UPDATED 05/18/12 6:27 a.m.

CHICAGO (CBS) — Commuters on Metra and South Shore Line trains are prepared for major headaches as the NATO Summit approaches in just two days.

As CBS 2’s Vince Gerasole reports, on Friday, many employers have been giving workers the option to stay home.

LISTEN: WBBM Newsradio’s Bob Roberts reports

And while no major restrictions begin on the train lines Friday, commuters boarding trains can expect an increased security presence, and more police officers and canine patrols at the stations.

Restrictions do begin on the train lines starting Saturday and continue through Monday night. On Metra trains, passengers can expect screenings at stations, and may be asked to show ID or subject themselves to a search.

Bags may not be larger than 15 inches by 4 inches – smaller even than the average purse – and backpacks and luggage are prohibited. Food and beverages are also forbidden on Metra trains during the summit period, even if they are sealed.

In addition, no tools or pepper spray are permitted on the trains.

Commuters are reminded that forbidden items can be confiscated.

Meanwhile, the stations at 11th Street, 18th Street, McCormick Place, 27th Street and 47th Street on the Electric District will close from Saturday morning through Monday night.

The big service changes occur Monday, when 19 stations on the Electric District will close, including the entire Blue Island branch, although Metra Deputy Executive Director George Hardwidge said security will be tighter no matter what line you ride the next few days.

“With the resources we have available, we can accommodate what amounts to a full ridership and a full train schedule on Sunday,” Hardwidge told WBBM Newsradio’s Bob Roberts. “On Monday the ridership is much higher, there are many more trains, and the train schedule is much more complex.”

On Monday, the five stations closest to McCormick Place will remain closed, along with the entire Blue Island branch, four stations on the South Chicago branch, and stations between 63rd and 11th Streets on the Electric District main line — with the exception of 95th Street.

Metra announced Tuesday that the resources had been found to keep the 95th Street station open on Monday.

In addition, no trains scheduled to arrive inbound at Millennium Station terminal between 12:57 p.m. and 6:46 p.m. will operate on Monday. Outbound service on the Electric District Monday is expected to be normal all day, except on the Blue Island branch.

Metra is making announcements periodically to remind commuters about the rules, and advising passengers to prepare for a considerably longer commute than usual.

Passengers on Friday morning didn’t seem to be too happy about the inconveniences.

“I’m just avoiding the train altogether – not because of the security screenings, but, you know, I have to be there on time, so it’s like, you’ve got to do what you’ve got to do to get there,” said South Shore Line commuter Steven Vasquez.

Commuters also noted that the volume of passengers on trains was far less than usual Friday morning.

“Usually, there are a lot of people out here; it’s like standing room only,” said South Shore Line commuter Neva Hawkins. “But this morning, it’s like a ghost town.”

“I know that a lot of people have stayed home,” added South Shore Line commuter Sheila Piani. “Unfortunately, I don’t have that luxury of staying home, so I have to go in.”

Some changes are also taking effect on CTA bus routes. Only a few changes were in effect Friday – the No. 20 Madison bus, the No. 56 Milwaukee bus, the No. 60 Blue Island/26th Street bus were being rerouted.

The Chicago Transit Authority Web site has a breakdown of the changes.

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