Missouri DOT’s Leader Follower System Truck Mounted Attenuator Pilot Deployed in the Kansas City and Southwest Districts to Identify Potential Benefits and Costs of Implementing the System.
Kansas City, Missouri, United States
Protecting the safety of work zone workers is a priority for local and state transportation agencies. Advancements in technology, such as automated leader-follower vehicle systems for truck mounted attenuators (Leader-Follower TMA) system, allow for the further separation of the work zone workers from threats to mobile and slow-moving operations, such as lane striping, sweeping, bridge flushing, and pothole repair. This study evaluated MoDOT’s pilot program for Leader-Follower TMA system in the Kansas City and Southwest Districts to identify the feasibility and potential benefit and cost of implementing the system. The evaluation of the TMA system included DOT surveys and interviews from 43 agencies, field study in August 2022 as well as economic analysis. The economic analysis to quantify the benefits and costs of the Leader-Follower TMA deployments, incorporated system integration cost for existing equipment, training costs, and annual maintenance and support costs.
The costs of using the Leader-Follower TMA system mainly include three cost items: 1) the system integration cost on existing trucks and TMAs, 2) the training cost, and 3) the maintenance and support cost.
The system integration cost for existing equipment was $298,245/unit, based on the cost data of MoDOT Southwest District Leader-Follower TMA project. This study assumed that the Leader-Follower TMA system was upgraded from trucks and TMAs already operated and owned by MoDOT. Therefore, there was no need to procure new trucks and TMAs.
The vendor of the Leader-Follower TMA system provided a week-long training module for MoDOT staff who were new to the Leader-Follower TMA system. The training module was complimentary and could also be offered by MoDOT engineers, therefore the training cost primarily included the staff time of four trainees, trained together for each Leader-Follower TMA unit in the Kansas City and Southwest districts for 40 hours. The training cost per unit was estimated considering the trainees’ hourly rates. Finally, the annual maintenance and support costs were budgeted as $1,000/unit, based on a previous study in the literature by Florida DOT in 2021. The total cost is calculated as $36,442.58, as shown in the table below.
Table 1. Cost Breakdown
| Agency Size | Amount | Source/Note |
| Number of TMAs owned by MoDOT | 500 | Project data |
| Number of TMAs upgraded to Leader-Follower TMAs | 1 | Project data |
| Cost Item | Amount | Remarks |
| System integration cost per unit | $298,245 | Project data |
| Support and maintenance/unit/year | $1,000 | Literature from FDOT |
| Leader-Follower TMA life cycle (years) | 10 | Project data |
| MoDOT worker hourly rate | $14.00 | Project data |
| Training cost/unit | $2,240 | 4 trainees per unit x 40 hrs x $14 per hour per trainee |
| TOTAL $/unit | $36,442.58 | Considering follower TMA risk rate (0.582) and annuity factor (0.02) |
