Comment 118727

By Haveacow (registered) | Posted May 20, 2016 at 12:09:07

2 things to add and or correct.

Most or nearly all conventional railway vehicles (electric or diesel powered) do accelerate slower than a bus or car! That is because rubber tires on asphalt or concrete have more friction. More friction vehicles accelerate faster. It takes however a lot more power to accelerate them because of that friction. Steel wheels on steel tracks have a lot less friction thus take longer to accelerate but require significantly less power. This is the incredible advantage of the rail vehicle especially with heavy freight. One of the earliest guides to by from the early 20th century went something like this. Let me paraphrase here, a train is considered functional if, 1 horsepower can move 1 ton of cargo at 1 mph for every ounce of fuel, without a increase in fuel use, greater than this ratio! This basic relationship is why even today rail is used for moving cargo.

I will try to be brief on the next subject, you can wright entire books about this subject and many have. I have worked with projects in both LRT and BRT planning.

As long as a planned BRT system has a passenger carrying capacity that is similar to most conventional LRT projects passenger carrying capacities then yes, they both are actually comparable to each other. This is the reason a private or physically segregated right of way for the BRT projects is often needed so it can to be competitive with LRT. Painted lines on the road do offer some increase in passenger carrying capacity over general mixed roadway use but have a much lower upper limit than a physically segregated right of way. This subtle but giant difference is often forgotten by most BRT proponents when comparing it to LRT!

But there is an upper limit to what BRT in a North American operating environment can handle, due to its very steep escalating operating cost scale compared to LRT. Once BRT peak hourly passenger levels start exceeding certain levels (different for every system but usually 5000-7500 p/h/d or about 80-100 buses/h/d)the BRT infrastructure's limitations and multiplier effect on operating cost take hold and start to seriously effect system wide operations and planning. This operating cost limit is why Ottawa is switching now to LRT on the Central Transitway but many other Transitway sections will remain Bus only.

Lastly, for LRT supporters and BRT supporters, once you have a well operating system proper system operations features make further basic comparisons difficult. BRT systems can do certain things operationally that LRT just can't do and must be operated like a BRT system not a LRT system with Buses. Thus LRT systems can do certain things that should never be attempted by BRT systems. The common myth that BRT and LRT systems are similar and can be successfully operated the same way, don't hold past this point. They are not the same and will require technology specific experts for both types of operations for continued success in both. I give you this last piece of advice, you can forgive politicians if they say even after a few years of operations that, "BRT is just like LRT but only cheaper", if your operating experts continually say this publically, run for the hills!

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