This paper presents a calibration-free model to estimate the average speed
of moving vehicles in a link, from the upstream intersection until 40-60 m
from the downstream intersection's stop line. The proposed model calculates
link speed from travel time, which in turn has two components: cruise time
and signal delay. The cruise time is based on the speed measured by loop d
etectors. The signal delay is first calculated using the Webster formula. A
coefficient is derived to portion the signal delay to the link segment ups
tream from the stop line. This model, which takes input from loop detectors
and signal timing parameters, has been tested against simulated data. The
results show that the model is able to provide link speed estimate to withi
n 5 km/h error at least 95% of the time. This accuracy is better than that
of the British and Iowa models and is only slightly lower than the Illinois
model. However, being calibration-free, the proposed model here has a dist
inguished advantage in practical implementation.