entities 55 (1984) (discussing Williams and Polyard). Moreover, the burden of proof with regard to the palpable unreasonableness of the State’s action or inaction is on the plaintiff in a case of this type. Fox v. Township of Parsippany-Troy Hills, 199 N.J.Super. 82 (App.Div.), certif. den., — N.J. -(1985); H. Margolis & R. Novack, supra, at 54; Comment, “The N.J. Tort Claims Act: A Step Forward?”, 5 Seton Hall L.Rev. 284, 294 (1974).
Of the four essential elements of the plaintiffs’ cause of action, only one, the existence of a dangerous condition, was discussed in any detail by the courts below. The term itself is defined in N.J.S.A. 59:4-1, which states:
“Dangerous condition” means a condition of property that creates a substantial risk of injury when such property is used with due care in a manner in which it is reasonably foreseeable that it will be used.
Moreover, courts have defined a “substantial risk” as “one that is not minor, trivial or insignificant.” See Polyard v. Terry, supra, 160 N.J.Super. at 509. In Polyard, the Appellate *494Division further stated that “[ejach case where the issue arises must be pragmatically examined by the judge, to determine whether the particular highway irregularities were such that reasonable minds could differ as to whether they manifested that the highway was in a dangerous condition.” Id. at 510.
Applying the foregoing principles to this case, we agree with the State that it cannot be a tort to communicate accurately a properly established speed limit. We also agree that the setting of the speed limit in the first instance is a discretionary function. In the pre-Act case of Fitzgerald v. Palmer, 47 N.J. 106, 109-10 (1966), this Court stated, “[wjhether a road should have * * * traffic lights, or traffic policemen, or a speed limit of 50 or 60 miles per hour — such matters involve discretion and revenue and are committed to the judgment of the legislative and executive branches.” Moreover, in N.J.S.A. 39:4-98 the legislature has specifically empowered the Commissioner of Transportation to “designate a reasonable and safe speed limit” under certain circumstances, an exercise of discretion under a specific legislative delegation.
The dissent suggests that the “lawful” speed limit at Walkers Hollow is not 50 miles per hour, the currently posted limit there, but rather the speed only at which the curve itself may be traversed safely — that a “reduced speed in fact is the lawful” speed. Post at 507. (emphasis in original). This ingenuously contrived proposition provides the convenient springboard for the remarkable conclusion that the posted sign “did not accurately communicate the lawful speed limit applicable to the stretch of road in question.” Post at 499. (emphasis in original).
The dissenter’s point, so persuasively made, misconstrues the statutory and administrative provisions that govern this case. That the speed limit in the vicinity of Walkers Hollow is 50 miles per hour cannot be disputed. See N.J.A.C. 16:28-1.123. Moreover, N.J.S.A. 39:4-98 empowers the State Highway Commissioner to erect and maintain “signs or billboards at such *495points of entrance to the State as are deemed advisable, setting forth the lawful rates of speed * * *.” Significantly, the predecessor to N.J.S.A. 39:4-98 contained the following provision regarding unsafe movement: “In any case where any such [designated] speed would be unsafe it shall not be lawful.” L. 1939, c. 211, § 1. That provision was removed from the statute in 1951, see L. 1951, c. 23, § 55, at which point the following was added:
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. [Emphasis added.]
This latter provision remains today. See N.J.S.A. 39:4-98.
These statutory changes make it unmistakably clear that the “lawful” limits of speed are simply those that are posted, namely, those limits above which a motorist using our roadways will be held to be in violation of the traffic regulations. In the case before us that limit is 50 miles per hour, precisely that which is communicated by the posted sign. The onus of reducing speed to some appropriate level when approaching a curve such as the one at Walkers Hollow is on the driver. Thus, the State cannot be subjected to liability for the posting of a sign so long as the sign itself does not misinform the public with regard to the actual, lawful limit as permitted by statute and as enforced by the appropriate officials.
In this connection we recognize as it relates to this case that there is a distinction to be made between a planning-level or discretionary decision, which is generally entitled to immunity, and an operational or ministerial action, which is not. See N.J.S.A. 59:2-3; Costa v. Josey, 83 N.J. 49, 58-60 (1980). As one court has explained, “[a] discretionary act * * * calls for the exercise of personal deliberations and judgment, which in turn entails examining the facts, reaching reasoned conclusions, and acting on them in a way not specifically directed.” Miree *496v. United, States, 490 F.Supp. 768, 774 (N.D.Ga.1980) (emphasis added). We believe that the posting of a sign is merely one form of acting on the decision to set a certain limit, a decision that is discretionary in nature and therefore entitled to immunity. Thus, both the decision and the act of implementation are one and the same for the purposes of the statute. Even if this were not the case, the posting of a sign that does nothing more than inform the public of the lawful speed limit could hardly be viewed as “palpably unreasonable” within the meaning of that term as used in the Act.
Nor is the State liable for its failure to warn of the hazardous nature of the curve itself. In Aebi v. Monmouth County Highway Dep’t, 148 N.J.Super. 430 (App.Div.1977), the plaintiff was injured, and another driver killed, on a county-owned bridge that was considerably narrower than the road on which it was located. The plaintiff sought to predicate liability on the basis that the county had failed to warn motorists “that the width of the roadway was being suddenly reduced to the width of the bridge.” Id. at 432. In rejecting that argument the court relied on N.J.S.A. 59:4-5, which provides:
Neither a public entity nor a public employee is liable under this chapter for an injury caused by the failure to provide ordinary traffic signals, signs, markings or other similar devices.
In interpreting this provision, the court concluded: “The determination as to the advisability or necessity of a traffic sign or warning device at any particular place requires the exercise of discretion, and hence N.J.S.A. 59:4-5 simply specifies one particular type of discretionary activity to which immunity attaches.” Id. at 433.
Likewise, in Johnson v. Township of Southampton, 157 N.J.Super. 518 (App.Div.), certif. den., 77 N.J. 485 (1978), a motorcycle rider was seriously injured when he smashed into a guardrail at a “T” intersection that was unmarked and partially obstructed by trees and other vegetation. The court held that by virtue of N.J.S.A. 59:4-5 the municipality was immune from liability for its failure to have marked the intersection. The *497court also concluded: “The limited ability to make observations on either side of the road caused by trees and vegetation simply served as a warning that due care must be maintained.” Id. at 523.
Finally, we have considered the additional points raised in plaintiffs’ briefs and are satisfied that they were correctly resolved by the courts below. In particular, we agree that insofar as the “sag curve” could be considered to be a dangerous condition, that condition is insulated by the provisions of N.J.S.A. 59:4-6, granting immunity for construction in accordance with approved plan or design. We agree, as well, that the public entity could not be held liable for failure to provide “emergency signals, signs, markings or other devices” under N.J.S.A. 59:4-4. We have considered these points despite the fact that they are not properly before us on this appeal, there having been no dissent below on those issues, see R. 2:2-l(a)(2), and no petition for certification that raised those additional points, see R. 2:2-l(b); cf. State v. Del Fino, 100 N.J. 154, 165 (1985) (Court would not consider grounds urged for reversal of conviction when not addressed by Appellate Division and not the subject of a grant of certification).
IV
It is well established that the burden is on the public entity both to plead and prove its immunity under our Act, see Ellison v. Housing Auth. of South Amboy, 162 N.J.Super. 347, 351 (App.Div.1978); and that to succeed on a motion for summary judgment, the entity must “come forward with proof of a nature and character [that] would exclude any genuine dispute of fact * * Id. However, once a moving party has met that burden, summary judgment is warranted and, indeed, desirable, as a matter of judicial economy. See Judson v. Peoples Bank & Trust Co. of Westfield, 17 N.J. 67, 74 (1954); *498R. 4:46-2; cf. Sutphen v. Benthian, 165 N.J.Super. 79, 82 (App. Div.1979) (summary judgment “entirely unwarranted”; defendant’s conduct “clearly not the type of high-level policy decision contemplated by * * * the Tort Claims Act”). In light of the provisions discussed above, the State has met its burden in this case and is therefore entitled to prevail.
The judgment of the Appellate Division is reversed. The cause is remanded to the Law Division for entry there of judgment in favor of defendant State of New Jersey.
The claims against the Borough of Alpine and the County of Bergen were disposed of in summary fashion in favor of both defendants and are not at issue in this appeal.
Although throughout this opinion we refer to the condition at Walkers Hollow in the present tense, we were informed after oral argument that in fact an "alteration project" for the area was "substantially completed" in 1983.
The plaintiffs’ expert submitted an affidavit at the trial level in which he explained:
On a highway such as Route 9W, it is both reasonable and prudent for a driver to accelerate as rapidly as the existing traffic and weather conditions will allow to reach the speed at which other traffic is flowing or is expected to flow because of the risk that other traffic will come upon the slower moving vehicles unexpectedly without adequate opportunity to slow or stop. Therefore, the posting of a speed limit of 50 miles an hour on a roadway such as Route 9W can be expected to have the effect of encouraging drivers entering the roadway to bring their vehicles to that speed as soon as possible.
********
It is generally considered that the posting of any given speed limit gives rise to a belief on the part of the driver that the road can be traversed safely at such speeds.
For a broader look at the historical origins of governmental immunity, see 1 F. Pollock and F. Maitland, The History of English Law 515 (2d ed. 1952); E. Borchard, "Governmental Liability in Tort,” 34 Yale LJ. 1 (1924); A. Van Alstyne, "Governmental Tort Liability: A Decade of Change," 1966 U.Ill.L.Forum 919 (1966); J. Henderson and R. Pearson, The Torts Process 620 (2d ed. 1981); W. Prosser and W.P. Keeton, The Law of Torts § 1341 at 1032-33 (5th ed. 1984).
The Attorney-General was authorized by the legislature to begin his study on immunity in 1966, some four years before the decision in Willis. See N.J.S.A. 52:17B-4.1. However, in light of Willis and another decision abolishing the State's immunity in contract actions, P, T & L Construction Co. v. Commissioner of Transp., 55 N.J. 341 (1970), Attorney-General Kugler stated that "a more intensive examination of the subject was required.” Report of the Attorney General’s Task Force on Sovereign Immunity (1972), at 1. Thus, the Kugler Report is a product of both the Court’s decision in Willis and an earlier legislative mandate.