Area officials came away from a Thursday meeting with PennDOT encouraged by proposed improvements along the Interstate 81 corridor that they hope will reduce the number of crossover crashes.
“It’s clear we’re all on the same page and have a lot of options to consider while working towards shared goals,” said Nathan Harig, assistant chief of administration at Cumberland Goodwill EMS and an advocate of safety improvements.
Harig was among dozens of officials including state representatives, municipal officials and representatives from law enforcement and county government who attended the meeting at PennDOT’s Cumberland County maintenance office on Army Heritage Drive at which Mike Keiser, director of PennDOT’s District 8, set out a plan for safety improvements along the highway that slices through the county. The meeting, which was scheduled last fall, comes after a series of crossover crashes in the Carlisle area.
“A lot will happen in the next two construction seasons,” Keiser said.
Cable median barriers will be included in the lane extension project between the Mechanicsburg (Route 114) and Route 581 exits on I-81, where work will start this year. The barriers will also be installed in areas west of Carlisle from the Franklin County line up to Route 233.
Cable median barriers will also be part of a pavement and bridge rehabilitation project between the Newville exit (Route 233) and the Hanover Street (Route 34) exit in Carlisle. PennDOT not only made a commitment to try to move that project up in its schedule, but also to make plans for safety improvements between Hanover Street and the Middlesex exit (Route 11) that will likely include more traditional safety barriers.
“We’re pretty confident it’s going to move up,” Keiser said.
“That area around Carlisle will be the toughest nugget to solve,” Keiser said.
Improved technology in the cable systems have made them a feasible solution for some locations along the highway through the county, and the number of potential locations for their use will increase as the control devices improve, Keiser said.
“When these cable systems came out initially, they were for very flat areas,” he said.
The technology has improved to the point where cable median barriers can now be used in medians with a 6:1 slope ratio or even a 4:1 ratio, given the right conditions. The slope ratio measures in feet the vertical drop over a horizontal distance so a 6:1 ratio would be a slope that drops one foot over a horizontal distance of six feet.
Design standards require a slope of 6:1 or better, and slopes between 6:1 and 4:1 must be approved by PennDOT’s central office. Designs will also be limited by setback distances of eight feet away from swales and a preferred setback of 12 feet off the travel lanes.
Though cable median barriers have been among the most oft-cited solutions to crossover crashes by the public, Keiser said they may not be a cure-all, and may create a new set of problems.
When certain safety measures are applied in the field, there are measurable results. For example, adding edge line rumble strips have resulted in a 38 percent reductions in accidents in which vehicles went off the road. In the case of I-81 and cable median barriers, the same linear comparison can’t be drawn, Keiser said.
For example, cable median barriers are not designed to prevent large trucks from crossing the median, Keiser said.
Despite the magnitude of crossover crashes, the median does provide an area in which a driver can recover control of a vehicle.
“We have a lot of vehicles that enter the median and do not cross over,” Keiser said. “When we add these barrier systems, keep in mind that we lose the recovery area.”
There’s a chance there could be an increase in severe accidents. It may also cause more crashes as cars are deflected back onto the pavement, which will bring more delays and more congestion.
“What would have been a minor accident can turn into a big deal because the driver is no longer able to drive away,” Keiser said.
When considering the median barriers, PennDOT weighs the benefits and costs of introducing a new object into the clear zone against the potential for crossover accidents.
“We don’t want to check a different box for what the fatality happened,” Keiser said.
The safety improvements come as PennDOT deals with a number of trends affecting travel on the interstate. The total traffic volume on the highway now stands at 10.2 million daily vehicle miles traveled.
“It went up 800,000 in just one year,” Keiser said.
The overall traffic volume includes a high volume of commercial vehicles as the state’s highways carry 12 percent of the nation’s freight. Pennsylvania is within a one-day haul of 40 percent of the population of the United States and 60 percent of the Canadian population.
The overall volume and the volume of tractor-trailer traffic through the area is only expected to increase, Keiser said.
Local warehouses have also added to the use of the interstate through the area, which is itself a result of the interstate’s existence.
“You don’t build warehouses and an interstate shows up,” Keiser said.
The proximity of interchanges with each other through the Carlisle area also adds to safety factors on I-81. There are five interchanges within a four-mile stretch of the highway. Though PennDOT will look at acceleration and deceleration lanes for those exits as it works on designs for highway improvements through the area, Keiser said it isn’t likely that new interchanges would be built to alleviate problem areas.
That the area falls between being fully urban and fully rural also creates problems that could result in crossover crashes. Drivers in major cities, for example, can’t reach higher speeds due to the volume of traffic.
“If you’re doing 35 miles per hour, it’s hard to have a crossover fatality,” Keiser said.
In the western part of the county, especially, there is a sense of being in a more rural area, and drivers go a little faster before suddenly coming upon more urban areas when they reach the Carlisle and West Shore areas, Keiser said.
Speed reductions and additional signs to alert travelers to congested conditions have also been suggested, but neither of those solutions are considered effective.
If speeds would be reduced, there would be a percentage of people who “want to do the right thing,” Keiser said, and they will follow the speed limits. Another component will not do so, creating an unsafe difference in speed that can make the problem worse. It’s possible that trying to suppress the speed limit can have the undesired effect of increasing the number of accidents.
“Getting anything less than 55 on the interstate is something we wouldn’t consider,” Keiser said.
Additional signage would not be practical as people simply do not notice them. Keiser cited the example of a trip he recently made to the site of a bridge replacement during which a vehicle followed him through three sets of signs warning of the bridge closure ahead. When he stopped, the driver of the vehicle complained about the inadequate signage, Keiser said.
Still, PennDOT said it would share information about traffic conditions on its overhead message boards. The department would also use education and enforcement initiatives to promote safety through the corridor. Information will also be shared with local officials who can then pass information along to their constituents.
County Commissioner Jim Hertzler said the meeting showed there are no perfect solutions and no easy answers to the problem of crossover crashes that he said has claimed 13 lives since 2012. He said he came into the meeting having declared that he would not take “no” for an answer when it came to demands for safety improvements, and that his concerns were met.
“I think what we heard today is yes, and we’re going to do it the right way,” Hertzler said. “PennDOT is paying attention and we appreciate that.”
Rep. Stephen Bloom said he appreciated the time PennDOT took to listen to officials’ concerns.
“I’m encouraged that PennDOT has made a clear commitment to deploy appropriate safety technology into the Carlisle corridor of Interstate 81,” Bloom said.
Harig said he had been concerned that PennDOT had not shared his “view on the necessity of an engineered solution to these crashes.
“I was very glad to hear that the areas around Carlisle, particularly hot spots near exits 44 and 45, are under examination for solutions by PennDOT. I now understand their decision-making process much better than before and am hopeful of the progress that can be made reducing crossovers,” Harig said.
Harig said the meeting also opened the door for further collaboration, and brought out ideas to share information between government, emergency responders and drivers to prevent crashes as well as to respond to and manage major incidents.
“I will continue to advocate for all things safety-related, and left the meeting today very optimistic of what can be accomplished,” Harig said.