Handheld SLAM vs. TLS for Highway Bridge Surveys, A Comparison Study

Case Studies2026.01.124 min read

110m × 27m Bridge: SLAM vs. Terrestrial Laser Scanner

The Challenge

Atlıhan Engineering needed as-built documentation of a 110-meter highway bridge with heavy pedestrian and vehicle traffic. The question: could handheld SLAM technology deliver accuracy approaching terrestrial laser scanner (TLS) standards while dramatically reducing field time and traffic disruption?

Head-to-Head Comparison

Head-to-head comparison between XGRIDS Lixel L2 Pro handheld SLAM and Leica RTC360 terrestrial laser scanner (TLS) for as-built bridge documentation. The L2 Pro completed the full 110m × 27m survey in 6 hours total versus 7.5 days for TLS, while achieving sub-centimeter accuracy validated against the TLS baseline.

Infographic summarizing the handheld SLAM versus 3D laser scanning comparison with centimeter-level accuracy

Scanning Equipment: XGRIDS Lixel L2 Pro and Leica RTC360

Handheld SLAM: XGRIDS Lixel L2 Pro with 6 GCPs (non-linear distribution across the bridge)
TLS Baseline: Leica RTC360 terrestrial scanner

Field Work

Surveyor documenting a highway bridge with a handheld Lixel L2 Pro lidar scanner amid live traffic

Operational efficiency breakdown:

L2 Pro required just 3 overlapping scan loops versus 350 individual TLS setups.

Field time reduced from 1.5 days to 45 minutes, with full mobility access to areas restricted by traffic—a key advantage for infrastructure surveys on active roadways.

Metric	L2 Pro	TLS (RTC360)	Advantage
Scan Method	3 loops	350 setups	117× fewer setups
Field Time	45 minutes	1.5 days	16× faster
Site Access	Full mobility	Limited (traffic)	No constraints

Processing Time

LixelStudio's automated dynamic object removal feature cleaned up around 90% of the heavy pedestrian and vehicle traffic present during the scan, and the remaining manual clean-up completed in 1 hour, versus 6 days of manual cleanup for TLS data.

Total processing: around 5.5 hours for L2 Pro versus 7 days for terrestrial scanning.

Processing-time breakdown comparing L2 Pro and TLS point cloud registration and cleanup

Accuracy Validation

Cross-section comparison against TLS data:

Average error: <1 cm
Maximum error: 1.5 cm (occurred in narrow staircase section, likely technique-related)
Point density: L2 Pro delivered 6-7× lower density than TLS, yet met all project accuracy requirements

Cross-section deviation diagram validating the handheld scan against the TLS baseline at centimeter-level lidar accuracy

Cross-section accuracy diagram with deviation measurements at multiple points.

Second cross-section comparison confirming centimeter-level agreement for the SLAM point cloud

Results & Deliverables

Colorized point cloud model of the highway bridge, road, and walkway for as-built documentation

Colorized Point Cloud Model of the Bridge

Lidar SLAM point cloud of the bridge underpass and the roadway passing beneath

Colorized Point Cloud Model of the Bridge

Colorized point cloud of the bridge deck and surroundings, ready for as-built modeling

Colorized Point Cloud Model of the Bridge

Complete as-built documentation including site plans, cross-sections at specified intervals, and bridge wear analysis. The L2 Pro data proved sufficient for structural assessment without requiring TLS-level detail.

Okan ATLIHAN, Atlıhan Engineering:

"For this type of work, the achieved level of accuracy and detail meets expectations, so I prefer the L2 Pro. Time, cost, and the benefit index are the most important factors. Another reason for choosing it is the very high level of detail in the L2 Pro compared to other SLAM devices, which is also due to its software algorithm."

When to Use Each Technology

Choose L2 Pro for: Bridge inspections, as-built documentation, condition assessments where <1.5cm accuracy is acceptable, particularly when traffic, safety constraints, or time pressure exist.

Choose TLS for: Applications requiring maximum detail and sub-millimeter precision where additional time and cost are justified.