01476812

Component

Existing methods of estimating travel time from GPS data are not capable of simultaneously taking into account the issues related to uncertainties associated with GPS and spatial road network data, low sampling frequency, vehicle coverage on the network, time window length and vehicle sample size. This paper reports the results of a research study that sought to better estimate travel time using vehicle trajectory data from moving sensors (i.e. probe vehicles equipped with GPS) in ‘near’ real-time. In the proposed methodology, accurate locations of vehicles on a link are first determined by map-matching (MM) so as to reduce the potential positioning errors associated with GPS and digital road map. Two mathematical methods are then developed to estimate link travel time from map-matched GPS fixes, vehicle speed and network connectivity information with a special focus on sampling frequency, vehicle sample size and time window length. GPS data from Interstate I-880 (California, USA) for a total of 73 vehicles over 6 hours were obtained from the UC-Berkeley’s Mobile Century Project. The original GPS dataset that was in 3 sec sampling frequency has been extracted at different sampling frequencies such as 6, 30, 60 and 120 seconds. This facilitates to evaluate the performance of a travel time estimation method at different sampling frequencies. The results are then validated against reference travel time data collected from high resolution video cameras. The results indicates that factors such as vehicle sample size, data sampling frequency, vehicle coverage on the links and time window length all influence the accuracy of link travel time estimation. The performance has found to be better in the 5 minutes time window length for 60 sec GPS sampling frequency.

This paper was sponsored by TRB committee ABJ30(3) Travel Time, Speed and Reliability.

01470560

13-3909

English

16p

2013

Transportation Research Board 92nd Annual Meeting

Digital/other

Figures; References; Tables

Data collection; Global Positioning System; Network links; Traffic data; Travel time

Map matching

Data and Information Technology; Highways; Operations and Traffic Management; Planning and Forecasting

Transportation Research Board Annual Meeting 2013 Paper #13-3909

TRIS, TRB, ATRI

Feb 5 2013 12:45PM