Massachusetts North Shore MBTA – Track Monitoring

Engineering teams at the Massachusetts Bay Transportation Authority (MBTA) found themselves tackling the effects of numerous downpours.

Floods damaged rail earthworks, including cuttings and embankments - events that can lead to significant disruption on the busy Greater Boston network operated by Keolis Commuter Services.

Failed cutting slopes can lead to soil, rock, and vegetation sliding onto the tracks, and embankments can be weakened by washout of supporting material, sometimes leaving track crossties and rails suspended in mid-air.

Emergency repairs typically follow soon after identification of such problems, but they do not completely remove the concern about ongoing ground movement. Concern had also arisen relating to replacement of an under-track culvert and its possible effects on the track.

To manage the impact of severe weather and construction activity, Keolis engineers chose to pilot the use of intelligent wireless monitoring technology to detect any further ground movement.

The InfraGuard™ solution, developed by Senceive, comprises highly sensitive tilt sensors mounted on metal stakes that can detect sub-millimeter movement and send immediate data updates wirelessly to remote users via the cellular network. The system includes automated cameras that are triggered to send pictures of the site in the event of movement outside pre-set thresholds.

Keolis engineers installed it at two sites adjacent to MBTA tracks.

First, eleven tilt sensors went onto a cutting adjacent to an overbridge over Route 495. As pictured, the sensors were placed on stakes near the bottom of the slope to monitor any further slippage.

Secondly, nine tilt sensors and InfraGuard™ were placed along an embankment in a residential area following culvert renovation works. The objective here was to assess the stability of the railway and ensure that no threat was posed to train movements by ongoing settlement.

The monitoring program provided high precision, continuous data and built confidence that engineers would get immediate alerts in the event of potentially damaging ground movement at locations identified as being at-risk. Data will enable early intervention to fix any problems and reduce disruption to passengers.

Keolis has been happy with their system and are now looking to expand their application of Senceive’s rockfall solutions to another region of concern on the Commuter Rail, this time to a large rock cut. With the ongoing threat of falling rock causing issues for train traffic, keeping tabs on the state of the railways is essential for public safety.