L.A. Engineers Battle Gridlock : Downtown Traffic: Take 1 Block Away and It’s Chaos

One week ago Friday, Metro Rail construction engineers discovered unexpected stress on the steel struts holding up Hill Street. They quickly considered the worst-case scenario: collapse of the street’s temporary timber decking, a calamity that might send dozens of cars and buses hurtling 80 feet deep into the cave-like subway excavation.

Within 30 minutes, authorities had closed the suspect block and set workers to bolstering the roadway with additional steel supports. While this eased the immediate hazard, it created a potential crisis of another sort: the prospect of a week of downtown gridlock.

The city’s traffic engineers know that in a downtown street system already nearing capacity, the closure of a single block can create a massive ripple effect, causing mile-long traffic jams that can back up to already overworked freeways.

“Downtown is so sensitive it’s frightening,” said one city transportation expert. “One street gets blocked and there are just not that many different alternatives.”

Ed Rowe, general manager of the city’s Department of Transportation, added:

“Traffic has built up to the point in downtown Los Angeles that any significant disruption, whether it be the closure of a portion of a street, the cordoning off of a small area due to a fire or a rainstorm, can cause a major gridlock situation unless we respond to it quickly with all the resources at our disposal.”

And so the traffic engineers began a daily struggle, largely invisible to the estimated 426,000 motorists who travel through downtown Los Angeles each day, to keep their fragile and often cranky machine from breaking down altogether. They had at their disposal 30 white-capped traffic officers, a three-man emergency response team, a helicopter and a new method of manipulating signal lights with a computer that sits in an underground control center five floors below City Hall.

Hill Street has taken on the appearance of an obstacle course these days as construction goes on beneath it for Metro Rail. Cement trucks and cranes frequently block several lanes at a time, making navigation difficult along the critical artery, which carries southbound traffic one-way from Chinatown through downtown and beyond.

Because of the fragility of the downtown traffic system, engineers designing Metro Rail had planned never to close Hill Street completely for even a single workweek day during the time it will take to build the subway.

But eight days ago, when the structural problems were discovered, that plan had to be revised. It would be necessary to shut down the 1,000-foot stretch of Hill Street between Temple and 1st. It was not an insignificant loss: With easy access from the Pasadena, Harbor and Hollywood freeways, an estimated 2,400 vehicles--including buses from six heavily used RTD lines--travel the block each workday between 8 and 9 a.m.

Traffic engineers had worked over the weekend to prepare for the loss.

On Monday, Sean Skehan, an operator of the Department of Transportation’s Automated Traffic Surveillance and Control (ATSAC) computer system, arrived at his office at 6 a.m., an hour early, to adjust the timing sequences for traffic signals adjacent to Hill Street.

The ATSAC system was installed just before the 1984 Olympics to change signal timings automatically at 118 intersections near the Coliseum according to fluctuations in traffic. Two months ago, at a cost of $8 million, ATSAC was extended to include 212 intersections and mid-block signals in downtown Los Angeles.

At this point, many of the system’s underground sensors are not in place downtown. As a result, Skehan and other operators must manually manipulate the length of traffic light cycles based on data gleaned from two 25-inch color computer monitors, a TV camera on top of City Hall South and suggestions radioed in by city transportation engineer Timothy F. Crowder, key traffic control officers and helicopter spotters.

An hour later, eight extra traffic officers had been placed at key intersections, reinforcing a regular corps of 12. A city helicopter was sent aloft.

And Crowder, who can instantly contact the ATSAC nerve center with a hand-held radio, headed out into traffic in his pickup. Crowder heads a new three-member emergency team, the “Traffic Action Team,” which roams downtown during traffic crises, attempting to alleviate jams and prevent gridlock.

Despite the additional manpower and newfangled technology, the Monday morning commute was a mess. As late as 10 a.m., cars stretched bumper-to-bumper north into Chinatown. Vehicles were backed up on the off-ramps of the southbound Hollywood and Pasadena freeways.

Many motorists apparently had missed weekend warnings on radio and in newspapers. They failed to take alternative routes and, by the time they reached intersections manned by traffic officers, they already had suffered through the worst of the infuriating backup.

City traffic officials, determined not be overwhelmed again on Tuesday, developed new strategies.

They added 20 more traffic officers to the Chinatown and Civic Center sectors. A stronger effort was made to keep traffic from piling up at the intersection of Hill and Temple (thus forcing vehicles to make between one and four extra turns in the thick of the chaos). Traffic instead was diverted to parallel thoroughfares before it reached the Civic Center.

“When motorists take a lot of turns because they see congestion, we have a problem,” said Sgt. Fred Johns, head of the downtown traffic detail. “So we try to out-predict them. If we don’t, then we’d get gridlock.”

Crowder’s team, meanwhile, posted makeshift paper detour signs on orange-and-white barricades.

“People really know you mean business when the signs are taped up to the barricades,” said Crowder, whose emergency team is referred to in-house as “DOT SWAT.”

Buses Add to Problem

Little could be done about the wide RTD buses, half a dozen of which conclude their routes on Hill Street. Hill Street routes were diverted to Spring Street. But this required a jog down two blocks of Temple, a narrower street often congested by courthouse-bound pedestrians, and the added presence of these buses posed a major problem.

“It’s a lot like herding elephants,” Crowder said of the buses. “They are big, slow and awkward.”

Farther south, at 2nd Street and Broadway, other white-gloved officers were stationed to keep motorists moving once they had navigated the major tie-ups.

When all else failed, Crowder and Johns broadcast suggestions to ATSAC headquarters to ease the load on individual blocks.

Usually, the city’s downtown traffic lights operate in 70-second cycles--35 seconds on green on each side of an intersection.

But when the traffic flows too heavily in one direction, operators can manually reprogram the computer to what they call a “flush” plan: a 100-second cycle, split 60-40 in favor of the street needing to be drained of excess traffic.

In cases of extreme congestion, Crowder added, the cycle can even be changed to a 70-30 rotation.

“We call that the royal flush,” he said.

Regaining Control

By the end of the Tuesday morning commute, traffic officials felt better. They had regained tentative control of the beast.

Wednesday, after even further refinement of the battle plan, was smoother still--practically normal, with downtown traffic delays of no more than 10 minutes.

Thursday it threatened to rain, creating a setback. Even the forecast of rain can slow traffic, experts said, as more commuters decide to drive rather than be soaked at bus stops. And Thursday was no exception. But by the end of the commuting time, traffic engineers could take solace in the fact that things had gone smoother than on Monday.

And Friday was almost normal, despite the Hill Street closure--until rush hour, that is, when pouring rain clogged traffic.

Crews were scheduled to work through the weekend readying Hill Street for traffic. It seemed a long shot, however, that they could finish the repairs before the Monday morning traffic rush.

The traffic forces--man, helicopter and computer alike--were ready to return to the fray Monday.

“You kind of control the fires here or there,” Crowder, who has been a transportation engineer for 23 years, said last week at the height of the crisis. “Sometimes, it seems like you’re running around stamping on the fires and not doing much good. Sometimes you can’t do much at all. But it’s always better than sitting on the corner and crying.”

As he spoke, the lanky engineer sat behind the wheel of his yellow city pickup truck, stuck in traffic at an intersection on Broadway.