There hasn’t been this much excitement about a new arrival in the region since the birth of baby panda Bao Bao at the National Zoo in late 2013.

The Silver Line enjoyed an impressive opening last month, with thousands of new riders enjoying a smooth ride and plenty of room. Unfortunately, most of the trains running on the rest of the Metrorail system still consist of six cars each. Too often, they are overcrowded and uncomfortable.

The original design of the Metro system did not incorporate extra rail lines for express trains or more frequent service, which is often how capacity issues are addressed. While the new Silver Line adds new stations, much of the line runs along track already used by the Orange and Blue lines. The new trains can move more people — until they can’t.

Metrorail is at capacity at the core of its system. No new tunnel, track or extension is able to fix this challenge. Professional “people pushers,” as they have in other countries, are not the preferred solution either.

The best way to alleviate overcrowding on Metro is to extend all trains from six-car to eight-car lengths. Immediately the capacity of each train is increased by one-third. Well, “immediately” is disingenuous. More rail cars must be purchased to run all eight-car trains. The ability to power all eight-car trains throughout the system would need significant attention and upgrading of electric circuits. Storage, pocket tracks and additional operational requirements combine for a solution that is not inexpensive. But it is the most cost-effective, practical and immediate solution available.

To achieve transportation improvements in this region will require collaboration among elected officials and business leaders in the District, Maryland and Virginia. This has been the case on the extension of rail to Dulles, the InterCounty Connector, the Woodrow Wilson Bridge, the Capital Beltway express lanes and so much more. Joined by forward-thinking government officials, a group of business leaders have come together to advocate on behalf of riders and call for funding for eight car trains systemwide.

All involved parties recognize that more capacity is gained when extending the trains by 33 percent. Less-crowded stations mean less discomfort and less waiting. People can get to work easier and get home faster. Metro will become more attractive to commuters and ridership will grow in numbers and improve in comfort. Best of all, we can accommodate the steady growth this region is enjoying without undertaking expensive and disruptive measures.

This commentary was prepared by a coalition of business leaders calling themselves the 8carcoalition. They include: Harry Wingo, president and CEO, D.C. Chamber of Commerce; Jim Corcoran, president and CEO, Fairfax County Chamber of Commerce; Ginanne M. Italiano, president and CEO, Greater Bethesda-Chevy Chase Chamber of Commerce; M.H. Jim Estepp, president and CEO, Greater Prince George’s Business Roundtable; Jim Dinegar, president and CEO, Greater Washington Board of Trade; Georgette “Gigi” Godwin, president and CEO, Montgomery County Chamber of Commerce; David Harrington, president and CEO, Prince George’s Chamber of Commerce; and Robert E. Buchanan, president, 2030 Group.

The math for relief

Sometimes it’s hard to wrap one’s head around just how many people Metrorail can move. But where Metrorail operates in heavily congested corridors, seemingly small improvements can yield big results. In fact, matching the capacity of all eight-car trains systemwide would require 16-18 lanes of freeway into downtown, each way.

In Arlington for instance, going to eight-car trains on the Orange Line as part of [ Metro’s plan to do so by 2025] is like widening Interstate 66 by two lanes. Let’s do the math:

1 One lane of highway can move around 2,200 cars per hour, at its theoretical maximum.

2 Today, every morning Metrorail runs about 18 trains per hour eastbound on the Orange Line through Arlington, and about a third are scheduled eight-car trains. That’s a train every three minutes, and equates to around 121 rail cars per hour, or 12,060 passengers per hour.

3 By 2025 with eight-car trains, Metrorail would be able to run 21, eight-car trains per hour eastbound on the combined Orange and Silver Lines, which equates to 168 rail cars per hour.

4 This would bring the line’s capacity to 16,800 riders per hour, or an increase of 4,740 passengers per hour.

5 To accommodate 4,740 more people on I-66 at 2,200 cars per hour, two people per car, we’d need 4,740 divided by 2 divided by 2,200, which equals 1.1 highway lanes in each direction.

That means we’d need at least two new lanes on I-66 to match the capacity of Metro.

Eight-car trains on Metro also would be more than two times cheaper: The estimated cost to widen I-66 works out to about $3.50 per rush-hour trip over the life of the project, whereas [adding all eight-car trains] would be about $1.50.

Metrorail would likely move travelers faster than I-66 in the end. Orange Line trains today normally run at around 35 miles per hour, while congested travel speeds on I-66 average around 18 miles per hour.

Justin Antos is a transportation analyst for the Washington Metropolitan Area Transit Authority. This commentary was adapted from a post on the agency’s PlanItMetro blog.