## 5 Results and Discussion
### Temporal Distribution of Freight Trips  
An examination of the 24 h trip shares for each HDT category, as shown in Figure 6, reveals a broadly consistent diurnal pattern alongside notable inter-type differences in variability and peak timing. Across all vehicle types, the trip proportions rise gradually from the early-morning transition period (04:00-07:00), reach their highest cumulative share between 07:00 and 16:00 (accounting for approximately 50-70% of daily trips, depending on vehicle type), and then decline steadily into the late evening and at night. The lowest activity levels occur during the silent hours of 00:00-04:00, when only essential or round-the-clock operations persist. This pattern contrasts with passenger traffic, which typically  
Figure 5: Trip volume distribution by vehicle type.  
features bimodal peaks in the morning and evening, and instead reflects a unimodal midday apex unique to freight systems.  
Tractor trucks (Std: 0.254) and refrigerated trucks (Std: 0.239) exhibit the flattest temporal distributions, indicating relatively stable demand across the entire day. Tractor operations are tightly coupled with port and multi-modal terminal schedules, which run 24/7 to minimize container dwell time and optimize cargo throughput; their nighttime share (approximately 22.5%) underscores the imperative of continuous asset utilization in global supply chains. Similarly, refrigerated trucks support critical cold-chain logistics, transporting perishable goods, pharmaceuticals, and other temperature-sensitive commodities. The slow decline in their freight intensity during the evening off-peak period and sustained high activity levels overnight and in the early morning likely reflect strategies to align with downstream recipients' operational rhythms, such as supermarkets and pharmacies scheduling stock replenishment during non-business hours to minimize disruptions to customer service.  
In contrast, fence-sided trucks (Std: 0.508) exhibit the highest diurnal variability in activity levels, a pattern likely attributable to their alignment with fragmented, daytime-dominated commercial and industrial operations. These vehicles, commonly used for transporting construction materials, furniture, and general merchandise in medium-sized batches, are tightly coupled with the operational rhythms of small-to-medium enterprises (SMEs), retail stores, and wholesale markets. Freight demands in these sectors are tightly aligned with daytime business hours to coincide with customer access and workforce availability. Their pronounced daytime peak and steep nighttime decline reflect a dependency on daylight-dependent logistics processes, such as open-air material handling and retail store deliveries requiring the presence of staff.  
The remaining four categories, car carriers (Std: 0.393), dump trucks (Std: 0.42), general cargo trucks (Std: 0.377), and specialized trucks (Std: 0.357), exhibit intermediate levels of variability. These four categories share a common temporal pattern: a steep increase in trip  
Figure 6: Trip temporal distribution by vehicle type.  
share beginning around 04:00, a tapering growth rate after 09:00, a peak near 12:00-13:00, and a gradual decline from 14:00-15:00 to midnight, with minimal movement between 00:00 and 04:00. Among these vehicles, dump trucks and specialized mixers/tankers follow construction project schedules, constrained by daylight working hours and urban noise ordinances, hence the sharp midday surge and abrupt post-17:00 drop-off. General cargo trucks support retail and manufacturing supply chains, with activity aligned to warehouse receipt times and customer delivery windows, producing a moderately peaked but more extended distribution. Car carriers coordinate with automotive assembly plant shifts, generating deliveries that cluster around production start and end times.