18. Trade and other receivables

(in millions of euros)

December 31, 2016

December 31, 2015

Receivables from clients from projects in progress

1

1

Trade receivables

228

227

Unbilled revenue

202

106

Other taxes and social security charges

23

33

Other receivables

270

292

Total

724

659

'Trade and other receivables' includes an amount of €104 million (€16 million in 2015) that concerns related parties.

The combined credit risk exposure from trade receivables and other receivables (excluding the construction contract work in progress) and the impairment losses are shown in note 30.

The ‘Other receivables’ show the current part of the receivable (€120 million) payable by the Railway Pensions Fund and the current part of the receivable connected to correction mechanism concession fee (€15 million).

Work in progress

(in millions of euros)

December 31, 2016

December 31, 2015

Costs of work in progress

10

22

Realised gains and losses

-1

-2

 

9

20

Less: billed instalments

12

23

 

-3

-3

Presented under:

  

Receivables from clients for projects in progress

1

1

Advance payments received for projects in progress

-4

-4

The trade payables and other liabilities are stated in note 27.