Research Triangle Park, N.C. - More Triangle area residents are taking the bus as gasoline prices in the Triangle hit an all-time high. Prices in the Triangle hit a new high today when the Carolinas AAA Motor Club reported it cost $1.67.4 for a gallon of self-serve unleaded regular gasoline in Raleigh, Durham, and Chapel Hill. The Triangle figure is higher than the North Carolina average of $1.66.4 for March 24.
A new TTA analysis shows a positive correlation between daily bus ridership and the previous month’s gas prices. John Tallmadge, TTA’s director of Commuter Resources said, “the analysis provides compelling evidence that gas prices do influence the commuting habits of Triangle residents.”
The analysis compares average daily ridership to average gasoline prices between 2000 and 2004. TTA bus ridership levels have tended to rise and fall with gasoline prices. In fact, in the last three months gasoline prices have risen 6.0 percent over the same period last year while TTA average ridership has grown by 6.6 per cent.
Tallmadge says it’s not uncommon for ridership to trail the rise in gasoline prices. “The record high prices at the pump may not show up in TTA boardings for another month, so we expect to see increases in our ridership with the cost of fuel which may not level off until later this year.” In the four year comparison, the statistical correlation suggests that for every one cent more for gas a driver paid, additional passengers were riding TTA buses each day the following month. Other factors driving TTA ridership levels include regional employment levels, bus service hours and marketing campaigns.
TTA Bus Ridership Analysis Brief
Comparison of Average Daily Ridership to Average Gasoline Prices (2000-2004)
Triangle Transit Authority staff has analyzed average daily bus ridership for the past three years, comparing it to average conventional retail gas prices in the Southeast (source: Energy Information Association of the US Department of Energy). The comparison found an important and statistically significant positive correlation between TTA bus ridership and the previous month’s gas prices. Over the three months, as gasoline prices have risen 6.0% over the same period last year, TTA average daily ridership has grown by 6.6%.
While it is certain that there are numerous other factors that are correlated with TTA ridership levels (including regional employment levels, TTA service hours, marketing campaigns, etc.), this analysis provides compelling evidence that gas prices do influence the commuting habits of Triangle residents.
Methodology
Average daily TTA ridership figures for each month from January 2000 through February 2004 were regressed against average conventional retail gas prices in the Lower Atlantic states (as defined by US Department of Energy) for the first week of each month between December 1999 through January 2004. We assumed that there would be a one-month lag in the change in gasoline price and the change in bus ridership. With 49 observations, the Gas Price coefficient is 6.24 (meaning that for every 1-cent rise in gas price, TTA saw additional passengers per day the following month.) The t-statistic for this coefficient is 3.38 indicating a statistically significant correlation between these two variables. The R2 value was .195 indicating that 19.5% of the variation in TTA ridership can be explained by the variation in the previous month’s gas price.
TTA is a regional public transportation provider, offering a wide variety of transit services to North Carolina's greater Triangle Region and outlying counties. In addition to its regional bus services and commuter resources, TTA plans to implement a 35-mile rail transit system with 16 stations connecting Durham, RTP, Cary and Raleigh, with shuttles linking RDU International Airport and RTP. The rail transit system is expected to be operational in late 2007 or early 2008. For more information, visit www.rideTTA.org or call (919)549-9999.
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