(concurring in part and dissenting in part). These consolidated cases address whether *638the highway exception to governmental immunity imposes liability on state and county highway authorities for failure to install street lighting (Scheurman) or to remove off-road visual obstructions (Prokop). In both cases I disagree that the highway authorities enjoy immunity and that the standard is as stated by the majority, namely whether the services or installations that affect safety or travel on the improved portion are located off-road. However, in Scheurman, notwithstanding the lack of immunity, the highway legislative scheme does not impose a general duty on state highway authorities to install street lighting on non-freeway, trunk line highways. In Prokop, notwithstanding the lack of immunity, such a determination of the duty to remove off-road visual obstructions has not been addressed by the Court of Appeals. I would affirm the decision in Scheurman but would remand in Prokop to determine the issue of liability.
i
This Court has examined the "improved portion of the highway designed for vehicular traffic” language of MCL 691.1402; MSA 3.996(102)1 on only a few occasions and has yet to clearly set forth our understanding of its legislative intent. These cases present that opportunity.
The majority concludes that the "improved portion” language of § 2 "refers only to the traveled *639portion, paved or unpaved, of the roadbed actually designed for public vehicular travel.” Ante, p 623. The majority holds that §2 provides no cause of action under the facts of these cases because "neither street lighting nor vegetation growing on private property adjacent to a road can be classified as being part of the improved portion of the highway designed for vehicular travel.” Ante, p 623.
I would conclude that the obvious purpose of this section expresses the Legislature’s intent to impose a duty on state and county highway authorities to maintain the improved portion of a highway in a condition safe and fit for travel and to provide liability for the failure to do so. Although the Legislature clearly did not intend liability for a failure to maintain the unimproved portion of the highway in a condition safe and fit for travel, nothing in the wording of § 2 suggests an intent to limit the liability of governmental agencies to only certain factors that are necessary to safely maintain the improved portion of the highway. Because many factors enter into maintaining the improved portion of a highway fit and safe for travel, such as the surface of the road, its design, and its freedom from dangerous accumulation of ice, snow, water, or unnecessarily poor visibility or unnatural obstructions, the exception to immunity should apply to any cause of action alleging negligence arising out of such conditions. Of course, immunity and liability under § 2 comprise interrelated but analytically distinct elements. Where, as in these cases, a plaintiff alleges negligence arising out of the condition of the improved portion of the highway, § 2 does not entitle a state or county highway authority to immunity. However, a plaintiff’s mere avoidance of immunity does not necessarily impose liability *640on a highway authority; the plaintiff still must prove duty, causation, and negligence.
At the outset of its analysis and before examining the statutory language to determine its purpose and scope, the majority announces its commitment to a strict interpretation of the highway exception because it derogates from the common-law of sovereign immunity. The majority’s common-law derogation analysis foreshadows its finding of immunity for the highway authorities in these cases. However, this Court should not employ a canon of strict construction to negate the fundamental legislative purpose underlying the highway exception to immunity. In this connection, the principle articulated long ago by Mr. Justice Holmes of the United States Supreme Court regarding statutory interpretation remains cogent: "[T]he general purpose [of a statute] is a more important aid to [its] meaning than any rule which grammar or formal logic may lay down.” United States v Whitridge, 197 US 135, 143; 25 S Ct 406; 49 L Ed 696 (1905).2 The highway exception to governmental immunity reflects a clear legislative purpose and policy to compensate persons injured because of a governmental agency’s failure to maintain highways in a condition safe for public travel.3 The majority fundamentally undermines this purpose by imposing an overly narrow construction on the "improved portion” language of §2._
*641II
The majority’s restrictive interpretation as applied to these cases does not comport with the legislative purpose of §2. The majority concludes in Scheurman that the state has no duty to install street lighting "because the physical structure of the lights falls outside the traveled or paved portion of the roadbed actually designed for public vehicular traffic.” Ante, p 633. In the majority’s analysis, the fact that the source of light emanates from a structure not directly on or connected to the roadbed itself immunizes the state from tort liability. Similarly, the majority concludes in Prokop that because a visual obstruction exists "on private property and [has] no connection with the roadbed or public travel thereon[,] ... it cannot be categorized as a defective condition upon 'the improved portion of the highway designed for vehicular travel ....’” Ante, p 635 (emphasis supplied).4
In my view, the majority errs in shifting the mandate of § 2 from a requirement on governmental agencies to maintain highways "in reasonable repair and in condition reasonably safe and fit for travel” to a result eliminating any cause of action for some factors which may contribute significantly to unsafe conditions on the improved portion of the highway. It seems clear even from a literal reading that the "improved portion” language of § 2 does not distinguish the surface of the highway as opposed to conditions other than the surface of the highway which may well foreclose the highway from being "reasonably safe.” Rather § 2 contrasts the "improved portion of the highway *642designed for vehicular traffic” in opposition to "sidewalks, crosswalks or other installation outside of [sic] the improved portion of the highway designed for vehicular travel.” (Emphasis supplied.)
The "improved portion” language of § 2 reflects a dividing conceptual line. On one side, §2 removes immunity for state and county highway authorities that fail to remedy unsafe conditions affecting the "improved portion of the highway designed for vehicular traffic.” On the other side, state and county authorities remain immune for conditions on "sidewalks, crosswalks or any other installation outside the improved portion . . . .”
In a departure from the language of the statute, the majority apparently draws the line between the surface of the improved portion and, on the other hand, conditions affecting travel on the surface of the improved portion originating separately from the roadbed itself. The majority’s analysis immunizing state or county authorities from liability for any unsafe conditions, the source of which do not originate on the surface of the roadbed, contravenes the plain meaning of the statutory language of § 2 and its principal import.
hi
The majority’s analysis in these cases that §2 immunizes state or county highway authorities for unsafe conditions created upon the paved or traveled roadbed by off-pavement visual obstructions or lighting also does not comport with well-reasoned precedent developed in this Court and the Court of Appeals. Case law interpreting § 2 has consistently, and in my view, correctly, rejected arguments equating "improved portion” with phys*643ical roadbed, consonant with the mandate of § 2 to maintain highways in safe and reasonable repair.5
This Court in Salvati v State Highway Dep't, 415 Mich 708, 715; 330 NW2d 64 (1982), recognized that a highway authority could incur liability for its failure to post signs warning of hazardous highway conditions. Although Salvati did not squarely address the "improved portion” language of § 2, the case demonstrates that immunity would not shield the state for failure to warn of known defective conditions affecting the improved portion. While warning signs exist apart from the paved or traveled portion of the highway, we did not hesitate to state that the failure to install such signs could remove immunity (i.e., expose highway authorities to liability) for accidents resulting on the improved portion.6
This Court first analyzed the improved portion language of § 2 in Roy v Dep’t of Transportation, 428 Mich 330; 408 NW2d 783 (1987). We held in Roy that the improved portion language of §2 precluded a cause of action for a bicycle accident occurring on a bicycle path. In my judgment, no better example of the purpose of the limiting "improved portion language” exists than that pre*644sented by the facts in Roy. The plaintiff in Roy could prove no facts showing the accident resulted from negligent conditions either on or affecting the improved portions of the highway designed for vehicular traffic. We commented in Roy on the line between immunity and nonimmunity imposed by the limiting "improved portion” language of § 2:
Indeed, to the extent it shows any legislative judgment on the benefits of separation, the exclusion of sidewalks, crosswalks, and other installations from the duty of maintenance and repair, reflects a conclusion that pedestrians and users of these installations have been sufficiently protected by the separation of them from motorists, without any need to impose a duty of maintenance and repair enforced by liability for resultant injuries.
Whereas the prior acts specifically included bridges, sidewalks, crosswalks, and culverts as subject to the duty to maintain and repair enforced by liability, the new legislation specifically excluded from liability "sidewalks, crosswalks or any other installation outside of [sic] the improved portion of the highway designed for vehicular travel.”
Section 2 does not reveal a legislative purpose to protect bicyclists in general, as suggested by the Court of Appeals. Indeed, the statute does not offer general protection to pedestrians or motorists without regard to location. The statute announces a duty to repair and maintain the highway so that the improved portion designed for vehicular travel is reasonably safe and convenient for public travel. The criterion used by the Legislature was not based on the class of travelers, but the road on which they travel. [Roy, supra, pp 336-341. Emphasis supplied.]
The essence of our distinction in Roy illustrates that the duty to safely maintain highways in *645reasonable repair extends not merely to the surface of the highway or conditions on the roadbed, but to the location of the duty.
The Court of Appeals has more extensively analyzed §2, and its viewpoints on the definition of the "improved portion of the highway” remain instructive and, in my view, correct. The Court first addressed the meaning of "improved portion” in Lynes v St Joseph Rd Comm, 29 Mich App 51; 185 NW2d 111 (1970). The plaintiff in Lynes alleged negligence in the county’s failure to properly maintain a stop sign. The Court of Appeals reversed the trial court’s decision granting summary disposition on the basis of § 2:
The trial court, by equating "the improved portion” with "traveled portion” (pavement), construed the statute to provide the defendant with immunity from liability for injuries proximately caused by the defendant’s negligence in the construction and maintenance of traffic control devices. In so construing the statute, the trial court erred. [Id., p 55. Emphasis supplied.]
The Lynes Court emphatically rejected the defendant’s argument urging immunity because the stop sign existed outside the "improved portion” of the highway:
The argument presented by the defendant, and accepted by the trial court as the basis for granting the defendant a summary judgment, that [MCL 691.1402; MSA 3.996(102)] exempts the defendant from liability in the instant case because the stop sign is not part of the "improved portion of the highway designed for vehicular travel” is not persuasive. Under defendant’s interpretation of the statute, the duty of the defendant to keep the highways safe and ñt for travel would be limited to the pavement itself and whatever equip*646ment physically touches the pavement. Although this interpretation would provide a certain ease in the application of the statute, it would completely negate the ñrst part of the statute, as well as that part of [MCL 224.21; MSA 9.121], both of which impose the duty on the defendant to keep the highways safe and ñt for travel. We cannot accept the argument that the legislature intended such a result. It is recognized law that in construing a statute effect must be given to every part of it and one part must not be so construed as to render another part nugatory. [29 Mich App 59. Emphasis added.]
In a case that sheds considerable light on the distinction at issue here, Miller v Oakland Co Road Comm, 43 Mich App 215; 204 NW2d 141 (1972), a tree on the unimproved portion of the highway fell and struck a motorist driving on the improved portion. The plaintiff alleged that the county road commission had been warned that similarly situated trees had previously fallen on the road, but had failed to take preventive action. The trial court granted summary judgment for the county. The Court of Appeals addressed whether § 2 imposes liability for an agency’s failure to keep a highway " 'in condition reasonably safe and fit for travel . . .’ and for failure to remove known hazards from the side of the road . . . causing] injury to [a] plaintiff by falling on '. . . the improved portion of the highway designed for vehicular travel ....’” Miller, supra, p 217. In other words, the Court asked whether or not immunity would absolve a road commission from removing trees on the unimproved portion of the highway which resulted in unsafe conditions on the improved portion. In reversing the decision of the trial judge, the Court pointedly rejected the argument "that because the tree fell on top of plaintiff’s truck, the defendant is somehow immu*647nized from liability under [§2] because the tree was not yet on the highway. This argument exalts words over logic.” Id., p 219. More specifically, the Court said, "Given this knowledge of the potential road hazards, the defendant failed to keep '. . . in condition reasonably safe and fit for travel . . .’ the road on which plaintiff was driving by failing to remove potential hazards from the side of the road. . . . [Defendant’s liability was incurred on '. . . the improved portion of the highway designed for vehicular traffic ....’” Id. Similarly, in Prokop the fact that an obstruction exists apart from the improved portion should not immunize a highway agency’s failure to correct a hazard directly affecting safety on the improved portion.
Cryderman v Soo Line R Co, 78 Mich App 465; 260 NW2d 135 (1977), represents a case factually closer to Prokop. The Court in Cryderman addressed "whether the duty, imposed upon the road commission to provide and maintain highways 'reasonably safe and fit for travel,’ extends to clear vision areas which lie beyond the improved portions of the highway proper.” Id., p 476. The Court noted that a separate statutory procedure existed by which highway authorities and railroad companies could voluntarily enter into "clear vision area” agreements, but held, relying inter alia on Lynes, supra, that § 2 affirmatively imposed a duty to maintain such areas. Today’s opinion overrules this holding in Cryderman, as "contrary to our decision today, as well as to our decision in Roy, supra.” Ante, p 634. Although Cryderman is obviously inharmonious with today’s majority decision, the majority fails to support its assertion that Cryderman is inconsistent with Roy and the highway exception statute.
On the basis of this line of cases, it hardly seems surprising that the Court of Appeals in Scheurman *648held that lighting constitutes an integral part of the improved portion of the highway notwithstanding that the light posts themselves exist off the roadbed. The Court of Appeals in Prokop, in contrast, departed from prior cases and held that immunity precluded a cause of action because the hedge obstruction did not comprise part of the improved portion of the highway. The Prokop Court did not even attempt to distinguish the many cases finding no immunity for defendant agencies where unsafe conditions existed on the improved portion regardless of whether the factors causing the unsafe condition originated off or away from the roadbed itself.7 Similarly, the majority’s holding that immunity under § 2 applies to any unsafe condition not coextensive with the actual paved or traveled portion of the roadbed seriously undermines the legislative mandate of § 2 to maintain safe highways.
Of the many cases interpreting § 2, only Zyskowski v Habelmann (On Remand), 169 Mich App 98, 103-104; 425 NW2d 711 (1988), suggested that immunity applies to "the physical structure of the road itself.”8
On reconsideration, we are convinced that the language of the § 2 exception to immunity evinces an intent to limit the imposition of tort liability in highway maintenance cases. The first sentence of the statute sets forth the duty in terms of ”reason*649able repair.” Such a phrase suggests that only the physical structure of the road itself was contemplated. . . . We therefore hold that the illumination or lack of illumination does not constitute part of the "improved portion of the highway designed for vehicular travel” ....
Unlike the majority today in Scheurman, the Zyskowski panel did not base its decision on the fact that the light poles illuminating the highway exist apart from the roadbed itself. Very simply and without citing any authority, the panel concluded that the duty of governmental agencies to maintain the roads in a safe condition did not extend beyond the physical roadbed.
IV
It is not difficult to understand that the Legislature in making an exception to the general principle of governmental immunity would do so only to the extent of insuring safety on the improved portions of the highway, as opposed to sidewalks, bicycle paths, and other installations unrelated to vehicular traffic. However, the notion of predicating a statutory scheme on the use of tort liability exposure as an incentive to maintain safe conditions on our highways on the one hand and then sharply restricting the corresponding duty and liability to only some factors that affect conditions on the improved portion on the other, stretches any plausible explanation of legislative intent. This is the result of the majority’s holding in these two cases.
It seems almost unimaginable that the Legislature would intend to provide an incentive for governmental highway agencies to safely maintain the roadbed of the highway but not to maintain unobstructed visibility for vehicular traffic because *650the obstruction does not originate from the roadbed itself. Certainly, § 2 does not reflect a legislative intent to impose unreasonable burdens on highway authorities to provide safe highway conditions. However, the law of negligence provides adequate safeguards against the imposition of unwarranted liability. The ultimate result of today’s decision eliminates any cause of action alleging unsafe conditions affecting the improved portion of a highway which do not orginate from the highway’s physical pavement. Neither the plain language nor the underlying purpose of §2 requires this unjustified restriction of liability.
The "improved portion” limitation in §2 does not mean, as the majority suggests, that the government’s duty is confined to that which makes it improved, that is, the roadbed, but the duty that is exempted from immunity is confined to the area of the improved portion as opposed to the area adjoining the improved portion. In other words, it is a spatial limitation, not a limitation on the factors and conditions that contribute to the safety of the improved portion as opposed to the safety of adjoining walks and installations. Maintaining a safe highway requires many activities and facilities off the road, including the proper mixture of the concrete that goes into the roadbed.
The focus of the exception of § 2 is on the safety of the improved portion of the road, not on the location of services, facilities, or installations that affect the conditions of travel on the improved portion.
v
I believe the Court of Appeals in Scheurman, while correct in holding that immunity would not bar plaintiff’s cause of action, erred in finding *651defendant liable for non-freeway state trunk line street lighting. The plaintiff in Scheurman conceded that §2 imposed no general duty on the state to install street lighting on non-freeway trunk line highways. The Court of Appeals recognized that MCL 247.651b; MSA 9.1097(lb)9 relieved state highway authorities from a duty to install non-freeway street lighting.
However, although the Court of Appeals correctly stated that "[w]hile various statutory schemes regulate who must pay for the costs of highway maintenance and repair, those statutes do not mention governmental immunity and do not affect it,” then, in my view, erroneously went on to assert that "[t]he statutes pertaining to the costs of repairs and maintenance of state trunk line highways have nothing to do with defendant’s ultimate responsibility for making sure that the highways under its jurisdiction are safe.” 162 Mich App 774, 783; 413 NW2d 496 (1987). The Court of Appeals should have resolved this legal question in the defendant’s favor where the plaintiff conceded no general duty to light non-freeway trunk line highways, and a later-enacted statute similar in purpose to § 2 specifically relieves state authorities from providing such lighting. Assuming these stat*652utes should be read in pari materia, it would seem illogical for one statute to impose liability on highway authorities for an item that another statute relieves the authorities from maintaining.
As stated previously, the questions of duty and liability are separate from immunity. Therefore, I would concur in the result in Scheurman.
In Prokop, a situation totally different from Scheurman existed, in that the hedge obstruction creating the unsafe condition on the improved portion violated both state law10 and a township ordinance.11 The Court of Appeals concluded that the "defendant’s duty . . . extended only to the improved portion of the highway and not to the hedge obstruction located on private property.” 168 Mich App 119, 125; 424 NW2d 10 (1988). The *653Court went on to say that "[o]ur conclusion is buttressed by MCL 239.5; MSA 9.525 which provides that it is the duty of every landowner to trim hedges that are growing along a public highway to a height not exceeding AV2 feet. We believe that this statute evidences the Legislature’s intent that liability for hedges that obstruct a motorist’s vision should rest with the private landowner, not with the state or county road commissions.” Id.
The Court of Appeals erroneously, in my view, used the hedge-trimming statute to buttress its argument for defendant’s immunity. It confused the duty of a landowner to trim vegetation on private property with the duty of a county to maintain the "improved portion” of a highway under its jurisdiction fit and safe for vehicular travel. Again, whether in the end the county has the duty to take action to abate the obstruction is a question separate from whether the county is immune from liability.
Although MCL 239.5; MSA 9.525 imposes a duty on landowners to trim vegetation along a highway on private property, nothing in the statute implies that a highway authority is absolved from its duty to maintain the improved portion safe and fit for vehicular travel. The existence of the state statute and city ordinance it would seem, if anything, should buttress the duty of the county to proceed against a private owner’s failure to abate a visual obstruction affecting safety on the improved portion of the highway. The question whether the county acted negligently by failing to take steps to correct a hedge obstruction could not be answered solely by reference to the state and township hedge-trimming statutes. Because of the erroneous conclusion of the Court of Appeals that the exception to governmental immunity did not apply to this case, it did not analyze the duty issue.
*654For these reasons, I would vacate the judgment of the Court of Appeals and remand the case for a determination of the extent of defendant’s duty to see to it that the obstruction was corrected and whether that duty was carried out.
Levin and Archer, JJ., concurred with Brickley, J.The statute provides in pertinent part:
The duty of the state and the county road commissions to repair and maintain highways, and the liability therefor, shall extend only to the improved portion of the highway designed for vehicular travel and shall not include sidewalks, crosswalks or any other installation outside of [sic] the improved portion of the highway designed for vehicular travel.
See also Jamison v Encarnacion, 281 US 635, 640; 50 S Ct 440; 74 L Ed 1082 (1930). “The rule that statutes in derogation of the common law are to be strictly construed does not require such adherence to the letter as would defeat an obvious legislative purpose or lessen the scope plainly intended to be given the measure.”
See Killeen v Dep’t of Transportation, 432 Mich 1, 9; 438 NW2d 233 (1989). "[The highway exception to immunity] clearly and unequivocally expresses] legislative intent that a person injured by reason of a 'failure’ 'to keep’ a highway fit for travel shall have a cause of action against a governmental agency.”
The majority also suggests that the county had no duty to trim obstructing hedges on private property and implies that the absence of such a duty bolsters a finding of immunity under § 2.
Michigan courts have held that the obligation of governmental agencies to prevent or correct defective highways encompasses three duties: to design and construct highways properly so reasonably safe for public travel, to repair defects and remove obstructions, and to warn of defective conditions affecting highway safety. See comment, Governmental immunity from tort liability in Michigan: A comprehensive analysis of the doctrine and related statutory and judicial exceptions, 28 Wayne L R 1761,1792 (1982).
Similarly, in O’Hare v Detroit, 362 Mich 19, 22; 106 NW2d 538 (1960) we dealt with a predecessor highway exception statute in addressing whether the failure of the city to "replace or warn concerning [a] knocked-down stop sign represented 'neglect to keep . . . streets ... in condition reasonably safe and fit for travel’ within the meaning of [the] statute.” Although we did not have to analyze the "improved portion” language of § 2 in O’Hare, we had no difficulty in finding that the duty to maintain safe highways was not limited solely to the surface of the highway.
See Johnson v State of Michigan, 32 Mich App 37; 188 NW2d 33 (1971) , Williams v State Hwy Dep’t, 44 Mich App 51; 205 NW2d 200 (1972) , Detroit Bank & Trust Co v State Hwy Dep’t, 55 Mich App 131; 222 NW2d 59 (1974), Van Liere v State Hwy Dep’t, 59 Mich App 133; 229 NW2d 369 (1975), Bennett v City of Lansing, 52 Mich App 289; 217 NW2d 54 (1974), Hall v Dep’t of Transportation, 109 Mich App 592; 311 NW2d 813 (1981), and McKee v Dep’t of Transportation, 132 Mich App 714; 349 NW2d 798 (1984).
The Court of Appeals in Alpert v Ann Arbor, 172 Mich App 223; 431 NW2d 467 (1988), following Zyskowski, held that street lighting did not comprise part of the "improved portion” of the highway.
MCL 247.651b(l); MSA 9.1097(lb)(l) provides:
The state transportation department shall bear the entire cost of maintaining, in accordance with standards and specifications of the department, all state trunk line highways including highways within incorporated cities and villages except that the cost of maintaining additional width for local purposes as provided in section lc shall be borne by the city or village. For the purposes of this act except for sections 11 and 12, maintaining of state trunk line highways shall include, by way of enumeration but not limitation, snow removal, street cleaning and drainage, seal coating, patching and ordinary repairs, erection and maintenance of traffic signs and markings, . . . but shall not include street lighting, resurfacing, new curb and gutter structures for widening. [Emphasis added.]
MCL 239.5; MSA 9.525 provides:
It shall be the duty of every owner, occupant or person having charge of lands in this state, to cut or trim, or cause to be cut or trimmed, to a height not exceeding four and one-half feet and a width not exceeding three feet, all hedges or hedge rows along or on the public highway or adjacent thereto in each and every year, except such hedges as shall have been set out for the protection of fruit trees and nursery stock. Trimmings or brush from such hedge rows shall not be left lying within the limits of the highway, but shall be forthwith removed: Provided, That this section shall not apply to streets or highways within incorporated cities.
Township of Redford, Ordinance No. 149 provides in pertinent part:
Unlawful to permit dense growth. It shall be unlawful for the owner or occupant or any person or persons, firm or corporation in charge of any lot or parcel of land within the Township of Redford to permit or allow to grow thereon any weeds, shrubbery or trees which, because of height or density, shall constitute a public hazard to pedestrians, drivers of motor vehicles or other persons while engaged in the lawful use of the sidewalks, roads or streets in the Township of Redford. In all such locations, shrubbery shall not exceed twenty-four (24) inches in height, weeds shall not exceed six (6) inches in height, and tree limbs shall not hang lower than six (6) feet above ground level.