CMV Safety | Freight Logistics & Policy | Truck Size & Weight | TACT | Wireless, Vehicle-to-Infrastructure Communication

Alternative Approach to TACT Evaluation (and "Treatment"):

Some Additional NCSU/ITRE Thoughts and Suggestions

Rather than focusing on catching the 'violator' (the typical enforcement approach), and 'alternative' might be to focus on having an effect upon 'conditions' that are associated with 'risky' behavior; in the case of TACT, it's a combination of speed and following distance (i.e., those instances where if one or the other of the vehicles were to have to stop, the other vehicle would not have adequate time to avoid a collision.

Evaluation in this case could involve continuous, automatic (unmanned) capture of vehicle speeds and following distances and the determination from those data, on an instance by instance basis, whether the event was 'risky.'

Where you could make this determination in real time (as opposed to manual review of video data), you could provide this as real time 'feedback' to the driver (and to the traffic stream in general) via some sort of message sign (could be as simple as that used on a speed trailer).

Since the device that is monitoring the variable(s) can also be continuously capturing the data, a primary dependent measure and measure of program success can be the percentage of total following distances captured that are 'risky.' The measure can be further related to current traffic conditions (vehicle volumes, vehicle speed ranges, time of day, etc.)

This approach would make it possible to determine whether the 'treatment' was having an effect upon the 'speed' component of the risky situation, and/or the following distance component. One would expect that if ones treatment was effective in significantly reducing the frequency of risky events, it would also, over the longer term, lead to a reduction in either the frequency of crashes, the relative frequency of serious injury crashes, the reduction of rear end collisions, and/or the reduction of fatal crashes. This (automated) focus on vehicle speeds, following distances, and the like) is consistent with more traditional, manned emphasis on enforcement. One could even take a more strategic, longer term enforcement look at moving the 'driver feedback' approach to an automated (e-ticketing approach) if feedback alone without enforcement proved not to be sufficient in bringing about the desired change in conditions.

This method is most appropriate to conditions where you are looking at interventions for free flow traffic conditions. Where problems (e.g., those not on the interstate that deal often with access points with limited or no traffic control device other than stop/yield signage), the problem is often vehicles pulling out in front of trucks as the smaller vehicle attempts to cross the major traffic lane or to merge with it in the same direction (often results in collisions where the truck is cited for failure to reduce speed-often not an appropriate charge).

If one were to identify critical (high crash) locations where this occurs as treatment sites, one could install the same type of continuous, automated data collection capability (speed and arrival time of vehicle approaching on the main line). This information could be provided to the driver of the vehicle on the minor route as indication of a safe gap. It could also be provided to the vehicle in the major route as presence of vehicle on minor route – sort of an intersection collision warning device to use FHWA program nomenclature).

From an evaluation standpoint, the interest is whether the treatment (which in this case is also serving as the data collection device) detects a 'risky' situation (which may not always result in a crash, but which certainly increases the likelihood of a crash).

Both of these suggestions involve the integration of routine and continuous data collection methods with a treatment that involves direct feedback to motorists of risky conditions that logically are correlated with crashes. By also capturing speed as a component in the equation in addition to 'distance' they permit you to capture what might be a successful treatment effect on vehicle speeds where you may or may not also have a successful treatment effect on the 'distance' component (vehicle following distances in the free flow situation or time to arrival distance in the intersection case).

These 'treatments' represent interventions whose purpose it is to achieve a direct and measurable impact on some aspect of the traffic stream that is logically related to the type of crash situation that is the focus of the study. The determination of whether a treatment has an effect upon 'crashes' per se must be determined in the longer term.

t is the type of treatment that comes into contact with every driver, unlike media-based treatments that have to be seen or heard to claim an effect and which deal more with factors like awareness and driver intent than they do actual driver behavior. That does not mean that a media component to TACT is not of value. It is just that 'awareness' of a problem while 'necessary' is not always 'sufficient' to bring about a change in the behavior of the target audience (evidence abounds in the public health field - efforts to modify eating, drinking, smoking disorders, etc.)

This can be a focus on a 'truck problem' (FMCSA) but can also be a broader focus on a 'traffic management' problem (FHWA). The two agencies should be equally involved in this effort, and should provide more of the technology support for the development and implementation of these types of technology-based treatment and data collection approaches. This type of technology development support should be done centrally, at a Federal level, and made available to the states for implementation.