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ased on the time action is particularly useful in estimating and predicting the cost of
resource consumption and efficiency (Szychta, 1999).
Use of TDABC in the cost of supply (purchasing) - a case study.
The supply at the time is a substantial determinant to make investments properly.
Reflection to this stipulation becomes time-controlled account. The point of this bill is to
include time as a carrier of costs. Time Driven Activity Based Costing is a bill specifying the
cost of one minute of activity or sub-activity. It uses only the resources needed for the
process but also gives the opportunity to the valuation of time of unnecessary resources and
downtime. Moreover, it is a concept that allows control the number of suppliers, delivery
time, cost of purchases of materials, and a model identifying and providing information to
improve controlling, supply management process and significantly lifting the level of quality
of service (Radziejowska, 2001). Competent forecasting of costs, included in the budget of
construction, leads to changes in demand for resources resulting from improvements in
processes (Leszczyoski, 2012).
Time equation used in the bill is a reflection of the time estimated for the activities and subactivities
in the process of building supplies. The logical system of equations of time
determines the cost items of TDABC. Using the equation of time, it is possible to construct
account-specific processes, namely the purchasing process of the construction investment in
this case. In 2014, there was a conducted research using focus groups of 22 Polish
construction companies. One element of research was to analyze the cost and determine
the catalog of costs based on the purchasing process of construction project. By studying it
is possible to identify the determinants of ensuring the implementation of the TDABC as a
permanent supply cost analysis of construction project. Study participants determine the
following determinants of application of the TDABC model:
1. To TDABC was possible to use, the company should be able to accurately determine the
quantity and quality of available resources.
2. The company should have the human resources capable of building, maintaining and
operating TDABC and conduct proper inference of the management based on the
account.
3. The company should have the resources to accurately estimate the duration of projects.
4. The company shall have an entity providing proper conduct of the procurement process,
including purchasing, supply planning, vendor selection, making offers.
5. The company should carry out more than one project simultaneously.
6. The company must have the resources to valuation of projects, and must keep a
budgeting system of projects.
Certain determinants mean that the main objective TDABC in the supply of construction
services is not the possibility of eliminating stocks, but estimating the cost and time
consumption of actually used resource potential. Priced unit of time (eg. one minute) is a
factor influencing the cost of the project in time. Therefore, the study found a set of
equations of time for purchasing process of a construction project. Equations of time are
being shown in Table 1.
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