Page:Final Report - The Columbia River Interstate Bridge.pdf/37

 of the bridge as a marker for the old Oregon Trail a simple stone drinking fountain which bears a bronze tablet symbolic of the Spirit of the Trail. The Oregon chapter of the same organiza- tion applied for and received similar permission for the erection of the trail marker at the Oregon end of the bridge.

Along both sides of the Union Avenue approach there have been planted roses and Scotch broom and there is similar plant- ing about the entrance columns (seventeen hundred rose bushes and thirty-five hundred Scotch broom plants were set out). With a small amount of care and attention there will soon be added beauty to the substantial utility of the approach embankments.

LOADS FOR WHICH THE BRIDGE IS DESIGNED
The attention of your Commission is particularly called to the loads for which the steel portions of the structure were designed. In addition to the actual calculated dead load weight of all parts, and wind loads, provision was made for the follow- ing live, or moving, loads:

For the ﬂoor system and for girders:

On Street Car Tracks—Two 50-ton cars on each track.

On Roadways—12-ton motor truck, with special provisions for 24—ton machinery truck or loads per linear foot for each line of traffic varying with loaded length from 812 pounds for 25 feet to 735 pounds for 100 feet.

On Sidewalk—600 pounds per linear foot.

Impact allowance of 50 per cent is added to all except side- walk loads.

F or trusses:

On Street Car Tracks—Two 40-ton cars on each track.

On Roadways—Loads per linear foot for each line of trailic of about 500 pounds, but varying with the loaded length.

For impact allowances the following percentage of each load is added to it:

For roadway loading—I = NL21°300 but not greater than ﬁfty per cent.

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mind not greater than fifty

For street car loading—I = per cent.