When it comes to sweeping the ground, angle matters.
“People may have seen street-sweeping trucks spray water on the road, but afterwards the dust tends to remain where it was, and once the water dries off, the dust is blown around and covers cars and pedestrians,” Environmental Protection Minister Steven Shen (沈世宏) said yesterday.
To resolve this problem, the Environmental Protection Administration’s department of air quality protection and noise control spent six months to improve the nozzles fitted on street-sweeping trucks to find the best angle for sweeping dust to the side of the road, Shen said.
The nozzles on the trucks normally spray water directly downward, which is not effective in dislodging dust on the road, said Ben Huang (黃超群), the manager of New Systems Environmental Technology Company, the firm the administration commissioned to solve the problem.
Huang said his team realized that the nozzles needed to squirt water at an angle to dislodge dirt from the road surface so that it can be washed away by roadside drainage systems.
After numerous experiments, Huang’s team found that a 30 degree angle worked best on trucks traveling at 20kph.
“The amount of water used by the trucks remains the same, but the current dust-lifting efficiency of between 40 and 50 percent will be increased to 70 percent,” Huang said.
All 78 of the trucks in use around the nation are expected to be converted within the next month or two, Shen said, adding that the nozzles would need to be powered by an independent water pump, while the nozzles on some trucks would have to be replaced completely.
The entire conversion project is expected to cost NT$6 million (US$177,600), Shen said, adding that the benefits would be significant.
“Cleaner roads will mean better air quality in our cities,” he said.