Travelers are trying to understand the impact of two major changes coming to the D.C. region’s transportation system in 2012: Metro’s Rush Plus and Virginia’s 495 Express Lanes on the Capital Beltway. These two topics were a significant part of my online chat with readers Monday. These are a few reader questions and comments about Rush Plus that I didn’t get to publish.

Rush Plus

When they start the new Yellow Line service to/from Springfield in June, what will be the message on the front of the train? When northbound, Yellow makes sense, but southbound will it say Blue?

Will the message board tell the riders when the next Rush Plus train is? It generally will not make sense to wait for one, but nobody will if they don’t tell you when it is.

There are only three lines on the PID [passenger information display]. In a Green/Yellow station, there might not be enough lines to tell you when a Rush Plus Springfield line train is due. Will trains switch colors to keep the frequency in sync? Will a train that pulled into Springfield as a Blue, switch to a Rush Plus Yellow because it is time for a Yellow train, or will the riders be waiting for a specific train set?

What about the length of the remaining trains on Blue. The six-car trains between 4:30 and 6 p.m. are full. With fewer train sets, they will be even more packed. Will there now be eight-car sets on the Blue Line? If not, the delays may be even longer than Metro is advertising.

DG: The transit authority has a big campaign to publicize the reshuffling of rush hour trains starting June 18, but this major change in service is very complicated, affects riders on four of the five lines and can lead to commuters winding up in the wrong place.

The basic idea is that Metro is going to subtract three peak period trains per hour from the Rosslyn tunnel. At the same times, three Orange Line trains will be added to the tunnel crossing and three Yellow Line trains will be added at the Potomac River bridge crossing.

The beneficiaries are commuters on the west side of the Orange Line, or those with origins and destinations along the north-south corridor through D.C. and into Virginia and Maryland. The biggest group taking a hit are those who now board the Blue Line in Virginia to reach Rosslyn and the stations on the west side of D.C.

But the rider asking this question was focused on how to recognize the right train.

There won’t be a special “Rush Plus” sign on the trains or on the next-train message boards at the platforms. Do the same thing you do now: Look at the next train sign to see the line color and destination, then make sure the line colors and destination sign on the arriving train actually match up with what the message board said.

If you do a long commute at rush hour, it will be more important than ever to check the destination sign. There won’t be any new line colors, but there will be new destinations.

Whether Metro needs to shift rail cars around to make longer Blue Line trains probably won’t be clear till after Rush Plus starts. For example, if you normally board a Blue Line train at Franconia-Springfield and take it to L’Enfant Plaza via the Rosslyn tunnel, you may get to L’Enfant faster under Rush Plus by boarding a Yellow Line train. So subtract that passenger — and others — from the remaining Blue Line trains using the tunnel.

Rush minus

So, I am one of the unfortunate thousands who will be inconvenienced by the reduction of Blue Line service coming next month. (I commute between Ballston and King Street.) Will Metro be reducing the “rush hour” fares for those of us who will not be receiving rush hour levels of service? Is it possible to program the system to charge a lower fare to those of us connecting from the south end of the Blue Line to the west side of the Orange?

DG: No, Metro has no plans to change the fare structure because of this.

Blue Line train frequency

Every day for the past week, when transferring at King Street at 9:30 a.m., I’ve noticed that the Blue Line trains are running at 18-minute intervals, instead of the previous 12 minutes. Metro has stated that once Rush Plus starts next month, it expects an increase of six minutes in time between Blue Line trains. Does this mean if I miss my train, I will have to wait 24 minutes during rush hour on my commute to Foggy Bottom?

DG: Rush Plus will be in effect from 6:30 to 9 a.m. and from 3:30 to 6 p.m. weekdays.So a rider boarding a Blue Line train at 9:30 would have missed the Rush Plus effect by half an hour.