Project DescriptionTwo other rapid transit projects that utilized disk bearings were the Sound Transit Tukwilla and Airport segments and the RAV line in Vancouver. The Sound Transit project is a 7.4 km (4.6 mile) long elevated guideway consisting of precast segmental concrete short span bridges typically ranging from 30 to 37 meters (97 to 120 ft.) that also required uplift bearings of the design shown in Figure 4. The design also called for shock transmission units to deal with the seismic forces at certain locations (Fig. 12). 94 disk bearings were utilized with a load range of 2225 kN to 4900 kN (500 to 1100 Kips). The horizontal loads were excessive ranging from 68 to 200% of the vertical capacity. Similarly the uplift forces due to seismic were up to 79% of the vertical loads. Very few bearings are capable of this type of loading.