We have no doubt that al Qaeda, having likely tried to attack the Capitol with an airplane on Sept. 11, 2001, would try again with a car or truck bomb if it could. So we’re willing to err on the side of security when new information about a threat surfaces. That said, it’s time for Congress, the Capitol Police and D.C. officials to agree on a coherent security plan for Capitol Hill, rather than make sudden, disruptive decisions.

All of a sudden last week, Congressional leaders and Capitol Police Chief Terrance Gainer decided to close First Street Northeast between the Dirksen and Russell Senate Office Buildings and to set up security checkpoints at 14 intersections around the Capitol complex — decisions that clogged traffic along Independence and Constitution avenues and Second Street, all of which are major East-West and North-South travel routes.

The moves seem to stem from an excess of caution. So far as we know, the Capitol was not cited as a target in the recently discovered cache of al Qaeda surveillance of targets in Washington, New York and Newark, N.J. Gainer and the Capitol Police Board apparently decided to impose their own Orange Alert on Capitol Hill to coincide with that established near the downtown headquarters of the World Bank and the International Monetary Fund.

In the process, the Capitol Police Board drew outrage from local officials who weren’t consulted, including Mayor Anthony Williams (D), D.C. Del. Eleanor Holmes Norton (D) and D.C. Police Chief Charles Ramsey, who said, “We weren’t part of any kind of planning. They just told us what they were going to do.”

We’re not opposed to any of the specific steps that have been taken. For one thing, we figured that the closing of First Street on the Senate side of the Capitol made sense in parallel to the closing of other streets between Congressional office buildings.

That said, sudden security decisions now threaten to make travel and parking on Capitol Hill the same kind of nightmare that already exists near the White House. We once supported the idea of building a traffic tunnel under Pennsylvania Avenue in front of the White House. That didn’t fly. Now, we hope someone will have the sense to build one under the Ellipse so traffic can move efficiently around the White House.

Back on Congressional territory, we urge D.C. and Congressional officials to get together on a master plan for traffic, security and parking. If Independence Avenue, Constitution Avenue and First and Second streets are going to be subject to frequent clogs, planning ought to be done to define and streamline alternative travel routes. Wherever streets are permanently closed, traffic lights should be removed or reset to allow traffic to move unfettered on cross streets. At least one parking garage needs to be built off the immediate Capitol campus to allow employees and visitors to avoid congestion, with shuttle bus service provided to the Capitol.

In short, it’s time for some clear, practical thinking. Al Qaeda is not going away — so officials need to be able to cope with threats while also keeping Capitol Hill accessible.