The transit routes that tie the urban centers of the region together will in large part form the boundaries of residential districts. Along parts of these routes, especially at the intersections of arterial highways, will be minor or neighborhood business districts, containing neighborhood stores, banks, moving-picture theaters. Within the space they found will be a residential area large enough to support one or more schools, playgrounds, small neighborhood parks, a branch library, a community center, churches, so that children at least will have small occasion to cross the busy main traffic streets.

These main traffic streets or arterial highways are one of the most interesting of the problems that confront regional planners. Their primary function is to carry traffic from center to center within the region or to more distant destinations. How they should be designed, what width should be secured for rights-of-way to provide against future needs, whether they should contain facilities for rail as well as for road vehicles, are questions outside the scope of this paper. But it is necessary to point out that they will carry not only a heavy volume of traffic, in some cases a constant stream of traffic by day and a considerable and increasing amount of traffic by night, but that they will carry heavy vehicles. The increasing weight of trucks and busses has become a matter of public concern. Admitting, what seems to be the fact, that the large truck and bus make for economy of operation for their owners, they at present cause great expense to the community as a whole and to property owners along many of their routes where they are permitted to range at will. Street paving that would carry passenger cars for years goes to pieces quickly under their pounding, which also cracks the walls of dwelling houses and which, together with their noise, seriously depreciate the value of whole residence districts. The main arterial highways apparently must be designed and built to carry such vehicles, which will some day be excluded from residential streets. But what concerns us here is ... . the proper development of the abutting land.

We used to have a theory that every street-car street was potentially a business street. It was a poor theory, based upon inadequate experience. But inadequate as the basis always was it is becoming every day less adequate. Not only are our merchants realizing that the string business district can not compare with the compact district, not only are busses that operate on parallel streets applying the same argument to those parallel streets, but we are learning that business could never occupy all the frontage on street-car streets. Recent studies have indicated that, outside the principal downtown shopping district, not more than five per cent of an area will be occupied by business.

If this is borne out by further studies, it means that the frontage on the main arterial highways of the region must in very large part be devoted to other than business uses. Attempts to develop such frontages as residential are not proving permanently successful, even when the residences are multi-family houses. The inhabitants of multi-family houses object less to noise and movement than do those of one-family houses, but even they are beginning to find that noise and movement can be increased to such a degree as to become intolerable. So while we may zone the nonbusiness frontage of these arteries for multi-family house occupancy, we shall have to give even such dwellings protection if they are not to be blighted. The suggestion I offer is that in addition to the ample right-of-way for traffic purposes the community shall take possession of strips on either side of the traffic artery. These strips should be parked, and behind on either side should be a minor street serving the dwellings. The dwellings themselves should then be set back. This will provide for two screens of planting between the dwellings and the traffic highway. The park strip might be so wide that when, as and if business expansion can utilize it in part, it will provide suitable sites for business buildings.

This may seem extravagant but my belief is that it will prove less costly than the slow and spotty development of property abutting directly upon a main traffic highway and the inevitable depreciation of such dwellings as may be there erected.