Study: Higher prices attract drivers to HOT lanes

Our HOT Lane study makes the Star Tribune: Study: Higher prices attract drivers to HOT lanes:

“In a surprise finding, University of Minnesota researchers say that motorists who pay to drive in the carpool lanes on Interstates 35W and 394 are more likely to use them when tolls are high and to travel in the general traffic lanes when prices are low.

They also found that drivers who use the HOT lanes (High Occupancy Toll) are paying $1 to $2 per minute to save time. That’s more than $60 an hour.

Authors David Levinson and Michael Janson concluded in their ongoing study that drivers use the advertised toll price at entry points as an indication of the severity of congestion in the general purpose lanes and are more likely to use express lanes when prices are high to avoid sitting in traffic.

MnPass uses dynamic pricing, meaning the cost to drive in the HOT lane changes based on traffic conditions. Prices range from 25 cents to $8 and are adjusted every three minutes based on conditions. The average price is $1.50 to $2, said Brian Kary, MnPass freeway operations engineer.

Kary said he agrees with the study’s premise that drivers use toll information to judge how bad congestion will be downstream, but that there is a point when people will stop paying. MnDOT research indicates HOT lane use starts to drop off when the price hits $5. The U study did not indicate at what price HOT lane usage increased or decreased.

“There is a point when people will stop paying,” Kary said. “There is a limit to that. If we put it at $9, people won’t pay. When the HOT lanes are moving at the same speed as the regular lanes, people are less likely to jump in.”

Levinson and Janson calculated time savings and found that drivers in the I-394 HOT lane saved about 1.7 minutes in the mornings and about one minute in the afternoons. Time savings on 35W were about three minutes in the mornings and 1.2 in the afternoons.

Motorists use HOT lanes on average two to three times a week, Kary said. And even though time savings might not be that significant, there are other tangible benefits.

HOT lanes provide an absence of stop-and-go traffic and predictable travel times. It also provides for a lower-stress commute.

“You don’t have to worry about having to leave 10 minutes early to be to work by 8,” Kary said.

Levinson and Janson used two years of tolling and traffic data and modified pricing models on I-394 for three weeks in December 2012 and January 2013.”

It is also in Toll Road News: Study of Minneapolis dynamic priced lanes shows drivers see posted tolls as proxy for congestion – more likely to choose toll lanes when posted prices high

The full working paper (PDF) is: HOT or Not: Driver Elasticity to Price on the MnPASS HOT Lanes

Value of Reliability: High Occupancy Toll Lanes, General Purpose Lanes, and Arterials

Recent working paper:

In the Minneapolis-St. Paul region (Twin Cities), the Minnesota Department of Transportation (MnDOT) converted the Interstate 394 High Occupancy Vehicle (HOV) lanes to High Occupancy Toll (HOT) lanes (or MnPASS Express Lanes). These lanes allow single occupancy vehicles (SOV) to access the HOV lanes by paying a fee. This fee is adjusted according to a dynamic pricing system that varies with the current demand. This paper estimates the value placed by the travelers on the HOT lanes because of improvements in travel time reliability. This value depends on how the travelers regard a route with predictable travel times (or small travel time variability) in comparison to another with unpredictable travel times (or high travel time variability). For this purpose, commuters are recruited and equipped with Global Positioning System (GPS) devices and instructed to commute for two weeks on each of three plausible alternatives between their home in the western suburbs of Minneapolis eastbound to work in downtown or the University of Minnesota: I-394 HOT lanes, I-394 General Purpose lanes (untolled), and signalized arterials close to the I-394 corridor. They are then given the opportunity to travel on their preferred route after experiencing each alternative. This revealed preference data is then analyzed using mixed logit route choice models. Three measures of reliability are explored and incorporated in the estimation of the models: standard deviation (a classical measure in the research literature); shortened right range (typically found in departure time choice models); and interquartile range (75th – 25th percentile). Each of these measures represents distinct ways about how travelers deal with different sections of reliability. In all the models, it was found that reliability was valued highly (and statistically significantly), but differently according to how it was defined. The estimated value of reliability in each of the models indicates that commuters are willing to pay a fee for a reliable route depending on how they value their reliability savings.