Semisequicentennial Transportation Conference Proceedings
May 1996, Iowa State University, Ames, Iowa

Commercial Vehicle Operations (CVO) Electronic Screening System for the State of Missouri—Implementation Through Current ITS Technologies

Larry L. Buschjost, Marilyn Kuntemeyer, Bill McCall,

Arlene McVey, and William R. Wilson

The state of Missouri is actively pursuing a project that will allow commercial vehicles to have electronic screening service available at the weigh/inspection stations along major highways throughout the state with the application of currently available Intelligent Transportation Systems (ITS) technologies. With this electronic screening concept, vehicles that are safe and legal and have no outstanding out-of-service citations will be able to pass the weigh/inspection facility without delay. The Missouri ITS/Commercial Vehicle Operations (CVO) project proposes to combine technologies currently used in electronic toll collection (ETC) with a fiber optic communication system available along 350 miles of interstate highway in Missouri. Commercial vehicles traveling the Oklahoma and Kansas Turnpikes often travel through Missouri as well, and both turnpike authorities have adopted Electronic Toll and Traffic Management (ETTM) processes and technology that include the use of Automatic Vehicle Identification (AVI) transponders (tags) to pass through toll facilities without delay. This provides an opportunity to bundle ITS/CVO services with ITS/ETC services in compatible vehicle-to-roadside communication systems. This paper presents the following information: existing conditions for commercial vehicle operations and the communications infrastructure in Missouri; architecture of the proposed Missouri Electronic Screening System; and current status of planning and implementation. Key words: CVO, ITS, electronic screening, weigh stations.

State agencies in Missouri are interested in the application of intelligent transportation systems technologies to improve the efficiency and safety of commercial vehicle operations (CVO). The CVO vision shared by state agencies in Missouri is the same as the National Intelligent Transportation Systems (ITS) Program Plan developed by ITS America for the Federal Highway Administration. The vision is "Assisted by advanced technology, trucks and buses will move safely and freely throughout North America" (1). The applied technology will take the form of electronic screening that will enable transponder-equipped trucks and buses to have safety status, credentials, and weight checked at mainline speeds. Vehicles that are safe and legal and have no outstanding out-of-service citations will usually be allowed to pass the inspection/weigh facility without delay.

The Missouri Highway and Transportation Department (MHTD) and the Missouri State Highway Patrol (MSHP) have jointly undertaken a number of initiatives to "promote the economic well-being of Missouri and the nation by facilitating goods movement for business, industry, and motor carriers" (2). In addition to the Kansas-Missouri ITS Institutional Issues Study conducted at the request of the MHTD, the MHTD has contracted for the installation of a fiber optic telecommunications network called the "Digital Teleport State Wide Network." The MHTD and MSHP have cooperated in the design and installation of the network to provide for nodes at weigh stations throughout the state.


Primary responsibility for motor carrier regulation and credentialing is shared by four agencies in the state of Missouri (3): 1) Missouri Highway and Transportation Department (MHTD); 2) Missouri Department of Revenue (MDOR); 3) Missouri Department of Economic Development, Division of Transportation (MDOT); and 4) Missouri State Highway Patrol (MSHP).

The MHTD administers the oversize/overweight permit program in the state of Missouri. Carriers wishing to operate a vehicle that exceeds Missouri dimensional or weight limits must obtain on oversize/overweight (OS/OW) permit for that vehicle. Carriers moving loads exceeding 120,000 pounds Gross Vehicle Weight (GVW) may be subject to bridge stress studies which are conducted by the MHTD.

The MDOR oversees several motor carrier functions including vehicle titling and registration (including the International Registration Plan, or IRP, for interstate carriers); motor fuel taxes (International Fuel Tax Agreement or IFTA); commercial drivers licensing; and the issuance of temporary permits. In conjunction with these functions, the MDOR is responsible for accepting and reviewing applications, issuing credentials to approved carriers, and auditing and collecting fees when required.

The MDOT is responsible for regulating common, contract, and private motor carriers in the state of Missouri. Motor carriers that fall into one of these categories and conduct intrastate or interstate operation must obtain operating authority from the MDOT. MDOT operating authority may be granted to motor carriers who are registered with the Interstate Commerce Commission (ICC), as well as to ICC-exempt carriers.

The MSHP enforces the credentials issued by the agencies listed above and operates all fixed and mobile enforcement facilities. The MSHP is also responsible for administration of the Motor Carrier Safety Assistance Program (MCSAP) funded by the Federal Highway Administration (FHWA). Weight and safety enforcement is the responsibility of the MSHP's Commercial Vehicle Enforcement (CVE) Unit. Vehicles may be weighed at fixed inspection stations located throughout the state or by mobile inspection units. The CVE Unit also conducts vehicle and driver inspections. Enforcement personnel have the authority to put drivers out of service for certain vehicle or driver safety violations, or for operating without the proper credentials.

Under the current weight enforcement strategy, all trucks must stop at weigh stations when the scales are open. This causes unnecessary delays for legal carriers, and the requirement for all of the trucks to exit and enter the traffic may have a negative impact on safety. Under the current enforcement system, driver and vehicle credentials cannot be inspected without the truck stopping, either at a weigh station or a roadside spot check. Requiring all trucks to stop, whether or not they are operating legally, dilutes the effectiveness of enforcement efforts and reduces carrier productivity.

The State of Missouri currently operates weigh stations at 19 locations as shown in Figure 1.

During 1995, the Center for Transportation Research and Education (CTRE) conducted a study for Missouri to focus on the enforcement activities that currently take place at the permanent weigh stations and to investigate Automatic Vehicle Identification (AVI) technologies that could be easily implemented for electronic screening at the weigh stations along I-70 and I-44.

Table 1 shows general traffic flow information at the weigh stations on these two interstate highways through Missouri. I-70 carries the highest volume of truck traffic with more than 7,500 trucks using this route each day, and I-44 is the second busiest with truck volumes over 6,000 per day.

The Oklahoma and Kansas Turnpikes have adopted Electronic Toll and Traffic Management (ETTM) processes and technology that include the use of AVI transponders (tags) to pass through toll facilities without delay. Trucks operating on I-44 and I-70 in Missouri are often users of the Oklahoma and Kansas Turnpikes and may already have toll tags on the vehicles. Both turnpike authorities have selected a common technology so future customers will not have to purchase more than one tag and to assure compatibility between the toll facilities.

The MHTD decided to investigate the use of enhanced toll tags to facilitate electronic screening for trucks at weigh stations on I-44 and I-70. Because trucks operating on the Oklahoma and Kansas Turnpikes are likely to already have toll tags, the same identification tags could be used to identify trucks with valid and current Commercial Vehicle Safety Alliance (CVSA) safety inspections and with current and valid credentials. In conjunction with mainline Weigh-In-Motion (WIM), the opportunity appears to exist, at a minimum level of investment and risk (both financial and technical), to electronically screen trucks for current safety inspections and possibly for credentials and weight.

As a first step in determining if toll collection transponders currently on commercial vehicles could support electronic screening at weigh stations, the MHTD first wished to know approximately how many tag-equipped trucks were currently passing the weigh stations. Field data were collected during the summer of 1995 in order to estimate the number of trucks passing weigh stations along I-44 and I-70 that are currently equipped with toll tags from either Oklahoma or Kansas.

During June 1995, an AVI reader system was placed along the side of the eastbound travel lanes of I-44 just before the exit ramp for the Joplin weigh station. Data were recorded from Monday, June 12, 1995 through Tuesday, June 20, 1995, and the highest number of tags recorded was more than 1,500 on Friday, June 16, 1995. The vehicles carrying tags from the Oklahoma Turnpike Authority (OTA) were easily identifiable in the tag numbers recorded, and the OTA tags ranged from 89 percent to 94 percent of the total number of tags recorded.

During the time period that the toll tags were recorded, traffic volumes from a nearby permanent count station showed eastbound travel on I-44 at approximately 8,000 vehicles on weekdays (range = 7,378 vehicles per day to 8,571 vehicles per day). Total traffic on Friday, Saturday, and Sunday was substantially higher with volumes ranging from about 10,000 vehicles per day to more than 11,000. The percent of vehicles in the eastbound traffic flow with toll tags ranged from about 24 percent to 35 percent.

The I-44 data does show that a significant number of vehicles are already carrying toll tags and have the potential to qualify for a CVO electronic screening program, but it cannot be assumed that all of the toll tags recorded were on commercial vehicles. An attempt was made to determine the exact number of OTA toll tags records that were actually on commercial vehicles. The Pike Pass of the OTA is sold for commercial vehicle accounts as well as those for private, passenger vehicles. Assistance was requested from both the manufacturer of the OTA toll tags and from officials at the Oklahoma Turnpike Authority to see if these toll tag records could be sorted into groups of commercial vehicles and private, passenger vehicles. At present, due to legal constraints on the release of information, the Oklahoma Turnpike Authority is unable to provide assistance that would allow more detailed sorting of the toll tag records.

The AVI reader system was also placed along the eastbound travel lanes of Interstate 70 at the Odessa weigh station from June 22 through July 10, 1995. The data records of the tag readings were not useable for the entire time period, but for the days with valid data, the number of toll tags recorded on I-70 ranged from 215 to 513 per day.

The number of vehicles equipped with toll tags is currently much higher along I-44 (with a maximum reading of more than 1,500) than along I-70 (with a maximum reading of slightly over 500.) Vehicles from the Oklahoma Turnpike are not as likely to be traveling on I-70 since there is no direct connection from Oklahoma. Vehicles from the Kansas Turnpike are much more likely to be traveling on I-70, but the Kansas Turnpike Authority only began using ETTM during 1995 and penetration of the toll tags has not reached the level that is seen in Oklahoma. (The Oklahoma Turnpike Authority has been using electronic toll payment since 1991 (4).) In general, the data collected about current toll tag use along I-44 and I-70 shows that a sufficient number of vehicles are currently equipped with tags to support building on this technology for CVO electronic screening.


The term "architecture" is used in many contexts to mean many different things. For research currently being conducted for ITS, the overall structure (i.e., major components and interfaces) and unifying design characteristics (i.e., principles and standards) of a system are referred to as the architecture of that system. This section will describe a general architecture for electronic screening for the state of Missouri. The architecture is intended to provide guidance to implementers of the CVO electronic screening system.

The Missouri State Highway Patrol currently verifies the following information when trucks come through the weigh stations: 1) Vehicles are weighed to check for compliance with weight limits. If overweight, does the vehicle have valid OW permit from MHTD. 2) Vehicle credentials may be checked to verify that the vehicle has all necessary permits to operate in the state of Missouri. 3) Vehicle credentials may be checked to verify that the vehicle has paid fuel tax and has fuel permit. 4) Driver credentials may be checked to verify that the driver has a valid Commercial Driver's License (CDL) to operate a commercial vehicle in the state of Missouri. 5) Vehicle inspection may occur to determine if the vehicle meets all applicable vehicle safety codes.

Under the current weight enforcement procedures, all trucks must stop at weigh stations in Missouri when the scales are open. The credentials of trucks and drivers cannot be inspected without the truck stopping, either at a weigh station or a roadside spot check. Table 2 lists the credential check and inspections actions that could be accomplished by screening of information on a transponder or by automated field review.

Figure 2, Typical Weigh Station Configuration, shows the configuration that could be used at a typical weigh station that combines Weigh-In-Motion (WIM) scales with AVI readers of transponders that contain data elements about the truck passing the weigh station. Through the WIM scale and AVI reader shown in Figure 2, many credential checks and inspection actions could be accomplished by verification of information on a transponder or by automated field review.

In order to accomplish the screening actions listed in Table 2, information exchange will need to be accomplished very effectively. Figure 3, Information Exchange Architecture for State Motor Carrier Functions, illustrates the information exchange that will be required for the motor carrier functions of the State of Missouri. Information exchange will be required between the following state government agencies involved in motor carrier functions: Missouri Department of Revenue, Missouri Highway and Transportation Department, and Missouri State Highway Patrol.

Figure 4 shows the general architecture of the proposed Missouri Electronic Verification System and identifies subsystems that Missouri can evaluate for implementation. The illustration is organized beginning at the Roadway AVI and WIM subsystem and flowing to the subsystem of the processors at the weigh stations. The weigh station processors then connect to the processors at the state, regional, and national levels.


Missouri will consider two alternatives to support implementation of the Roadway AVI and WIM subsystem for electronic screening: 1) Missouri owning the Roadway AVI and WIM subsystem; and 2) Missouri contracting with a company to provide the data necessary to support the Roadway AVI and WIM subsystem for electronic screening.

Although many options could be considered for this subsystem of electronic screening, ownership and contracting are the two major alternatives. Other options could include contracting for only certain elements of the Roadway AVI and WIM subsystem such as training or maintenance.

Ownership of the Roadway AVI and WIM subsystem by Missouri will include purchasing the equipment, either installing or contracting the installation, commissioning the subsystem, and maintaining the subsystem. Contracting for the service will include the establishment of an agreement with a company to provide the data necessary to support roadside electronic screening. In either case, Missouri will make a financial and technical resource investment.

A first step leading to conducting a financial analysis that will support the decision that Missouri either own the subsystem or contract for data is identifying the associated cost elements. Table 3, Roadway AVI and WIM Subsystem Cost Elements, identifies cost elements to consider when making the decision to either own this subsystem or contract for data. In Table 3, the Cost Elements are subdivided into non-recurring and recurring. Non-recurring costs are typically incurred once during the program, and periodic charges are incurred for recurring costs. Each of the cost elements is discussed in the following paragraphs.

The non-recurring costs include the following elements:

The recurring costs include the following elements:

If Missouri decides to pursue a contract agreement with a service provider, this will relieve Missouri of the responsibility for major non-recurring and recurring tasks. However, establishing a contract with a service provider requires that Missouri conduct a concentrated contract administration. For example, the contract must clearly establish the time period the service provider will be expected to place failed equipment and software back in operation. Further, the Missouri contract administrator must make sure the service provider meets the downtime specification in the agreement. Therefore, although Missouri is relieved of subsystem facility maintenance and upgrading, Missouri's contract administrator must assertively follow up on service provider performance levels established in the contract agreement.

During the coming year, the State of Missouri will be actively working on implementation of a CVO Electronic Screening System that builds on toll tag technology. This will include a bid process that will allow the state to perform financial evaluation of ownership versus contracting for service.

  1. National Program Plan for Intelligent Transportation Systems (ITS), Final Draft. November 1994.
  2. Kansas-Missouri ITS Institutional Issues Study, Final Report. Cambridge Systematics, Inc. with WHM Transportation Engineering, Inc. December 1994.
  3. Kansas-Missouri ITS Institutional Issues Study, Final Report. Cambridge Systematics, Inc. with WHM Transportation Engineering, Inc. December 1994.
  4. Fact Sheet on "Electronic Toll Collection in the U.S." from the ITS America Information Clearinghouse, June 8, 1995.

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