First introduced in Norway in the mid-1980’s, Electronic Toll Collection (ETC) has since been adopted and implemented in many countries across the globe. ETC brings many benefits, including vehicle free-flow, reduced traffic congestion, a decrease in harmful emissions and lower vehicle operating costs to name a few.
Traditionally, an ETC installation consists of three gantries, two featuring a set of cameras that respectively capture front and rear images of vehicles license plates, and one for vehicle classification and radio system equipment to collect electronic toll fees of vehicles equipped with on-board transponders.
The New Generation of Electronic Toll Collection
Q-Free ASA (Trondheim, Norway), a leading global supplier of solutions and products for road user charging and advanced transportation management, has developed an ETC installation based on a single gantry which relies on the latest machine imaging systems, radio systems and Automatic License Plate Recognition (ALPR) software technologies to collect toll data. This versatile system is designed to do pure video tolling or a combination of video and radio tolling depending on the needs of the responsible authorities where it is installed.
Q-Free’s single gantry features currently two Prosilica GX1920 digital cameras by Allied Vision Technologies (AVT) per lane and on both sides of the gantry to capture high quality images of a vehicle’s front and rear license plates. In addition, the single gantry also features two AVT Manta G-125B monochrome cameras per lane. These cameras are used to track each individual vehicle as they enter and leave the detection zone around the gantry, and when a lane change occurs. Accurate vehicle tracking ensures that front and rear pictures of vehicles license plates are reliably captured in all lighting and weather conditions, as well as in situations ranging from urban environments to multi-lane free-flow highway infrastructures. The combination of accurate vehicle tracking and the machine vision cameras’ superior image quality output guarantees a high ALPR accuracy rate.
The gantry also features DSRC units to electronically collect fees from vehicles equipped with transponders, a Sick LMS500 3D laser to classify vehicles (i.e. passenger or commercial), and Q-Free’s Intrada ALPR software for automatically reading the registration numbers from the pictures. The ALPR data is then processed by an operational back office for fee charging and subsequent billing by the local authorities based on each vehicle’s road usage and the tariff in charge. The video tracking ability is used to reliably integrate the input for all these sensors into single transactions.
A single gantry offers many benefits including a reduced need for infrastructure, civil work, physical space and maintenance. The single gantry is linked to the operational base via an Ethernet network and can be remotely serviced and configured by operators.
Video tolling: Lower operating costs
Q-Free’s single gantry can be operated in pure video tolling mode as identification performance is extremely high. Video tolling is commonly used in “closed zones” (motorways, city centres, bridges, etc) and continues to gain popularity in many areas where vehicle registry is good. Video tolling technology has vastly improved in the past few years thanks to high performance machine vision cameras, which when combined with infra-red flash, can handle vehicle speeds of up to 250 km/h and volumes of over 2,500 vehicles per lane per hour in a multi-lane free flow environment. The Prosilica GX1920 used in Q-Free’s single gantry is a 2.82 Megapixel camera with High Definition resolution. The GX1920 features the Sony ICX674 EXview HAD CCD II sensor that provides high sensitivity and near IR performance making it ideal for night-time imaging using an IR light source, minimizing shutter times and producing sharp, high quality images with excellent dynamic range in all weather conditions. The Manta G-125B/C, used for tracking, is a versatile 1.2 Megapixel GigE Vision camera featuring the Sony ICX445 EXview HAD CCD sensor that provides high sensitivity and high image quality.
Machine vision cameras offer many benefits for tolling and outdoor imaging applications due to a wide array of advanced features: low-latency trigger for timely image capture when vehicles enter the detection zone, flexible exposure, gain and binning modes to adapt to any outdoor lighting conditions, digital shutter, high sensitivity to minimize motion blur and image distortion, as well as configurable I/O to synchronize the image-capture process with traffic system peripherals such as IR lights, ground loops, radar or laser triggers.