Weathering the storm: How RTD responds to different severe weather events

Denver has an average of 300 days of sunshine a year. However, the other 65 days are anything but sunny and roses. The city’s unique geographical location—the westernmost part of the metro is tucked right underneath the shadows of the foothills, and the easternmost parts are in what many joke about as “western Kansas”—allows intense weather events to pop up, sometimes with little or no warning. To effectively deliver transit services to its customers, RTD must be ready for whatever Mother Nature throws.

RTD covers 2,342 square miles, 40 municipalities, six counties and 3.09 million residents. This includes the mountain communities of Nederland, Evergreen, Conifer, and Aspen Park, as well as cities outside the traditional Denver metro area, such as Boulder and Longmont, and even Denver International Airport, the easternmost point in the RTD system.

When it comes to weather, the metro area can experience it all, sometimes with entirely different weather events just miles apart, providing unique challenges for RTD services.

Winter Weather

The most common disruptive weather event along the Front Range comes in the form of winter storms.

“When we’re talking about winter weather planning, the question of service impacts and suspensions and when we commit to a plan is a hotly discussed item,” Manager of Emergency Management Diana Rawles said.

Rawles, who joined the agency in 2022, manages the agency’s response to emergencies, including planning and responding to adverse weather conditions.

“When we’re talking about snow, ice and other winter weather conditions, it can have such different impacts,” Rawles said. “Are snowfall totals resulting in lengthy delays for buses? Are our operators able to safely operate their buses and trains? These are things we must consider before taking more drastic measures like suspending service.”

Winter weather can cause headaches for all modes of service, but bus service is especially affected. That’s where the snow desk comes in.

“Once we have buses getting stuck at a rate that on-duty staff can’t keep up with, we activate what is called the ‘snow desk,’” General Superintendent of Street Operations Tim Lucero said. “We have an on-call maintenance employee tasked with manning the desk and dispatching tow trucks and resources to get operators to safety and buses back on the road.”

The snow desk triages inbound calls from operators who cannot continue their routes due to road conditions, accidents or the inability to get their buses moving again.

“The dispatcher writes down the bus number and location, hands it off to the snow desk, and then they prioritize who needs the most help the fastest,” Lucero said. “Does the bus have customers? Is the bus on a route or are they pulling into the garage? Where is the bus stuck?”

The snow desk works to alleviate calls into dispatch about stuck buses so dispatchers can focus on assisting operators with other issues.

Even though every attempt will be made to safely return the operator and bus to the garage, there is the unlikely event that the snow and ice are so severe that it is impossible to dispatch a tow truck. In this case, the priority would be to ensure the safety of the customers and operators.

“In that situation where we get into rescue mode, we are just going to go out and get our customers and operators to safety and return for the equipment later,” Lucero said.

“However, in my 23 years at RTD, we’ve only had to do that once, thankfully,” Lucero said.

While bus services may be most affected by winter weather, light and commuter rail services are also affected.

Ice buildup is the main threat to RTD’s rail services, especially on the overhead catenary system (OCS), the tracks, and at track switches. However, RTD’s train operators and Maintenance of Way teams are well-equipped to combat ice buildup.

“Light rail uses switch heaters and smudge pots to keep interlocking sections of track free of ice and snow, preventing them from freezing,” Assistant General Manager of Rail Operations Dave Jensen said. “A switch heater uses available electric current from the infrastructure to heat the area around a switch to melt ice and snow. Smudge pots are portable devices placed at the switch, creating a small flame that creates heat to melt the snow and ice.”

For the OCS wire, all trains are equipped with heated carbons on the pantographs that keep the wire free of dangerous ice buildup while in operation. That, combined with the nonstop operation of trains throughout the winter weather event, has proven effective time and time again to ensure tracks remain clear of accumulation, OCS wires remain free of ice and service can continue as effectively as possible.

“When icing conditions are present or are predicted to be present, RTD will operate trains during non-revenue service to prevent icing on the overhead wires,” N Line’s Manager of Rail Service Delivery Phil Washington said.

Commuter and light rail trains use the same tactics to keep the tracks free of ice and snow, but operators must still use caution and reduce speeds, especially when there is heavy snowfall.

Despite these efforts, winter weather events have been severe enough to require operations to be suspended entirely.

“One metric we look at when determining if we should suspend service is if buses are getting stuck faster than they are being recovered,” Rawles said. “If we can’t keep up with buses getting stuck, we’ll consider temporarily suspending service until the weather improves.”

For light and commuter rail, it’s a matter of operators being able to see ahead of them. If operators have to move slowly on the tracks, considerations must be made to suspend service until operators can safely operate their trains again.

Severe thunderstorms

As the seasons change and temperatures warm, the threat of winter weather gives way to severe weather season.

Those who have lived along the Front Range for any length of time are aware of the threats that May, June and July can bring. In those months, the threats of severe thunderstorms, large hail, strong winds, flash flooding and even the occasional tornado can pop up, sometimes without warning.

Denver’s unique geographic location can make these storms even more violent, courtesy of a geographical and meteorological phenomenon known as the Denver Convergence Vorticity Zone (DCVZ).

According to the American Meteorological Society, the DCVZ occurs when southerly low-level winds riding along the foothills of the Rocky Mountains interact with the Palmer Divide, an east-west caprock ridge that splits Denver and Colorado Springs. This accelerates the winds from a southerly to an easterly direction. Once these winds interact with the warm air of the plains, the air is directed north, creating convection and acting as high-octane fuel for severe thunderstorms to form fast and sometimes with little warning.

The DCVZ creates microvortices when strong winds are already present and can spark sudden microbursts. The National Weather Service (NWS) defines a microburst as a localized column of sinking air (a downdraft) within a thunderstorm. This sudden burst of air can create damaging winds of up to 100 miles per hour, extremely heavy rain, frequent cloud-to-ground lightning, and even tornadoes.

Regarding impacts on RTD’s service, employee safety and facilities, severe weather season keeps Rawles on her toes.

“We coordinate a lot with the NWS in Boulder and the Colorado Department of Transportation (CDOT) to prepare for severe weather,” Rawles said.

The biggest concern Rawles has when severe weather strikes? Damage to power lines.

“Branches from trees impacting power lines are my biggest focus because when the power goes down, it has so many downstream effects,” Rawles said. “We even have a specific power outage plan to address how we will react in a power failure.”

Wind events

Many weather events can cause power line breaks or failures, but the most common are wind events, which are largely due to the effects of the DCVZ. Strong winds accelerated downward into the city by the foothills can dislodge tree limbs and other items and fall on power lines, causing power outages. Thankfully, RTD has a tried-and-true system in place to ensure customers can still reach their destinations even when a power outage knocks out train service.

In the event of a power outage, whether caused by weather or human error, light and commuter rail operations will work with RTD’s Bus Operations Division to order a “bus bridge,” more commonly known as shuttle buses, to supplement rail service between impacted stations. This will ensure customers can continue their trips and reach their destinations safely.

Strong winds can also impact rail service without knocking out power by causing crossing gate arms to malfunction.

“High sustained wind gusts have the potential to interfere with gate arms along the system,” Washington said. “If gate arms are not functioning as intended, dispatchers are required to put a stop order in place, which can cause service interruptions or delays.”

When this happens, flaggers are dispatched to the impacted crossings to serve as crossing guards. They ensure cars and pedestrians do not cross tracks when trains come through. Train operators must also slow to designated speeds when flaggers are in place to ensure safety.

Wind events can affect buses, too, especially along Route GS.

The route follows CO-93 between Golden and Boulder. With the dramatic elevation changes on both sides of the highway, it is not uncommon for sustained winds in the area to exceed 45+ miles per hour. When winds become too dangerous, Route GS operators can take a designated wind route to avoid the strong winds.

“The Route GS has alternate routing that operators can call into dispatch to request taking,” Lucero said. “They will usually call us when they feel the winds are getting pretty bad, and we’ll let them take the alternate route based on their description.”

Wildfires

Strong winds alone can cause damage, but when the conditions are ripe for wildfires to spark, winds can become an x-factor in wildfire spread.

For those who lived in the Denver metro area and worked at RTD in 2021, the Marshall Fire is still fresh in their minds.

Just after 11 a.m. on Dec. 30, 2021, a small grass fire was reported in Boulder County near CO-93 and Marshall Road. In just one hour, the grass fire, which encompassed a few acres, grew into an inferno that quickly swept through Broomfield, Louisville, and Superior.

The winds resulted from a massive cold front moving through the area, which would bring significant snowfall to the Front Range the next day. Sustained winds of over 74 miles per hour, with gusts over 100 miles per hour, caused the fires to expand eastward rapidly. The wildfire would affect over 50,000 residents of the three communities.

When the event was over, 1,084 homes were destroyed, displacing tens of thousands of families.

As dark as the day was for the region, RTD’s operators stepped up to ensure their customers’ safety from the fires.

“These operators are brilliant individuals, and they make the same decisions that the street operations teams make,” Lucero said. “What’s safe? Where can I go? Where can’t I go and how do I do it? Their task is to make those decisions in real-time if they don’t have a supervisor or dispatcher available to help them.”

While Rawles was not with the agency during the Marshall Fire, she says she has reviewed the after-action report and is working on ways for RTD to be ready if another urban wildfire sparks.

“I have been working on our wildfire emergency plans for the past two years,” Rawles said. “Many considerations need to be taken when determining a response to a wildfire. How many buses do we have? How quickly can we get extra buses dispatched for evacuation purposes?”

“We all have the same understanding that saving lives is paramount, but the logistics of supporting evacuation efforts can be tricky,” Rawles said. “It’s something I’m continuing to work out with our local partners.”

Hail

Anyone who has lived along the Front Range for any period of time knows that hail is a significant weather threat in the spring.

According to the National Oceanic and Atmospheric Association (NOAA), hailstones are formed when raindrops are carried upward by the thunderstorm updrafts into extremely cold areas of the atmosphere and freeze. As hailstones grow, they become heavier, eventually becoming so heavy that the storm’s updraft can no longer support their weight. When this happens, all the hailstones in the upper levels of the cell begin to fall.

Hailstorms are a common threat for Front Rangers, especially as they are fueled faster than usual by the effects of the DCVZ. RTD services are just as much at risk of being impacted by hailstorms as anybody else.

“We have had impacts when we’ve had large hail and have had to stop buses because windshields and roof hatches were getting smashed,” Lucero said. “When major hailstorms happen, we’ll stop the vehicles until the storms have stopped, then assess the situation to determine the best course of action.”

Keeping customers informed

When severe weather strikes, customers are the first to be impacted by the effects. Customers will turn to RTD’s Customer Care Division for the latest information in the heat of the moment, and the division’s Digital Customer Relations Liaison (DCRL) team serves as the division’s information relay.

“When disruptions take place, we inform our information specialists with details of the disruption to relay to customers over the phone, as well as informing customers of adverse weather conditions in the form of service alerts,” Lead Digital Customer Relations Liaison Kory McNail said. “We update the website to inform customers of anything affecting service.”

RTD’s service alert management system is directly integrated into several key customer-facing systems, including Next Ride, Trip Planner and even social media, all managed by the DCRL team.

The team maintains close collaborative relationships with light rail control, bus dispatch, and commuter rail’s Operations Control Center (OCC) to ensure customers and employees are notified about disruptions as soon as they occur. This information helps Customer Care’s information specialists inform customers who call about disruptions.

While Customer Care takes care of the customer-facing communications, RTD’s Media Relations team is tasked with relaying the same information to local and regional news outlets so that they can get the word out to the masses.

Mother Nature can be unpredictable, but RTD stands ready to respond to her fury at a moment’s notice.