BUSY ROAD:Garden State Parkway’s Amazing Feat

Oh dear, we wondered for a moment, had some statistician from the Transportation Research Board got into the NJHA accounts department? The guy who rated all the NY Hudson River toll crossings in print a couple of years back at about the traffic flow on 2-lanes of Wisconsin Avenue NW outside the TRB building perhaps? Then the penny dropped. These guys don’t mean what they write. They don’t mean vehicles traveling the road in 1998. They mean trips on the road in 1998.

Joseph Buckelew chairman of the board of the NJHA in his letter to Gvnr Christie Whitman at the front of the report claims that there was a 5.4% increase in traffic on the parkway in 1998 over 1997 and says this is “proof that New Jersey’s reputation as a vibrant economic engine for the region is well founded.”

Good stuff, but where does this 5.4% come from?

Trips on a barrier system

How would they would measure those 390.2m trips since GSP’s a barrier system, a mix of mainline plazas and ramp plazas, and quite a bunch of ramps without any tolls at all. You’d have to have some method of identifying every vehicle as it enters and leaves – in effect a trip toll system like the NJHA’s sister agency the NJ Turnpike in order to measure trips and trip lengths. If you had good vehicle counters at all the entry and/or exit ramps you’d get a measure of trip numbers but that would give you no idea of trip lengths.

We’re told, sure, this is an old toll road, and even modern roads have trouble keeping those troublesome inductive loops working at 90% accuracy, so no way can they actually count trips. Turns out that four times a year they mobilize rubber tubes and other vehicle count devices to get counts at all the ramps and they claim to have a solid four days of trip counts and from that they make an estimate of annual traffic. But given the day by day fluctuations to produce that 390m number from just four days data is very much an estimate, not a count or a measurement.

Well I don’t think anyone would be sent to jail for being a few million out in trip estimates but you might get put there for being a few thousand out in accounting for toll transactions. The NJHA collected 576,187,200 tolls, they report, an average of almost 1.6m/day. It is up there with the Illinois system as doing the most toll transactions in the country. Toll revenue in 1998 was up 2.8% to $184m, for an average of 32c/toll. The Pwy’s tolls are generally 35c at the barriers and 25c at the ramps.

But what’s happening here?

If toll revenue was up 2.8% and trips were up 5.4% then there has been a decline of 2.5% (1028/1054) in toll revenue/trip. The Authority was only collecting 47c/trip in 98 compared to over 48c in 1997. Why is the per-trip revenue in decline?

A little more skimming? More driver bolt-throughs to avoid the toll? No, says the authority. Minimal. Though, we interject, one of silliest arrangements imaginable is a state of NJ law which denies the NJHA revenue from violators fines. Talk about an institutionalized perverse incentive not to do their job of enforcing tolls.

Faster Growth in Untolled Sections

We wondered if the sampling error in the trip estimate might account for much of the discrepancy? Especially as they report gallonage of fuel sold on the pwy rose 2.2%. Officials insist that “absolutely” the 5.4% increase in trips is a solid estimate. (Do have absolute faith in the judgment of people who write that they had half the world’s vehicles on their road last year? Still have visions of millions of tiny mini-Fiats jostling for position on the GSPwy with the the Voyagers, Explorers and Accords...)

They weren’t definitive but they point out that 20% of total trips on the parkway are in sections without tolls, especially in Monmouth and Ocean counties. And these tend to be areas of greater development and growth in traffic. So it appears the decline in revenue per trip may in part be accounted for by increasing use of the untolled sections of the parkway.

The annual report says that “the average customer pays 1.48 tolls per trip” (576/390). But apparently there are about 312m toll trips (390x0.8) if 20% of trips are in free sections of the road, so average tolls/tolled trip are 1.85. By a slim margin there are fewer stops on average than there would be under a trip toll or ticket system.

The report says that the average trip length was 25km (15.7mi) for 9.6b veh-km traveled. Those have to be extremely iffy numbers. Trip numbers themselves tell you nothing about trip length. The NJHA apparently relies on periodic origin-destination survey data for indications of trip distance, and they only do those about once a decade and it is tough to get a representative sample of trips anyway... the people who fill in those forms are hardly likely to be typical riders.

Well help is coming. As electronic toll transponders proliferate (and NJHA patrons will be getting them in about a year) it will be rather simple to do entry and exit matching and to gather higher quality data by making use of supplementary ramp readers.

Construction

The NJHA’s pride for 1998 was a new connector ramp GSP-south/I-80-east IC-159 in Saddlebrook which opened Jan 99. This direct connector is greatly appreciated by patrons from the north traveling toward the Geo Washington Bridge. It’s an elegant compound curve trapezoidal steel box girder 244m long, the first of its kind in the state, and supervised by NJHA engineers. The concrete deck and parapets use stainless steel rebar. Their attention is now on the twinning and rehab of the Driscoll Bridge over the Raritan River in Perth Amboy, serious work to upgrade IC-142 in Union city where the Pwy crosses I-78 where two movements were never built. Probably a $30m project. Design and permiting work proceeds for widening 85km of the southern section of the Pwy from IC-80 at S Toms R to beyond Atlantic City at IC-30, a new IC-89 at NJ-528 Cedar Br.

And the NJHA is involved in discussions about a role in completing the 30km missng link in the NJ-55 Philadelphia-Cape May. The motorway presently peters out south of Millville and there are plans to extend it to the GSPwy at Clermont.

Toll authorities support some bizarre sideline activities (the Triborough Authority’s NYC subways for example) but the NJHA owns a concert hall. Though privately operated it earns the Authority rent ($650k), an excuse for NJHA to enliven its annual report with pictures of a couple of gorgeous women who entertained during the year. Tolls produced the $184m, 8 service plazas $13m, and overall revenues were $202m. Toll collection cost $37m (78% tolls were automatic coin machine 22% collectors), policing $22m, maintenance $36m and admin $26m, for total operating expenses of $122m to produce an operating surplus of $80m. It retired $16m in bonds, paid interest on bonds outstanding of $34m, added $30m in capital improvements to the parkway, and paid a regular $10m (a kind of dividend) to the state government which owns it.

Deaths

The NJHA reports its 1998 death rate at 0.64/100m veh-mi, the second lowest in its history, apparently 38 deaths. That in a year in which the posted speed limit was raised from 55mph to 65mph. They say it is speed variance and inappropriate speed, not speed as such that kills, and maybe the higher speed limit helped reduce speed variance.

Like most toll roads the GS Pwy is safer than the free interstate system by somewhere between a quarter and a third - given that interstate deaths run about 0.8 to 0.9/100m vmt nationwide. Urban interstates run deaths of 0.6 and rural 1.2. We assume the GSP is about half rural and half urban so it should be compared with the composite. Turnpikes seem to be significantly safer because of... a little better performance in maintenance, in pavement markings, debris removal, deicing, signing, buffering of off-road obstacles, lighting, better median barriers, and policing. Maybe they attract better vehicles, and a higher class of patrons?

Who really knows why, but the numbers are there again and again: TOLL ROADS SAVE LIVES relative to free-ways. (Contact Dennis Ingoglia NJHA 732 442 8600x1/6503)