road verges on rural roads - NERC Open Research Archive ...

CHAPTER 4. VERGE MANAGmENT - METHODS AND COSTS
This chapter discusses the methods of management of <strong>road</strong>side vegetation by
machines or chemicals, and estimated costs. It should be noted that the information
on which it is based was collected in 1972 but generally refers to 1971.
MACHINES
F~~~ kinds of machine, conventionally described as flail, (reciprocating)
cutter bar or haymower, horizontal rotary cutter, and cylinder cutter, are
available in a variety of forms for grass cutting and vegetation control. From
Table 7 it will be seen that the flail is almost universally used in rural areas,
replacing hand labour and the cutter bar over the period approximately from 1963
to 1970. The majority of these machines are owned by County Councils although in
some instances, notably Durham, Cambridgeshire and Essex, the machines are generally
hired on contract. Flails were developed from silage harvesters by the Hampshire
County Council in 1963 and have gone through a number of hydraulically operated or
direct drive type modifications over the intervening years. Current models are
versatile and powerful; although it is claimed by a small number of Councils that
flails cannot satisfactorily deal with dense vegetation after the middle of July,
most Councils do not have this difficulty. The limiting factor may be the power
available from the tractor rather than any inadequacy of the cutter itself. The
outstanding advantage of the flail has been the mulching of the cut vegetation,
encouraging its biological breakdown and eliminating the problem of carting.
Rotary machines also mulch the vegetation but are less versatile, only operating
satisfactorily on the flat. Flails are available in rear mounted or side mounted
forms, greater width of cut is possible with the rear mounted (up to 7 feet)
machines and these are most economically used on the flat. As the cutting head
necessarily follows the tractor these machines cannot be used on most ordinary
<strong>road</strong>side banks, but with specially modified low centre of gravity tractors (e.g.
as pioneered in Leicestershire) they can be used on slopes up to 1 : 3 on the
Motorways and similar areas providing the ground is dry. Side mounted machines
are more flexible, usually equipped with a 3 foot to 3 foot 9 inches cutting head,
although more recent models may go up to 6 feet. Most Highway Departments find
that 3 foot 9 inches is quite adequate and that the 6 foot head is too wide for
general work. Machines in common use reach out in an arc from the tractor from
5 feet to 23 feet depending on the model, the most popular ones reaching out to
about three widths of the cutting head or approximately 10 feet. The heads can
be angled to cut either the near or the far side of adjacent hedges or banks, or
to reach down to clean out the near or far side of ditches or at any other angle
between these extremes. Because the tractor can very often operate from the
carriagewa~,use of the machine is not restricted by wet ground conditions. ~ i ~ ~