Adapted from 3rd edition, Encyclopaedia of Occupational Health and Safety.
Prevention of dirt-borne disease, prevention of damage to vehicles by harmful objects and the joy of viewing a neat, attractive city are all benefits derived from clean streets. Herded animals or animal-drawn vehicles, which in earlier times caused unsanitary conditions, have generally ceased to be a problem; however, the expansion in world population with the resultant upsurge in waste generated, the increase in the number and size of factories, the growth in the number of vehicles and newspapers and the introduction of disposable containers and products have all contributed to the amount of street refuse and added to the street-cleaning problem.
Organization and Processes
Municipal authorities recognizing the threat to health posed by dirty streets have sought to minimise the danger by organizing street cleaning sections in the public works departments. In these sections, a superintendent responsible for scheduling frequency of cleaning various districts will have forepeople responsible for specific cleaning operations.
Normally, business districts will be swept daily while arterial roads and residential areas will be swept weekly. Frequency will depend upon rain or snowfall, topography and the education of the populace toward prevention of litter.
The superintendent will also decide the most effective means of achieving clean streets. These could be hand sweeping by one worker or a group, hose flushing or machine sweeping or flushing. Generally a combination of methods, depending on the availability of equipment, type of dirt encountered and other factors will be used. In areas of heavy snowfall, special snow-clearing equipment may be used on occasion.
Hand sweeping is generally done in the daytime and confined to cleaning of gutters or spot cleaning of pavements or adjacent areas. The equipment used consists of brooms, scrapers and shovels. One sweeper generally patrols a specified route and cleans about 9 km of curb per shift under favourable conditions; however, this may be reduced in congested business districts.
Dirt collected by one-person sweeping is placed in a cart which he or she pushes ahead and dumps in boxes placed at intervals along his or her route; these boxes are emptied periodically into refuse trucks. In group sweeping, dirt is swept into piles along the gutters and loaded directly into trucks. Normally a group of 8 sweepers will have 2 workers assigned as loaders. Group sweeping is particularly effective for massive clean-up jobs such as after storms, parades or other special events.
Advantages of hand sweeping are: it is easily adjusted to meet changing cleaning loads; it can be used in areas inaccessible to machines; it can be conducted in heavy traffic with minimum interference with vehicle movement; it can be done in freezing weather and it can be used on pavements where surface conditions do not permit machine cleaning. Disadvantages are: the work is dangerous in traffic; it raises dust; dirt piled in gutters may be dispersed by wind or traffic if not collected promptly; and hand sweeping may be costly in labour-expensive areas.
Hose flushing is not considered an economical operation today; however, it is effective where there is a large amount of dirt or mud adhering to the pavement surfaces, where there are large numbers of parked vehicles or in market areas. It is generally done at night by a two-person crew, one of whom handles the hose nozzle and directs the stream and the other connects hose to the hydrant. Equipment consists of hoses, hose nozzles and hydrant wrenches.
Machine sweepers consist of motorized chassis mounted with brushes, conveyors, sprinklers and storage bins. They are generally used in late evening or early morning hours in business districts and during the day in residential areas. Cleaning action is confined to the gutters and adjacent areas where most dirt accumulates.
The machine is operated by one worker and can be expected to clean approximately 36 km of curb during an 8 hour shift. Factors affecting output are: number of times and distance which must be travelled to dump dirt or pick up sprinkling water; traffic density; and amount of dirt collected.
The advantages of machine sweepers are: they clean well, rapidly and raise no dust when sprinklers are used; they pick up the dirt as they clean; they can be used at night; and they are relatively economical. The disadvantages are: they cannot clean under parked cars or in off-pavement areas; they are not effective on rough, wet or muddy streets; the sprinkler cannot be used in freezing weather and dry sweeping raises dust; and they require skilled operators and maintenance personnel.
Flushing machines are essentially water tanks mounted on a motorized chassis which is fitted with a pump and nozzle to provide pressure and direct the stream of water against the pavement surface. The machine can be expected to clean about 36 km of 7 m wide pavement during an 8 hour shift.
The advantages of flushing machines are: they can be used effectively on wet or muddy pavements; they clean rapidly, well and under parked cars without raising dust; and they can operate at night or in light traffic. The disadvantages are: they require additional cleaning to be effective where street, litter or sewer conditions are not favourable; they annoy pedestrians or vehicle operators who are splashed; they cannot be used in freezing weather; and they require skilled operators and maintenance personnel.
Hazards and Their Prevention
Street cleaning is a hazardous occupation due to the fact that it is conducted in traffic and is concerned with dirt and refuse, with the possibility of infection, cuts from broken glass, tins and so on. In crowded areas, hand sweepers may be exposed to a considerable amount of carbon monoxide and to a high level of noise.
Traffic hazards are protected against by training sweepers in ways of avoiding danger, such as arranging work against the traffic flow and providing them with highly visible clothing as well as attaching red flags or other warning devices to their carts. Machine sweepers and flushers are made visible by fitting them with flashing lights, waving flags and painting them distinctively.
Street cleaners, and in particular hand sweepers, are exposed to all the vagaries of weather and occasionally may have to work in very severe conditions. Illness, infection and handling accidents can in part be prevented by the use of PPE and in part by training. Mechanical equipment such as that used for snow cleaning should be operated only by trained workers.
There should be a conveniently accessible central point providing good washing facilities (including showers where practicable), a cloakroom with arrangements for changing and drying clothes, a messroom and a first-aid room. Periodical medical examination is desirable.
Environmental Concerns of Snow Disposal
Snow removal and disposal introduces a set of environmental concerns related to the potential deposition of debris, salts, oil, metals and particulates in local waterbodies. A particular danger exists from the concentration of particulates, such as lead, that originate in atmospheric emissions from industrialized areas and automobiles. The danger of melt-water runoff to aquatic organisms and the risk of soil and groundwater contamination has been countered by the adoption of safe handling practices that protect sensitive areas from exposure. Snow disposal guidelines have been adopted in several Canadian provinces (e.g., Quebec, Ontario, Manitoba).