Metro’s proposal to alter service on five of its six lines is a short-range effort to compensate for the Silver Line’s impact.

Jim Hughes, a senior planning official with the transit authority, outlined the proposal on Wednesday night for the Metro Riders’ Advisory Council. The transit staff’s proposal would set the rush hour gap between trains at eight minutes on the Silver, Blue, Orange, Green and Yellow lines. On all lines but the Blue, that’s a greater gap than under today’s schedule.

Here are five key points in evaluating the idea.

Impacts on reliability and crowding. “We’re trying to see if we can provide more reliable, consistent service,” Hughes said. Each of the five lines under review connects with another line at some point. Metro planners think there are too many trains competing for space at the junctions, and this — along with important factors like the condition of the tracks and the rail cars — contributes to the delays riders commonly experience. “The on-time performance of our railroad is not up to our goal,” Hughes said in a statement that many riders would wholeheartedly endorse.

Planners think that by increasing the space between trains, Metro is more likely to get you where you’re going on time, because the trains will move more smoothly through the junctions. So far so good. Unreliable service is a top complaint among riders. But so is crowding on platforms and aboard trains. So what happens when you widen the gaps between trains? “We will see more crowding,” Hughes said. This would happen even as Metro adds more rail cars to the trains remaining in service. Planners say the platforms and the trains can handle this additional crowding, but Hughes said it’s something riders will want to consider in evaluating the proposal.

On-time decline. “Something that happens on one of our lines affects our other lines,” Hughes said. The most frequently discussed junction is Rosslyn, where the new Silver Line now competes for space with Orange and Blue trains. But lines also join up at East Falls Church, Pentagon, Stadium-Armory, King Street and L’Enfant Plaza. “We’re not getting all the trains through that are scheduled,” Hughes said. This is why so many lines are included in the proposal to widen the gaps between trains. The Green Line schedule would be adjusted to ease congestion where it meets up with the Yellow Line at L’Enfant Plaza. The Yellow Line has the same issue at L’Enfant Plaza, but it also merges with the Blue Line inbound at King Street and outbound at Pentagon.

Hughes described this proposal as a relatively short-term effort — “four, five, six years,” was his rough estimate — for one important factor contributing to delays. He did not say that increasing the gaps between trains would solve all of Metrorail’s reliability problems. It doesn’t fix the track switches or the rail car doors and brakes. But Metro officials expect that the long-term rebuilding program, plus the arrival of hundreds of new rail cars, will make the system reliable enough to allow them to consider an increase in train frequency.

Role of the Silver Line. The opening of the Silver Line last summer increased rail traffic at the Rosslyn junction and, since the line required 64 cars to operate at rush hours, stressed Metro’s ability to maintain the entire car fleet. Hughes showed a chart showing a decline in Metrorail on-time performance dating from last summer. Reliability dropped dramatically during the harsh winter, but it’s still below Metro’s goals — and certainly below riders’ expectations.

Meanwhile, ridership at the new stations on the west side of the line is below estimates. The end of the line station at Wiehle-Reston East and the Tysons Corner station near the malls are doing well, but ridership at other new stations in Tysons is unlikely to pick up until some of the planned office and residential developments open.

Effect on the Blue Line. To fit in the Silver Line trains, Metro cut service on the Blue Line so that trains now are scheduled to arrive every 12 minutes. That’s the biggest gap between rush-hour trains in the system. Metro has been looking for ways to address riders’ complaints about this. The Blue Line service is the only one that becomes more frequent under the Metro proposal. But the proposal was not designed specifically to benefit the Blue Line at the expense of the other lines involved.

In fact, it’s unclear whether Blue Line riders will like the strategy. It kills Rush Plus service on the Yellow Line. Metro estimates that 30 percent of Blue Line riders shifted to the Yellow Line when it got the extra trains and the Blue Line was cut back. If Blue Line service is increased and Yellow Line Rush Plus service eliminated, those riders are likely to return to the Blue Line.

Metro estimates that the Blue Line at rush hour carries 106 people per car today. Under the proposal, Metro estimates that Blue Line cars will carry an average of 108 people at rush hours. That would make it the third most crowded of the lines involved. Metro estimates that the Orange and Silver lines would carry 111 people per car. (The Blue Line’s 106 people per car makes it the most crowded among all these lines today. The runner up is the Orange Line, at 91 people per car.)

While the strategy would create an eight-minute gap between trains on each of the five lines, equity in train spacing was not the goal in drafting the proposal. More reliable service was the key factor for the planners.

What’s next. This is a very ambitious undertaking. It could come undone at many stages in the development process. The transit staff plans to present the proposal to a Metro board committee next week. At this point, the staff is simply looking for board approval to draw public comment in various forms, which would include public hearings. A formal plan could be presented for board approval this fall. Among the steps: The board would need to revise its standards for rush hour service.

If the board approves some version of this proposal, it would take months for the staff to set up the necessary operating procedures and change its maps, signs, brochures and online scheduling information.

Hughes said it’s possible that a plan could be implemented in the first part of 2016. But the experience in creating the Rush Plus system shows it can take years to plan and implement widespread changes in rail service.

This is a summary of a complex, high-impact plan, so riders are bound to have question. I invite them in the comments field and also in Monday’s online discussion. You can submit questions and comments for that now, using the link.