Background
Speed-limit bands on high-speed corridors are a core operational control for expressway traffic management and road safety. The Phnom Penh–Sihanoukville expressway defines separate minimum and maximum speed ranges by vehicle class to regulate flow and vehicle interactions.
The expressway specifies that family cars and light trucks may operate between 60 km/h and 120 km/h, while heavy trucks without semi-trailers and motorcycles of 500 cc (27 kW) or greater are allowed between 60 km/h and 100 km/h. Posted maximum-speed signs take legal precedence over the default vehicle-class speed bands; drivers are required to follow signage where present.
Scope of Application
The rules apply to vehicles using the Phnom Penh–Sihanoukville expressway and distinguish among family/light vehicles, heavy trucks without semi-trailers, motorcycles at or above 500 cc/27 kW, and vehicles towing trailers or semi-trailers. Entry-ramp speed management is included: drivers are to enter adjacent access links at 40 km/h before merging to the expressway and then increase speed to the expressway minimum of 60 km/h where appropriate.
Key Provisions or Decisions
- Family cars and light trucks: minimum 60 km/h — maximum 120 km/h.
- Heavy trucks without semi-trailers and motorcycles 500 cc / 27 kW and above: minimum 60 km/h — maximum 100 km/h.
- Vehicles with trailers, semi-trailers, or recreational trailers: minimum 60 km/h — maximum 80 km/h.
- Where posted maximum-speed signage exists, drivers must comply with the posted limit instead of the default bands.
- On curved sections and adjacent access links, drivers are instructed to travel at 40 km/h on the access link before accelerating to 60 km/h on the expressway; rumble stripes are installed in locations requiring speed reduction to alert drivers.
Implications for Investors, Businesses, or Compliance
Transport operators and logistics companies using the corridor must align fleet operations with vehicle-class speed bands and posted signage to remain compliant with MPWT guidance. Road safety measures such as mandated entry-ramp speeds and rumble-stripe installations can affect travel-time calculations, route scheduling, and vehicle selection for freight operators.
Official Source
Ministry of Public Works and Transport (MPWT) social media post: https://www.facebook.com/reel/1090569900626342/
