Management Techniques Applied to Right-of-Way Tree Maintenance

Scheduling a day's work

One crew assigned 10 trees to trim during the day may only complete trimming on 3 trees due to their size. Another crew may finish trimming 15 small trees in a day's work.

Performance

Crew performance can be measured by comparing the estimated standard time versus the actual time. All crews will be compared to the same standards. Using the assembly TRIM ONE TREE, a crew in one location with mainly large trees could not be fairly compared to the same crew working in a location with mainly small trees. The size of trees were divided into three categories — 4-12 dbh, 13-20 dbh, and 21-over dbh. They are in inches of diameter at a point 4½ feet above ground (Diameter Breast High or dbh). By the same token neither can a roundover be compared to a side trim. Types of trimming were classified by the following definitions.

Roundover — Roundover one tree in accordance with Distribution Manual Sheets P-1.12 through P-1.18.

Side Trim Light — Trim side of one tree in accordance with Distribution Manual Sheets P-1.12 through P-1.18. Light trimming can be performed with a pruner.

Side Trim Medium — Trim side of one tree in accordance with the Distribution Manual Sheets P-1.12 through P-1.18. Branch size requires use of hand saw for removal.

Side Trim Heavy — Trim side of one tree in accordance with Distribution Manual Sheets P-1.12 through P-1.18. Heavy trimming requires the use of power saw.

Preferred type crew

Trimming is basically accomplished by two types of crews on our system, conventional and bucket crews. We decided to use the following definitions to indicate the preferred crew:

Front Line — Along a street, alley way, or any location accessible to a tree equipment vehicle

Back Line — An area not accessible to a tree equipment vehicle.

One other area needs to be stabilized before we start writing out assemblies for tree maintenance work. Brush cutting is needed periodically to maintain right-of-way conditions where lines are accessible to line construction vehicles and restringing of wire can be performed expeditiously during emergency storm outages. We adopted industry standard definitions for trees and brush:

Tree — A woody plant 4 inches or larger dbh.

Brush — Plants with a dbh smaller than 4 inches. Brush will be measured in square yards. Brush shall be cut in accordance to Distribution Manual Sheet P-1.28. (4840 sq. yds. = 1 acre).

Brush assemblies will be made to indicate the type of equipment to be used since some equipment is considerably faster than others (not necessarily less expensive).

Putting all the definitions together to describe the work, we created a group of assemblies which are self-explanatory if one is familiar with the basic definitions above.

Once the assemblies were made and given a standard manhour figure, how did we use them? Some district locations began pre-estimating projects for tree crews and believe it is well worth the extra cost of sending a man in front of the crew to draw up the jobs. If necessary, this person will contact customers prior to the arrival of the crews. Locations using this method believe that sending a tree crew out without a drawing or job would be the same as sending a line construction crew to build a line to a customer without a preengineered job. One of the main advantages of pre-engineered work seems to be getting the best type crew to do the job. A conventional crew might take hours to do brush cutting which could be done in a few minutes with a brush hog.

Other locations are self reporting the assemblies described above. As the assemblies are performed, they will be indicated on a log sheet carried by the crew. The log sheet will show the total quantity of each assembly and the total time spent working on the group of assemblies. This time will be compared to the estimated time for the assemblies to give the crew performance. Also, the quantity of assemblies can be obtained over any time period for each crew, crew type, and contractor. Totalizing of the quantities of assemblies will be extended to location, division, and system reports to assist in budgeting future needs.

Both methods of using the assemblies (preengineering and self reporting) are being used. Local option is available to our locations for reporting tree maintenance work since the input data and output reports will be the same.

Our first generation of output reports showed quantities of assemblies and their associated estimated and actual manhours along with an efficiency ratio which is the estimated MHs ÷ actual MHs × 100. As mentioned earlier, they can be accumulated by crew, crew type, and contractor and totalized by location, division and system.

The second generation of output reports which are being programmed will add the dollar cost by assemblies. The dollar cost will be the actual crew and equipment costs rather than some estimated or averaged cost. The cost data will then provide information such as our actual system cost to remove a 13-20 dbh tree, cost to side trim a tree, cost for a conventional crew to remove a square yard of brush versus a kershaw cutter, cost of a three-man conventional crew to do an assembly versus a four, five, or six-man crew, etc. We believe the addition of the dollars to the reports will provide a much clearer picture of our program that can be projected by the use of manhours.

Briefly, we would like to expand on another use which was made with our assemblies. Utilizing sampling techniques we chose a geographically random sample of spot locations on our system in several divisions. Each spot was a square containing 2000 ft. sides. The trees which were growing into our lines or would be in our lines within the next 5 years were surveyed. In the sample locations, assemblies were estimated and placed in the year the trees actually would touch our lines. By using the sample data, we projected a picture of what our present tree conditions were and what to expect in the future. The conditions and extended forecast comprised of assemblies gave us some data to either verify or not verify the opinions and statements made by supervision in the past. Some of the more generalized conclusions were as follows:

• 1) Some locations are behind in their right-of-way maintenance because a sufficient number of crews were not available.

• 2) Some locations are behind in back-line trimming and should have more conventional crews to correct their conditions.

• 3) Large crew reductions in 1974 and 1975 due to austerity did not drastically increase their right-of-way maintenance conditions in all areas even though the growing season was longer during 1975. These locations had very little backlog of work in 1975 because of their efforts the previous year.

• 4) An additional brush hog is needed on a full-time basis in one division.

• 5) Our present tree conditions predict a variance in work load from year to year. The sample indicated a shift of 1975 work into 1976 as expected by the crew reductions. This will cause our work loads to peak in 1979, 1981, 1984, etc. Hopefully we can smooth or balance out our peak work load during the next five years.

Although we feel we have come a long way toward successful management of our distribution right-of-way maintenance by creating assemblies and using sampling techniques for forecasting, Duke Power Company has only begun to meet our goals of improving our maintenance work. By using these new tools to monitor our work, we will in the future be continually evaluating in more detail subjects such as crew complements, equipment usage, contractors, and our organization for supervision. Research needs to be done to find better ways to schedule work assignments and measure or audit the quality of our right-of-way maintenance work.

We are all familiar with the high degree of professionalism given to the art of trimming and shaping our trees. We at Duke Power Company have attempted to retain this professionalism by establishing similar production techniques used by other areas of industry to monitor the production and quality of their product. Right-of-way maintenance by our Company is considered an important area which affects the environment in which we live. For this reason we will be continually upgrading where possible our own production techniques.