MANKATO — Among the various options to improve the busy Riverfront Drive-Stoltzman Road intersection, a roundabout would bring the most benefit and the most expense, according to a nearly completed study presented to the Mankato City Council Monday night.
But the major concern for council members, more than the cost, was the potential that a roundabout would be a safety hazard for West High School students and other pedestrians.
“That scares the living daylights out of me personally,” Mayor Najwa Massad said of hungry students rushing to Kwik Trip, Cub Foods West and other off-campus eating options during their lunch break.
The study is being conducted by Alliant Engineering Inc. under a contract with the Mankato-North Mankato Area Planning Organization, which serves as the urban transportation planning body for Mankato and nearby jurisdictions. The consultants have looked at existing conditions at the intersection, traffic projections through 2044, several possible fixes and a comparison of the alternatives.
The study concluded that the design would greatly reduce the danger of severe crashes while improving travel times through the intersection — cutting average delays by more than 12 seconds during the morning rush hour and more than 6 seconds in the afternoon rush. Safety for walkers and wheelchair users would be enhanced, according to the study, by creating crosswalks with pedestrian refuge areas midway between the traffic lanes.
The only significant negatives of the option were a possible increase in sideswipe and rear-end crashes and the estimated construction cost of $2.65 million. That price tag doesn’t include the cost of purchasing right-of-way from adjacent commercial properties to make room for the roundabout.
Council members appeared to favor a roundabout when focusing strictly on vehicle movement and crash reduction but Massad was not alone in wondering if pedestrians would be worse off.
Council member Dennis Dieken noted that a roundabout, when functioning well, creates continuously flowing traffic, which can be problematic for pedestrians.
“It’s kind of a water and oil situation,” Dieken said.
Council President Mike Laven was more optimistic that a final roundabout design could be developed that would work for both drivers and walkers.
“I think there’s other ways to work with pedestrians on that corridor,” Laven said.
The consultants did identify one alternative to a roundabout that they said offered significant improvements over the existing intersection.
The design would retain the current signal lights but improve them and create dual left-turn lanes for traffic heading north on Stoltzman Road and looking to turn west on Riverfront Drive.
The redesign would allow the elimination of “split phasing” of the lights, which currently requires longer waits at red lights because simultaneous movements are not permitted for traffic coming from the north and south.
Under the new design, which carries an estimated cost of $185,000, northbound drivers on Stoltzman and drivers leaving the Cub Food West shopping area would get their green lights and their green left-turn arrows at the same time as their counterparts coming from the opposite direction.
The dual left-turn lanes would also reduce the conflict between northbound Stoltzman drivers hoping to turn left at Riverfront and those planning to turn right. During high-traffic times, the right-turners can’t get to the right-turn lane because traffic aiming to turn left is backed up well to the south of where the right lane comes into existence. Because those right-turners are blocked from advancing to the intersection and making the turn, they’re becoming intermingled with the stacked-up traffic and causing the backup to grow even longer.
At the busiest times, waiting vehicles can stretch nearly to the entrance to the West High School parking lot, forcing drivers to sit through multiple cycles of signals to get through the intersection.
Although the current intersection is not crash-prone, it has a lot of traffic and was recommended for a yet-to-determined upgrade during a 2017 Riverfront Drive corridor study. An average of 12,600 vehicles travel Stoltzman each day, and Riverfront carries 15,200 vehicles east of Stoltzman and 19,800 west of Stoltzman. Statistics weren’t available for the private drive leading through the Cub Foods shopping area, but traffic flowing to and from there is continuing to grow as more and more housing is built on and near Sibley Parkway.
Alliant Engineering will be wrapping up a final draft of the intersection study by early December after considering the opinions of the council, the Blue Earth County Board (which has jurisdiction over Stoltzman Road) and the MAPO Board.