IMO, the monorail at EWR is a cute relic from a world fair, or disney world. You can almost see the animitronic characters and the monotinous, family friendly music, conveying the message that in the future, we will all ride on monorails!
In practical terms, the Newark Airtrain is an isolated, limited system. Its sort of the next step up from a moving walkway; but travel on the airtrain should be measured in feet, not miles.
At Philadelphia International, the Septa regional rail tracks run right up to the terminals, stopping at A, B, C-D and E-F. Then the train runs miles and miles away from the terminal. Most riders get off at 30th street station, or one of the other downtown stations, but they keep going into the northern suburbs (typically terminating at Warminster or West Trenton, NJ). Conversely, the trains also collect outgoing passengers from a large area on their way in. Since the lines are built to regular railroad gauges, electrification and standards, Amtrak has in the past run trains directly to the terminals as well.
The next step in bringing this usefulness to EWR, would be to extend PATH not only to the Amtrak/NJT station, but to loop around through the terminals as well. Imagine going from baggage claim, up an escalator, and onto a PATH train, directly to Manhattan. With this upgrade, I can easily see Amtrak eliminating EWR as a stop altogether, and anyone who wishes to transfer can take the PATH from Newark Penn to their terminal.
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