In principle there are a number of ways you could say this, such as "light and sound signals", for example, and a few examples of most of them can be found, but mostly in translated texts. This formulation is at least used in genuine English texts on rail crossings. Examples from US, UK and Australia:

"Midland Accident Puts New Spotlight on Rail Safety
[...] Federal regulations already require warning lights and sounds to activate at least 20 seconds before a [...]
Subscriber content; quotation from Google search
http://stream.wsj.com/story/latest-headlines/SS-2-63399/SS-2...

"A total of 104 pedestrians were also charged with running across level crossings once the warning lights and sounds had started."
http://trainwatch.co.uk/forums/viewtopic.php?t=1131&p=1490

"Protected or Active Crossings – road users or pedestrians are warned of an approaching train by warning lights and sounds or/and the closing of gates or barriers.
Unprotected or Passive Crossings – no warning of an approaching train."
http://quezi.com/15361

"Sargant, T., Trevaskis, R. & Lyons, G. (2005). Railway pedestrian crossings,
Centre rd, Bentleigh. Public Transport Safety.
Majority of offences occurred when the warning lights and sounds were going and the gates were forced from the “No Entry” Side.
• Therefore, the high risk groups are people who are hurrying, school children who are intentional bypassing safety warnings."
http://www.transportsafety.vic.gov.au/__data/assets/pdf_file... (p. 27)