RELATIONSHIP MODELS BETWEEN HYDROCARBON CONCENTRATIONS IN ROADWAY AMBIENT AIR WITH TRAFFIC CHARACTERISTICS

The increasingof air pollution from transportsector in Indonesia is influenced by traffic flow characteristics.This research employsthe model provided relationship between hydrocarbon gas concentrations in roadway ambient air and traffic flow characteristics at Padang primary road network, which are represented by Sudirman street as arterial road, Imam Bonjol street as collector road, and M. Yunus street as local road.The research focuses on traffic volume, speed, and density. Samplings of hydrocarbon gas are taken based on SNI-19-7119.9-2005, using ambient gas sampler. The result shows that hydrocarbon gas concentrations inallthree roads ranged from 55.62 to 119.58 mg/Nm3 . They are below the tolerance of ambient air quality standard in accordance to PPno. 41/1999 (160 mg/Nm3 ). Correlation and regression analysis indicate that there are very strong and significant correlations between hydrocarbon gas concentration in roadway ambient air with traffic flow characteristics (at level of significance α<0.05), with linear and exponential functions. The validation test showed that the model of hydrocarbon gas concentration in roadway ambient air and traffic density provide the smallest error, about 5%.