substantial additional rights-of-way such as highways have become subjects of controversy. Therefore, the multiple use concept, air rights, appears to be a valuable tool for engineer planners and administrators in their effort to stay abreast of the increasing demands for the movement of people and goods, and yet at the same time assist in preserving the viability of the central city. Certainly it would assist us in the Nation's Capital with respect to providing solutions for and being responsive to some of the principal objections to urban freeway projects within the confines of the city that have been raised by our citizenry, namely: 1. The displacement of families.

2. The displacement of businesses with the attendant tax loss for those that cannot be relocated.

3. Aesthetics.

4. Separation of neighborhoods.

I have with me today some photographic slides that will pictorially show what the District of Columbia Government has accomplished to date (even in absence of enabling legislation of the type now being considered) with respect to joint use projects. The first Figures 1 through 7 depict early joint use-air rights projects in the District.

Figures 1 through 4 show a series of grade separations wherein main arterials and expressways have been relocated below the ground surface, and the surface air rights restored for park and other purposes. The latest, Washington Circle, was completed in 1962, but the others were all built twenty or more years ago.

Figure 5 shows the access ramp to the 14th Street Bridge through the Liberty Loan Building. This ramp was constructed in 1952.

Figure 6 is the 12th Street Expressway under the Great Mall, completed in 1962.

Figure 7 shows air rights usage for vehicular parking under the Southwest Freeway.

CURRENT JOINT USE-AIR RIGHTS PROJECTS

The following figures depict current joint use-air rights projects and, as I mentioned earlier, show continuing progress toward final completion of certain projects discussed at the 1967 Hearings.

Figures 8 through 10 delineate pictorially the 9th Street Expressway under the Great Mall. This project consists of a 1,600 foot three-lane tunnel facility, requiring ventilation. It will complement the existing 12th Street Expressway by handling traffic in the reverse direction to the south.

Figure 8, identified as the L'Enfant Plaza Hotel-Office Building over the 9th Street Expressway, is a photograph of the model of the entire 10th Street Mall area in the Southwest Urban Renewal Area. The hotel over the 9th Street Expressway is shown in the lower center; the 10th Street Mall and L'Enfant Plaza are shown in the center; and the Forrestal Building, extending across the 10th Street Mall, in itself a fine example of air rights joint usage, is shown at the upper right.

Figure 9 is a close-up model looking southwest, and in the left center it shows some of the expressway and hotel joint use details.

Figure 10 is a recent oblique air photograph looking north, with Maine Avenue, S. W., in the foreground. It shows the current status of construction in this general area.

Figures 11 through 18 relate to Interstate Route 95, the Inner Loop Center Leg joint usage across the Great Mall directly west of the United States Capitol building. This project is approximately three-quarters of a mile in length, and it will cost in the neighborhood of $50,000,000. Figure 11 is an oblique photograph of the model looking north and showing the Capitol in the right center, the curved alignment of a new ceremonial Louisiana Avenue, and a handsome reflecting pool. Also in Figure 11, at the north portal of the Mall tunnel, is the large new Department of Labor Building. This structure is estimated to cost approximately $40,000,000 and to house approximately 6,000 employees. Figure 12 shows the schematic alignment arrangements of the Labor Department Building, the underground freeway and the reflecting pool. Figure 13 presents a crosssectional view of the area indicating the relationship of the freeway, the reflecting pool, etc.

The Department of Highways and Traffic and the General Services Administration have coordinated their planning efforts over the past four years in the design of the Center Leg tunnel and the Labor Department Building. The building will extend for a two-block length between Constitution Avenue and D Street, with wings constructed on air rights over 2nd and 3rd Streets. A closer view of this same structure is shown in Figure 14, which shows tunnel ventilation shafts

that have been incorporated into the building, one of the exit ramps on C Street, and the freeway in a depressed section beyond. On this project, joint purchase of property has resulted in the surface and above air rights being retained by the General Services Administration, with the undersurface rights for freeway construction remaining with the Department of Highways and Traffic in the District of Columbia Government.

We are confident that, when completed, the building will be recognized as one of the world's outstanding examples of the joint use concept. Figures 15 through 17 are presented in order to show the rather elaborate system needed for ventilation. Figure 15 shows the location of the freeway in substructure with the ventilation shafts. Figure 16 is a cross-section showing blower and air duct system, and Figure 17 is a longitudinal section through the building.

As noted in Figure 16, the Labor Department Building will enclose vertical ventilation shafts that are approximately 100 feet high. Equipment will consist of 28 fans, having a wheel diameter of 109 inches, with a scroll height of 17 feet. The total blower fan capacity is equal to 4,500,000 cubic feet of air per minute with total exhaust fan capacity designed to handle 3,000,000 cubic feet per minute. The ventilation system for the main through roadways will be of transverse type. Fresh air will be supplied through ports arranged along and normal to the tunnel wall at an elevation level with an automobile's window area. Ventilated air will then be removed through exhaust ports on the opposite tunnel wall near the ceiling. The system is designed to prevent gas concentration from exceeding 211⁄2 parts of carbon monoxide in 10,000 parts of air.

The tunnels will have a television system for viewing all of the lanes of the tunnel at various strategic points. In the event of a traffic stoppage anywhere in the tunnel, observers in a central office will be alerted by way of a display panel and will be able to focus in on the trouble spot. The situation will be monitored and TV tapes will be recorded. The observers in the central office will, if needed, man the emergency control devices and alert the necessary emergency teams to restore traffic.

Figure 18 is an air oblique photograph of the area from a point south of the Southwest Freeway and shows the current status of excavation and construction on the entire Center Leg Freeway Project.

While not currently visible in the photograph, work has commenced on portions of a future Federal Building to be located between Independence Avenue and C Street, S. W., and immediately east of Third Street. This building will contain ventilation equipment, stacks, etc., similar to the Labor Department Building to assist in the overall ventilation of the south portion of the Center Leg Freeway Tunnel. Actually a corner of the building (the portion including the stacks) will be in air rights over the freeway. The same kind of coordination in planning between the Department of Highways and Traffic and the General Services Administration as required for the Labor Department Building was carried out at this location.

Figure 19 is of a proposed air rights joint use concept for a full block area (7th and 8th Sts., S. E.) under the Southeast Freeway. The freeway structure is presently under construction, but the air rights detailed use has not yet been finalized. Air-rights legislation will be required to develop this site for commercial or other usage.

Figure 20 is an artist's rendering of an approved, but as yet unbuilt, housing project on the upper end of the Center Leg of the Inner Loop Freeway lying between H and K Streets, N. W., and 2nd and 3rd Streets, N. W. The study was made by the consulting firm of Tippetts-Abbett-McCarthy-Stratton, after thorough research with the D. C. Redevelopment Land Agency and the Department of Housing and Urban Development. In addition, the study also considered, to a great extent, the desires of the local area office of the Urban League. In summary, the report found:

The development of the proposed housing is technically feasible. Structural and environmental problems can be solved readily. A livable, healthful and attractive residential community can be constructed over and adjacent to the freeway, provided the latter is covered either with buildings or decking throughout the length of the two-block site. Complete decking is necessary to prevent harmful fumes, noise and dirt from arising near buildings. This would occur if apertures were left in the decking on this relatively constricted site.

"The problem remaining to be solved then becomes that of providing financial feasibility. The first part of the financial problem is to overcome the cost of the freeway decking and related ventilation and lighting. The next part of the problem is to design and develop livable housing which will contain enough dwelling units

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not to require an excessive land writedown per dwelling unit, and whose capital costs will not be too high to preclude the moderate rentals which are necessary." We are pleased to report that this project, after a great amount of review and coordination between the Redevelopment Land Agency, the Department of Housing and Urban Development, the local community and the Department of Highways and Traffic, appears to have overcome all hurdles and will now quite likely be built. All responsible planning agencies, including the local area office of the Urban League, have approved a concept plan and the Mt. Carmel Church, which is currently situated and will remain within the site, has been selected informally as the developer of the complex.

The concept has been changed slightly from that proposed in the TippettsAbbett-McCarthy-Stratton study in order to be responsive to the desires of the citizens in the Northwest No. 1 Redevelopment Area. Statistics show that 192 families would be displaced in the site, and that the plan now provides for 290 medium and some low-income dwelling units, in two (2) seven-story apartment buildings and forty (40) townhouses. Also included would be park and recreation areas, sitting spaces, a 202-space parking area, provision for some commercial activities, and a day care center. Tunnel ventilation would be by air shafts through the apartment buildings.

It is estimated that the average dwelling unit cost under this scheme would be $21,000 per dwelling unit. This compares favorably with current prices for low-cost and medium income housing.

Figures 21 and 22 show conceptually the project as now approved.

Figure 23 is an air oblique photograph of the Potomac River Freeway, the Virginia Avenue grade separation, and the adjacent Watergate and Columbia Plaza apartment air rights treatment. The area was know locally as "Foggy Bottom," and its condition had deteriorated to a great extent. The construction of the Inner Loop Freeway segment was the catalyst that sparked a renaissance in building that resulted in uplifting the area, as shown in this photograph.

It is interesting to note that the edge of the Watergate Apartment building is within 55 feet of the adjacent Potomac River Freeway and 30 feet from the Freeway tunnel under the reconstructed Virginia Avenue, N.W. As far as we know, there are no problems with noise or air pollution at this location, which would seem to confirm that housing over freeways, if properly designed, can be made entirely liveable.

Figure 24 shows the Interstate Freeway System in the District of Columbia as contained in the 1968 Federal-Aid Highway Act and the location of current, proposed and potential air rights sites.

Mr. Chairman, the use of air rights in the Capital of the United States, Washington, D. C., as sponsored by the District of Columbia Department of Highways and Traffic, has been well received. Such use is continuing on a satisfactory basis and the Department contemplates an even greater demand for this type of treatment in the future.

Most certainly, however, we will need legislation to permit full development of the joint use concept so necessary to any transportation plan if it is to be responsive to the needs of the city and its citizens.