A Paradigm Shift for Paratransit and Shuttle Bus Electrification

Transit fleets were among the first to experiment with, and ultimately integrate battery-electric vehicles (BEVs), into their mainstream operations. Today, full-size electric buses make up an ever-expanding segment of the total bus population. However, advancements in, and acquisitions of, shuttle and paratransit buses have been slower to catch on.

Through their early adoption of the technology, many transit officials have experienced first-hand, the trials, tribulations, and triumphs of BEV evolution. Some say that now, the electric shuttle and paratransit segments of the market are overdue for some evolving of their own.

“We made the purchase of our first Proterra Catalyst electric buses more than 37 months ago now,” said Tom Hingson, transportation services and transit director for Everett Transit in Everett, Wash. “With projected lifespans of 12 years each, we’re just getting started, but our stated objective is to be operating an almost-all-electric fleet by 2024.”  

Part of the reason Hingson said “almost-all-electric” is because he hasn’t been able to find an electric paratransit bus that’s quite up to the task as he sees it. Hingson suggests that something gets lost in the translation when converting gas and diesel vehicles to electric. As Hingson explains it, part of the issue is simple math.

“Most of the electric paratransit and shuttle buses are built on the Ford E-450, Ford Transit, Chevrolet Express, or GMC Savana platforms, so they start out as gas or diesel cab and chassis and have to be converted,” Hingson said. “So, we understand that to run ancillary components, like hydraulic or pneumatic wheelchair lifts, HVAC systems, electronics, and anything mechanical, you need more power, but that reduces range, so you add batteries, but batteries add more weight, and at a certain point a small chassis can't handle all that weight.”

Hingson also listens to the musings of other transit officials, who complain that the current BEV product offerings simply don’t meet the duty cycle requirements of the real world, which includes the work the vehicles have to perform, the distances they need to travel, and environmental factors like weather.

“Part of my information is more anecdotal and derived from the few colleagues I know who attended trade shows in the last few years,” Hingson admits. “They’ll talk to a vendor and the vendor will say something like, ‘Upfitted with this equipment, this vehicle has got a 60-mile range,’ and my cohorts will go, ‘Yeah, but I need a 150-mile range, and I need that same range in the summer and the winter.’”

As Hingson explains it, a paratransit operator gets a different assignment every day and a paratransit bus will go out and do an eight- or 10-hour day and they won’t come back to the bus barn between trips. The bus has to continue to function for long periods of time between trips, while the bus and driver are idle and waiting for the next scheduled trip, or for one to be assigned on the fly.

“I’m hoping for BEV technology to mature to the point we’re no longer trying to convert gas and diesel chasses into electric versions,” said Hingson. “And that those technical advancements will alleviate the range anxiety associated with electric shuttle and paratransit buses and the impact weather has on them.”

An Uphill Climb

If Hingson hopes to come anywhere close to his all-electric fleet by 2024, things will have to change fast, at least when it comes to the shuttle and paratransit vehicles in his fleet. Others in the industry agree that this segment has lagged behind in both attention and development.

“The transit market has really led the way in BEV adoption and bus OEMs have been rapidly developing and refining larger electric bus designs for the last four or five years,” according to Joseph D’Urso, VP of Toronto-based City View Bus Sales & Service, a bus dealership serving public transportation, education, and healthcare markets. “The higher sales volumes and profit margins in the large metro bus category have been an obvious and rational incentive for manufacturers.”

D’Urso observes the development of electric shuttle and paratransit bus offerings have lagged behind, like it has for their cousins, the Type A-1 and A-2 school bus. He estimates that these smaller buses with capacities of up to 26 ambulatory passengers, have only been in serious development for about two or three years.

“It was only a matter of time, but now we’re starting to see more and more inquiries for these smaller electric buses, said D’Urso. “However, another mitigating circumstance is that any electric shuttle and paratransit bus order requires a partnership with a third-party upfitter.”

D’Urso explains that non-electric chassis for any shuttle, paratransit, or Type A school bus are most commonly sourced from one of the big three, usually from either GM or Ford. Since neither OEM currently offers an electric powertrain, that means a conversion is necessary.

The challenges are many and varied when converting a gas or diesel vehicle to electric,” D’Urso said. “From the physical mounting standpoint of your hardware, to making sure you have the proper suspension, and then there’s the high-voltage electrical system that’s got to be stepped down to work with standard low-voltage equipment like HVAC systems.”

D’Urso also points to the complexity of interfacing a new powertrain with an electrical system that talks to the rest of the vehicle as both difficult and challenging. “I've seen folks that are out there doing it, and I tip my cap to them because I think it's a huge technical undertaking, and unique from vehicle to vehicle,” he said.

The Road Ahead

A recently announced collaboration between two companies may address the engineering challenges that are endemic with converting gas and diesel platforms to electric. The stated intent of their alliance is to change the trajectory of electric shuttle and paratransit bus development, performance, and reliability.

Zeus Electric Chassis Inc. is a White Bear Lake, Minn.-based company that has engineered a versatile, severe-duty BEV cab, and chassis dubbed the Zeus Z-19 Power Platform. Pegasus Bus Company is a Dunkirk, Ohio-based company spearheaded by veterans in the school and transit bus industries.

Together, the companies will use the Zeus Power Platform to deliver a shuttle and paratransit bus that they say will be categorically different from any gas or diesel conversion. The ground-up design of the Zeus Z-19 cab and chassis is purpose-built and optimized for bus body installation and system integration.

“It’s robust frame rail construction and purpose-built electric chassis makes the Z-19 unique right out of the gate,” said Brian Barrington, president of Pegasus Bus Company. “Honestly, those two things alone separate what we’re doing from anything else that’s currently on the market.”

With all-wheel-drive, independent suspension and a gross vehicle weight rating (GVWR) of up to 19,500 pounds, a Pegasus Bus on a Zeus Z-19 Power Platform is different from other vehicles in the shuttle and paratransit bus category. Its electric motors generate a continuous rated 290 horsepower and 2,040 foot-pounds of torque, enabling it to operate in inclement weather, on challenging topographies and allowing it to transport a payload of up to 8,000 pounds within a standard range of 150 miles.

“Compared to the 14,500-pound GVWR of the standard gas or diesel conversion models on the Ford and GM platforms, the Z-19 gives us 5,000 more pounds of payload to play with,” said Barrington. “Most shuttle and paratransit buses will hold up to 26 ambulatory passengers and we’ll probably be able to get to 28 to 32 with the Zeus Power Platform.”

The Z-19s Lithium Ion NMC batteries sit protected between the chassis frame rails and have an expected life span of approximately 3,000 charging cycles, which should provide transit fleets with between eight to 10 years of service depending on their duty cycles. The system automatically heats and cools the batteries with glycol to maintain optimal performance in both hot and cold climates. The charging configuration is designed to support Level 2 and DC fast charging, and the system has export power capabilities to suit customer needs.

It’s the Z-19’s ability to integrate with existing shuttle and paratransit bus subsystems that Zeus expects to turn upfitters heads. According to Bill Brandt, chief revenue officer for Zeus, seamless system integration was at the forefront as the company designed the Z-19 from the ground up.

“Until now, everybody that's been upfitting a bus body on a modified gas or diesel chassis has had challenges converting gas- and diesel-engine-driven components, like HVAC, pneumatics, and hydraulics.” said Brandt. “In a traditional bus, the HVAC and all other subsystems are driven off the engine, so when you remove the engine, you remove the power source. Upfitters often try to repurpose some of the OE hardware or try reengineering their own solutions.”

Brandt insists that simple and versatile systems integration was a central issue at the start of the Z-19’s design and remained so throughout. He also believes the convenience and versatility of the Zeus approach is key to Zeus’ value proposition for bus builders.

“Our systems integration is more efficient, and a safer method that will minimize liability and warranty issues,” said Brandt. “This will make the Zeus Power Platform attractive to companies like Pegasus, because it drastically reduces the amount of time and labor it takes to put a bus body on a chassis and to make all the systems work correctly.”

In part, Zeus relied on Nott Company, a systems integrator based in Arden Hills, Minn. Nott engineers helped with the Z-19’s electronic controls, telematics, e-pumps for steering and braking, on-board charging/export power, and other systems. The result is an electric chassis that comes fully equipped for the total integration of mechanical, electrical, hydraulic, and pneumatic auxiliary functions and CAN bus communication.

Body builders, up-fitters, and bus companies should also recognize and feel comfortable with Zeus’ list of key suppliers, which include, ZF Commercial Vehicle Solutions (formerly WABCO), Meritor, Webasto, Parker, and Curtiss-Wright. The vehicle’s aluminum cab was manufactured by Marion Body Works.

“Both our Z-19 and Z-22 Power Platforms received Certificates of Conformity from the U.S. Environmental Protection Agency in December of 2021,” said Brandt. “We are excited to join with Pegasus to help market a truly differentiated electric school and shuttle bus solution to targeted segments of the transportation industry that we believe will immediately benefit from this technology.”