On February 23, 2026, SEPTA’s [D] Media-Sharon Hill Line service began operating with a new Communications-Based Train Control (CBTC) system. CBTC is a modern signal system that provides a higher level of safety, utilizing radio communications between the vehicles and the signal system. CBTC establishes operating times between trolleys, enforces safe stopping distances and prevents trolleys from exceeding established speed limits.
The CBTC system was put into place to improve safety and system performance on the line, and the new technology has unlocked many opportunities to do so. However, due to a combination of legacy operational rules and the new technology itself, this transition has resulted in a significant increase in overall run-time on the line, as well as a disruptive experience on the vehicles due to the alarms the CBTC system produces.
How We’re Improving the Signal System and Reducing Service Delays
Helping operators adjust to the new system.
- Operators are still acclimating to this new system, and the ride should become smoother over time as they adjust. We are offering additional support and guidance on the new system for operators to support this transition.
Mitigating the volume of the warning alarm on the vehicles.
- The new CBTC system produces a loud warning alarm when the vehicle is approaching (but has not yet hit) the speed limit for that specific area of the track. Please note: the fact that this alarm is going off does not mean that the operator has violated the speed limit; it is just a warning. However, we recognize that this noise is very loud and is negatively affecting the rider experience. While there is no simple way to turn down the volume on the new system, we are actively testing ways to dampen the volume to improve the experience for both operators and riders.
Actively monitoring the performance of this line, and making some schedule adjustments in June to improve run-time.
- After close analysis of the D1 and D2 actual running times, we will implement some adjustments to the schedules as part of the June 2026 schedule change, which will modestly improve run time on each line, as well as reduce the potential for additional delays in certain areas.
Evaluating the allowable speed limits to improve the run time overall on the line.
- We have already modified temporary speed restrictions at Scenic Rd, Congress Ave and between Marshall Rd and Creek Rd that were no longer required.
- We are reviewing the safe allowable speed limits at many grade crossings for possible run-time improvements, in partnership with regulatory agencies and the CBTC system vendor. Any modifications will take some time to implement even if approved.
We apologize for the inconvenience for D1/D2 riders in recent months, and appreciate your patience as we mitigate the impacts of these new safety measures.