Operating expenses NS’s operating expenses rose from €4,876 million in 2015 to €4,965 million in 2016, mainly as a result of higher personnel expenses, higher infrastructure levies payable to ProRail, lower franchise fees and lower other operating expenses.Operating expenses (in millions of euros)2016 2015 €%€%Wages, salaries and social security charges 1,813371,68034Other personnel expenses 752691Staff hired in 15131243Depreciation, amortisation and impairments 34573307Consumption of raw materials, consumables and stocks 5081050410Subcontracted work and other external costs 4811048110Infrastructure levies and franchise fees 8611785217Other operating expenditure and own capitalised production7311483618Total operating expenses 4,965100%4,876100%Wages and salariesWages, salaries and social security charges rose by €133 million from €1,680 million in 2015 to €1,813 million in 2016. This was due to an increase of 823 FTEs in the number of employees and the rise stipulated in the collective labour agreement in wages, salaries, social security charges and pensions. Abellio experienced a rise in the number of FTEs and in wage costs mainly because of the Saale-Thuringia-Südhartz franchise in Germany, while NS in the Netherlands increased the number of operational employees because of the 2015 personal safety agreement. Furthermore, costs have risen largely because of the 2% increase in the collective labour agreement, higher pension and social security contributions and the inclusion of the supplement for irregular hours in the holiday pay following changes in the regulations. In addition, the costs of hiring temporary agency staff rose by €27 million due to ongoing projects and job vacancies that were difficult to fill.Infrastructure levies and franchise feesThe access charges for the rail infrastructure (infrastructure levy plus franchise fee) increased by a total of €9 million to €861 million. Higher costs for the use of the infrastructure provided by ProRail (€34 million) were to some extent offset by a lower franchise fee for the main rail network (€25 million). This is a consequence of the lower levy for the HSL and the adjustment mechanism for the main rail network franchise that was included in the implementation agreement with the Ministry of Infrastructure and the Environment.Other itemsThe other operating expenses fell by €92 million in 2016. The main reason for this was the reserve formed in 2015 for the period 2012-2015 in response to regulations concerning whether or not the supplement for irregular hours should be paid during holidays. After reaching an agreement on this with the trade unions in 2016, a retrospective payment was made to those employees of NS who were entitled to this.