Valise – video balise for dependable train positioning

Author: Richard Shenton
Day: Aspect Day Two
Session: Innovation and Future Development (1)

Valise is a virtual balise system which builds on recent advances
in vision-based positioning for autonomous cars and adapts them
for the rail environment. It offers an alternative to track-mounted
transponders and balises. Integrated with GNSS and inertial
sensors, the technology provides continuous dependable trackprecise
train positioning. It offers reliable positioning information
for degraded mode working in the event of failure of the primary
signalling system. In addition, providing advice of the position
with route information to the driver could enhance safety and
confidence when operating in these conditions. As a result, the
system improves operational resilience in response to signalling
failures and other out of course operations. The content of the
paper is described below. Valise technology In parallel to wider
industry activities to develop virtual balises using GNSS, RDS has
focussed on developing a complementary technology based on
real-time image processing of forward-facing CCTV images. The
RDS Video Train Positioning System (VTPS) uses a dead
reckoning approach measured from a known location. For this
absolute or spot location, the forward facing camera initially read
bar code signs (‘visual balises’) at the side of the track. Feedback
from infrastructure managers indicated a reluctance to deploy
additional signs at the trackside. Now a new approach has been
developed to locate a train at a point on a specific track using
video - a video balise. Broadly, the live images from the camera
are matched with a database of images taken at known locations
on previous journeys. When a match is found, the location of the
train is known. In order to optimise the matching process, the
system compares small ‘fingerprints’ that are derived from the
much bigger images. The design of the fingerprint enables the
technique to be resilient to changes in environmental conditions,
such as day, night rain and snow. The paper will describe the
system in more detail, including overall operations and
maintenance of fingerprints and track databases. Performance
and safety A project is now underway in the UK to evaluate the
technology. The project partners are Network Rail (infrastructure
manager), First Group (train operator), Omnicom Balfour Beatty
(survey and monitoring) and Nottingham Scientific (GNSS
specialist) together with RDS. Nottingham Scientific with its
experience in virtual balise research and development is working
with RDS and its video based approach to provide a combined
system which has the dependability needed for safety related
applications. The performance results and safety approach will be
presented in the paper. Initial applications The paper will present
the initial applications that are being demonstrated: - Track
precise positioning for infrastructure monitoring from service
trains (fitted to Network Rail New Measurement Train and
compared with Omnicom’s existing ‘state of the art’ Real Time
Positioning System) - Positioning for selective door operation (on
service trains operating on route from Manchester Airport to
Leeds) - Virtual temporary and emergency speed restrictions,
eliminating the need for trackside boards (vehicles and routes
same as previous).