Real-time Monitoring, Surveillance and Control of Road Networks under Adverse Weather Conditions
Road Weather Modeling in the
Framework of Action TU0702
Action Keywords:

Road networks

Traffic modeling & management
 Adverse weather
Final Conference, Helsinki, Finland, 21-22 May 2012
Pertti Nurmi, Finnish Meteorological Institute
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Background
Extreme Weather Impacts on European Networks of Transport
ROAD TRANSPORT
(FMI analysis)
Finland : Average annual road accident costs  226 million €
 Estimated annual savings based on current weather services  36 million €
Europe : Average annual road accident costs  20 billion €
 Estimated annual savings based on current weather services  3,4 billion €
 100% forecast accuracy estimated to increase benefits by 240 million €
Helsinki, 21 – 22 May 2012
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2
TU0702 Goals
a) To gain a better understanding of the impacts of adverse
weather (snow, rain, slipperiness, poor visibility, …) on
traffic operations …
b) To develop and promote strategies and tools to mitigate
the impacts of adverse weather
… and proposing best practices and guidelines…
c) To develop weather responsive traffic management plans
and tools…
 … A strongly multi-disciplinary project !
Helsinki, 21 – 22 May 2012
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TU0702 Goals
Because of the multi-disciplinary nature  Necessity to ...
Define “Adverse Weather“
(WG_1 / chair: Pertti Nurmi)
“ The Action established a task force to define adverse weather to clarify the
meaning and reach a common understanding of this keyword within different
disciplines: traffic engineering, pavement engineering, meteorology ”…
SEVERE
Chapter 1.1 in
Final Report
EXTREME
Multi-dimensionality !
HIGH-IMPACT
RARE
ADVERSE
Helsinki, 21 – 22 May 2012
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Definitions
Multi-dimensionality !
SEVERE
Adjective rigorous, violent; very strict; unsparing; hard to endure; inflicting (physical) discomfort or hardship.
Latin origin severus. Antonym mild.
EXTREME
Adjective exceeding the ordinary-usual-expected; highest limit or degree; outermost; greatest; very violent;
stringent.
Latin origin extremus. Antonyms moderate; mild.
HIGH-IMPACT
Noun shocking or striking effect or influence; forceful contact.
Latin origin impactus.
RARE
Adjective uncommon; unusual; infrequent ; seldom occurring or found.
Latin origin rarus. Antonyms abundant; common; usual.
ADVERSE
Adjective harmful; unfavorable; inclement.
Latin origin adversus ‘against, opposite’. Antonyms advantageous, propitious.
Does not sound as bad as "severe". Adverse weather, in general, can cause some disruption but does not necessarily
lead to very large losses and, hence, cannot commonly be considered as severe or high-impact. May be used as a
general term for “unfavorable” weather conditions, though.
Helsinki, 21 – 22 May 2012
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Risk = Hazard probability * human vulnerability
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Definitions
Multi-dimensionality !
Severe Events
 Cause large losses:
•
of human lives
•
of money
•
for the environment
 Can be estimated by expected losses  Risk estimation
•
Probability of event
•
Exposure to event (number of exposed people)
•
Vulnerability of society to event
 Are a function of both the meteorological event **and** state of human affairs
•
E.g. increased traffic volumes  increased exposure to meteorological features
affecting traffic
Helsinki, 21 – 22 May 2012
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6
Definitions
Multi-dimensionality !
Extreme Events
 Extreme values of specific meteorological variables, causing damage
•
Heavy rainfall  Flash flooding
•
Large amounts of precipitation  Flooding
•
Heavy snowfall  Malfunctioning of all transport, electricity lines etc.
•
Very strong winds  Malfunctioning of sea and air transport, falling trees etc.
•
Very high temperatures  Notorious health effects
•
Very low temperatures  Increased energy consumption
 Defined as taking maximum values and/or exceeding pre-existing (measured) high
(low) thresholds
 Generally rare events
•
E.g. 1% probability of occurence during a given year at a given location
Helsinki, 21 – 22 May 2012
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Definitions
Multi-dimensionality !
High-impact Events

Typically severe events
i.
Short-duration weather events
ii.

•
Fast-moving, strong cyclone
•
Convection-induced heavy precipitation
•
Overnight freezing of road surfaces due to cooling of atmospheric surface layer
caused by outgoing radiation
Long-duration weather events
•
Blocking high pressure associated with a prolonged heat wave and drought
•
Monsoon circulation
World Meteorological Organization prefers the term “high-impact” to “severe” weather
to cover (i) and (ii)
Rare Events

Low probability of occurrence

Society and environment are not adapted  Large damages when occuring

Despite rarity, large vulnerability leads to large losses
Helsinki, 21 – 22 May 2012
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Definitions
Multi-dimensionality !
Binary (Dichotomous; Yes/No)





Rainfall vs. no rainfall
Snowfall vs. no snowfall
Strong winds vs. no strong wind
Fog vs. no fog
Night frost vs. no frost … or Freezing of road surface temperature
or Multi-category




with
Rainfall >>> Heavy precipitation
various
Snowfall >>> Heavy snowfall
thresholds
Strong winds >>> Gale force
Road surface temperature Ts < -30oC … -1oC < Ts < +1oC … 50oC < Ts
Helsinki, 21 – 22 May 2012
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Illustration
Temperature distribution at a cold station in Finland (50 years, c. 55000 observations)
1. year >>>
Helsinki, 21 – 22 May 2012
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>>>
>>> 50. year
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Illustration
Temperature distribution at a cold station in Finland (50 years, c. 55000 observations)
Hot Extreme Event
+30oC
-45oC
Hot Rare Events above line
Cold Rare Events below line
1. year >>>
Helsinki, 21 – 22 May 2012
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>>>
Cold Extreme Event
>>> 50. year
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Illustration
Temperature distribution at a cold station in Finland (50 years, c. 55000 observations)
Hot Extreme Event
5%
+18oC
Hot “Scarce” Events above line
90% Quantiles
-23oC
Cold “Scarce” Events below line
5%
1. year >>>
Helsinki, 21 – 22 May 2012
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>>>
Cold Extreme Event
>>> 50. year
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Illustration
Temperature distribution at a cold station in Finland (50 years, c. 55000 observations)
+1 oC
- 1 oC
Common but High-impact Events  Freezing of road surface
( 1000’s of cases ! )
1. year >>>
Helsinki, 21 – 22 May 2012
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>>>
>>> 50. year
13
Illustration
Temperature distribution at a cold station in Finland (50 years, c. 55000 observations)
Rare Events
90 %
High-impact
for road traffic
Helsinki, 21 – 22 May 2012
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Illustration
Temperature distribution at a HYPOTHETIC station maybe somewhere in S. Europe
Rare Events
90 %
High-impact
for road traffic
-5
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Chapter 4 in Final Report
4.1 Observing the weather
4.1.1 Surface weather observations
4.1.2 Atmospheric soundings
4.1.3 Satellite data
4.1.4 Radar data
4.1.5 Weather observations for aviation
4.2 Modeling and forecasting the weather
4.2.1 General principles of nowcasting
4.2.2 General principles of numerical weather prediction
4.3 Applications
4.3.1 Road weather forecasting
4.3.2 DLR’s WxFUSION concept
4.4 Modeling the impact of weather upon traffic
4.4.1 FMI statistical forecast model for road surface friction
4.5 Summary
Helsinki, 21 – 22 May 2012
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Road Weather Is an Issue…!
(Sochi, 3/2011; Photo © Pertti Nurmi)
Helsinki, 21 – 22 May 2012
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Use and Users of RW Services
 Weather forecasters
Products
 Road maintenance authorities

Road & pedestrian weather
forecasts

Specialized, tailored warnings

Road maintenance scheduling

Route planning
 Road traffic controllers
 Drivers and pedestrians
Benefits
 Safety and fluency on roads
 Reduction of

Maintenance costs

Injuries and casualties
(Sochi, 3/2011; Photo © Pertti Nurmi)
Helsinki, 21 – 22 May 2012
[email protected]
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Road Weather Model
Model
resolution
Driving
atmospheric
NWP model
. . .
. . .
. . .
~ 5 km
Helsinki, 21 – 22 May 2012
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SIRWEC (ID-21) Quebec City 5-7 February 2010
RW Model Schematically
Output:
Input data:
Driving Index
• Temperature, humidity
• Wind speed
• Precipitation intensity
• Lighting conditions
• Normal
• Bad
• Very bad
State-of-Road
• Surface temperature
• Storages
- Water, snow
- Ice, frost
Helsinki, 21 – 22 May 2012
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1. Dry
2. Damp
3. Wet
4. Wet snow
5. Frost
6. Partly icy
7. Dry snow
8. Icy
Road surface
Temperature
+ Friction
( New11.6.2012
product )
Applications… to Operations
FMI Road Weather Model :
 Developed during 1999-2000,
thereafter operational
 One-dimensional energy balance
model  calculates vertical heat
transfer in the ground and at the
ground-atmosphere interface
 Background information taken
from NWP model(s) (ECMWF,
HIRLAM) as such, or edited by
operational meteorologists
 Model output : Road surface
temperature, state of road,
thickness of water, snow and ice
layers on surface (in equiv.mm)
 New output variable:
Friction coefficient
 Slipperiness
Helsinki, 21 – 22 May 2012
[email protected]
www.roadidea.eu
TU0702 Synergy
Applications… to Operations
TU0702 Synergy
Statistical Model (PerfProg) for Surface Friction (CF) :
Helsinki, 21 – 22 May 2012
[email protected]
Applications… to Operations
Friction Model and Its Evaluation :
 Statistical friction formulae evaluated
using independent data
 Friction forecasts are verified against
DSC111 observations on a daily basis
 Friction formulae can be derived for
new forecast areas (in connection
with the road weather model) 
Sochi Olympics FROST-2014 project
 Friction measurements (DSC11) are
required for equation development
and fine-tuning
 Major challenge: How to tackle road
maintenance actions (salting, ploughing)
Helsinki, 21 – 22 May 2012
[email protected]
TU0702 Synergy
Applications… to Operations
TU0702 Synergy
Correspondence between friction and driving conditions
 Forecasting
0.30
0.15
Driving conditions
< 0.15 = very bad
< 0.3 = bad
> 0.3 = normal
Helsinki, 21 – 22 May 2012
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Applications… to Operations
TU0702 Synergy
ITS  Wireless Traffic Safety Network between Cars

Wireless traffic service platform  Test service delivery to vehicles

Vehicle-to-Vehicle V2V and Vehicle-to-Infrastructure V2I communications

En route (road stretch) weather forecasts and incident warnings
Tampere
Helsinki
Helsinki, 21 – 22 May 2012
[email protected]
2009-2012
Applications… to Operations
TU0702 Synergy
Down-scaled numerical weather model grid
From model grid to en-route road positions
Helsinki, 21 – 22 May 2012
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2009-2012
Applications… to Operations
TU0702 Synergy
Test sites:
A99, A9 and A92
M 12
Baixo Alentejo
A2 (3rd stretch)
A2 (1st stretch)
PATHE Motorway
Algarve Litoral
Helsinki, 21 – 22 May 2012
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FMI is the only meteorological partner in the consortium
Applications… to Operations
TU0702 Synergy
- WMO FDP & RDP forecast verification
- Road weather R&D application
Helsinki, 21 – 22 May 2012
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 Project funding submitted early 2012
Applications… to Operations
 Road weather forecast is based
on output of 3D NWP models
and local measurements
 FMI exploits operationally run
High Resolution Limited area
model
 Model’s domain covers whole
Europe, including the Sochi
region
Helsinki, 21 – 22 May 2012
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TU0702 Synergy
Atmospheric water content simulated by HIRLAM
Applications… to Operations
 To run road weather model at a
higher spatial resolution the
road stretch is divided in
segments (yellow pushpins)
 Resolution of segments can
vary from some kilometres
down to metre-scale depending
on available computer
resources
Helsinki, 21 – 22 May 2012
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TU0702 Synergy
Zooming to road stretch from coast to sports sites
DLR (Germany) Application

TU0702 Synergy
Integrated adverse weather forecast system for aviation : WxFUSION
 Applicable to Road Traffic

Adverse weather affecting road traffic and road conditions

Utilizes in-situ ground observations + remote sensing observations

Includes nowcasting tools  shortest forecast ranges

Includes high-resolution NWP models  forecasts up to several hours

Combines observations + nowcasting tools + NWP simulations

Produces more reliable interpretation than any one single source

Includes user-defined target weather objects to depict

Expected to close the gap between nowcasting and forecasting

Fusion process is based on fuzzy logic approach

Conceptual model + expert knowledge to be incorporated into account

Local constraints wrt specific weather conditions can be taken into account
Helsinki, 21 – 22 May 2012
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DLR (Germany) Application
Helsinki, 21 – 22 May 2012
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TU0702 Synergy
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Thank You for
Future prospects… New COST Action maybe?
Your Attention

Need for more detailed and accurate localized forecasts
(bridges, hills, valleys, ramps, urban areas…)

High quality, high resolution observations

Detailed information on terrain, elevation

Detailed information on the structure of road and ground
… Inclusion of above information into the models

Detailed road stretch forecasts  Num. statistical forecasting techniques

Info of maintenance actions and salt *IS* instrumental as model input

Wireless communication techniques  Forecast output transmission

Increased cross-collaboration with various stake-holders and end-users
(“owners” of observations, road authorities, rescue and health services, city
planning, telecom companies)
 Increased international collaboration
Helsinki, 21 – 22 May 2012
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