Infrastructure Challenges
Workshop
OECD / ITF Study on
Truck Transport Safety, Productivity and Sustainability
Transportation Research Board 89th Annual Meeting
Washington DC
10 January 2010
Bernard Jacob
Laboratoire Central des Ponts et Chaussées
Matthieu Bereni, Hervé Guiraud (SETRA)
France
1
Outline
Q
Effects on Pavements
• Pavement issues
• Effect of axle configuration
• Methodology
Q
Effects on Bridges
• Methodology
• Extreme loads and load effects
• Fatigue
Q
Other Impacts
• Impacts on safety barriers, bridge piers and tunnels
• Impacts on road perception and operations
Q
Conclusions and Recommendation
Bernard JACOB, LCPC, 2010/1/10
2
Pavement issues
Q
Q
If pavements and trucks are developed together, transport is
facilitated while reducing its cost
It requires to take into account many aspects :
–
Pavement and Environment
•
•
•
–
Pavements (type, strength, …)
Climate
Availability of resources (aggregates, soils, …)
Truck configurations
•
•
•
•
•
Axle load
Group of axles (number, spacing)
Wheel and tyres
Load distribution
Suspensions and steerable axles
Bernard JACOB, LCPC, 2010/1/10
3
Example : influence of axles and tyres
Aggressiveness against a 40T HGV
5
tridem single tyres spacing 1m35
tridem dual tyres spacing 1m35
tridem dual tyres spacing 1m40
tridem dual tyres spacing 1m60
3 isolated dual tyres (spacing > 2m)
4
3
2
1
0
24 T
25 T
26 T
Bernard JACOB, LCPC, 2010/1/10
27 T
28 T
29 T
Axle group load
30 T
31 T
32 T
4
Method for evaluating truck aggressiveness
Q
Relative Vehicle Wear Factor: VWFrel (truck x ) =
Q
Reference truck
40 t / 16.5 m
Q
Wear factor of a group of axles: WF group of axles i
where :
¾
¾
¾
VWF (truck x )
VWF (truck ref )
⎛ Wi
= ki .⎜⎜
⎝ Wref
⎞
⎟
⎟
⎠
αi
ki and αi are two parameters which depend, for each group of axles i, on
the type of pavement and the expected traffic volume;
Wi is the total weight carried by the group of axle i ;
Wref is the total weight carried by the equivalent reference group of
axles
Bernard JACOB, LCPC, 2010/1/10
5
Bridge issues
Q
Bridges are key/critical elements of the road network
Q
Bridges must be: reliable, safe, durable, and not too costly
Q
Heterogeneous bridge stock (ages, design, state, etc.)
Q
Q
Traffic loads evolve with time:
truck configurations, weights and dimensions
Comparison/assessment of different truck
configurations against aggressiveness
Q
Extreme load effects
Q
Fatigue (repeated loading)
Bernard JACOB, LCPC, 2010/1/10
6
Traffic loads and load effects
Q
Q
Q
Q
Q
Modelling bridges as beams : simple supported,
continuous (2-3 spans)
Influence lines : transfer functions
Bending moments + shear forces
L = 10, 20, 50 and 100 m
Calculation done for 39 heavy
vehicle configurations (OECD)
Maximum load effect (1 truck)
Fatigue: (Max-min)α , α = 3, 5
Comparison to a reference 40 t
articulated truck
8
Q
Q
Q
Bending moment (kN.m/kN)
6
4
2
0
0
20
40
60
80
100
-2
-4
Moment at x=15m
Moment at x=30m
Moment at x=50m
-6
Bernard JACOB, LCPC, 2010/1/10
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Heavy vehicle configurations
8
Aggressiveness (max load effect)
Coefficient of aggressiveness (truck n) : Kn= Max(Sn)/Max (Sref)
Ex.: 10 m simple supported beam, shear forces
250
40,0
200
Shear Force (kN)
20,0
150
10,0
0,0
100
-10,0
50
Vehicle's shear force variation / ref HGHV (%)
30,0
-20,0
0
-30,0
Shear forces
Delta Shear forces
9
Maximum load effects and US bridge formula
Q
Q
Q
US bridge formula limits the total mass carried by any
series of consecutive axles in a truck or combination :
W = 500(L N/(N-1) + 12N + 36) (W in lbs, L in ft)
Ex: 5-axle articulated 16.5 m = 73730 lbs or 33.5 t max
(40 t in EU), cref = 40/33.5 = 1.194
For any truck n: cn = Wn / Wbf , Cn = cn / cref load coefficient
US-1w : cn=0.903, Cn=0.756
N=5, L=17.33 m, W=36.35 t
Wbf=40.25 t
Q
Comparison of Kn and Cn
AUS-2h: cn=1.232, Cn=1.03
N=9, L=22.75 m, W=68 t
Wbf=55.20 t
10
0,60
Bernard JACOB, LCPC, 2010/1/10
1,60
1,40
US7-v
1,80
US6-v
Coefficient mid span moment
US5-h
US4-h
US3-w
US2-w
US1-w
UK2-w
UK1-w
ZA4-h
ZA3-h
ZA2-w
ZA1-w
NL3-h
NL2-h
NL1-h
MX4-v
MX3-w
MX2-w
MX1-w
DE1-h
EU4-w
EU3-w
EU2-w
EU1-w
DK5-h
DK4-h
DK3-w
DK2-w
DK1-w
CA4-v
CA3-h
CA2-w
CA1-w
BE2-h
BE1-w
AU3-v
AU2-h
AU1-w
Ref
Aggressiveness 1 – max mid-span moment
2,00
10 m
20 m
50 m
100 m
Bridge
Formula
1,20
1,00
0,80
11
0,60
Bernard JACOB, LCPC, 2010/1/10
1,60
US7-v
1,80
US6-v
2,00
US5-h
US4-h
US3-w
US2-w
US1-w
UK2-w
UK1-w
ZA4-h
ZA3-h
ZA2-w
ZA1-w
NL3-h
NL2-h
NL1-h
MX4-v
MX3-w
MX2-w
MX1-w
DE1-h
EU4-w
EU3-w
EU2-w
EU1-w
DK5-h
DK4-h
DK3-w
DK2-w
DK1-w
CA4-v
CA3-h
CA2-w
CA1-w
BE2-h
BE1-w
AU3-v
AU2-h
AU1-w
Ref
Aggressiveness 2 – max moment on pier
2,20
Coefficient pier moment
10 m
20 m
50 m
100 m
Bridge
Formula
1,40
1,20
1,00
0,80
12
Bernard JACOB, LCPC, 2010/1/10
0,60
U S7 -v
U S5 -h
U S6 -v
1,80
U S4 -h
2,00
U S2 -w
U S3 -w
Coefficient max / Load effect
U S1 -w
U K2 -w
Z A4 -h
U K1 -w
Z A3 -h
Z A2 -w
N L 3 -h
Z A1 -w
N L 2 -h
M X4 -v
N L 1 -h
M X3 -w
M X2 -w
D E1 -h
M X1 -w
EU 4 -w
EU 3 -w
EU 1 -w
EU 2 -w
D K5 -h
D K3 -w
D K4 -h
D K2 -w
D K1 -w
C A3 -h
C A4 -v
C A2 -w
C A1 -w
BE1 -w
BE2 -h
AU 3 -v
AU 1 -w
AU 2 -h
Ref
Aggressiveness 3 – all lengths vs max effects
2,20
Mid span moment
Pier moment
Shear force
Mean
1,60
Bridge Formula
1,40
1,20
1,00
0,80
13
Fatigue aggressiveness
Q
Q
Miner’s law + S-N curve (resistance to fatigue)
Assumptions (crude !) :
– one truck run → one stress cycle ΔS (for moment on pier x 2 !)
– 40 t reference truck → (Max S – min S) ≡ ΔS* (fatigue limit)
– coefficient of aggressiveness: K’n= (ΔS/ΔS*)α
Q
Q
where α=3 if ΔS>ΔS* and α=5 if ΔS<ΔS*
Bridge formula: Cn= (cn/cref)α
where α=3 if cn>cref and
α=5 if cn<cref
Bernard JACOB, LCPC, 2010/1/10
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0,00
Bernard JACOB, LCPC, 2010/1/10
4,00
Bridge
formula
U S7-v
100 m
U S6-v
5,00
U S5-h
U S4-h
U S3-w
6,00
U S2-w
U S1-w
U K2-w
U K1-w
Z A4-h
Z A3-h
Z A 2-w
Z A 1-w
N L3-h
N L2-h
N L1-h
M X4-v
M X3-w
M X2-w
M X1-w
D E1-h
EU 4-w
EU 3-w
EU 2-w
EU 1-w
D K5-h
D K4-h
D K3-w
D K2-w
D K1-w
C A4-v
C A3-h
C A2-w
C A1-w
BE2-h
B E 1-w
AU 3-v
AU 2-h
AU 1-w
R ef
Aggressiveness 1 – fatigue mid-span moment
9,00
Aggressivity mid span moment
8,00
10 m
7,00
20 m
50 m
3,00
2,00
1,00
15
R ef
0,00
Bernard JACOB, LCPC, 2010/1/10
8,00
50 m
7,00
100 m
6,00
Bridge
formula
U S7-v
20 m
U S6-v
9,00
U S5-h
U S4-h
U S3-w
Aggressivity pier moment
U S2-w
U S1-w
U K2-w
U K1-w
Z A4-h
Z A3-h
Z A2-w
Z A1-w
N L3-h
N L2-h
N L1-h
M X4-v
M X3-w
M X2-w
M X1-w
D E1-h
EU 4-w
EU 3-w
EU 2-w
EU 1-w
10,00
D K5-h
D K4-h
D K3-w
D K2-w
D K1-w
C A4-v
C A3-h
C A2-w
C A1-w
BE2-h
BE1-w
AU 3-v
AU 2-h
AU 1-w
Aggressiveness 2 – fatigue moment on pier
11,00
10 m
5,00
4,00
3,00
2,00
1,00
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Dynamic amplification, traffic load and
stress monitoring
Q
DAF rarely exceeds 1.1 to 1.2
– for heavy loaded vehicles
– for more than one truck on a bridge
Q
1.05 applies to extreme load cases
B-WIM:
- mature technology
- more bridge types
- more parameters
- part of bridge monitoring
systems
Q
Bridge (B-)WIM is an appropriate tool: stress + load +…
17
Impacts on safety barriers, piers and tunnels
Q
Q
Q
Q
Q
Safety barriers: designed for a given vehicle
mass, speed and impact angle, e.g. EN 1317
H4b: 38 t, 65 km/h, 20°
Design depends on: consequences of an
accident, traffic volume, type of road, local
conditions/geometry, etc.
Bridge pier: design + protection, FE calculations
Not all trucks contained, decisions to be taken
for LHVs…
Tunnels: main issue is fire, up-grade of the EU
legislation since the Mt Blanc fire (1999)
- dangerous goods to be monitored
- permanent access and inter-distance control
- maintenance + fire detection/suppression in trucks
- fire resistant materials, fuel tank protection
- driver education and training
18
Impacts on road perception and operation
Q
Road perception:
– … and visibility affected, leads to “improper maneuvering”
– length and distance underestimation ! Overtaking !
– splash and spray in wet conditions, - night time signaling
Q
Road traffic operation:
– to smooth the traffic flow and reduce congestion:
- speed limit harmonization (between trucks)
- overtaking limitations/bans
- to locally allocate dedicated lanes to trucks
– to improve safety and efficiency:
- crossings and turns design, LHV’s prohibited in some area/sections
- adapted speed limitation vs. the infrastructure (roundabout, curves…)
and the vehicles (load, height of the gravity center, performances…)
- extension of parking lots
- IAP (Int. Access Program) to be developed
Bernard JACOB, LCPC, 2010/1/10
19
Conclusions and recommendation (1)
PAVEMENTS
Q
Axle loads and configurations are much more important than the gross
vehicle mass
Q
Distributing the load evenly among all the axles substantially reduces
the aggressiveness
Q
Method exists to evaluate these aspects respecting the characteristics
of the studied network
Bernard JACOB, LCPC, 2010/1/10
20
Conclusions and recommendation (2)
BRIDGES
Q
Truck aggressiveness mainly depends on the axle loads and the UDL
(kN/m)
→ do not increase axle load, increase truck length more than load
Q
The heaviest trucks govern some bridge effects (medium span, semilocal effects), multiple presence events and long spans, fatigue can be
an issue
Q
The US federal bridge formula is applicable for short/medium span
bridges, has been designed for 20 m / 73 200 lbs trucks. To be updated and extended/exported.
Q
Dynamic effect is NOT a major issue, bridge load and stress monitoring
can be very effective (e.g. with B-WIM) + IAP and truck routing
Bernard JACOB, LCPC, 2010/1/10
21
Conclusions and recommendation (3)
OTHERS
Q
Safety barriers and bridge piers to be re-assessed/reinforced/protected
(LHVs)
Q
Better hazard monitoring (truck/driver/infras) in tunnels…
Q
ITS to be developed for road operation, strategies to be developed for
LHVs
Thank you !
Bernard JACOB, LCPC, 2010/1/10
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