we have a paper that i need to get at least one more review on.
unfortunately, i can't find anyone to review it. below is the abstract.
the paper was passed to us by another committee and in my opinion
should be lodged somewhere between whatever committee knows how loop
detectors work and the statistics committee--like the expressway
surveillance folks. but anyway we got it. if anyone want to take a
crack at it let me ASAP.
====================
An Improved Travel-time Estimation Algorithm using Dual Loop Detectors
This paper presents an algorithm for the off-line estimation of
route-level travel times for uninterrupted traffic flow facilities, such
as motorway corridors, based on time-series of traffic speed
observations on the sections that constitute a route. The proposed
method is an extension of an existing and widely used method known as
the trajectory method. The novelty of the new method is the fact that
trajectories are constructed based on the assumption of piecewise linear
(and continuous at section boundaries) vehicle speeds rather than
piecewise constant (and discontinuous at section boundaries) speeds.
Based on these assumptions, mathematical expressions are derived that
describe the trajectories within each section. These expressions can be
used to replace their existing counterparts in the traditional
trajectory methods. A comparison of the accuracy of the new method and
the existing method has been carried out based on simulated data. This
comparison shows that the RMSE value for the new method is about half
the RMSE value for the existing method. After decomposing this RMSE
error in a bias and a residual error, it turns out that the existing
method significantly overestimates the travel time. However the largest
part of the reduction of the RMSE value is still due to a reduction of
the residual error. In other words: if both methods are corrected for
their bias the new method performs significantly better.
Forwarded by Phillip A Salopek/POP/HQ/BOC on 09/03/2002 02:12 PM
It is with deep sorrow that I inform you of the untimely death of Dr.
Charles (Chip) Alexander, Jr. Chip drowned at Virginia Beach while
swimming with his daughter over the Labor Day weekend. Chip was an
Assistant Division Chief in the Demographic Statistical Methods Division
since 1993. Chip is best known for his leadership in pioneering the
development of the American Community Survey.
Chip is survived by his wife, Diane (DSD), his daughter, Emily and his
son,
David. This is a terrible shock and a tremendous loss to the Census
Bureau. We will miss Dr. Alexander's keen intelligence, his gentle
spirit,
and above all, his fine character.
Funeral arrangements have not yet been made, but we will keep you
informed.
----------------------------------------
Ed Christopher
Metropolitan Activities
Midwest Resource Center
Federal Highway Administration
19900 Governors Drive
Olympia Fields, Illinois 60461
708-283-3534 (V)
708-283-3501 (F)
