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Seasonal issues
20th of May 2011
Autumn leaves, frost, ice, blossom – which are the worst seasonal problems that street cleaning teams have to cope with? Ann Laffeaty talks to manufacturers of street cleaning and grounds maintenance equipment to find out whether they can supply their customers with a machine for all seasons.
Street cleaning would be relatively straightforward if all streets were the same width and length and featured no obstacles to impede the progress of cleaning machines But equipment manufacturers have to factor in any number of variables when developing their machines. For example, they need to be able to clean around parked cars and bus stops while also removing litter from grass verges. And their equipment should be able to cope with seasonal issues such as autumn leaves, spring blossom and winter ice and snow.
So which is the most problematic season for street cleaning, and how do manufacturers get around the issues involved? According to environmental PR for Karcher David Wickel the spring poses the biggest problems for machine manufacturers.
"Temperatures can fluctuate enormously in the spring," he said. "Sweeping may be required one day due to dust exposure and then the next day there may be a need to grit the roads again because the temperature has fallen back down below zero. This can lead to complications, especially where interchangeable bodies for cleaning machines are involved and where there's a need for conversion from winter road maintenance to sweeping and vice-versa."
Fine dust settles
He said the summer months can also lead to problems due to the fine dust that settles on the roads, particularly in dryer climates. "The result is that in addition to sweeping, surfaces need to be frequently washed down," he said.
"In autumn when the leaves fall, sweepers are taken to the limits of their container volume because dry leaves in particular are very bulky. And in winter the standby service required when the weather takes a turn for the worse is an important issue in view of the traffic chaos that can occur."
Kärcher claims to supply equipment for all seasons including the MC 50 compact sweeper for use in town centres. "This has interchangeable mounting kits which allow the machine to be run all year long to carry out different tasks," said Wickel.
Rain water huge issue
Sales manager of Johnston Sweepers Graham Howlett agrees that the spring poses major problems. "Spring rain water can be a huge issue," he said. "This can contain heavy metals, salt, oils from road vehicles and even hazardous chemicals. In many regions this water needs to be disposed of in a controlled manner to prevent it from reaching the water course, so collecting it can be expensive."
He says other spring issues include the need to remove the remains of any winter salt and grit while also clearing away blossom from walkways and gutters. Johnston Sweepers offers a flexible vacuum tube option for collecting blossom and other loose material, while the problem of excess water is addressed with the use of water recirculation systems on its sweepers.
"During the summer months, the lack of rain causes crowded cities to become dusty," said Howlett. "It is essential to control dust since many European cities are measured on their dust emissions." Johnston offers a dust PM10 suppression water system that atomises water around the brushes.
"Autumn presents a natural 'litter problem' on a large scale as drifts of leaves and twigs block drains and gutters while causing slip and trip hazards," said Howlett. "Combine this with harvest time in agricultural regions and mud is an additional factor. This season can be the busiest for street sweepers and many authorities hire additional equipment to cope with the volume of leaves."
Johnston machines come with a Wanderhose suction option for sweeping around street furniture and grassed or planted areas, plus a jet washing facility allowing the operator to direct litter and detritus into the path of the sweeper brushes. The company also offers sweepers with a snow plough option for use in winter.
"A small sweeper fitted with a snowplough is ideal for snow clearing in urban areas and shopping precincts, and can even clear snow from pavements and pedestrian areas that larger equipment cannot access," said Howlett.
"With the VT650 truck-mounted sweeper we go a step further with a demountable sweeper/spreader model. This allows the sweeper equipment to be replaced on the chassis with a spreader/gritter body during the winter. The transfer can be carried out in 40 minutes, representing a huge cost saving because only one chassis is required."
According to sweeper manufacturer Dulevo the autumn and winter pose even greater problems than the spring. "Problems in sweeping activity are generally due to freezing and ice, especially in winter," says marketing and communications manager Chiara Peterlini. "Autumn can also be a problem since it is quite difficult to collect the leaves once they have become wet."
Dulevo sweepers have a mechanical suction system that allows them to operate without the use of water. "This means Dulevo models can sweep in any kind of weather even where large quantities of wet leaves need to be collected," said Peterlini.
Dulevo models 850 and 5000 can now be equipped with optional snowblade and salt-spraying equipment. "This allows the machines to provide a global service during the winter without any loss of power or productivity," said Peterlini.
Snow clearing and gritting
Dulevo also offers a filter said to be capable of filtering 99 per cent of PM10 particles from the atmosphere. Developed following a tie-up with Gore in 2007, this is said to be particularly useful in dusty summer months.
Marketing communications manager of Tennant Agnes Knapen agrees winter poses major street cleaning problems, with autumn coming a close second. "Snow, if it comes, causes huge disruption in many European countries," she said. "Street cleaning in the normal sense is not possible and all resources are directed towards snow clearing and gritting. Roads take priority over pavements so streets are often left uncleaned. And once the snow melts, there is also the problem of residual grit which cannot be easily collected by litter sweepers."
She says the sheer volume of leaves in autumn can be hard to manage. "Leaf collection is a high priority and how this is done will vary between municipalities," she said. "Many litter sweeping machines will also pick up leaves but there are some bespoke leaf collection systems - normally a large suction intake hose connected to a fan and collection tank."
Tennant claims to offer solutions for both leaf collection and snow clearing. The company's smaller pedestrian Green Machines 400 series of sweepers can be fitted with large capacity hessian leaf sacks which, in conjunction with a compaction or shredder fan, are said to allow large volumes of leaves to be uplifted. The sub-compact Green Machines 636 has a cyclonic separation fan to prevent light litter and leaves from sticking to the top of the hopper screens.
Hako-Werke product manager Dr Olaf Heinemann agrees winter can be the most demanding season. "The legal situation demands regular maintenance of road and path safety – no matter how unpredictable the winter may be," he said. "Street cleaning teams often need to work long hours under unfavourable working conditions."
He said the main issue in spring was the need to clear away salt and grit debris left behind after the winter. "Meanwhile, restoration work needs to be carried out on damaged roads and worn-down lawn and grass areas," he said.
Wet cleaning necessary
"In the summer, wet cleaning might become necessary while an additional need for mechanical weeding may arise. And where outdoor public events are held there will be a need for cleaning away large volumes of lightweight litter."
Removing autumn leaves can be a problem due to the unpredictably of the leaf fall, said Heinemann. "Large amounts of leaves need to be removed from paths and walkways for the sake of safety and appearance, and this can be quite a challenge since it could take weeks for the leaves to fall - or it could happen in just a few days."
According to Heinemann it makes sense for machine manufacturers to provide multifunctional machines to cope with seasonal issues. "This makes it simpler for machine operating staff to handle the equipment since there will be less training, less damage and fewer breakdowns," he explained.
Hako-Werke offers various multifunctional machines that can be converted into winter service machines using a standard blade/spreader or sweeper/spreader combination, while brine sprayer equipment can be used in emergency situations or for local applications. According to Heinemann it is perfectly possible to provide street cleaning and grounds maintenance equipment that can function well year-round. However, there are some provisos, he said.
"The technology involved needs to be easy to use and comfortable to handle by the operator," he said. "Meanwhile the customer's internal organisation needs to be prepared to have the machines continuously running. And the supplier needs to be carefully selected for its ability to react where a quick repair is needed, or where additional cover in required during peak demand."