Experts Dispute Caltrans Data Showing Rise in Car-Pooling : Transit: Critics say methods used to evaluate Team Rideshare’s success were flawed. State agency’s officials insist they doubled their goal.

When Caltrans officials launched their ambitious campaign to increase car-pooling on Thursdays, their hope was to boost ride-sharing by about 15%. Six months later, they reported they had as much as doubled their goal.

Several experts, however, contend that their methods were so statistically flawed that it is impossible to determine whether there was any increase in car pools on Thursdays, the day of the week targeted by the Team Rideshare campaign in Los Angeles and Orange counties.

According to these experts, the researchers based their results on comparisons with traffic volume on some days that did not reflect typical driving patterns.

“No question about it, they are stacking the deck in favor of car-pooling,” said Jim Moore, an assistant professor at the USC School of Urban and Regional Planning, who reviewed the Caltrans data for Los Angeles and Orange counties at the request of The Times.

“You can’t draw any conclusions from these numbers,” said Cy Ulberg, an associate professor at the University of Washington’s State Transportation Center.

Caltrans officials said they stand behind their results.

“Are they reasonable figures? Are they in the ballpark? I think they are,” said Chuck O’Connell, deputy director of operations for Caltrans District 7, which includes the Los Angeles area. “The figures we have are reasonably accurate. The bottom line is that we have seen significant increases in both L.A. and Orange counties and we are tremendously pleased.”

For Caltrans, the stakes are high. The state is about to launch a $6-billion program that will add car-pool lanes to virtually every freeway in the Los Angeles area. This week, officials will pitch their case to the Metropolitan Transportation Authority, hoping to get $383 million to construct additional car-pool lanes.

The ambitious $4-million Team Rideshare program was launched Jan. 13 with a blizzard of radio and television advertising. Billboards throughout Los Angeles and Orange counties were plastered with a simple message: Ride-sharing once a week on Thursdays would ease congested freeways. In July, the program will officially conclude and Caltrans hopes to conduct a telephone survey to help gauge its effectiveness.

To measure the results of the Thursday ride-share program, Caltrans officials posted college students at overpasses on selected freeways every Thursday morning during rush hours. Those monitors were trained to count the number of passengers as the cars whizzed by during a two-hour period. New results are reported every week. (Sensors planted in the pavement can indicate the number of cars on the road, but not the number of passengers.)

So far, the recent weekly results reported by Caltrans surpass those of other ride-sharing campaigns--including efforts triggered by the oil crisis of the 1970s, and van pool promotions of the 1980s. As of June 24, in Los Angeles County, Caltrans reported an 11% increase in ride-sharing; in Orange County, the increase was 37%. During the previous week--the best one so far--it reported a 21% increase in car pools in Los Angeles; in Orange County, the increase was 46%.

Before the Team Rideshare campaign kicked off, a study showed that 79% of Southern California drivers traveled alone to work and 15% used car pools. With the $4-million Team Rideshare campaign, Caltrans officials say the number of commuters using car pools will have risen to about 20%.

If Caltrans has achieved such success, the results would be more apparent on the highways, some experts say.

“If you really increased ride-sharing by 24% that would mean a reduction in cars on the road, which would mean all cars ought be traveling more quickly--and they are not,” said Genevieve Guiliano, an associate professor at the USC School of Urban and Regional Planning. “All agencies are in the business of making themselves look good and showing they are doing a good job rather than a bad job. Since there’s so much pressure to increase the rate of ride-sharing in the region, it’s a critical issue.”

Caltrans officials say a detailed study of how the ride-sharing program might have affected traffic volume and driving speed would be too expensive.

These officials also acknowledged that because they only monitor Thursdays they are unaware of the amount of ride-sharing on days other than Thursdays. Experts say this makes it impossible to know whether there has been an overall increase in car pools and whether Team Rideshare can take the credit.

Since 1987, employers have been required to make a good-faith effort to increase ride-sharing among their workers. One study released last summer found that the number of car pools had risen from 14% to 19%, and researchers attributed the increase to the employer requirement alone.

“The only answer is that we know the increase occurs on Thursdays, and that Team Rideshare is (on) Thursdays,” said Lew Bedolla, deputy district director of planning for District 7.

To measure the impact of the ad campaign, Caltrans officials needed to compare the number of car pools on Thursdays with the number before the program was launched. Their choice of a yardstick, or the days upon which the comparisons were made, is what some experts believe is flawed.

Caltrans engineer Joe El-Harake, in Orange County, said his office had less than 72 hours to choose a day that would be used to compare the results. They selected what they considered an average day--Tuesday, Jan. 12, the day before the ad campaign was to begin.

But weather forecasters had predicted that a rainstorm would batter the region that day--a factor that experts say would have deterred many potential car-poolers.

Caltrans officials said they did not take the rain into account. “We don’t analyze that,” said El-Harake, who designs car-pool lanes and supervises the Team Rideshare monitoring.

Asked about the validity of using one rainy day as a comparison, O’Connell said: “It’s not a base that I’d stake my life on, in all candor, but it is fairly representative.”

When Caltrans reported a 37% increase in car pool usage in Orange County since the campaign began, it was comparing the results of recent monitoring to that one rainy January day.

In Los Angeles, Caltrans used a different method to determine the program’s success. Officials selected from one to three days at each of several different sites on which to base their comparisons. Of the 14 days selected, six were during the same week as a holiday or in summer, when traffic patterns are altered because people vacation and schools are out of session.

In monitoring the northbound San Diego Freeway at Spring Street in Long Beach, Caltrans selected July 1 as its comparison day. During much of the rest of the year, the highway is used by some of the 30,000 students at Cal State Long Beach and 27,000 students at Long Beach City College. But on July 1, the regular semester was over at each campus.

“If I wanted to find out how many car pools there were, the summer would be a bad sample,” said David Berg, a traffic design engineer with the Department of Transportation in Seattle. “And certainly, the week of a three-day weekend and that following week, you see changes in travel patterns. You should definitely avoid (using) the four-day workweeks.”

Experts say the highly touted results of the Team Rideshare campaign--offered up in weekly press releases--may have more to do with hype than science.

“They have done everything they can to imply a dramatic change in the state of traffic,” said Moore of USC. “Team Rideshare is in the business of promoting car-pooling and it’s logical that they’d report the outcome of their efforts in as positive a way as possible. But when you look at the big picture, this represents a very small change.”

But Caltrans officials countered that the results of using summer days or days near holidays would only marginally affect their results.

“Our experts looked at the reasonableness of the data we collected and determined it was reasonable,” O’Connell said. “The whole basis of the campaign is to get people’s attention and have them be part of the solution. . . . I can’t look you in the eye and say this is all attributable to Team Rideshare but in my best judgment, this general response is. Team Rideshare has been the name of the game.”