01475330

Component

Traffic forecasting is an essential part of project development. The impact that forecast traffic has on infrastructure planning and design is essential for project approval. This study compared forecast traffic levels from Traffic Impact Analysis Reports prepared between 1976 and 2002 to actual traffic volumes recorded by the Hawaii State Department of Transportation in the city and county of Honolulu. The information extracted uniformly from 11 reports included year of report, consultant, type of project, location, movement, forecast horizon, forecast traffic volumes and forecasting method. This study focused on road and residential developments and examined the accuracy of traffic demand forecasting, the conservative or optimistic tendency in traffic forecasts and the potential factors affecting accuracy. The results revealed that traffic forecasts are on average overestimated by 35% and there is a clear tendency to overestimate future traffic volume. Location and preparer (consultant) were variables with significant effects on forecast accuracy. Also seasonality and accuracy of the actual volumes has a substantial impact on forecast accuracy. There are several reasons for the inaccuracies in traffic forecasting in Honolulu, such as a carpooling rate that is more than double the respective US average, seasonal variation in tourism traffic, and high population growth in the 1970s and 1980s. In combination with research elsewhere, a major lesson from Honolulu is that locations that are substantially different in local culture, population mix, geographic features and transportation infrastructure (e.g., Honolulu and San Juan, but also Miami, New York City and San Francisco) may require extensive customization of both traffic forecasts and design volume specifications for achieving more accurate project estimates.

This paper was sponsored by TRB committee ADB50 Transportation Planning Applications.

01470560

13-1398

English

18p

2013

Transportation Research Board 92nd Annual Meeting

Digital/other

Figures; References; Tables

Accuracy; Regional development; Traffic forecasting; Traffic volume; Travel demand

Hawaii Department of Transportation

Honolulu (Hawaii)

Highways; Planning and Forecasting; I72: Traffic and Transport Planning

Transportation Research Board Annual Meeting 2013 Paper #13-1398

TRIS, TRB, ATRI

Feb 5 2013 12:22PM