SURVEY OF TRAFFIC-INDUCED VIBRATIONS

THE EFFECT OF TRAFFIC-INDUCED VIBRATIONS ON PEOPLE AND STRUCTURES IS SURVEYED AND COMPARED WITH THE EFFECTS OF VIBRATIONS FROM OTHER SOURCES. INFORMATION DERIVED FROM FIELD MEASUREMENTS IS INCLUDED TOGETHER WITH EXISTING SCALES FOR ASSESSING INTENSITY OF VIBRATIONS. VIBRATIONS ARE GENERATED BY FLUCTUATIONS OF WHEEL CONTACT LOADS AS VEHICLES TRAVEL OVER ROAD SURFACE IRREGULARITIES. IRREGULARTITIES OF THE ORDER OF 20 MM IN AMPLITUDE CAN CAUSE PEAK PARTICLE VELOCITIES IN THE GROUND OF UP TO 5 MM/S AT WHICH LEVEL 'ARCHITECTURAL DAMAGE' MAY OCCUR IN BUILDINGS. HOWEVER, BEFORE THIS LEVEL IS REACHED, VIBRATIONS BECOME INTRUSIVE AND EVEN ANNOYING TO OCCUPANTS OF BUILDINGS (AT ABOUT 2.5 MM/S) AND COMPLAINTS MAY RESULT. VIBRATIONS INCREASE IN SEVERITY WITH DYNAMIC AXLE LOAD. AS HEAVY AXLE LOADS ARE INCREASING BOTH IN MAGNITUDE AND NUMBER, VIBRATIONS ARE LIKELY TO BECOME MORE WIDESPREAD. THE PROBLEM OF VIBRATION TRANSMISSION AND ISOLATION, BUILDING RESPONSE AND DISTURBANCE OF EQUIPMENT WITHIN BUILDINGS IS ALSO CONSIDERED. THE NEED FOR MORE PRACTICAL INFORMATION ON BUILDING RESPONSE AND DAMAGE IS EVIDENT. VIBRATIONS ARE ALREADY NOTICEABLE ON MANY BRIDGES. METHODS OF DYNAMIC ANALYSIS ARE REQUIRED WHICH WILL ENABLE DESIGNERS TO ALLOW FOR THE DYNAMIC STRESSES GENERATED BY VEHICLES AND TO TAKE INTO ACCOUNT THE REACTION OF PEDESTRIANS. THE TREND TOWARDS MORE SLENDER DESIGNS AND HENCE MORE 'LIVELY' BRIDGES IS ACCENTUATING THE NEED FOR THIS INFORMATION. THE MOST SATISFACTORY WAY TO MINIMIZE THE EFFECT OF TRAFFIC-INDUCED VIBRATIONS IS TO REMOVE THE PROBLEM AT ITS SOURCE BY MAINTAINING STANDARD ROAD SURFACES. /TRRL/