If the feed_end_date field in the feed_info.txt file is not provided, the feed will be auto extended for 1 year from the day the feed is uploaded.
For instance, if the feed was uploaded on 10/1/16, and expired on 12/5/16. Google Maps will auto extended it to 10/1/17, and no trip planning results will be shown after that date.
The automatic extension may incorrectly extend or miss services which only run seasonally. To control the automatic extensions, be sure to include feed_start_date and feed_end_date in the feed_info.txt file.