Quote:
Originally Posted by miketoronto
And this brings us to the real issue. It does not matter if you use a heavy rail train or a light rail train for your system. What matters is if the system is grade separated or only operates in the middle of the road, or mixes with traffic, or has to wait at traffic signals, etc.
And the systems that are fully grade separated, regardless of technology, have higher ridership, because the service can offer speed and travel times comparable to the car.
There is an article in Transport Politic, about how the author feels we are going to be kicking ourselves in 20 years for building so much LRT that is not grade separated. Because in the long run, these systems do not offer competitive service to the auto, and ridership will languish because of this.
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I agree with most of what you stated, but not entirely. Calgary light rail transit attracts many more riders than American cities, and its not entirely grade separated.
I'm very familiar with DART and DCTA, and I suggest there are ways to be running light rail trains at grade without speed penalties.
Such as running in an existing rail corridor, or running in a new corridor outside of streets, except crossing the streets at barricaded crossings. As most commuter rail operators do, in their own corridors.
It's only where they enter the streets and run in shared or dedicated lanes in the streets when they see speed penalties - because they don't have barricades protecting them and therefore use traffic signals for protection, where they share the streets with other traffic.
At barricaded crossings, the barricades provide traffic priority all the time - at signalized intersections within the street environment the traffic priority is usually shared with other traffic.
When traveling in their own corridors (not dedicated lanes), trains can run at independent speeds, they aren't limited to the posted speeds of other street traffic.
I therefore disagree that at grade light rail has to be always slower than grade separated light rail.
Now, like DART in downtown Dallas, even running in its own corridor, DART chose to use signalize lights vs barricades. That was a choice they made to go slower, and allow other traffic to move much as it does in the rest of downtown. They didn't want to make a traffic jam by taking priority inclusively. Even their new proposed D2 line will have at grade sections. But that's their choice they made along with their community.
The Green Line northwest of downtown Dallas is basically grade separated from other traffic everywhere except in Farmers Branch, where it runs at grade. Why did DART chose to run it at grade through Farmers Branch? Because that's what Farmers Branch wanted. DART could have ran the Green Line at grade almost the entire distance, without penalties to time using barricaded crossings, because it was using an existing rail corridor. The reason why it was elevated, grade separated in most of Dallas and Carrollton was to reduce traffic impacts to other traffic.
Therefore I also disagree that grade separated rail always increases train speeds.
But I will agree there are locations in any rail line where grade separations is appropriate to increase train speeds and increases the effective speeds of other traffic as well.
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