Weigh in motion and ANPR techology aid highway protection
First publishedin World Highways
Kistler Lineas WIM sensors were used in a two-year WIM pilot on the A1 highway between Berne and Zurich.
Weigh-in-motion technology manufacturers have been involved in a number of significant highways tolling projects across the world in recent months, while others are looking to become involved in major new initiatives. Guy Woodford reports.
The continuing global economic crisis did not prevent UK-based TDC Traffic Systems from recently securing the prized US$2.84million (€2.14million) contract to supply 20 high speed weigh-in-motion (WIM) systems for overweight pre-selection and enforcement in Saudi Arabia.
The Saudi Ministry of Transport are reported to be keen to improve the country's road safety record, while protecting its bridges and highways from damage caused by overweight vehicles.
The key contract secured by TDC will see the company's WIM system, comprising industry standard HI-TRAC 100+, the HI-TRAC Automatic Number Plate Recognition (ANPR) camera and the Kistler
Lineas quartz crystal WIM sensor, used on key highways across the kingdom.
The WIM sensors are installed in the road at strategic sites, and each time an overloaded vehicle is detected, the information generated is used to divert the vehicle into a weighing station for inspection and enforcement.
The first phase of a three-phase installation project, which will be delivered and managed by TDC in partnership with the Shibh Al Jazriah Contracting Company, was due to begin in February 2012. TDC said the coveted Saudi contract had reinforced the firm's status as one of the world's leading suppliers of WIM systems.
Another recent success for TDC was the award of the contract to supply and install a WIM system on the Hammersmith flyover in west London, England.
The WIM technology will allow Transport for London
(TfL) to automatically collect data, capturing the weight and classification of vehicles passing over the flyover at normal traffic speed. The system also requires the flexibility to work with the lanes configured for operation during the London Olympics 2012, as well as being capable of reverting to regular use at the end of the Games. TDC intend to install the HI-TRAC 100+ WIM System using the Class 1 MEAS BL Piezoelectric Sensors.
Toll fees on major highways across the world are usually based on the distance travelled and the class of vehicle, mainly using the rule of: "the more axles, the higher the fee". However, this type of tolling does not take into account if the vehicle is loaded or not and, it could be argued, it is the overloading which increases maintenance costs due to additional highway surface damage.
Weigh-in-Motion (WIM) systems are capable of measuring the actual axle loads and vehicle weight of each vehicle passing a road section. The addition of WIM to an existing tolling system offers a 'Tolling-by-Weight' capability. Setting fees in relation to a vehicle's weight and axle load provides a more accurate, and fairer, appraisal of the damage it will cause on the toll road.
WIM sensors can be installed at toll booths under low speed or stop and go conditions, or at a toll gantry under free-flow high speed conditions. Swiss firm Kistler's Lineas WIM sensors have proven to be suitable for each of these three applications.
In China, WIM systems are used to calculate toll fees based on the vehicle weight.
In cases of overloading, an additional penalty fee applies. Kistler's Lineas WIM sensors have been installed in hundreds of the country's toll lanes, around 22metres before the toll booths, since 2007. Many of these installations have taken place within the last six months.
In Switzerland, toll fees are based on a combination of the distance travelled, the emission class and the allowed gross weight of the vehicle. Kistler Lineas WIM sensors were applied over two traffic lanes and combined with the national LSVA (Leistungsabhängige Schwer Verkehrs Abgabe) gantry equipment for truck tolling in a two-year WIM pilot on the A1 highway between Berne and Zurich.
Kistler Lineas WIM sensors were used in a two-year WIM pilot on the A1 highway between Berne and Zurich In China, Kistler's WIM technology has been installed in hundreds of the country's toll lanes the LSVA, checked that the actual gross vehicle weight did not exceed the vehicle weight declared by the driver. The pilot finished in the latter part of 2011, with the Swiss authorities considering the option of permanently incorporating WIM sensors with other LSVA tolling systems in the country.
Tolling-by-Weight requires WIM-data with a high and especially constant quality. Based on innovative quartz technology, the Kistler Lineas WIM sensors are said by the firm to provide a response that is perfectly linear to the applied load. The company says they are distinguished by their excellent accuracy, stability, long life and temperature independency. The sensors can be installed in all types of pavements (asphalt, open asphalt or concrete) and, Kistler claims, can measure weight accurately at any speed, from walking pace to highway driving.
CrossWIM technology has been used recently in Szczecin and Opole in Poland.
Further benefits of the Lineas WIM sensors are, say Kistler, their fast and easy installation, typically between four and six hours per lane, that requires only a small intrusion of 55mm depth and 72mm width to be thoroughly secured in the pavement. Furthermore, no maintenance of the sensors is required. Annual checks of WIM sensor accuracy should be performed but, according to Kistler, there is usually no need for recalibration. In case of increased rutting or cracks in the pavement, the topcoat of the sensors can be grinded in order to follow the profile of the pavement.
The sensors are said to have been proven to be rugged and reliable for more than a decade in operation worldwide in very diverse environmental conditions.
Czech Republic firm Cross has had nine of its CrossWIM systems installed on highways in the Polish cities of Opole, Sczeczin, and Poznan.
Last year saw Cross's CrossWIM system chosen to take part in a pilot WIM project under closed highway conditions in Koshienhama, southern Japan. The company said it will be taking part in a further pilot on the same highway, this time under live traffic conditions, in May 2012.
Cross has also exported ten of its CrossWIM pre-selection systems (3 and 4 lane free-flow configuration, with height measurement and ANPR cameras) to Saudi Arabia. The systems are due to be installed by April 2012.
Using Kistler quartz sensors and inductive loops, the CrossWIM system measures the load on each vehicle wheel and calculates the axle load and total weight to determine its category and speed. The system's computing unit then processes and evaluates the measured and processed data. Vehicle information and image is recorded in case of exceeding the weight or speed limits, and stored in a database. All database data is immediately available for display in a web browser, and all functions are remotely monitored and controlled by a control centre with the possibility of remote service access.
In the United States, a WIM system manufactured by Canadian firm International Road Dynamics (IRD) has recently been supplied to the Washington State Patrol and Washington State Department of Transportation (WSDOT) to automatically screen commercial vehicle traffic based on gross vehicle and axle weights, dimensions, safety, and credential criteria on the I-90 mainline and on the ramp leading into the weigh station at the Spokane Port of Entry (POE). The project has included the relocation of the weigh station as well as WIM automation and integration.
IRD supplied and integrated its Single Load Cell (SLC) and IRD-PAT Bending Plate WIM Scales, Automatic Vehicle Identification (AVI), Tracking Sensors, Over-height Detection, Variable Message Signs (VMS), Changeable Message Signs (CMS), Side View Cameras, and License Plate Readers (LPR) with Optical Character Recognition (OCR). All of the equipment is being connected to IRD's iSINC (Intelligent Sensor Interface and Network Controller) Electronics. The firm is also integrating its automated weigh station system with Washington State DOT Commercial Vehicle Information Systems and Networks (CVISN). Washington State is a member of NORPASS (North American Preclearance and Safety System).
The Spokane system is IRD's twelfth WIM Preclearance System fitted for WSDOT in the last 20 years.
In the US state of Idaho, IRD is upgrading the Lewiston and Boise Port-of-Entry Weighin- Motion (WIM) and Automatic Vehicle Identification (AVI) Systems for the Idaho Transportation Department (ITD). The contract includes two years of equipment, software, and database maintenance to begin upon completion of the upgrades.
The Idaho sites are being modernised from IRD 1060 series electronics to iSINC controller electronics. The iSINC receives vehicle weights from SLC scales and vehicle information from AVI transponders. The iSINC connects with IRD's Intelligent Roadside Operations Computer (iROC) to transfer information via the Commercial Vehicles Information Systems and Network (CVISN) program. The CVISN programme is said by IRD to be a key component of the Federal Motor Carrier Administration's (FMCSA's) drive to improve commercial vehicle safety. Vehicle safety and licensing information will be passed to IRD's roadside system and a decision will be made in real-time whether a truck is permitted to bypass the weigh station or come in for inspection.
According to IRD, weigh stations often exceed capacity at peak traffic times and are forced to close while the back-log of trucks is cleared. By combining CVISN information with a vehicle's weight, as measured by IRD's WIM systems, the weigh station can focus on high risk vehicles, allowing weight compliant carriers with good safety records to bypass the weigh station. Not only is this said to substantially improve the operation of the weigh station, but it is of considerable benefit to the trucking industry, reducing wait times at weigh stations for reputable carriers and cutting fuel bills and emissions in the process.