* Deal expected to close by September

* Atlantia sees operating and growth synergies with Yunex

* Latest deal as Siemens simplifies its business

FRANKFURT, Jan 17 (Reuters) - Italian infrastructure group Atlantia has agreed to buy Siemens' Yunex Traffic division for 950 million euros ($1.1 billion) to expand its cutting-edge transport services.

The deal, announced by Siemens on Monday, is expected to close by September.

Atlantia, controlled by the Benetton family, last year clinched a deal to sell its Italian motorway unit Autostrade per l'Italia to end a dispute triggered by the deadly collapse of a motorway bridge operated by Autostrade in Genoa.

The Autostrade sale is expected to add about 8.2 billion euros to Atlantia's coffers by the end of March, part of which will be used to drive expansion in new sectors.

The acquisition of the German company would deliver savings and new business opportunities when integrated with its existing assets, Atlantia said in a statement.

"We aim to deliver operating and growth synergies between our assets and Yunex ... in the management of infrastructure, services and technological innovation, in order to improve the travel experience," said Atlantia CEO Carlo Bertazzo.

Atlantia owns motorway toll-road groups including Spanish group Abertis, operates Rome's airports and controls digital toll payment company Telepass.

Yunex Traffic supplies infrastructure and mobility services including advanced emissions-based dynamic tolling systems, vehicle-to-infrastructure communication solutions, digital traffic lights and street lighting systems.

Dubai, London, Berlin, Bogota and Miami are among its customers for mobility services and infrastructure management.

Atlantia hopes to expand its business in urban areas thanks to Yunex, it said, adding the German company could enter countries where the Italian group has a significant exposure.

"We are certainly keen to expand Yunex Traffic's business in countries of interest to us, such as Italy, France and Spain," Atlantia's CEO told analysts, adding the Intelligent Transport System sector could generate a business value of around 1.5 billion euros a year in those three countries.

Siemens has been simplifying its business in recent years, separating and floating its energy and health equipment divisions as it seeks to become a more focused technology company and lose the conglomerate discount that has weighed on its stock price.

The German engineering company changed the name of the unit to Yunex Traffic from Siemens' Intelligent Traffic Systems in February as part of preparations for a possible sale.

($1 = 0.8769 euros) (Additional reporting by Tom Sims in Frankfurt Editing by David Goodman and Mark Potter)