Border Patrol Plans Bottleneck : Immigration: Southbound I-5 into Tijuana will be restricted to two lanes in an effort to keep undocumented immigrants from running through traffic to U.S.

Border Patrol officials will close four of the six southbound lanes of Interstate 5 entering Mexico as part of a plan to prevent illegal immigrants from racing across the border and onto the busy freeway to cross into the United States, immigration officials said Tuesday.

Beginning Thursday, the Border Patrol said, the last 100 yards of freeway before the border will be reduced to two lanes. It will also station another 25 agents along the freeway.

Even as officials announced the plan at a news conference on a pedestrian bridge overlooking the port of entry, two teen-agers bolted north from Mexico into U.S. territory, sprinting onto the freeway and dodging oncoming cars like broken-field runners.

Their dash illustrated the perilous new border-crossing tactic used by hundreds of illegal immigrants each day: running north past Mexican customs officers and into southbound traffic.

They use the vehicles as a shield against capture for hundreds of yards into U.S. territory, knowing that the Border Patrol will not chase them. Then they take to the comparative safety of the freeway divider to hike north to prearranged pickup points.

The crackdown is expected to delay drivers entering Tijuana from the U.S. side. It will further snarl traffic at a congested port of entry where long delays--especially northbound from Tijuana--have been criticized by business leaders in both cities for harming tourism and the cross-border economy.

But William Veal, the assistant chief of the Border Patrol in San Diego, said his agency must act before someone is killed or seriously injured.

“Obviously there is going to be some backup,” Veal said. “But the current situation is intolerable and cannot continue.”

There have been no major accidents or deaths this year because of the freeway dashes. But many immigrants have died in accidents near the border and at the San Clemente immigrant checkpoint in the past.

Until now, drivers entering Mexico rarely encountered U.S. officials; they were often simply waved on by Mexican customs agents after slowing momentarily. The new plan calls for traffic to funnel into two lanes controlled by U.S. Border Patrol agents 100 yards from the border, Veal said.

The 25 additional agents are being brought in from other states, he said, and will remain as long as necessary. They will monitor the two open lanes to try to stop immigrants. They may chase them a few yards but not down the freeway, officials said.

Mexican authorities had no immediate comment on the plan. They have recently discussed the problem with U.S. immigration officials. Mexican police, historically reluctant to interfere with illegal emigration to the United States, have arrested some of the polleros, the smugglers of illegal immigrants, who orchestrate the mass freeway dashes.

The freeway is an increasingly popular route in part because of a seven-mile border fence built by U.S. authorities last year. It made it more difficult to illegally cross through canyons and residential neighborhoods, and pushed the flow of immigrants toward the port of entry, according to experts and immigrant smugglers.

One Mexican immigration expert criticized Tuesday’s initiative. Jorge Bustamante, dean of the College of the Northern Border in Tijuana, said he believes the Border Patrol has intentionally relaxed enforcement at the southbound freeway lanes, fomenting dramatic images of men, women and children risking their lives, to force Mexican authorities to cooperate with them in fighting illegal immigration.