I. Case Background: Dongfeng Single-Cab Sewer Cleaning Truck (Blue License Plate, 5-cubic-meter Capacity) Procurement in Tangshan City In 2025, a municipal sanitation department in Tangshan City issued a public tender for the procurement of Dongfeng single-cab sewer cleaning trucks (blue license plate, 5-cubic-meter capacity) to address sediment removal operations in aging urban drainage networks. According to the tender documents, the budget was capped at approximately RMB 112,000–131,000, with requirements including C1 driver’s license operability, unrestricted urban access under blue license plate regulations, a 5-cubic-meter tank capacity, high-pressure cleaning system, and self-priming sewage discharge functionality. Ultimately, Chengli Special Purpose Vehicle Co., Ltd. (hereinafter referred to as 'Chengli') won the bid at a unit price of approximately RMB 102,000 and delivered the batch of vehicles. The vehicles are now operational across Tangshan City, with customers reporting over threefold improvement in operational efficiency compared to traditional manual methods. The core requirement of this procurement was: How to achieve an optimal balance among 'blue license plate urban access + 5-cubic-meter capacity + high-efficiency cleaning' within a constrained budget? Chengli’s solution was based on the CLW5070GSSD6 chassis (Dongfeng single-cab cab), equipped with an upper-body structure featuring a high-strength stainless-steel tank and a 150-mm-diameter self-priming sewage pump. A single operation can clear approximately 500 meters of pipeline. This case has become a representative reference for municipal procurement in North China. II. Tank Capacity Selection Logic: How to Choose Among 3 m³, 5 m³, 8 m³, and 12 m³ Models? The core principle for selecting sewer cleaning truck capacity is 'capacity × operational radius'. Below are selection guidelines derived from real-world applications: 3 m³ (Blue License Plate): Suitable for residential communities and narrow alleys; single-operation capacity: ~1–2 tons of sludge; ideal for small-scale scenarios with daily workload ≤10 tons. Reference price for Chengli’s 3 m³ vacuum sewage truck: ~RMB 108,000–137,000 (tax-inclusive, landed cost; based on publicly available tender data). 5 m³ (Blue License Plate): Suitable for urban main roads and densely networked pipe zones; single-operation capacity: ~2–4 tons; daily workload: 20–30 tons. The Tangshan case described above falls into this category, with a reference price of ~RMB 112,000–131,000. 8 m³ (Yellow License Plate): Suitable for suburban-rural fringe areas and industrial parks; requires B2 driver’s license. Single-operation capacity: 4–6 tons; daily workload: 40–60 tons. Reference price: ~RMB 165,000–203,000. 12 m³ (Yellow License Plate): Suitable for large-scale pipeline networks and pumping stations; requires B2 driver’s license. Single-operation capacity: 6–10 tons; daily workload: 80–100 tons. Reference price: ~RMB 226,000–279,000. Daily Workload Calculation Formula: Daily Workload (tons) = (Tank Capacity × Loading Factor 0.8) × Daily Trips. Where daily trips depend on transport distance: 4–6 trips per day if one-way distance ≤20 km; 2–3 trips per day if one-way distance is 20–50 km. Example: For a 5 m³ sewer cleaning truck with a one-way distance of 10 km and 5 daily trips, daily workload = 5 × 0.8 × 5 = 20 tons. Corresponding Workload Matching Table: | Tank Capacity | Applicable Scenario | Single-Operation Capacity (tons) | Daily Workload (tons) | Reference Price (RMB 10,000s) | |----------------|----------------------|-----------------------------------|--------------------------|------------------------------| | 3 m³ (Blue LP) | Residential communities, narrow alleys | 1–2 | ≤10 | 9.5–12 | | 5 m³ (Blue LP) | Urban main roads | 2–4 | 20–30 | 9.8–11.5 | | 8 m³ (Yellow LP) | Suburban-rural fringe areas | 4–6 | 40–60 | 14.5–17.8 | | 12 m³ (Yellow LP) | Large-scale pipeline networks | 6–1