* Model for the construction industry using pre-determined times Jasper Van Gilsa, Leo Vaningelgema Abstract This paper is based on our work experience with Office-line. This company prepares standard times for companies in the industrial sector. Standard time is productive time that is required and achieved by an employee. Standard time contains everything that is necessary for the work specified to be completed. The reason why Office-line only prepare standard times for the industrial sector rather than the construction industry is due to the repetitive nature of the work.
One example is the car industry which uses assembly lines. In the construction sector, this kind of repetition is not so evident. There is repetitiveness in some part of the work, but this would only occur as part of a larger concept. It is therefore impossible to give an estimated time spent on work that is non-repetitive. In this model we will use some standard times in the construction industry for scientific purposes only. This means that we will not be using a chronometer or any subsequent calculations but we will act on the basis of pre-calculations to find out what the times will be.
These times are the (average) established times for an able bodied worker. Recordings of these were made and the resulting times have been analysed in 2 different ways: * the speed rating system * the theory of Leon Carlos Willemarck (LCW) Subsequently we can compare these times with current times. The resulting times in this paper will often differ from the current times. This is because we used a different basis from which to make these calculations. There are many aspects which were not included and this is why making comparisons can be difficult.
You need to have exactly the same conditions for each situation measured to be able to compare these times. Keywords: construction industry, yields, repetitive, rhythm * Contact information ajasper. [email protected] artesis. be Dept. Of Applied Science & Technology, Artesis Hogeschool Antwerpen Paardenmarkt 92, B-2000 Antwerpen, Belgium Introduction In metal industry predetermined time systems are being used to calculate standard times. This is mostly used for tasks that have a large repetitivity of short cycles. An example is line production in the automotive industry.
Officeline is a company that has large experience in this field. This company has clients as Volvo and Tupperware for which it creates standard times and workload for employees. In this paper we will try to see if these predetermined time systems can be used in the construction industry as well. Our goal is to see if it’s possible to create standard times for some specific tasks in the construction industry. For this purpose we’ve made an appeal to the company Officeline which helped us by setting standard times that we have compared to classic standard times that are already used in the construction industry.
Classic standard times are not measured on a scientific way but they are based on experience and average times of executed works. These times are not transparent enough towards the building owners although they are used by almost every building contractor. Pre determined time measurement There are a lot of systems for predetermined time measurement. Motion time measurement (MTM) is the most used. This system was designed to avoid the need to judge the level at which an employee is working. This systems analyses the motions that are necessary to complete a specific task.
These motions have predetermined times which are the result of years of investigation. The sum of the motion times give the production standard for the job. For our research we will use the system of Leon Carlos Willemarck (LCW). This is a simplified system of MTM. In this system only six different motions are defined: 1/4V, 1/2V, 1/8V, step, bend and power step. MTM classifies motions into around 400 different codes. This makes LCW much easier to use and a lot faster in comparison to MTM. Chrono Tempo Not every task can be analyzed using the LCW-system.
For tasks that last longer or that don’t have a specific way to complete we must use a chrono to measure the time. This includes that we have to make a more than one measurement to become a reliable average for these tasks. A second importance that we need to take notice of using chrono, is the performance level at which the employee is working. An execution time of a specific person can not be used as a reference for or employees and as a consequency we can’t set these specific times as standards. Tools that can help us by adding a tempo to our measurements are tempo scales.
These scales will make sure that execution times will be calibrated and that we become standard times. Standard times can be executed by any valid employee in a social acceptable space of time. Bedaux-scale This tempo scale was designed by the Frenchman Bedaux. He saw that not all employees were working at the same performance level. So he had the idea to add a value from 0 to 100 to the performance levels where 100 stands for the maximum pace which can only be performed for a short period and zero for doing nothing at all.
A score of 60 is the level every valid employee should be able to perform for a complete week, 8 hours per day. For his scale, Bedaux compared the working tempo with walking (60) and running (100) that we know starts from a speed of 7,5 km/h. Walking at the speed of 4,5 km/h matches the score of 60 Bedaux-points. Berenschot-scale * For some people the Bedaux-scale was a bit strange to use. The most common level of performance for Bedaux was 60. That’s why Berenschot recalibrated the normal tempo to 100 which makes the maximum tempo 166,6.
This is the scale we will use in our research. Barnes-scale Both of the previous scales, Bedaux and Berenschot, are based on the speed that a person can walk in kilometers per hour. In the USA distances are expressed in miles. To have their own tempo-scale Americans set a reference point for the normal tempo at walking 3 mps which is equal to 4,8 km/h. This makes that the normal tempo (60 for Bedaux, 100 for Berenschot) is 6,6% higher compared the European scales. Method The standard times that we have tried to define are these for brickwork and for laying slab floor panels.
Sequences For brickwork we’ve measured the times for laying the bricks, for craning the bricks and mortar from the their depot to their destination on the construction site, for placing profiles, for cutting bricks in pieces and for placing strestles. The laying of slab floor panels was divided in laying the panels, laying a surface of neoprene on the walls and making the formwork which is subdivided into placing balks and placing the supports of the formwork. Analysis of videofragments We have executed the measurements by filming them.
The advantage of capturing the sequences on tape is that we can always prove our measurements and that we can reanalyze them if there are any doubts about it. The videofragments were analyzed with VRex. This is software that was developed by Officeline. VRex can analyze videos with chrono and predetermined times. We’ve used predetermined times for the analysis of the laying the bricks and for cutting the bricks. For all the other sequences we were necessary to use chrono analysis because they were to long and there was no specific method to execute the task. Surcharges When we have measured the sequences and we have calibrated them using the tempo scales, we still need to add some surcharges to become standard times. * At first we added 10% to the normalized times for rest. Construction work is a hard job and so construction workers must be able the stretch their back and their neck from time to time. * We also added 3% to the normalized times for infrequentional handlings. Sometimes construction workers will let a brick fall or they will have to remove a brick an place another one because it was not placed as it should be.
These are infrequentional handlings. * Construction workers have the right to take a pause in the morning from about 15 minutes. For personal hygiene we’ve counted 30 minutes per day: going to the toilet, to blow their nose etc. * After a break there are losses too. When starting the day, it lasts about 10 minutes before everyone on the construction site is working, after a short break or toilet visit about 5 minutes and after a long break about 10 minutes again. All these losses together take about 35 minutes per day. On the end of the day construction workers need to clear up the construction site which takes about 15 minutes per day. * When it’s raining construction workers will shelter in a container or somewhere else. For these time losses we counted 1 hour per week or 12 minutes per day. Off course this is something that can vary very hard. * Results Brickwork * * References * Books * Frank Vancauwenberghe. Figure 1 Bedaux. Tijdstudie in de 21e eeuw. 2006 * Frank Vancauwenberghe. Figure 2 Tempobeschrijvingen en temposchalen.
Tijdstudie in de 21e eeuw. 2006 * Frank Vancauwenberghe. Vrex 4-4 training Eng. 2005 * Internet * Frank Vancauwenberghe. Standaartijden en normtijden. Internet site office-line. Beschikbaar via: http://www. officeline. be/Industrial_Engineering/methode_en_tijdstudie/wie-is-officeline. php: * Frank Vancauwenberghe. Tabel 3. 2 Willemarck. LCW Leon Carlos Willemarck. Internet site Office-line. Beschikbaar via: http://www. officeline. be/Industrial_Engineering/methode_en_tijdstudie/wie-is-officeline. php