construction safety simulation paper presented in ICRA'15

1. An innovative methodology to calculate the safety
scores for the different plans based on motions and
distances of obstacles.
Methodology
1. Safety scores for the squares inside the obstacles (static
or dynamic) are,
2. The average safety score, rgrid: t → [0, 1], for a grid
with δ squares at time t is,
3. The total safety score, rtot, for a particular activity plan,
P, averaged over τ is,
4. Aggregated safety score over a time interval,[ti, tf], ragg,
a square gi is,
Prototype Experiments
Calculate safety scores and risk-based heat maps(Fig. 5)
based on the trajectories of moving equipment:
Qt is the queue of activities and Bk is the position of body k,
at time t and α and β are scaling factors. R(gi,t)=1 is the
score for an obstacle (most dangerous in red) and R(gi,t)=0
is the safest score for a square of the grid(green).
Background
Struck-by accidents are one of the four main causes of
fatalities in construction sites (Fig. 1). 75% of struck-by
fatalities include heavy-equipment [1].
Reason: the dynamic, changing nature of jobsites.
• Two coupled phenomena affect the level of safety
hazards related to struck-by accidents on
construction jobsites[2](Fig. 2):
1) Sequence of activities and jobsite layout
2) Movement patterns of workers and equipment.
Gap In Knowledge: Existing tools and methodologies
in safety planning and monitoring fail to consider[3]:
• Dynamic changes of jobsite layouts and how they
impact trajectories of workers and equipment
• Safety visualization tool such as a heatmap.
Objective
Safety Scores and Decision
References
A Coupled Discrete-Event and Motion Planning Methodology for
Automated Safety Assessment in Construction Projects
Md Mahbubur Rahman1, Triana Carmenate1 , Leonardo Bobadilla3 , Sebastian Zanlongo and Ali Mostafavi4
1,2,3The School of Computing and Information Sciences, Florida International University, Miami, FL, 33199, USA. Email: {tcarm002,mrahm025}@fiu.edu, bobadilla@cs.fiu.edu
4OHL School of Construction, Florida International University Miami, FL, 33199, USA. Email: almostaf@fiu.edu
Fig. 1 Workplace fatalities from 1992-2010
To develop an automated model for predictive
analysis of safety in construction projects[4] using
motion planning and discrete event simulation. Also, to
enable an automated system of safety monitoring
using sensors and an information space approach, to
proactively identify safety hazards and eliminate them.
Figure 3 illustrates our framework for this automated
model.
Fig. 3 Framework for Automated Safety Planning based on Motion
Planning and DEVS.
Alternate Construction Plans
All possible topological sorting to generate different
construction activity sequences.
.
Event Scheduling and Heatmap
1. Translate high level activity graphs to a Discrete
Event Simulation (DEVS) Model:
where E is the set of events for an activity, Z is the
configuration of all parameters, EL is the event list,
fn and fz are event transition functions, and zi is the
initial state.
2. Simulate trajectories using combinatorial and
sampling based motion planning algorithms (Fig.
4):
Fig. 4 Left: A path generated utilizing trapezoidal decomposition. Right: A
coordination space with trajectories of 3 bodies and a collision-free path (in
red) computed using A*.
Fig. 5 heat maps for the different construction activities; (a)
Excavation; (b) Concrete pouring/ Excavation; (c,d)Concrete pouring.
Conclusion
The automated safety planning aspect of our work is a
step towards improving existing discrete event and
motion planning approaches for automated detection of
struck-by hazards in construction job sites. The
monitoring aspect allows for a minimalist, non-invasive
and cost-effective approach to pro-actively eliminate
hazards in jobsites. Our future work will involve
deployment in actual jobsites and further simulations
with more complex jobsite scenarios.
[1] https://www.osha.gov/SLTC/etools/construction/struckby/mainpage.html.
[2] Carmenate T, Bobadilla L, Mostafavi A and Bista S. Predictive assessment
and proactive monitoring of struck by safety hazards in construction sites: An
information space approach. 15th International Conference on Computing in
Civil and Building Engineering, 2014.
[3] Lam K. C. Ning X. Cost safety trade-off in unequal-area construction site
layout planning. Automation in Construction, 32:96–103, 2013.
[4] Rahman M., Carmenate T., Bobadilla L., Zanlongo S. and Mostafavi A. A
coupled discrete-event and motion planning methodology for automated
safety assessment in construction projects. IEEE International Conference on
Robotics and Automation, ICRA, 2015.
Fig. 2 One cause of struck-by accidents is dynamic nature of a
construction jobsite.
Average safety
score( μ )
Standard
Deviation (σ)
Plan Evaluation
Low Low Safest
Low High Acceptable
High Low Very Risky
High High Very Risky
Sometimes