Experience Sharing of GPS Trial in Singapore

Transcription

1 Experience Sharing of GPS Trial in Singapore Lee Kim Huat Technical Director CSE-ITS Pte Ltd [email protected] Agenda Test results and observations 1

2 Agenda Test results and observations Some facts on Singapore Land Area : 619 km 2 Road Network: 8458 lane-km Vehicle Population : 799,000 Cars population : 472,000 Public Transport : BUS, MRT, LRT, Taxis Trips per day (Public Transport) : 5 million Current Public Transport Modal share : 69% 2

3 Agenda Test results and observations Singapore Electronic Road Pricing (ERP) Year Implement : 1998 No of ERP Gantry : 33 (1998), 49 (2006) Objective: Congestion management in Central Business District, Shopping Districts, Expressway Charges: All vehicles including motorcycles Changes made over the years Night Charging Orchard Cordon (Shopping Belt) 3

4 Moving Forward Look for a new ERP system that. Minimize disruption to road users Ease of deployment (Current : 5-6 months) Lower cost for deployment and maintenance look to GPS as an alternative Agenda Test results and observations 4

5 Test for GPS Test setup uses the ublox Antaris chipset TIM- LH (High sensitivity) and TIM-LR (Dead reckoning) with GPRS module and an in- vehicle combo antenna To understand the behavior of GPS under different conditions Test Conducted Test conducted for Startup time (static/dynamic) Assisted GPS Urban Canyon Housing areas (Dense highrise/low suburban houses) Expressway Open roads Roads under viaducts (train/road) Thick foliage 5

6 Agenda Test observations and results Test Observations - Positioning For most roads and highways, the GPS accuracy is typical (3-5 5 m) and dynamic tracking is not a problem Position drift takes place significantly when vehicle is stationary especially in urban canyon Test Location 6

7 Test Observation - AGPS Warm start time not affected Cold start time is reduced considerably GPS is coldstart before the test to simulate GPS unit left in vehicle over extended period without GPS reception AGPS data is obtained from AGPS server over GPRS communication VTMS Test Observation - AGPS Cold Start Static Test GPS receiver in stationary vehicle under open sky Time difference is not significant between normal and AGPS (range of 15-20s) 7

8 Test Observation - AGPS Cold Start Dynamic Test GPS receiver is driven around immediately after it is turn on Time difference is significant (as much as 20 minutes difference) Depend on route taken during the drive AGPS Dynamic Test Reason for much higher time difference between AGPS and no AGPS is that the GPS receiver has difficulty tracking the satellites to download the ephemeris data since it keeps losing contact with the satellites and has to restart from zero 8

9 Urban Canyon Urban Canyon in Financial District Urban Canyon Problems with Dead reckoning Inaccurate starting location before entering urban canyon GPS signal still available due to multipathing Problems with High sensitivity Receiver Multipathing effects 9

10 Dead Reckoning High Density Housing Long startup time due to lack of sky view Dynamic Tracking generally good 10

11 Agenda Test observations and results Future Works DGPS for improve accuracy of position Map matching to improve tracking especially in urban canyon 11