There is an ongoing and intensifying debate between advocates of deploying Dedicated Short-Range Communications (DSRC) as the radio medium for vehicle to vehicle safety communications and those who advocate using a newly-emerging cellular technology, Cellular V2X (C-V2X) as the radio medium for such communications. One of the factors involved is timing. DSRC has been extensively tested, with equipment deployed in thousands of vehicles for test and evaluation purposes, and complete products are available for commercial use. One vehicle model, the 2017 Cadillac CTS, currently includes DSRC as standard equipment. On the other hand, standards for C-V2V communications were just completed in the fall of 2016, and a chip set that products can be built around has only recently been announce by Qualcomm.

It is generally accepted that DSRC technology is more mature and can be deployed more quickly than C-V2X, which would yield additional benefits. Therefore, if all other factors turn out to be equal, there would be no reason to consider C-V2X as an alternative. If, on the other hand, C-V2X turns out to have advantages that DSRC lacks, as claimed by its proponents, then it makes sense to consider either waiting for C-V2X to mature or rolling out DSRC in the near-term, with an eventual transition to C-V2X. The argument for moving forward with DSRC in the latter case is that there are near term safety benefits that could be achieved by prompt deployment of DSRC and these additional benefits will be lost if the transportation community decides not to deploy the new safety applications until C-V2X is fully tested and available in production-ready products. At the same time, if a transition is required, earlier deployment of DSRC would entail additional costs that must be considered.

Although there have been published technical arguments for and against each alternative, and there have been qualitative arguments for moving forward with DSRC, there has not been a quantitative look at the advantages and disadvantages of moving forward with DSRC even if C-V2X should prove to have some advantage in the longer term. Based on the data published by NHTSA as part of their proposed rule-making on V2V deployment, I have quantitatively analyzed the options and documented the results in a white paper titled DSRC vs. Waiting for C-V2V: Lost Benefits and a Proposed Dual-Mode Solution.

The purpose of the white paper is to illuminate this aspect of the debate by providing an initial, rough quantitative estimate comparing the costs and benefits of moving forward with DSRC vs. waiting for C-V2X. More specifically, the paper examines the costs of delaying V2V safety deployment, both in lives lost and monetary costs. It then compares the costs and benefits of a new strategy, called “Dual-Mode Transition” that quickly deploys DSRC while maintaining the option to later transition to C-V2X, including a period of dual deployment of both technologies, with the strategy of delaying implementation of V2V safety applications while waiting for C-V2X to mature. The analysis shows that it is beneficial to move forward with DSRC deployment, saving thousands of additional lives and providing over $100B in additional benefits, regardless of whether a later transition to C-V2X or some other follow-on technology offers significant advantages.