The walkouts by thousands of members in General Grades and Controllers will take place on Thursday, August 18 and Saturday, August 20 after the union formally served notice to Network Rail.
It comes amid a summer of industrial action on the railways, with the dates of strike action in Network Rail aligning with those the union is also taking at Avanti West Coast, c2c, CrossCountry, East Midlands Railway, Great Western Railway, LNER and Southeastern.
Notice was served to Network Rail after the union asked for clear assurances and clarity on job security and working practices.
The union says no such assurances were forthcoming and 14 days' notice, required by law, has now been given.
The companies preparing for strikes on August 18 and 20 are:
Cross Country Trains
East Midlands Railway
Great Western Railway
South Western Railway
Avanti West Coast
West Midlands Trains
GTR (including Gatwick Express).
“Our members are simply asking for basic fair treatment: not to be sacked from their jobs, a fair pay rise in the face of a cost-of-living-crisis and no race to the bottom on terms and conditions.
“No one takes strike action lightly, but we have been left with little choice. Our General Grades and Controllers are a force to be reckoned with. Without them the rail network does not run, it is that simple.
"Sadly, it now looks as though we are about to see yet more disruption on our railways this summer. It’s time bosses at the company told the government they must get a grip.
“Our door remains open but only if there is a meaningful offer on the table which will give our members the fair deal they deserve for keeping our rail network safe every day of the year."