Mobile Measurement (MIMM)-Based Road Tunnel Soundness Evaluation Technology
1.Background

Over the past several years, infrastructure has suffered various types of damage associated with age-related
deterioration, and several accidents have occurred in road tunnels (Cases 1 and 2). Road tunnels are usually inspectedonce every three to five years. For these inspections, roads or lanes are closed, and close visual inspections areconducted. However, given the difficulty of securing funds for maintenance and ensuring the necessary workforce, it
has not been possible to inspect all tunnels. Soundness evaluation technology based on streamlined, low-costinspection methods is drawing attention as a solution to these problems.

【Case１】【Case2】

Ceiling panels falling onto an expressway (February 2012)

Concrete fragments falling onto a national highway (January 2013)

The main cause was said to be age-related deterioration of the hanging
bolts that supported the concrete ceiling panels in the tunnel.

Concrete fragments from a sidewall fell onto the roadway as a result of age-relateddeterioration.

2. Challenges and purpose of tunnel maintenance
NeedsChallenges
Difficulty identifying causes of damage and estimating the processof deterioration because the subject is surrounded by bedrock orcomprises complex materials.

Inspections capable of properly
identifying locations of damage

Decisions about repairs and the like could be inconsistentbecause they are made based on inspectors’ empirical judgments.

Inspections conducive toobjective judgments

Social loss associated with road/lane closures during surveys andinspections

Inspections that do not requireroad/lane closures

Insufficient funds for inspections and the likeMobile measurement vehiclebased method of inspection● Establish a method of evaluation basedon image data

● Establish a method of evaluation
based on laser data

● Establish an overall method of evaluation● Establish a method of estimating causes

Safe, low-cost inspections

Worker shortage due to poor working environments (e.g. vehicleexhaust) during inspections and surveys.

of damage● Establish specifications for mobile

Inspections with good working
environments

measurement

3. Mobile measurement system overview
The mobile measurement vehicle (MIMM) is capable of simultaneously gathering images of tunnel walls (Mobile Imaging Technology
System (MIS)) and point cloud data (coordinates in three dimensions) with lasers (Mobile Mapping System (MMS)) on a single pass-through.
Mobile Imaging Technology System (MIS)
LasersVideocameras
captureandmeasure images of tunnel walls toobjectively ascertain the locationsof cracks, leaks, and material
defects (honeycombing) on thesurfaces of the lining concrete. The
system features LED lighting as thesource of the light needed forimage
measurement,
andisoutfitted with twenty 380,000pixel cameras. (This enables thesystem to detect cracks as smallas 0.2 mm)

Mobile Mapping System (MMS)GPSIMU
Lasers
GPSLasers

Highperformancelasers

LED lights,
CamerasHigh-performancelasersThis system acquires data on theoutlines of the inner surfaces oflining concrete through threedimensional laser measurementin the form of three-dimensional
coordinates to ascertain thetexture and deformation modesof lining concrete surfaces.
Notably, the laser apparatus
installed on the rear of thevehicle has the capacity tomeasure 1 million points persecond.

4. MIMM-based evaluation method

Images and laser data are combined to conduct 3D analysis
and thereby evaluate tunnel walls.

MISimage measurement

MMS
laser measurement

In the field

In the field

Create image
analysisdevelopments

Laser analysis
Create contour drawing

MIMM measurement in action

Leaks identified from captured images

Identify locations

Identify locationsof damageof damage

Spalling, peeling, impact of external forces,etc.

Cracks, leaks, honeycombing, discoloration, etc.

Laser point cloud data

CAD data image

Data synthesis and evaluation

Crack development●Estimate causes of deformations●Evaluate soundness●Determine the need for detailed surveys●Determine the need for countermeasures

Laser contour drawing

5. Example of MIMM-based evaluation
Below are the results of an MIMM measurement conducted in a tunnel. We knew that deformations were occurring on the inner surfaces
where clusters of cracks were identified by the MIS, so we checked for consistency in the field. Consequently, we identified some diagonal
unevenness in the tunnel and confirmed that it was due to external forces.

Mobile image MIS

Crack development

Contour drawing (MMS)

Deformation mode drawing

6. Outcomes and challenges of evaluation

MIS evaluation

MMS evaluation① Spalling is highly likely in locations of peeling, leaks, free

① Contour drawings can be used to estimate the impact ofexternal forces or the causes of cracks.

② Similarly, spalling is highly likely where cracks close,② Laser analysis can be used to determine the progressiveness③ Spalling is highly likely when cracks extend longitudinally③ The system is capable of detecting unevenness as small as④ The system is capable of detecting cracks as small as 0.3④ Taking measurements when tunnels are constructed andlime, honeycombing, and joint deterioration/discoloration.
intersect, or cluster (hexagonal).
or where there is unevenness.
mm at a speed of 40 km/h.

⑤ When the aforementioned types of damage are confirmed
on images or CAD, it is necessary to verify by conducting
close visual inspections or hammering tests in the field.

of deformations.

0.5 mm at a speed of 40 km/h.

confirming subsequent differences enables more advancedmanagement.

⑤ It is necessary to save measurement data for use in
subsequent maintenance.

Contact for inquiries
Contacts: Yoshinaga, Ishimura, Matsuyama
Road Group, NEWJEC Inc.
1-1-10 Honjo-higashi, Kita-ku, Osaka-shi, Osaka

E-mail: yoshinagasg@newjec.co.jp
Web: http://www.newjec.co.jp

Tel: 06-6374-4031

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