The Finnish Meteorological Institute is currently testing two-way delivery of local weather data as Timo Sukuvaara explains.
Road weather information is one of the key ways in which ITS can help reduce traffic accidents and fatalities – which is why the Finnish Meteorological Institute (FMI) has long provided road weather services. Now, the CoMoSeF (Cooperative Mobility Services of the Future) project has been developing communication methodologies to deliver road weather services directly to vehicles and gather data directly from vehicles. This has resulted in the development of an architecture for vehicular networking-based road weather services.
The system combines a traditional road weather station (RWS) and a roadside unit (RSU) to create a dedicated service hotspot which interacts with vehicles using all major communications approaches (
In comparative field tests using a combined RWS/RSU, each of the communication methods was analysed. In general, it was observed that Wi-Fi offered the best peak performance, however IEEE 802.11p provided clearly a more stable and reliable data link throughout the passing of the RWS/RSU coupled with the lowest delays. And although 3G provided the lowest data rate and highest delays, it did offer an unlimited range.
Our proposal for a primary communication method is to offer combined IEEE 802.11p and cellular 3G, allowing fast response times and high data rates over short distances, but still offering lower capacity access everywhere. From the architectural perspective, the networking entity consists of the combined RWS/RSU (including services beyond the fixed network) along with instrumented vehicles and all kinds of local and wide area communication systems.
FMI has constructed a special combined Road Weather Station and Road Side Unit (RWS/RSU) to Northern Finland, near its facilities in Sodankylä, to support various vehicular networking and road weather service research projects. One of the CoMoSeF prototype deployments is FMI’s project to develop and deploy ‘Road Weather Testbeds’ with advanced communication to explore the potential of wireless networks and communications.
FMI’s combined Road Weather Station (RWS)/Road Side Unit (RSU) station is equipped with up-to-date road weather measurement instrumentation, compatible with the equipment normally installed on public RWSs. The procedure is to design, develop and test both the local road weather service generation partially based on vehicle-oriented data and the service data delivery between RWS and vehicles.
The main pilot area for this work is 240km of the E75 between Sodankylä and Kemi in Finland. Instrumented vehicles gather friction data from along the test area to supplement and extend the coverage of that gathered by the combined RWS/RSU in Sodankylä.
To fully exploit the local real-time information, the data needs to be delivered directly and instantly into other vehicles travelling in the area, necessitating networking between the vehicles and roadside infrastructure. Vehicle data is gathered into the combined RWS/RSU, while the up-to-date (weather oriented) service data is delivered in the opposite direction, respectively. It is also possible for a vehicle to have continuous connectivity via a direct connection to the fixed network infrastructure through the cellular network.
The RWS/RSU will act as a service hotspot, allowing delivery of all the up-to-date road weather data and related material to passing vehicles while the (weather oriented) service data is delivered into the opposite direction. But as the density of RWS stations is expected to be rather low, the 802.11p and Wi-Fi connectivity will be supplemented with 3G cellular network communication to deliver critical supplemental weather data elements to the vehicles outside the hotspots. It is also possible for a vehicle to have continuous connectivity via a direct connection to the fixed network infrastructure through cellular network.
Combining these different networking types (excluding in-car communication) into a single architecture is one of the projects key objectives.
In this project FMI will only consider broadcasting emergency (accident warning) information and friction measurements between vehicles while the permanent link to the fixed network means the roadside units can, hypothetically, provide the vehicles with temporary internet connectivity.
The accident warnings are simply initiated by pushing an emergency button on the in-vehicle computer unit (either the in-vehicle computer or, in this instance, an external and tailored computer installed in the vehicle). Such a system could be integrated with the vehicle internal systems and achieve accident initiation from the vehicle CAN-bus, for instance an airbag bursting indicator.
For friction measurement FMI is using two different optical sensors in the trial:
The RCM411 detects real-time surface conditions including Dry (indicated dark green line on the map), Moist (light blue), Wet (dark blue), Slushy (violet), Snowy (white) and Icy (red). It also measures water and ice layer up to 3mm thick in fractions of a millimetre. Its readings are also cross referenced with those from Vaisala’s DSC 111 in the RWS/RSU.
Friction monitoring occurs on the measuring vehicle continuously with the data collected at pre-defined intervals via 3G communication or through IEEE 802.11p, or Wi-Fi communication whenever entering the range of Sodankylä RWS. Friction data from other vehicles or from the RWS can be delivered back to the vehicle as reference data – although this is not in the scope of the project.
Beyond the vehicle-oriented data, the local server also gathers information from the Vaisala Rosa system and FMI weather station and delivers it all to a local FMI facility using 3G. This information is then processed in the FMI facility and sent back to the RWS/RSU for onward delivery to vehicles. A simplified version of the operational procedure is shown in the graphic on the first page.
The IEEE 802.11p VANET standard is used as the primary communication with traditional Wi-Fi (IEEE 802.11g/n) and cellular networking (3G) as reference methods for the existing operative solution and as an alternative if VANET is not available. When passing the RWS/RSU, up-to-date road weather related data and services are automatically sent to the vehicle and displayed in a specific user application, while vehicle-oriented data is delivered upwards. A local server in RWS/RSU is hosting the station operations. It is linked with a modem for IEEE 802.11p communication attempting and also has an internal Wi-Fi modem, and both of these communication channels are actively seeking passing instrumented vehicles.
FMI can access local road weather measurements in other European locations and as part of the CoMoSeF project, it provided local road weather service to the Sochi Olympics area, relying on local measurements, its own meteorological simulation models and an adjustment of service.
During the 2014 Winter Olympics in Sochi, the indoor sports were held in the coastal city of Adler and outdoor events 550m above sea-level in the mountain village of Krasnaya Polyana some 40km inland. The A148 road connecting the two follows a 3-6km wide valley surrounded by 2,000m (and above) mountains. As neither RWS nor vehicle-derived friction data was available, the trial involved delivering the road weather service to vehicles.
A meteorological simulation model combined large-scale (HIRLAM) and fine-scale (HARMONIE) 3-Dimensional numerical weather prediction for 26 selected points along the road while local road weather data was generated in real time by the Finnish skiing team support personnel, via mobile smartphones and local wireless networks. The service was offered as a graphical presentation, predicting temperatures, precipitation, friction and road surface coverage, respectively.
The display showed a graphical presentation of predicted temperatures, precipitation, friction and road surface coverage which was delivered to user devices - in practice, smartphones. The authorities forbade the deployment of local infrastructure.
The feedback received from the users (Finnish skiing team support personnel) was generally positive, both regarding to service availability and usefulness. Similar kind of tailored road weather service can be produced in any location in Europe, generally limited by the coverage of HIRLAM and HARMONIE models.
Initial findings of the trials show that the hybrid communication approach can be used to provide vehicles with real-time weather and traffic information. Detailed and more specific data contents with local area weather data can be delivered to vehicles in RWS service hotspots while 3G can deliver critical weather and traffic related information to vehicles further afield. Such deployments are easy to start, as from day one the operation can be immediately initiated with existing 3G networks.
