Cumulative effect of adding stops on a rail line

Factual Questions
1

I went to UC San Diego in the late 1970s and traveled up to L.A. about once a month, by train. In those days the trip took about 2 hours from Del Mar to L.A., or 2:30 hours from the downtown San Diego station. In those days, they had only three trains in each direction, each day.

Now they have almost hourly departures for the run, and I notice from the schedule that there are three additional stops that didn’t use to be there. And now the entire trip between L.A. and San Diego takes 3:00 hours. Is this likely because of the time lost by slowing and stopping for the new stations?

Or is it just congestion, because there are so many passenger trains as well as the freights, and, in many places, only a single line of track?

2

It’s probably a little of both.

Although trains don’t spend that much actual time in the station, they do lose a lot of time by having to slow down and then accelerate, vs. just traveling through at a constant speed.

In addition, trains must maintain minimum distances from one another. With block signalling, a train cannot enter the next section of track until the train ahead has cleared it. (Or in some cases it must clear multiple blocks before a signal will clear.) If things get too crowded, this leads to less-than-optimum speeds as red signals start propagating down the line.

3

Friedo is right, but it gets much more complicated. Railroad timetabling is one of the black arts.

On the suburban rail network here in Sydney, an electric commuter train will need an additional minute added to the timetable for each extra station it must stop at. “Dwell time” (stopped at station) is only about ten to fifteen seconds of this. The rest of that time is due to braking and acceleration.

Your Californian line sounds like a hybrid system that is running commuters, intercity, freights, you name it. This mixing of different train types is a major headache for timetabling, and is avoided as much as possible in the construction of new railroads. If you look at the cities with dedicated “metro” type commuter networks, you will see that they make very good headways, with the trains running very close together - often only a minute or so apart. They can do this because the signalling system (as described by friedo) is built around a single type of train - and that train is light, and capable of wickedly good acceleraton and deceleration. These trains can get closer together safely. Start putting freighters into the mix - even if it’s only one or two a day - and you need to rejig the whole signalling system. The block sections get much longer to allow the driver of a 3000 ton freight to pull up if he suddenly gets a red signal. Thus the freights become the weakest link, and all other trains must now adapt to them.

Dwell time itself is a whole 'nother kettle of fish. Metro and subway trains are designed for quick dwell times, at the expense of other things such as passenger comfort. These trains have two (or often three) very wide doors. Often up to half the side of the train is made up of open doors when you see one of these at a station. They can transfer people between the train and the platform at a high rate. All this extra space devoted to doors means fewer seats. In many systems, there are only longitudinal seats (to keep the inside of the car open plan for quick passenger movement). Even fewer seating positions! Now, on an intercity train, you don’t want to be standing for two hours, so those cars will tend to have small doors at the end, and comfortable lateral seating. This can involve a jumbo jet type of queue appearing in the aisle as people wait to get out at the station. In addition, people on these routes are trying to manhandle bulky luggage whereas the downtown commuters are not. Then there are things you wouldn’t even consider: how long is the roof on the platform? Does it run the full length of the platform, or is it a mean little forty foot long affair in the middle? If the latter, watch what happens on a wet day. Waiting passengers will crowd in one spot. When the train arrives, they will all attempt to get into the same one or two cars, resulting in queuing. Do last minute people try to run at the closing doors? There’s another ten seconds wasted as the conductor must repeat the whole procedure of giving the engineer the all clear. All this stuff has a significant effect on timetabling when multiplied by the number of stops.

You may find that the actual line speed limits are lower than they were in the 70s. Maybe funding cuts have made the line substandard and there are speed restrictions on certain sections. Here in Sydney, the speed limit over switches has been drastically cut. Not because the trains can’t handle the former higher speed with absolutely no danger of derailment, but because these days people are more likely to sue, and passengers being jostled on Sydney trains have done just that. This also applies to hard acceleration and braking. Engineers used to do this to make up time (or to keep to unrealistic timetables), and now they are scared to. They used to creep up over the speed limit a bit to, but no more. There are actually passengers who use GPS equipment to see if the engineer is speeding, and will then report him. The railroad companies themselves use police style lineside radar to catch speeding trains. They are too scared of their insurance premiums now. As you are in California, the litigation side of it is probably even worse.

The insurance and litigation side is almost definitely a factor. The technical stuff I mentioned earlier may be, but I don’t know what the situation was in the 70s compared to now. Some things may have changed either way, others probably haven’t. They are definitely variables to consider though. Timetabling is a very, very complex thing.

I would say the

4

…last sentence is a fragment, and I forgot what I was going to add. :smiley:

5

Thanks for your detailed answer. You are basically correct in this supposition; the trains are indeed used by some commuters, but they’re still basically regular short-run intercity trains. This means that station stops tend to be at least five minutes if not more.

This being America, the nationalized passenger rail company doesn’t own the tracks, but leases permission to run their rolling stock over them, which are owned by the freight companies. Naturally the freight companies give priority to their own trains.

As I mentioned, there’s only a single line for both directions, in many places; it’s remarkable that there hasn’t been a horrible accident, what with the amount of traffic there is. I’m told it’s one of the few Amtrak runs that actually makes money.