Keywords: vehicle tracking, GPS, operating speed, travel time, urban arterials.

GPS vehicle tracking techniques were utilised to measure and analyse the operating speed, travel time, and delay time for urban arterial roads and to develop operating speed models to estimate speed profiles based on roadway environments [1,2,3,4]. Statistical regressions were carried out to establish useful models to estimate operating speed at segments and horizontal curves, and acceleration and deceleration distances from the data collected [5]. A methodology has been developed to study travel time characteristics and operating speeds on urban streets with the GPS based vehicle activity data, including summarising GPS trips, selecting study sites, and analysing speed profiles.

Statistical models were developed that included design features such as road environment features, operation characteristics, cross-section features, alignment characteristics, and adjacent land use. The results can help roadway designers and planners to better understand expected operating speeds and, as a result, design and evaluate proposed urban roadways accordingly. The linear multiple regression model was found to be the most significant model to predict the relationship between operating speed and other variables related to road environment, traffic condition, and horizontal alignment. However, the significant variables of horizontal curve model were entering speed at the beginning of horizontal curve, deflection angle, the posted speed limit for a segment, and the combination of horizontal and vertical curves.

It was found that GPS tracking data collection could be useful to estimate the speed profile changes caused by the existence of road environment features such as humps. Thus, precaution signing can be determined from the speed profile analysis at the hump zone and the maximum hump spacing was evaluated to reduce driver speeds lower than the posted speed limits.

Although operating speed models have been developed for both tangents and horizontal curves with very promising results, it is recommended to expand this investigation using peak operating speed data to investigate geometric and operational variables. Other variables should be investigated to study driver speed behaviour such as vehicle and driver characteristics not only the road environment features and operational variables.

1

K. Fitzpatrick, P. Carlson, M.A. Brewer, M.D. Wooldbridge, "Design Speed, Operating Speed, and Posted Speed Practices", Presented at the 82nd TRB Annual Meeting, Washington, D.C., 2003.

2

C.A. Quiroga, D. Bullock, "Measuring Delay at Signalized Intersections Using GPS", Draft paper submitted to the ASCE Journal of Transportation Engineering, 1998.

3

H.R. Al-Masaeid, M. Hamed, M. Aboul-Ela, A. Ghnnam, "Consistency of Horizontal Alignment for Different Vehicle Classes", Transportation Research Record 1500, TRB, National Research Council, Washington, D.C., 178-183, 1995.

4

M. Poe, M. Mason, "Analyzing Influence of Geometric Design on Operating Speeds along Low-Speed Urban Streets: Mixed-Model Approach", Transportation Research Record 1737, TRB, National Research Council, Washington, D.C., 2000.

5

K. Fitzpatrick, P. Carlson, M. Brewer, M. Wooldridge, "Design Factors That Affect Driver Speed on Suburban Streets", Transportation Research Record 1751, TRB, National Research Council, Washington, D.C., 2001.

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