The Kallang-Paya Lebar Expressway (KPE) is a 12km long strategic road link between the existing East Coast Park Expressway (ECP) in the south and Tampines Expressway (TPE) in the north-east. The KPE comprises 9km of underground road and 3km of surface level road, together with major interchanges with the Pan-Island Expressway (PIE), ECP and TPE. It is currently the longest underground tunnel in South-East Asia.
The C424 design scope comprises a 2.6km section of KPE between Ubi Road 2 and Defu Road 3, the at-grade highway, 2 ventilation buildings, traffic signs and road markings, pedestrian overhead bridges and link sewers. As with C422, the scope includes significant temporary works design, such as a major signalised gyratory and instrumentation.