Median shoulders

[CentralPAGal]

When did having shoulders in the median, whether 4 or 10 feet, become a requirement for an interstate designation? Specifically, I'm wondering about the PA Turnpike Northeast Extension, which received the the extension of the I-476 designation in 1996, while other relevant highways at a similar standard at the time *cough* PA 581 *cough* did not receive a change of designation.

[briantroutman]

To my knowledge, the Interstate design standards have always required a paved left shoulder of at least four feet. I believe there is wording to allow for exceptions due to terrain and high ROW acquisition costs, etc.

As to why the NE Extension was designated as an Interstate despite its design deficiencies, I think it is solely due to PTC having the political will necessary to press the issue with AASHTO and get an approval–and PennDOT on the other hand not having that level of determination in the case of PA 581. And other than the marketability of the Interstate shield, it would make no difference in the case of 581–the state had already footed the bill for construction.

[CentralPAGal]

Thanks!

[froggie]

To my knowledge, the Interstate design standards have always required a paved left shoulder of at least four feet. I believe there is wording to allow for exceptions due to terrain and high ROW acquisition costs, etc.

The exceptions are for the right shoulder and median width, but even in mountainous areas, the design standards require a minimum 4ft paved left shoulder.

[cl94]

According to the Green Book, 4 ft is the minimum regardless of terrain. It always has been. 10 ft is the minimum left shoulder for 3+ lanes. 12 ft is recommended instead of 10 ft if truck traffic is high. The right shoulder can be reduced to 4 ft if there is a long bridge/tunnel or very rough terrain. A climbing lane can also reduce the required width. Of course, some things were grandfathered in and a shoulder was formerly not required on any bridge of any length.

The 10 ft inside shoulder is much newer, but I can't give you a date on that. I'm thinking late 70s-early 80s at the earliest. If this tells you anything, virtually none of New York's system has full-width inside shoulders where the pavement doesn't extend to the median barrier. I-990 is the only example I know of.

As far as median width is concerned, there is also an exception if population density is high or for interior widening, but the 4 ft shoulders must be maintained and a barrier is required under 30 ft, IINM.

[Rothman]

I think it is solely due to PTC having the political will necessary to press the issue with AASHTO and get an approval–and PennDOT on the other hand not having that level of determination in the case of PA 581.

The idea of PTC having more sway than PennDOT at AASHTO doesn't sound feasible to me. 

[cl94]

I think it is solely due to PTC having the political will necessary to press the issue with AASHTO and get an approval–and PennDOT on the other hand not having that level of determination in the case of PA 581.

The idea of PTC having more sway than PennDOT at AASHTO doesn't sound feasible to me.

Because it isn't. The Northeast Extension was likely grandfathered in because it made sense on a national scale and because it was constructed prior to the Interstate system. Note also that the designation happened shortly after the Blue Route made it up to Mid-County. The big thing preventing it from being designated earlier was the Lehigh Tunnel, whose second tube opened in late 1991. As it is now, the shoulders are the only thing making it substandard.

PA 581 was built long after the Interstate system was established (1980s). That likely played a part in why it didn't get grandfathered in.

[briantroutman]

The idea of PTC having more sway than PennDOT at AASHTO doesn't sound feasible to me.

That's not what I was suggesting. I'm saying that securing an Interstate designation seemed to be high priority for the PTC in the case the NE Extension and a much lower priority for PennDOT with 581. Therefore, the PTC had the motivation to pursue the issue vigorously.

PA 581 was built long after the Interstate system was established (1980s).

That's not entirely true. The section of PA 581 that is sub Interstate-standard was planned in the 1950s, constructed at roughly the same time as the adjacent section of I-83, and opened to traffic in 1960. It existed as the unnumbered "Harrisburg Expressway"  until 1992 when PennDOT, apparently having finalized plans for the missing link between the western end of the Harrisburg Expressway and I-81, designated that disconnected segment as PA 581. The remainder of the freeway was constructed in 1995 with 10' inner shoulders and meets Interstate design standards.

Honestly, I don't know whether PennDOT ever applied for an Interstate designation for 581 or whether it was even a consideration. The choice of the number, obviously, suggests that the thought had at least entered their collective mind.

[cpzilliacus]

That's not entirely true. The section of PA 581 that is sub Interstate-standard was planned in the 1950s, constructed at roughly the same time as the adjacent section of I-83, and opened to traffic in 1960.

Heck, most of I-83 in Pennsylvania is (and always has been) badly substandard by Interstate standards.   

Even though much of  it north of York was reconstructed (but none of the design deficiencies were remediated).