The document describes a refined approach for a railway bridge health monitoring system using a wireless mesh network. The system aims to be easy to deploy, require low maintenance, and operate long-term. It will use 3-axis accelerometers between 30-125m to measure acceleration in 3 axes from 0.25-20Hz for 40 seconds during and after a train's passage, with time synchronization accuracy of 5ms. Existing techniques like visual inspections are limited, while current wireless solutions have issues like being proprietary, bulky, expensive to set up, and having single point failures. The proposed system will use a time synchronized mesh protocol with >99.9% reliability and lowest power consumption. It will allow scalable installations without site

1. Railway Bridge Health
Monitoring System
A Refined Approach

2. Design Consideration
 Easy to Deploy
 Low Maintenance
 Long-Term

3. Application Requirements
30-­‐125m
3-­‐axis
accelerometers

4. Application Requirements
 What to measure? Acceleration in 3-
axis of motion
 Frequency components of interest
0.25-20Hz
 How long to measure?
 40 sec of total vibration during and after
train’s passage
 Time Synchronization
 Need accuracy of 5ms

5. Existing Techniques
 Visual inspection
 Mostly wired solutions
 Equipment is bulky and very expensive
 Large setup time (few days) for short-term
monitoring
 Few wireless solutions
 Proprietary non scalable solutions
 Wisden (USC)
 Golden-gate bridge (UCB)
 BriMon

6. Existing Approaches
 GSM Data Transmission (Data)
 Solar Panels (Power)
 GPS (Time Synchronization)
 Star Topology (head node)
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7. Star Networks
 Central base-station communicates directly to
sensor nodes - Generally mains powered.
 All routes are ‘linear’ where each node only has
one possible communication path.
 The failure of an individual link means that
information is lost.
 Generally requires site surveys and link-level
configuration.
 Each node must be positioned correctly and each
point-to-point link tuned for maximum reliability.

8. Mesh Networks
 Full-mesh networks provide fully redundant
routing to the edge of the network.
 Increased reliability, easy network installation and
long-term predictability.
 Every device has the same routing capabilities.
 Lower power consumption.
 True self-organising and self-healing without
constraints imposed by device type and
architecture.
 Easy network expansion.

9. Wireless Mesh Network (TSMP)
 Time Synchronized Mesh Protocol
(TSMP)
 >99.9% reliability
 Lowest power per delivered packet

10. How it Works: CSMA

11. How it Works: TSMP

12. Frequency Hopping: CSMA

13. Frequency Hopping: TSMP

14. Scalability: CSMA

15. Scalability: TSMP

16. Installation (Less work, Less wire,
Less conduit…)
 No Site Survey
 Installed Like a Wired Device
 Commissioned Like a Wired Device
 Operates Like a Wired Device

17. Maintenance
 redictive and timely
P
indication of failure
trends
Send Maintenance
 elivers accurate and
D ONCE to repair …
actionable data more
effectively than
monthly snapshots
… Not 20 TIMES
to CHECK

18. 25
Radio Performance
20 X With software:
cc2420
10 years  D cell
IRX (mA)
15
X
10 cc1000
With software:
5
10 years  coin cell
Molnar 04 (0.4mA) Cook 06 (300 µW)
X X X
Otis 05 (0.4mA) 100k 300k Bit rate (bps)
200k

19. Train
Detec+on
Data
Uploading
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2
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5
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20. Questions?
 Jose V. Ortega
 817-727-4530
 jvortega@sekiur.com