Safeguarding Our Bridges 



The cushion gate and the yielding 

 barrier are two effective remedies 



RECENT accidents in Boston, Chicago 

 and Vancouver have at last aroused 

 ■ the public to the realization that 

 changing conditions have made obsolete 

 devices used at the present time to protect 

 bridge approaches and railroad crossings. 

 A cushion barrier gate devised by the 

 Chicago bureau of engineering seems to 

 solved the problem of the improperly 

 protected 

 bridge approach 

 and the yield- 

 ing chain bar- 

 rier for railroad 

 crossings prom- 

 ises to do much 

 to lessen the 

 number of 

 accidents. 



The cushion 

 barrier gate, 

 which has been 

 installed at the 

 Lake Street 

 bridge, in Chi- 

 cago, consists 

 essentially of a 

 forty -two-foot 

 boom of Doug- 

 las fir, sixteen 

 inches in diam- 

 eter, suspended 



from the top of the bridge by two heavy 

 twelve-inch pipes. The boom, which weighs 

 a ton, serves as a buffer to stop a street 

 car or automobile running at high speed 

 without wrecking it or causing serious 

 injury to the occupants. When a car 

 bumps into the boom, the boom rolls for 

 two feet, then slides for eight feet, and 

 then for the next five feet slides and rises 

 two feet, so that the car not only has to 



Automobile run- 

 ning into the 

 yielding chain 

 barrier, which 

 consists of a 

 steel truss strung 

 between uprights 



overcome the 

 inertia of a 

 heavy weight 

 but acts against 

 gravity on a 

 total weight of 

 over five tons. 

 Danger of 

 dropping the 

 boom on a street 

 car is eliminated 

 by an ingenious 

 device. Each 

 time a street 

 car enters the 

 bridge, it auto- 

 matically turns 

 a cog wheel one 

 notch. The 

 boom, which is 

 in position 

 against the top of the framework, cannot 

 be dropped by the bridge tender until the 

 car pushes forward another cog wheel 

 when it passes off the bridge at the other 

 end. 



The lighting system, which is also unique, 

 has proved highly effective. The engineers 

 have utilized the well-known principle, little 

 used for bridge signals, that a light which 

 goes on and off at short intervals catches 

 the eye quicker than any other. The red 

 lights first come on at the "Stop" sign at 

 the left. Then in quick succession the 

 lights in the gate at the left, in the gate at 

 the right, and the "Stop" sign at the right 



The cushion barrier gate which re- 

 cently stopped a street car running 

 at ten miles an hour without damag- 

 ing the car. See diagram at left 



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