Pan Borneo Highway Sarawak:
Review as of 10 December 2020. Been getting queries on road conditions so here goes.
*Personal driving experience with a small car. Hilux different story.
Kilo Nol: Tg Datu- Sematan
Complete, gorgeous but not dual lane.
Sematan-Lundu: Gravelly, some smooth stretches.
Lundu-Bau: SHIT. Steep drops, gravelly and potholed. Dark at night. Just use Rambungan-Sampadi ferry instead, worth the detour for your car's sake.
Bau-Singai-Batu Kawa (Kuching)
Diversions plenty, but drivable
Kuching:
Stephen Yong - Kota Padawan
Road ok, clear diversion. Flyovers all in various stages of completion. Traffic clogs at Kota Sentosa and 10th Mile.
Kuching-Serian
11th Mile onwards complete, onwards to Serian
Serian: Roads still in the works but looks almost complete except for stretch going uphill/downhill after Ampungan.
Serian Bypass (flyover 1 & 2) both complete! Can zip and go straight out of town.
Simpang Gedong - Pantu Junction
Heaven is a place like this. Both dual lanes complete, but as of now only one side is open. Smooth, no diversions, blissful 120km/hour speed.
Then it starts to get patchy here and there (Balai Ringin, Sg. Tenggang)
Lachau: Bad, uneven, gravel.