Keeping a weather eye on road conditions

Drive C2X has shown that advanced warning of poor road conditions could cut fatalities, as David Crawford explains.   

Connected vehicle (CV)-based warning technologies could mean 6% fewer deaths and 5% fewer injuries in road traffic accidents in Europe, according to the final results of the European Commission (EC) co-funded 7890 DRIVE C2X project. According to the European Centre for Information and Communication Technologies (EICT) which provided management support, these “prove that CV systems work and can have a positive impact on safety”.

The three and a half years’ DRIVE C2X project involved more than 750 drivers in Finland, France, Germany, Italy, Netherlands, Spain and Sweden having tested safety-related cooperative functions in 200 vehicles. Six warning functions (Approaching Emergency Vehicle, Traffic Jam Ahead, Obstacle, Car Breakdown, Road Works and Weather) were tested along with in-vehicle signage and ‘speed to green’.

Its key finding was that in-vehicle signage (IVS) displaying speed limits and weather warnings has the best potential to decrease fatalities. With the speed limit function a pictogram of the speed limit sign was displayed as the vehicle approached the speed limit sign. Drivers exceeding the speed limit significantly were given both a visual and audible alert. If all cars were fitted with an IVS that continuously displays speed limit information the trial indicates it would, on average, reduce deaths by 23% and injuries by 13%.

The weather warning system used V2V technology to give drivers advanced notice of crosswinds, fog, heavy rains and snow or black ice on the road. It was automatically triggered by vehicles ahead encountering the adverse weather and encouraged following drivers to prepare and adapt to the weather conditions to avoid accidents. Trial results indicate that if this system was fitted to every vehicle it would reduce fatalities by 6% and injuries by 5%. 

Finland’s harsh winters provided a rigorous setting for weather warning technologies trials and a field operational test was orchestrated by the country’s VTT technical research. VTT’s trial site in the city of Tampere operated on public roads – urban routes in Tampere and sections of the E63 motorway and focussed on advanced automatic detection of road weather and surface friction conditions and forecasts. The trials ran in the subarctic winter of 2013 and the site was equipped with advanced cellular communications technology; allowing drivers to receive information on slippery surfaces and speed limits over a 22km stretch.

VTT had access to real-time weather data from road weather stations operated by 144 Vaisala and a number of monitoring points transmitted warnings to in-vehicle modules at distances of between 400m and 500m in advance of a hazard.

Key data from the roadside system were: road surface temperature and quality (dry, wet, ice, snow); atmospheric temperature; dew point temperature; surface friction value; depth of road surface water (mm), thickness of road surface ice or snow (mm) and relative humidity (%). The research team used the information to generate slippery road warnings at well-defined risk black spots - four tight bends on the test routes.

The team equipped each of the test cars with an onboard vehicle ITS station (developed for DRIVE C2X) which collect internal data from the cars’ onboard networks and was fitted with a communications unit. The communications unit handled information exchanges with other vehicles; with an intermediate roadside ITS station and with the in-vehicle unit which gave audible and visual messages to the driver.

VTT generated relevant messages and transmitted these to the roadside station via a 3G connection.

Results have shown the technology “having a positive impact on safety”, VTT senior scientist Harri Koskinen told ITS International. “DRIVE C2X has been of great importance in promoting and testing the use of CV systems in real-life conditions. “For Finland, it has proved to be the most important initiative in cooperative mobility to date”. Outside the country, he sees Russia as an interesting potential market.

2069 Daimler senior manager, driver support Matthias Schultze – who was also the overall project coordinator – added: “This has shown that the technology works. It makes the average driver feel more comfortable in adverse conditions.”

The company has already used its experience both in Tampere, and the parallel German simTD C2X project, to bring out what it claims as the first deployment by a European automaker of C2X technology for driver information. The Mercedes-Benz Drive Kit Plus and Digital DriveStyle app offer motorists advanced navigation and location support.

Andrew Marshall, who is responsible for technical communications at 4233 Opel, told ITS International that the company took part in the trials because, in Tampere, “Weather warning messages were provided by the infrastructure (and these are usually limited to accident hot-spots). As an OEM, we are able to access raw weather condition-measuring data coming from our own internal systems and sensor data, from anti-lock braking systems and electronic stability programmes, as well as from the outside temperature.

“The trials enabled us to check if combining all this information could trigger worthwhile weather warnings. Observed data suggested that the vehicle itself could be used as a sensor for slippery road conditions.

“Vehicle system data showed conditions both in areas that were covered by the official infrastructure, and in others that were not so covered. Conditions detected by the vehicle were typically very specific and precisely located, so it seems possible to inform other vehicles accurately of quite small slippery spots.”

Looking ahead to issues concerning implementation from the automaker’s perspective, Marshall highlights standardisation (in the form of stable, internationally harmonised standards), vehicle technology integration, links with the infrastructure, and the roles of public authorities eg road operators.

He sees the Tampere experience as contributing to Opel’s safety offer, in the form of driver-attractive services that will recognise dangers “before they become a threat.”

VTT’s partners in the project included Finnish tyre maker 205 Nokian Tyres and the City of Tampere.

Road grip

Recently VTT developed an automatic road grip detection system which utilises the existing onboard technology and provides immediate warnings to other vehicles in the area.

While the previous method was based on meteorological and other data and used SMS messaging, the new system detects
real-time changes in the level of grip using information from the vehicle’s own internal sensors. It is designed to detect low levels of grip after a few km of driving, and to relay the information to the driver before they register any change in road conditions.

The observations, including geographical coordinates, are wirelessly relayed to a back office which creates an overarching picture of adhesion levels along the network. Packets of information, tailored to the needs of specific vehicle types are then relayed from the back office to all vehicles that are connected to the system.

So far, VTT has applied the technology to heavy trucks, but says it will eventually be available for passenger cars. Field trials with a distribution specialist, business development consultancy and Nokian Tyres (which specialised in tyres for Arctic weather conditions) has verified the system.


DRIVE C2X

The DRIVE C2X project brought together 47 partner organisations to lay the technical foundations for the rollout of CV systems in Europe.  It set up seven national test sites and equipped them to start designing the infrastructure necessary for interoperability, both between CV system vendors and across national borders.

The DRIVE C2X system is based on three inter-communicating subsystems; the vehicle ITS station as the OBU, the roadside ITS station and the central ITS station. A typical roadside ITS station could be an existing variable message sign, or traffic lights, fitted with hardware to enable it to communicate with vehicles - or to forward received information via the internet to the central ITS station.