This is an action for declaratory judgment to determine the constitutionality of an appropriation contained in chapter 143 of the Laws of 1967, Extraordinary Session. The appropriation is in the amount of $250,000, and was provided in the following language:
Planning and Community Affairs Agency
Motor Vehicle Fund Appropriation to assist metropolitan municipal corporations to make the planning, engineering, financial and feasibility studies incident to the preparation of a comprehensive public transportation plan; it is the intent of the legislature, in providing for these studies, to promote future savings in the construction, *556reconstruction, repair and betterment of public highways, county roads, bridges, and city streets.....$250,000
Pursuant to this appropriation, the appellant entered into an agreement with the municipality of Metropolitan Seattle, whereby, for an agreed consideration of $250,000, that body would conduct the planning, engineering, financing and feasibility studies incident to the preparation of a comprehensive public transportation plan for the area of Metropolitan Seattle. These studies have been completed and the results have been published in a report described by the consultant, DeLeuw, Cather & Company, which prepared the report, as follows:
■It covers the design elements of the transit system which were not included in previous studies, and it provides a more accurate estimate of cost based on engineering studies ....
On motion for summary judgment, the trial court sustained the Attorney General’s contention that the appropriation was violative of the eighteenth amendment to the Washington State Constitution (Const, art. 2, § 40) which reads as follows:
All fees collected by the State of Washington as license fees for motor vehicles and all excise taxes collected by the State of Washington on the sale, distribution or use of motor vehicle fuel and all other state revenue intended to be used for highway purposes, shall be paid into the state treasury and placed in a special fund to be used exclusively for highway purposes. Such highway purposes shall be construed to include the following:
(a) The necessary operating, engineering and legal expenses connected with the administration of public highways, county roads and city streets;
(b) The construction, reconstruction, maintenance, repair, and betterment of public highways, county roads, bridges and city streets; including the cost and expense of (1) acquisition of rights-of-way, (2) installing, maintaining and operating traffic signs and signal lights, (3) policing by the state of public highways, (4) operation of movable span bridges, (5) operation of ferries which are a part of any public highway, county road, or city street;
*557■(c) The payment or refunding of any obligation of the State of Washington, or any political subdivision thereof, for which any of the revenues described in section 1 may have been legally pledged prior to the effective date of this act;
(d) Refunds authorized by law for taxes paid on motor vehicle fuels.;
(e) The cost of collection of any revenues described in this section:
Provided, That this section shall not be construed to include revenue from general or special taxes or excises not levied primarily for highway purposes, or apply to vehicle operator’s license fees or any excise tax imposed on motor vehicles or the use thereof in lieu of a property tax thereon, or fees for certificates of ownership of motor vehicles.
On appeal, the director of the planning and community affairs agency contends that under a liberal construction of the amendment, the planning of a public transportation system serves a “highway purpose.”
Certain applicable rules of construction must be borne in mind in approaching this question. The first of these is that the state constitution is not a grant, but a restriction on the lawmaking power; and the power of the legislature to enact all reasonable laws is unrestrained except where, either expressly or by fair inference, it is prohibited by the state or federal constitutions. Pacific American Realty Trust v. Lonctot, 62 Wn.2d 91, 381 P.2d 123 (1963).
The construction and interpretation of statutes and of provisions of the constitution is a judicial function. State ex rel. Humiston v. Meyers, 61 Wn.2d 772, 380 P.2d 735 (1963).
Words in the constitution must be given their common and ordinary meaning. State ex rel. Albright v. Spokane, 64 Wn.2d 767, 394 P.2d 231 (1964).
If the constitutional language is clear and unambiguous, interpretation by the courts is improper; but if the language is unclear and ambiguous, judicial interpretation is not only proper but is an essential responsibility of the *558courts. State ex rel. Swan v. Jones, 57 Wn.2d. 718, 289 P.2d 982 (1955).
Where the words of a constitution are unambiguous and in their commonly received sense lead to a reasonable conclusion, it should be read according to the natural and most obvious import of its framers, without resorting to subtle and forced construction for the purpose of limiting or extending its operation. State ex rel. Torreyson v. Grey, 21 Nev. 378, 32 Pac. 190 (1893).
It is not for the court to engraft an exception where none is expressed in the constitution, no matter how desirable or expedient such an exception might seem. State ex rel. O'Connell v. Port of Seattle, 65 Wn.2d 801, 399 P.2d 623 (1965).
Applying these principles and rules to the question before us, we find that the constitutional provision in question is free of ambiguity. In words of plain and commonly understood meaning, it provides that the revenues derived from motor vehicle licenses and excise taxes on fuel, as well as other state revenue intended to be used for highway purposes, shall be paid into a special fund to be used exclusively for highway purposes. Lest that term be too narrowly construed, the people have defined its scope in the succeeding subparagraphs (a) through (e). If there were any doubt that the funds were intended to be used exclusively for ways open to the public for motor vehicular traffic, these clarifying provisions should remove them. Bridges and ferries, which might not ordinarily be considered highways, are expressly included because they are a part of such highways; that is to say, motor vehicular traffic must use them in crossing rivers or bodies of water. Roads and streets are expressly included, thus removing any doubt that they come within the definition of highways. Expenses of administration, of construction, reconstruction, maintenance, repairs and betterment are expressly included. But all of the purposes which are listed pertain to highways, roads and streets, all of which are by nature adapted and dedicated to use by operators of motor vehicles, both public and pri*559vate, and none of them pertain to other modes of transportation, such as railways, waterways, or airways. Nor is there any authorization for the expenditure of these funds for the purchase or maintenance of any type of vehicle for public transportation purposes.
Thus the words of this provision are unambiguous, and in their commonly received sense lead to a reasonable conclusion, that the people in framing this provision intended to insure that certain fees and taxes paid by them for the privilege of operating motor vehicles should be used to provide roads, streets and highways on which they could drive those vehicles. Express provision was made for the financing of certain structures and activities which might not be considered strictly within the definition of highway purposes, but which were considered necessary for the effectuation of those purposes. For purposes of constitutional interpretation, the express mention of one thing implies the exclusion of another which might logically have been considered at the same time. Yelle v. Bishop, 55 Wn.2d 286, 347 P.2d 1081 (1959).
The appellant accepts the definition of highway adopted by this court in State ex rel. Oregon-Wash. R.R. & Nav. Co. v. Walla Walla Cy., 5 Wn.2d 95, 104 P.2d 764 (1940), which was taken from 25 Am. Jur. Highways § 2 (1940):
“A highway is a way open to the public at large, for travel or transportation, without distinction, discrimination, or restriction, except such as is incident to regulations calculated to secure to the general public the largest practical benefit therefrom and enjoyment thereof. Its prime essentials are the right of common enjoyment on the one hand and the duty of public maintenance on the other. It is the right of travel by all the world, and not the exercise of the right, which constitutes a way a public highway, and the actual amount of travel upon it is not material. If it is open to all who desire to use it, it is a public highway although it may accommodate only a limited portion of the public or even a single family or although it accommodates some individuals more than others.”
*560What is a public transportation system? It is not a “way” at all, but is a number of buses, trains, or other carriers each holding a number of passengers, which may travel upon the highways or may travel upon rails or water, or through the air, and which are owned and operated, either publicly or privately, for the transportation of the public. The mere fact that these vehicles may travel over the highways, or that, as the appellant points out, may relieve the highways of vehicular traffic, does not make their construction, ownership, operation, or planning a highway purpose, within the meaning of the constitutional provision.
If the fact that vehicles affording public transportation make use of highways and the fact that persons; who use these vehicles may be refraining from driving their own vehicles and thereby saving wear and tear and congestion on the highways were sufficient to bring the ownership and operation of such vehicles within the definition of “highway purpose,” then private bus companies would be justified in claiming subsidies out of the highway funds. This we believe the appellant would be quick to concede was not the intent of the framers of the amendment. We are convinced that it was no more the intent of the framers to provide subsidies for the planning, constructing, owning or operating of public transportation systems, however beneficial such a use of the funds might be to the state and its citizens.
The appellant cites the case of Automobile Club of Wash. v. Seattle, 55 Wn.2d 161, 346 P.2d 695 (1959), for the proposition that the motor vehicle fund may be drawn upon for purposes which indirectly aid the highway system. In that case a declaratory judgment was sought to the effect that the payment of damages in a tort action arising out of the negligent operation of a draw bridge was an unconstitutional diversion of state gasoline excise tax funds, and we sustained the contention of the plaintiff. We said in that case that it was not the intent of the people, in adopting the Eighteenth Amendment, to curtail or impede the road program of this state.
*561On the contrary, we think it was the intention of the people to limit expenditures from the motor vehicle fund to those things which would directly or indirectly benefit the highway system. Clearly, the payment of a tort judgment does not fall within this category. Such an expenditure could in no way contribute toward the safety, administration, or operation of our highway system, but, rather, would establish a precedent that could result in substantially decreasing those funds reserved for such purposes. This, we feel, would be a detriment rather than a benefit to our highway system. Automobile Club of Wash. v. Seattle, supra, at 168-69.
As the respondent points out, the cited case is more supportive of the trial court’s action than of the appellant’s contention. It is true that we said that funds can be used for purposes which indirectly benefit the highway system, but the same paragraph makes it clear that those purposes are the ones mentioned in the amendment itself, all of which contribute toward the safety, administration, or operation of the highway system.
It may be conceded that, as the appellant argues, taking traffic off the highway benefits the highway in one sense, but it is doubtful that that is the sense in which the framers were interested in obtaining benefits for the highway. It is obvious that it was the desire to secure the building and maintenance of highways so that they could be used; and we can take judicial notice of the fact that automobile drivers generally want more and better highways, leading to more places, rather than fewer, however nearsighted such an attitude may be. Also, it should be observed that the appellant’s argument is in more than one way self defeating. If taking drivers of private vehicles off the roads relieves congestion and reduces wear and tear, carrying these same persons in buses may add to the congestion and increase the wear and tear, perhaps not so much as it alleviates these problems, but it is certainly not a benefit to the highways.
Also, taking money from the motor vehicle fund and spending it on public transportation does not benefit the highway system, however much it may benefit the *562people as a whole or alleviate transportation problems. It may be that the people of this state no longer desire to have the taxes which they pay on motor fuel and licensing spent exclusively on highways and would prefer that some or all of it be spent on public transportation or other purposes. If so, the means of expressing this intent is provided in the constitution and is not so cumbersome that it cannot be utilized with reasonable facility. But courts should never allow a change in public sentiment to influence them in giving a construction to a written constitution not warranted by the intention of the founders. State ex rel. Clithero v. Showalter, 159 Wash. 519, 293 Pac. 1000 (1930), appeal dismissed 284 U.S. 573, 76 L. Ed. 498, 52 Sup. Ct. 15 (1931).
The appellant urges that, because the legislature has declared that the appropriation is to be used for the purposes of benefiting the highways of the state, this, court should assume that there is a factual basis for this declaration. This assumption alone does not render the act constitutional. We have noted the incidental benefits which will accrue to the highway system if Metropolitan Seattle establishes a comprehensive system of public transportation, but the appellant does not suggest that there were any other benefits which the legislature had in mind when it voted the appropriation. These benefits, we have held, do not change the purpose of the expenditure from that of a public transportation purpose to that of a highway purpose.
The respondent calls our attention to the fact that metropolitan municipal corporations are authorized to provide metropolitan public transportation but are not authorized to engage in construction, maintenance or planning of streets and 'highways, under RCW 35.58. Not only is this true, but the appropriation act makes it clear that the appropriation is to be used for the planning of a public transportation system. The statement that such a system will benefit highways does not change that purpose.
A statute is constitutional or unconstitutional in accordance with the way in which it operates and the effect *563that it has. 16 Am. Jur. 2d Constitutional Law § 150 (1964). The constitutionality of an act depends on its real character and on the end designed to be accomplished rather than on its title or the professions as to its purpose which may be contained in it, and therefore such declarations do not conclude the court. Stewart Dry Goods Co. v. Lewis, 294 U.S. 550, 79 L. Ed. 1054, 55 Sup. Ct. 525 (1934), rehearing denied 295 U.S, 768, 79 L. Ed. 1709, 55 Sup. Ct. 652 (1935); 16 Am. Jur. 2d Constitutional Law § 150 (1964), at 356. Mere declaration cannot give character to a law or turn illegal operation into legal. Bunting v. Oregon, 243 U.S. 426, 61 L. Ed. 830, 37 Sup. Ct. 435 (1916).
In Aberdeen Sav. & Loan Ass’n v. Chase, 157 Wash. 351, 364, 289 Pac. 536, 290 Pac. 697, 71 A.L.R. 232 (1930), this court said:
Such a legislative declaration is to be carefully considered by the courts and due weight given thereto. Courts should, however, in construing an act containing such a declaration, consider the true operation and effect of the law which must be dealt with on the basis of the practical results which follow its operation, and not alone by legislative declarations contained therein.
Later cases so holding are Jensen v. Henneford, 185 Wash. 209, 53 P.2d 607 (1936), and Clark v. Seiber, 48 Wn.2d 783, 296 P.2d 680 (1956). As we said in both of these cases, the legislative body cannot change the real nature and purpose of an act by giving it a different title or by declaring its nature and purpose to be otherwise, any more than a man can transform his character by changing his attire or assuming a different name.
As the trial court in its memorandum opinion observed, the constitution lists the purposes for which the motor vehicle fund can be used, and diverting traffic from the highways is not one of them. It would be difficult to ignore the merit in the appellant’s position that this is an objective worthy of the most earnest support, but until the constitution is amended by the people, it must be financed through other means.
The judgment is affirmed.
*564Hill, Weaver, Hamilton, and McGovern, JJ., and Poy-honen, J. Pro Tem., concur.