A flagman is pictured at the Ulster crossing in the Central Park Station. Flagmen are on duty 24 hours a day at all crossings pending approval of the Quiet Zone.

RTD estimates that problems with the Positive Train Control (PTC) system will require that horns for both the new commuter rail line and the pre-existing freight trains will continue to sound for at least three to four more months. RTD’s plans for the A Line had long included enough safety measures at the 11 at-grade crossings along the 23-mile route that the federal government would allow establishment of what is known as a “quiet zone.” The hope was that the Quiet Zone (QZ) would have been in place by April 22, the date that the A Line opened for revenue service. Now it appears the Quiet Zone will not be in place until late summer or early fall.

While train horns have always sounded along this stretch of the Union Pacific Railroad Company (UPRR) main line, the A Line’s frequency of service (or headways) of 15 minutes in each direction, has increased the frequency of horn sounding by a factor of 10. The A Line operates about 21 hours a day. According to a DTP spokesperson, train horns must be a minimum of 110 decibels.

At the A Line crossings, RTD patrons as well as area motorists have noted erratic patterns in the timing of warning bells and gate closures relative to train arrivals and departures. RTD acknowledged as such to the state’s Public Utilities Commission (PUC), which has regulatory authority over all rail crossings in Colorado. An order issued by the PUC on April 15 cited these unresolved “technical issues”: gate activation failure, gate false activation, commuter rail vehicles entering crossings while gates are descending, and traffic signals in flash condition.

Despite the UPRR’s request that the A Line opening be delayed a month, the PUC allowed the opening to proceed provided RTD implemented two temporary safety measures: to post human flaggers at each crossing 24 hours per day, seven days a week; and staffing of a “GO Team to respond to any crossing technical issues within 20 minutes of notification.” An RTD spokesperson described the GO team members as “signal and traffic experts who can quickly mobilize should there be any crossing issues.” RTD’s concessionaire for the A Line, Denver Transit Partners, is paying for the extra people to be stationed at the crossings.

Thus, the A Line is operating without a fully operational PTC. Once fully operational, the A Line will feature the first such system in the country for a new rail line service. In 2008, the federal government mandated PTC for rail lines in the wake of a horrific train collision in California resulting in 25 passenger deaths. PTC tracks train movements along the length of a corridor and can avoid operator error by remotely stopping or slowing a train. In the meantime, the traditional “automatic train control” (ATC) system is being supplemented by the flaggers and GO team. A recent article in Planning magazine compared ATC to PTC systems this way:

Automatic Train Control establishes communication between the train and the signal system that lets engineers know when to stop, go slow, or forge quickly ahead. Under ATC, if the vehicle passes an established signal point at a speed faster than the limit, alarms will sound in the cab. If the driver does not respond quickly enough, the ATC system will apply the emergency brake on its own.

Positive Train Control essentially marries this long-standing system with contemporary GPS technology to allow the warning system to kick in if the driver is going too fast at any point along the track, not just where the signal wires are standing sentinel …. It also allows for subtler regulations of train speed and can be calibrated differently in case of, say, bad weather or nearby track work.

Establishing a QZ is complex both in terms of technical requirements and jurisdictionally. Legally, the impetus for a QZ resides with local government, in this case, Denver and Aurora. The “notices of intent” for the A Line QZ were filed by Denver last August and by Aurora this January. Those local governments will not issue the notice of establishment (NOE) until advised by RTD that all the technical requirements have been met. DTP spokesperson Nadia Garas said three to four months for QZ establishment “sounds reasonable.”

Despite the legal role for Denver and Aurora in this process, it was RTD that committed to installing the necessary safety measures to make the QZ a possibility. They did this through the environmental reviews for the A Line as well as a “Responsible Rail Amendment” adopted in 2007. In addition to the PTC itself, crossing safety features include “quadrant gate arms” and medians (to block travel lanes in both directions and to prevent vehicles from going around the gates when descended), pedestrian gates, safety signage and audible and visual alerts.