How To Implement Driving Speed Limitations?
It’s a matter of common knowledge that speeding while driving is one of the top factors contributing to accidents on roads both in cities and on suburban highways. According to the National Highway Traffic Safety Administration (NHTSA) data, in 2016, speeding accounted for 10,111 fatalities – more than 27 percent of all traffic deaths that year. In 2017, speeding killed 9,717 people, accounting for more than a quarter (26%) of all traffic fatalities that year.
Companies and organizations are on the prowl for new ways to develop effective speed limit controls. Can software developers offer anything to resolve this challenge? In this article, we’ll look closer at the ways speed can be capped for cars and two-wheelers conceptually and find out how to implement speed limitation using the software.
Speed Limits – the US and the EU
Today, reducing speed limits is a hot-button topic. This problem is especially pressing in the areas with a lot of pedestrians and narrow or congested roads.
For years, drivers’ greatest fears when violating speed limits were police officers, who could issue them a speeding ticket or use speed camera data to bring them to court and possibly revoke their licenses. But speeding is more than just breaking the law. Reckless driving, such as speeding, involves the greater potential for loss of vehicle control and reduces the effectiveness of vehicle protection equipment. Driving at speeds that exceed the established limit increases the possibility of causing a crash and increases the degree of crash severity and severity of injuries it can lead to.
According to research from the Road Accident Research Unit of the University of Adelaide, the risk of involvement in casualty doubles with each 5km/hr increase in free traveling speed above 60 km/hr and. Equally important to know is that a 5km/hr reduction in speed can lead to at least 15% decrease in crashes. Economic implications of speed-related crashes also should be taken into consideration as well as increased fuel consumption while driving at high speeds.
The speed limits on the roads are in place to protect both drivers and other traffic participants. Upholding those restrictions is a matter of national safety. Speed limits have a long history – the first speed limit in the USA was passed in Connecticut as early as 1901. Then, the legal speed limit in cities was 12 mph and 15 mph on country roads. In the early 1970s, national speed limits were established due to the cost of rising fuel. The established limit of 55 mph resulted in a decrease in traffic fatality rates, dropping from 4.28 per million miles traveled in 1972 to 2.73 in 1983. Today’s speed limits are based on both safety and mobility considerations and increasingly also on environmental considerations, as the faster a vehicle moves, the more fuel it consumes and the greater emissions it generates.
Today, speed limit by the state can range from an urban low of 25 mph (40 km/h) to a rural high of 85 mph (137 km/h). Some states have lower truck speed limits and special speed limits at night time.
The general speed limit for rural roads in the EU Member States is mostly 80 or 90 km/h, and for urban roads, it’s 50 km/h. According to the European Commission data, the general speed limit for motorways in the EU Member States is mostly 120 or 130 km/h. In some countries, like Germany and the Netherlands, there is no general speed limit for motorways, many sections of the motorway have a local posted speed limit which may range from 80 km/h to 130 km/h, related to both safety and environmental considerations. EU countries apply a lower speed limit for heavy good vehicles (HGVs) and buses/coaches. The majority of countries only apply an overall maximum speed limit for HGVs (generally 80 km/h) and buses (varying between 80 and 100 km/h). Some countries apply lower HGV and bus speed limits for different road types (e.g. Denmark, Ireland, and the United Kingdom). For example, the HGV speed limits in the UK are 50mph on single carriageways and 60mph on dual carriageways (vehicles over 7.5 tonnes).
The speed limits for residential areas are usually much lower – there are 30 km/h zones in residential areas in the EU and 20-30 mph in the US. There are also special speed limits in school areas and campuses. As a rule, a typical school zone speed limit in most US states is between 15 mph and 25 mph (25 and 40 km/h) unless otherwise posted.
Capping Vehicle Speed – the New Trend in Auto Industry
The necessity to tighten up the grip over road safety and control speed limits observance resulted in a new trend: vehicle software controlled speed caps, which restricts engine acceleration past a predetermined threshold. This trend is not only related to cars, but also e-scooters and e-bikes.
New legislative initiatives in the EU for new vehicles include a raft of mandatory safety technology, such as “black box” recorders, automatic braking and even automatic speed limiters. The new safety measures require:
- New crash testing procedures and techniques
- Mandatory installation of driver assistance systems (DAS) including Automated Emergency Braking (AEB) with pedestrian and cyclist detection
- Intelligent Speed Assistance (ISA) and Emergency Lane Keeping
- New direct vision standard for HGVs and buses to allow a better view of other road users around their vehicle
Vehicle Speed Capping – How Is it Realized?
The idea of speed capping in vehicles is not new – automotive manufacturers have been doing it for decades. A simple example is speed capping during car and motorcycle engine break-ins when engine RPMs are artificially capped until a certain mileage is reached. There is also speed capping for certain models of cars and motorcycles depending on their class and application. But some auto manufacturers take things a step further.
Volvo announced speed caps as part of its 2020 goal to end deaths and serious injuries in Volvos. In April 2019 the company announced that its new sedans and SUVs will be electronically limited to a maximum speed of 112 mph. Other manufacturers also have their own speed caps, but higher ones. Two-wheelers, such as e-scooters, can also get capped to make urban driving, especially in the areas with low-speed limits, safer. Local governments are ready to move with the time and let e-scooters and e-bikes into the streets providing they have a speed cap, particularly for rentable electrical scooters. Such means of transport can accelerate only to a certain limit, and when reaching it, cannot move any faster.
What is the mechanism of physical speed capping?
Let’s get into some technical details.
Any modern vehicle has its own hardware “brain cells”, electronic control units – the embedded systems in automotive electronics that control various electrical systems of a vehicle. Types of ECU include Engine Control Module (ECM), Powertrain Control Module (PCM), Transmission Control Module (TCM), Brake Control Module (BCM or EBCM), Central Control Module (CCM), Central Timing Module (CTM), General Electronic Module (GEM), Body Control Module (BCM), Suspension Control Module (SCM), control unit, or control module. Up to date vehicles can have up to 80 ECUs.
The vehicle data are received and transmitted via the so-called CAN (Controller Area Network) bus. CAN bus is used in automobiles to allow communication between electronic control units and sensors. Using the metaphor of CCS Electronics engineers, CAN bus is the nervous system, enabling communication between all parts of the body. Nodes of the nervous system (the ECU) are connected via the CAN bus, which acts as a central networking system. The CAN bus protocol allows ECUs to communicate with each other without complex dedicated wiring in between. In turn, this allows for several features to be added via software alone, e.g. electronic engine throttle control.
Among the above-mentioned units, the most interesting for the purpose of speed capping is the engine control unit or module (ECM). The ECM is “a type of electronic control unit that controls a series of actuators on an internal combustion engine to ensure optimal engine performance. It does this by reading values from a multitude of sensors within the engine bay, interpreting the data using multidimensional performance maps (called lookup tables), and adjusting the engine actuators”.
In fact, the speed of a vehicle depends on the amount of fuel gets through engine throttle. And the amount of air-fuel mixture supplied into engine cylinders depends on throttle angle. So, by controlling the throttle angle you can control, or cap the speed of a vehicle.
How it can be implemented? Of course, with the help of the engine control unit and external hardware connected via OBD communication using special software to set the data on the throttle angle. In short, the process looks like this: the master unit of a vehicle (in this case, the engine control unit) transmits and receives data from several sensors, one of which is the throttle sensor. The unit inserted in the OBD II port sends a signal to the ECU saying the angle of the throttle is “n”, which corresponds to a certain amount of air-fuel mixture sufficient to accelerate a vehicle to a certain speed. If the angle cannot be wider, a vehicle cannot accelerate more. This way, we can control the acceleration signal capping vehicle speed in electric cars.
Sounds quite easy, doesn’t it? Yet, you have to remember that a vehicle’s control system is a complex structure dealing with numerous parameters and functions. Any interference with it must be very cautious and professional.
Archer ECar Project – Reading Engine Data and Using it as a Development Platform
Collecting and reading data from vehicle subsystems with the help of K line OBD II adapter allowed us to identify the data referring to current vehicle speed and acceleration parameters, the status of the battery, and low-level parameters like voltage, temperature, etc.
Using available sensors set to read the data, we can analyze the driving quality and overall driver behavior. Accelerometer, live GPS tracker, speed and acceleration data, wheel turning angles and dynamics, face and eyes recognition attempts – all these readings can give us a good idea on how aggressively the driver is speeding, taking turns, changing lanes, who is currently driving and whether he or she is attentive to the road or even falling asleep.
Currently, we have an app based on rather simple algorithms that can grant drivers with a safe driving score. This app can be used by a driver to control the speed of a vehicle with the help of speed limit notifications. Now we are working at integrating it with the data given from vehicle sensors.
Software Limiting Vehicle Speed
Today, almost every app using GPS navigation is able to warn a driver about speeding. Various GPS online maps and pathfinders use data on speed limits, current information about traffic jams, and road signs. And self-driving vehicles, which are already gracing public roads, use autonomous highly detailed cloud-to-car mapping systems, which allow manufacturers, suppliers, and users of driverless cars to get the most up-to-date information about the road network for locating, positioning and maneuvering the vehicle automatically, including enforcing speed limits.
The Intelligent Speed Assistance system, which will become mandatory for new cars in Europe soon, uses Traffic Sign Recognition (TSR) technology available in luxury cars only for the moment. The technology uses sensors which “read” and interpret roadside traffic signs and govern the speed of automated vehicles to the posted speed limit. According to Motorbike Writer, automated features have already been developed for motorcycles – Yamaha and BMW already have automated motorcycles, and other companies such as KTM and Ducati are working on similar radar technology.
And, of course, it is possible to build full-featured native apps featuring speed limitation based on Maps APIs, for example, Google Maps Roads API. The features of an app will depend on your company’s requirements and needs.
Want to get more information about possible solutions for the speed limitation of your fleet? Contact us to find out what our team of professionals can offer you.