Hypothesis Noise levels are higher in buses and trolleybuses of old models However, the noise levels do not exceed allowed levels.
Variables / Apparatus Dependent variable - noise level in buses and trolleybuses. Controlled variable - the model of bus (Ikarus, Karosa and Volvo) or trolleybus (Skoda and Solaris), where sound level was measured. Also, same person measures with the same Sound Level Meter.
Procedure A bus or trolleybus is caught; Using a sound level meter, an average and maximal sound level is measured and recorded. It is planned, that we go about 15-20 minutes by each vehicle to increase the accuracy of the average sound level.
Which model of the public transport is the most silent one? 1.Ikarus 2.Karosa 3.Skoda 4.Solaris 5.Volvo
Data Collection Model of investigated vehicle Average noise level, dB (uncertainty ±2 dB) Highest sound level, dB (uncertainty ±2 dB) 1.IKARUS8288 2.KAROSA7382 3.VOLVO7277 4.SKODA7680 5.SOLARIS7283 According to the standards of Ministry of Health of the Republic of Lithuania, changing sound level in transport must not exceed the limit of 110 dB
Conclusions Highest noise level was reached in IKARUS and SKODA None of the investigated vehicle reached the limit of 110 dB. Vilnius public transport system is safe and healthy for passengers. Newer models of public transport vehicles are healthier for passengers.
Difficulties The main difficulty faced when measuring an average noise level was a constant change of noise level We have measured not only the noise level of the vehicle, but also the noise of environment which wasn’t the subject of the investigation.
Improving the Investigation Measure and record the noise level every one minute. If total time is about 20 minutes, so the average of 20 measurements would be far more accurate. The tape recorder or notebook computer with a microphone could be used for noise recording. Using a record in the computer the clearer analysis could be done. While the noise level in different vehicles of the same model do not vary greatly, it would have been better to measure noise level in at least three vehicles of the same model. Measure the noise level of public transport in evening time, when there is less environmental noise.