A SURVEY of trees on the route of a proposed power line re-enforcement has been carried out by environmental consultants TEP using a LaserAce Hypsometer supplied by Measurement Devices Ltd (MDL).

The survey of 600 trees and 100 woodland groups along the path of the proposed 132k volt power line re-enforcement at Wrexham, North Wales, was carried out for Scottish Power Energy Networks using MDL’s multi-function LaserAce Hypsometer instead of a clinometer.

The proposed power line re-enforcement line is to run within a 80-metre path for 20 kilometres. Details of trees within a 20-metre corridor of the proposed route were required as part of the environmental impact appraisal which forms part of the planning process.

Scottish Power Energy Networks required the collection of various tree parameters, including tree heights and the potential reach of falling trees, were essential and Warrington-based TEP adapted its requirements from BS5837 (2005) `Trees in Relation to Construction – Recommendations’ in carrying out the survey.

MDL, based in York and Aberdeen, is a pioneer of laser-safe measurement technology applied in a wide range of industries and developed the multi-purpose LaserAce Hypsometer to help foresters easily and efficiently measure a tree’s height, diameter, lean and log volumes remotely.

The LaserAce Hypsometer incorporates a multi-function computer which stores the results of up to 2,000 trees for later viewing or downloading to PCs and PDAs using an onboard Bluetooth link so as to provide users with cableless data storage out in the field.

TEP used the hypsometer in the three-point mode to measure the heights of trees. In this mode the first shot’ measures the distance, and angle, to a section of the tree’s trunk. The second and thirdshots’ measure the angle to the base and top of the tree respectively.

TEP arboricultural consultant, Alistair McGregor, says: “Since in three-point mode only the second shot requires a good laser reflection, the unit proved very useful where the tree’s base was obscured by vegetation. The hypsometer was also beneficial where a tree could not be reached, such as on railway lines, or inaccessible islands on rivers.

“The survey results were then manually entered into the ArcPad data table which is automatically generated on the PC once a tree was mapped. The hypsometer was used in a range of weather conditions from heavy rain to fine sunshine and remained switched on all day - even when there were significant time lapses between the trees assessed.”

TEP says that the battery life was not timed precisely although it was noted that it had lasted for two to three days of field use with up to 50 trees surveyed each day and periods walking between them with the equipment switched on.

Alistair McGregor adds: “The hypsometer was easy to use with good ergonomics and, when belt mounted, the pouch provided ready access to the unit.

“The audible signals given for failed shot’ andgood shot’ were clear so that we did not need to refer to the visible display between the three shots necessary to assess each tree’s height. The LaserAce Hypsometer proved ideal for this survey. It was easy to use and easily taught to other surveyors on the project.”

08/06/07 10:06am