Who Sets Speed Limits?

Townbank Road cuts nearly straight across Lower Township, running from Seashore Road to the Delaware Bay, through neighborhoods, woods and past one of Cape May County’s first commercial wineries.
For most of its length, the posted speed limit is 45 mph, dropping to 40 mph near the bay. Lower Township Council says that’s too fast.
In March, the township approved a resolution asking Cape May County to reduce the speed limit, kicking off a process that includes traffic studies and recommendations from experts.
According to county Engineer Robert Church, once a traffic study is completed, if the results warrant a change in the speed limit, a resolution will be brought before the freeholders and, if approved, the new limit will be posted. 
You Can’t Always Get What You Want
Sometimes, residents seeking a change in the speed limit receive unwelcome news. Several traffic engineers contacted for this story described a similar process for determining the correct speed for a roadway: Measure the speeds drivers are already traveling.
According to Church, if a resident wants to change the speed limit on a county road, the first step is to bring that request to the municipal governing body. If the local body agrees and approves a resolution, like Lower Township Council did, the county begins a study.
“Several factors are considered, however, speeds are typically established primarily based upon the nationally accepted practice that drivers will travel at a speed that they judge to be safe and proper,” Church said. “Thus, although drastic speed reductions may be the objective of residents, the degree which a posted speed can be reduced is tempered by the reality of driver tendencies.”
In other words, if most people on Townbank Road are already driving 45 or 50 mph, the traffic study is unlikely to recommend any change.
Paul Dietrich, Upper Township’s municipal engineer, said residents are sometimes surprised when a traffic study ends up with a recommendation to increase the speed limit. One irony, Dietrich said, is that while it is usually the residents of a neighborhood who want to see speeds reduced, it’s just as likely it is their neighbors, the other residents, who are driving faster than they’d like.
“The rule of thumb is it should be 25 (mph) in front of my house, 40 (mph) in front of yours,” said Doug Bartlett. He’s now with MBO Engineering, a firm in Bordentown specializing in traffic safety engineering. Before that, he spent more than 37 years with the state Department of Transportation (NJDOT), almost all of that time working in traffic engineering.
In a recent interview, he said questions of speed limits took up more of his time than any other task.  
Who is the 85th Fastest Driver?
Residents often want the slowest speed possible in their area. But according to traffic engineers, most drivers operate at a reasonable speed of their own accord.
In New Jersey, the maximum speed allowed is 65 mph, along multilane limited access roadways like the Garden State Parkway. Most other roads are presumed to have a speed limit of 50 mph. Otherwise, residential zones and business areas drop to 35 mph, with 25 mph for school zones.
Other speed limits can be used, in increments of 5 mph, but to do that requires a traffic study.
Bartlett, Dietrich, and Church each described the same systems for determining speed limits, starting with a traffic expert and a radar gun. Set up the gun on a straight section of roadway, away from obstacles, where the traffic flows freely and gather data on how fast cars are driving. The car should be unmarked and unobtrusive, Bartlett said, because if drivers believe it to be a police officer, they will slow down.
While most drivers are reasonable, some are just reckless. Think about that friend whose driving has you bracing at every lane change and closing your eyes on the sharp curves. The engineers account for the outliers in a couple of ways.
One method is called the 85th percentile speed, the speed below which 85 percent of the drivers operate. That way, if 15 percent of the drivers like to pretend they’re Formula One drivers chasing a championship, it won’t increase the speed limit on the roadway.
Another method takes the range of 10 mph in which most of the traffic falls. For most roads, a graph of the speeds traveled would present a bell curve, with a small number going very slowly and a small number whizzing by, but most drivers falling between the extremes. Take the range of 10 mph right at the center of the middle and set the speed limit at the top of that speed.
“Now, it’s always going to be an oddball number,” Bartlett said. The average speed is likely to be 48.3 or 37.8 mph, something that would not make sense on a sign. He said he’d be suspicious if it were to come out nice and even. So the speed limit would then be set in 5 mph increments, with the speed rounded down. 
Designed for Speed, or the Opposite
Those little white signs on the side of the road have far less influence than most people expect.
“It’s clear that the roadway determines the speed,” Dietrich said. When there are sidewalks, close-set houses, narrow lanes or cars parked on either side of the road, experienced drivers naturally slow down with or without a speed limit sign. Where the road is wide open and straight, they tend to accelerate.
Engineers can encourage that process. For instance, downtowns can use “bump outs” to bring sidewalks closer to traffic lanes at crosswalks, or use speed humps or roundabouts in neighborhoods where drivers may otherwise hit the gas.
On wide streets, a planted median strip can lead to slower driving, like in Avalon along Dune Drive, where there are miles of straightaway, more than 100 feet between sidewalks and a posted speed limit of 25 mph. A bike lane and a long stretch of green help keep drivers from assuming it’s a speedway.
Otherwise, Dietrich said, the only way to consistently slow traffic is enforcement. When police start writing tickets, word gets around fast. Anyone who’s gotten a speeding ticket is likely to stay right at the limit in that area for years to come.
Consider the foot of the Roosevelt Boulevard Bridge at 34th Street in Ocean City. Drivers entering the city have just come off a 45 to 50 mph road and are coming downhill off a bridge. The road opens up to two lanes, with marsh to the left and a wide, planted median to the right, separating the houses from traffic.
For most experienced drivers, nothing seems to require slowing down except for two things, a small, probably unnoticed 35 mph speed limit sign and the knowledge there is often an Ocean City Police traffic safety unit officer with a radar gun parked on a patch of gravel on the side of the road up ahead.
Most cars slow down. 
Need for Speed
According to Church, a qualified engineer may consider other factors in determining a speed limit. A history of crashes in an area, the number of side streets or residential or commercial driveways entering the zone can be taken into consideration, along with the presence of senior centers, on-street parking or heavy pedestrian use of an area.
But even in those circumstances, the change is usually only 5 mph or a 10% reduction in speed at the most.
In some instances, towns have gone ahead and lowered speed limits on local roads despite what the traffic engineers have determined, only to see any speeding tickets successfully challenged in court. 
Traffic Speed Libertarian
For many drivers, what’s supposed to be the speed limit turns out to be the speed minimum, especially on highways. Those with any doubt can try driving 65 mph along the Parkway for the length of Cape May County and count the cars that pass.
One Monmouth County legislator wants to scrap that 65 mph limit entirely.
State Sen. Declan O’Scanlon, a Republican representing the 13th District in Monmouth County, has introduced a bill he calls the Speed Limit Sanity Act, which would require New Jersey rely on the 85th percentile method to set speed limits on limited access roadways.
“It would take the setting of speed limits away from legislators and leave that determination in the hands of the people that know what they’re doing; the traffic engineers,” O’Scanlon said. “We’re not talking about secondary roads, but some ought to be there, too.”
He does not want to abolish speed limits, O’Scanlon emphasized, but he said they are often set by politicians based on little more than a hunch.
But if drivers already assume they can travel 10 mph over the speed limit, wouldn’t that mean downright dangerous speeds if the limit is raised to 75 or 85 mph? O’Scanlon said he rejects the premise of the question. For proof, he points to an NJDOT study that found almost no difference in highway speeds when New Jersey went from 55 to 65 mph. In 1973, in an attempt to save fuel in an oil crisis, the federal government set a national speed limit of 55 mph. After that law was finally scrapped in 1995, New Jersey decided to increase the maximum speed on some highways to 65 mph.
An 18-month study found the change increased speeds by negligible amounts, with the difference amounting to 3 or 4 mph.
According to O’Scanlon, the most dangerous moment on a New Jersey highway is when drivers hit the brakes when they see a state trooper. Traffic engineers support the assertion.
In a recent interview, Bartlett said the safest traffic pattern is when vehicles are all traveling similar speeds in a free flow of cars. Cars hitting the brakes or maneuvering between lanes to pass slower moving vehicles presents far more danger, he said.
Cape May County is familiar with that effect, after years as the only section of the Garden State Parkway with traffic lights. Stopped traffic had resulted in horrific collisions before the overpasses were completed.
O’Scanlon believes setting the speed limit at the speed most drivers would decide to travel anyway will result in fewer tickets, more compliance, and safer roads. And while local traffic engineers say they rely on that method, he has doubts.
“That’s what they say, but it isn’t what really happens. They’re under political pressure. When the mayor who employs them says the limit should be dropped, you know what will happen,” he said.
Drivers would have more respect for speed limits if they knew they made sense, O’Scanlon argued.
“Right now, speed limits don’t mean anything,” he said.
Traffic studies for Townbank Road are being evaluated by a consultant now, Church said. It could result in a resolution being brought to the freeholders.
“Once the study is prepared, if it warrants a change in speed, we adopt a resolution to memorialize the change, then re-post the speed,” Church said.
To contact Bill Barlow, email bbarlow@cmcherald.com.