private void FillGUIsporen()
        {
            bc.Update();

            int rowCounter  = 0;
            int cellCounter = 0;
            int testCounter = 0;

            foreach (Spoor spoor in bc.Sporen)
            {
                foreach (Sector sector in spoor.Sectoren)
                {
                    if (sector.Status == SectorStatus.bezet)
                    {
                        if (sector.Tram != null)
                        {
                            dgvBeheer.Rows[rowCounter].Cells[cellCounter].Value = sector.Tram.TramNummer;
                            rowCounter++;
                            testCounter++;
                        }
                        else
                        {
                            dgvBeheer.Rows[rowCounter].Cells[cellCounter].Value = "";
                            rowCounter++;
                            testCounter++;
                        }
                    }
                    else
                    {
                        dgvBeheer.Rows[rowCounter].Cells[cellCounter].Value = "";
                        rowCounter++;
                        testCounter++;
                    }
                }
                cellCounter++;
                rowCounter = 0;
            }

            int rowCounterIU = 0;

            //int cellCounterIU = 0;
            dgvInEnUitrijsysteem.Rows.Clear();

            foreach (Spoor spoor in bc.Sporen)
            {
                foreach (Sector sector in spoor.Sectoren)
                {
                    if (sector.Status == SectorStatus.bezet && sector.Tram != null)
                    {
                        dgvInEnUitrijsysteem.Rows.Add();
                        dgvInEnUitrijsysteem.Rows[rowCounterIU].Cells[0].Value = sector.Tram.TramNummer; //TODO: nullreference, tram bestaat soms niet meer bij sommige sectoren.
                        dgvInEnUitrijsysteem.Rows[rowCounterIU].Cells[1].Value = spoor.SpoorNummer;
                        dgvInEnUitrijsysteem.Rows[rowCounterIU].Cells[2].Value = sector.Id;
                        dgvInEnUitrijsysteem.Rows[rowCounterIU].Cells[3].Value = sector.Tram.Status;
                        dgvInEnUitrijsysteem.Rows[rowCounterIU].Cells[4].Value = sector.Tram.VertrekTijd;
                        rowCounterIU++;
                    }
                }
            }
        }