Q: Usually around 4 p.m. I notice that westbound traffic on Route 22 moves at a snail's pace from Route 512 through MacArthur Road. I think part of the problem is that motorists going from northbound Route 378 to westbound 22 are forced to merge onto the travel lane of 22, even if they plan to exit at Airport Road northbound, a very short distance ahead. If PennDOT, at minimal cost, could extend the ramp lane from 378 to Airport Road as a third lane of 22, it would eliminate the need to merge, which contributes to the slowdown in traffic.
— Kermit Roth, South Whitehall Township
Q: Fogelsville has become a hub for New York deliveries and it's not going to get any better. Merging at the ramp from Route 100 to eastbound I-78 is a nightmare. If PennDOT could extend the on-ramp approximately one-quarter mile to intersect the third lane to Route 22 it would virtually eliminate congestion; vehicles headed for 22 would not have to merge at all, and those continuing on 78 would have about two miles in which to do so.
— Jerry Allbright, Lynn Township
A: Continuing the lane of a highway on-ramp from one interchange to the next is an extremely effective traffic-management tool. Traffic flows far more efficiently, but even more important is the tremendous safety gain. An unavoidable conflict point is created at the juncture of every on-ramp and travel lane, and though the design you gentlemen cite doesn't eliminate traffic conflicts completely, it diminishes their frequency, and with it the chance of collision.
We've covered some ground on this issue several times previously, including at your location, Jerry, and in those cases the on-ramp lane flows into the travel lane — it "drops out," as the engineers sometimes say. For several years Upper Macungie Township officials have been talking about the need to continue the lanes on I-78 east of 100, but so far, it's been only that, discussion, according to Joe Gurinko of the Lehigh Valley Transportation Study, a committee that helps PennDOT determine how state roadwork funding should be spent in our area.
"There's nothing in our plans about it, but I know the township has been interested in that," Gurinko said, adding that the topic comes up in the planning discussions from time to time. Extending the lane would vastly improve traffic flow and safety on 78, and in the eastbound direction there appears to be only about four-tenths of a mile's worth of lane missing. The sticker price might be a shocker, but I'd endorse the project, especially eastbound. The westbound dropout occurs well past the split, affording motorists a decent length of straightaway on which to jockey for position. Coming east you're forced to enter the highway from the 100 interchange just as some of the traffic on 78 anticipates moving to the right to access Route 22 at the split. It's the kind of classic merge battle that engineers specifically sought to eliminate in the design of Route 22's new MacArthur Road interchange.
A problem arises in the proposal to add this type of ramp-to-ramp lane between the Route 22 and Route 378 interchanges: Such a lane already exists, in each direction. I can see why it might be confusing, because the hash lines between lanes drop out to denote the area where motorists should merge. But the vast majority of motorists headed for Airport Road north remain on the extended lane between ramps, without encroaching onto the 22 westbound travel lane. Same thing eastbound, and in both directions, yellow signs over each linkage lane indicate "exit only."
Route 22 gets jammed routinely at rush periods around these interchanges not because the linkage lanes are missing, but because the roadway's capacity is overwhelmed even with them in place.
Though helpful, the connector lanes don't eliminate all the difficulties associated with interchange access. For example, motorists on 378 north who are destined for anything other than Airport Road north still need to enter the 22 westbound travel lane. Likewise, some motorists already on 22 west and headed for Airport north need to access our linkage lane. The merge battles are fewer, but they're not eliminated.
Some difficulties are hitched to driver behavior, not highway design. Regional transportation planner Joe Gurinko, who uses these interchanges regularly, noted that turn-signal usage often falls short of optimal, and that some drivers from 378 can appear to be headed straight to the Airport exit ramp, but in reality are trying to pass vehicles on the 22 travel lane to enter in front of those vehicles.
In several visits to check out the dynamics, I also noticed a fair amount of driver confusion. I saw several people moving from the 22 travel lane to the connector lane as though to exit at Airport north, only to shift back to the left almost instantly. One possibility: Their true destination was Airport Road south, the ramp for which is on the other side of the overpass.
I offered Gurinko my view of connector-lane design: that it may not be perfect, but it's definitely prettier than without the extra lanes. "I agree," he said.
The close proximity of the Airport and 378 interchanges likely helped keep the costs of the linkage lanes in low gear. To my experience, the design is rare. Other examples of missing connector lanes cited by fellow warriors over the years include Route 309 southbound approaching Saucon Valley Road/Center Valley Parkway, and Route 22 east to Airport Road south adjacent to the Airport Center shopping area.
PennDOT engineers have defended some of the linkage-less designs as being safer than including the lanes. Despite my lack of engineering expertise, traffic or otherwise, I find that approach to be debatable at best. Merging traffic, especially onto highway lanes, and especially as practiced by the many motorists who seem to think the entering traffic has the right-of-way, not only slows the flow of traffic but poses one of the greatest dangers on the road. Merge points should be eliminated whenever possible.
Road Warrior appears Mondays and Fridays, and the Warrior blogs at mcall.com. Email questions about roadways, traffic and transportation, with your name and the municipality where you live, to firstname.lastname@example.org, or write to Road Warrior, Box 1260, Allentown, PA 18105-1260.