Reducing Health and Safety Risks
on Poorly Maintained Rural Roads
Johan Granlund, MSc, IPMA B
Chief Technology Officer
Vectura Consulting AB, Sweden
Lateral forces and low / split friction
really don´t mix well
[Photo: Torbjörn Elverheim] [Photo: Niclas Thunborg] Instability crashes are not randomized. The paper in a nutcase
DisproporBonate risk on rural low volume roads. NVF statement on need of acBons to miBgate over-­‐risks. Health and safety issues raised by high ride vibraBon. Roadex-­‐project case study on the Beaver Road 331. IdenBfying road features decisive for risk factor such as: •  lateral force, •  poor road surface drainage, and •  low fricBon; oQen in combo with split fricBon, using available data from road profilers. Disproportionate risks in
the rural EU Northern Periphery
153 % higher risk to die in a vehicle crash in rural NP areas, than in metropols Stockholm, Gothenburg & Malmoe. [Photo: Torbjörn Elverheim] NP road crashes take 39 % more lives than the worst therapeuBcally treatable “big killer” Diabetes Mellitus. Truckies 3 Bmes higher prevalence of heart disease. Nordic Road Association Statement
“-­‐There is a need to implement new knowledge and prac4cal methods into new approaches, aiming to make an efficient reduc4on of the dispropor4onally high health and safety risks on hot spot sec4ons on the road network. This will improve the working environment for professional drivers and is expected to reduce crash risk for both heavy vehicle and light vehicle traffic as well”. NVF Working Group on Vehicles and TransportaBon Helsinki 2010-­‐02-­‐02 Health and safety issues
raised by ride vibration
[Highway Safety Research InsBtute] 2002/44/EC
Physical Agents Directive - Vibration
If the truck drivers exposure exceeds the Action Value
A(8)= 0.5 m/s2, the employer is obliged by law to
take measures to minimize vibration exposure.
EU Roadex III project
case study on the Beaver Road 331
A regional 170 km route across Västernorrland, Sweden. Annual Average Day Traffic, AADT, 350 to 2000 veh/day. Speed limits 90 and 70 km/h. Mounting truck ride sensors
Test truck Scania R480 164 G 6x4, GVW 60 ton incl trailer. Z-­‐axis 1 kHz at L and R frame and at front wheel axle. GPS + 6-­‐axis 100 Hz inerBal unit in the cab. X, Y, Z-­‐axis 1 kHz seat pad. Camera for right of way. Mic for interior noise. Daily vibration exposure A(8)
Results for normal driving shiQs, taking roundtrips from the Forests to the Coast: A(8) = 0.76 m/s2, over EU AcBon Value A(8) = 0.5 m/s2. Reference road measurement
[Photo: Mats Landerberg] •  Road alignment (curvature, grade, cross slope), •  roughness, •  texture, and more. Truck seat vibration vs road roughness
Truck seat vibraBon intensity @ 75 km/h: RMS(ax,y,z) = 0.18 + 0.30 * IRI Zero vibraBon (0 m/s2) during 100 min loading & pauses. Maximum road roughness for 380 driving min / day, without exceeding the AcBon Value A(8) = 0.5 m/s2: IRI < 1.27 mm/m, a challenge on low volume roads! Recommended minimum short-­‐term acBon: Seek to eliminate local road damage causing IRI20m higher than 3 mm/m, as well as steps at road/bridge joints and potholes causing Megatexture1m over 0.60 mm. Quasi-static lateral forces:
-Too sharp curves with insufficient outer banking
Side friction demand is used when
designing curve superelevation
[Swedish Vägverket, VGU] [Norwegian Statens Vegvesen, Håndbok 111] [UK Design Manual for Road s and Bridges ] Side fricBon demand can also be used as a control measure for instability risk in exisBng curves, using measured data on curvature and cross slope! Example side friction demand
in a fatal rural curve
5 crashes within 45 m, 2 of them were fatal Excessive fricBon demand Piwall: Many road design codes use too high side fricBon supply factors, overseeing the higher side fricBon need of long vehicles driven with large slip angles. Transient lateral forces on
roads without a strong shoulder:
-Deformed pavement edge, due to insufficient
lateral support
Rut Bottom Cross Slope Variance
-predicting truck roll and lateral buffeting
Cause to difference at HS Åkerö seen on next slide Photo: Max Risberg Read the paper for details on RBCSV calculaBon, draQ limit and correlaBon with hazardous sites. 3D laserscan at HS Åkerö
Note: Exploded truck Bre A 69 mm deep deformation
Insufficient drainage gradient (DG)
-Hot spots located at entrance/exit
of banked outercurves.
i E Right hand traffic LeQ hand traffic DG = √ (i2 + E2)
DG being lower than 0.5 % is one of the key causal factors behind the fact that outer curves show 5 Bmes higher rate in fatal crashes! Many new road construction projects
has a built-in skid risk:
- Insufficent drainage gradient
Photo: High Coast Rescue Dept 12 risk secBons with DG lower than 0.5 % in a 12 km long new road. All risk secBons located at entrance/exit of banked outercurve. Curve with 5 crashes within 2 weeks?!?
Improper asphalt patching gave extreme crash outcome when raining just aQer the road work. [Photo: Bengt Andersson] Patch with low texture
gave severe Split-friction
A 66 m long ”fat” patch in the near roadside wheelpath. Patch texture far below intervenBon level ”Minimum 0.6 mm”. This equals having slick worn Bres on one side of the vehicle. Summarizing the paper
NVF statement on the need of acBons to miBgate disproporBonal health and safety risk. Roadex III project case study on the Beaver Road 331. IdenBfying road features decisive for risk factor such as: •  Ride vibraBon and shock, •  lateral force, •  poor road surface drainage, and •  low fricBon; oQen in combo with split fricBon. Analysis based on available data from road profilers.