Investigation of subgrade conditions on the Airbara – Toboali road section to improve road quality

Abstract

The Airbara - Toboali Road Section is a national road located in South Bangka Regency, Bangka Belitung Islands Province. Some segments of this road often experience road damage, although road repairs have been carried out several times to overcome the damage. The subgrade layer is the most important layer in the pavement structure because it functions to withstand all the loads above it. CBR (California Bearing Ratio) is penetration test used to evaluate the subgrade strength of roads and pavement. Therefore, this study aims to investigate the subgrade conditions on the Air Bara – Toboali road section in order to improve road quality. This study uses hand boring testing with 4 sampling points and field CBR testing with the DCP tool. Field CBR samples were taken as many as 30 points every 50 meters from STA 0+000 – STA 1+450. The average CBR value obtained shows that the CBR of this subgrade is in the good category (10.77%). Subgrade conditions per layer, namely at a depth of 0-2 meters the roads have almost the same soil characteristics. However, the soil depth of more than 2 meters in several locations on the road segment has a different character. The results of this investigation are expected to assist road planning so that road quality can improve.