When a bus network evolves over a century in an old place like Philadelphia, idiosyncrasies build up that can complicate change.

For instance, planners got into the habit of drawing long bus routes to try to limit transfers, a fact of life before SEPTA restructured fares last year to allow one free transfer per trip.

“Some central routes have over 200 stops, and it’s really rare in the United States for a bus route to have more than 100 stops,” said Geoff Slater, a principal at Nelson\Nygaard, a transportation consultancy the transit authority has hired to examine and redesign the region’s biggest bus system.

“If routes are too long, buses get hung up in traffic, which affects the reliability everywhere else in the line,” Slater said.

SEPTA’s three-year Comprehensive Bus Redesign effort debuts in earnest Thursday with intensive data collection and analysis of the system as a whole and its more than 120 individual routes, as well as conversations with riders and regional leaders.

» READ MORE: SEPTA awards $3M contract for bus network revamp, eyeing a faster and easier-to-use system

How many bus stops are too many is just one of the thousands of questions the team of consultants, SEPTA officials, and the riding public will grapple with as they design a bus network for how people travel now, also taking into account changes wrought by COVID-19.

For example, Route 18, the bus that runs from Cedarbrook to the Fox Chase Station, has an average of nine stops each mile, about a two-minute walk apart, Slater said.

“If we went to six stops a mile, which is everybody walking less than one extra minute, we could reduce the travel times on that route by 15% to 20%,” he said. It’s a matter of the trade-offs users are willing, or can be convinced, to make.

The overall goal: challenge assumptions and create a bus network that’s easier to understand and use.

Before the coronavirus pandemic, the redesign was seen as a way to address a downward trend in bus ridership in Philadelphia and its Pennsylvania suburbs amid competition from other transportation options such as ride-sharing services, as well as changing commute patterns.

The pandemic has only accelerated change and highlighted other challenges faced by the bus network’s most reliable customers: people of color and those who have low incomes, many of them essential workers.

“We tend to have a one-size-fits-all approach to transit service planning,” said Bethany Whitaker, a Nelson/Nygaard principal who is working on the SEPTA redesign project. For example, service traditionally is organized around weekday morning-and-afternoon peak hours.

“Not everybody works 9 to 5, and not everybody’s traveling into Center City,” Whitaker said. “Do we need to provide more service during the middle of the day and at evenings? … For a lot of travelers, as many trips are being made on Saturdays as on the weekdays, and we need to respond and adjust and adapt.”

SEPTA approved a contract in December with Nelson/Nygaard for $3 million.

The consultants will use data from a variety of sources, including bus boarding and alighting patterns taken from SEPTA’s passenger counting software, cell phone data, and a travel-flow model built by the Delaware Valley Regional Planning Commission — along with informal surveys and more statistically rigorous ones.

“We’ve been tinkering around the edges for decades,” said Dan Nemiroff, a SEPTA senior operations planner who focuses on buses. “And taking a step back and asking how well does it all work together, how does it fit, you know, is it doing what it’s supposed to be doing — the timing is perfect for this type of work.”

More information on the project, as well as an informal survey, can be found at https://SEPTAbusRevolution.com.