|
|
| Canarsie Tunnel Single Track Operation (1500391) | |||
 |
|||
| Home > SubChat | |||
|
[ Read Responses | Post a New Response | Return to the Index ] |
|
||
|
Canarsie Tunnel Single Track Operation |
|
|
Posted by Stephen Bauman on Fri Jan 18 16:34:06 2019 The Canarsie Tunnel ran single track the last 4 midnight hours. This was to permit tunnel inspection.One big "if" regarding the no closure plan is how well the MTA can handle single track operation. If the last 4 nights' experience is any indication, the answer is not well at all. I captured the operation from the real time feed and present it as a spreadsheet that you can download. The spreadsheets show the data as schedules, with one sheet per day. Each day has 4 schedules: plans & results Manhattan bound; plans & results Brooklyn bound; plans Manhattan bound and plans Brooklyn bound. The plans for Tuesday and Wednesday (20190115 and 20190116) are basically the same. A Manhattan bound train will approach Lorimer St at 10, 30 and 50 minutes past each hour. These trains will depart Lorimer 30 seconds later. These trains will arrive at Union Sq at 17:30, 37:30 and 57:30 past each hour. Simultaneously, a Brooklyn bound train will arrive at Union Square at 17:30, 37:30 and 57:30 and depart 30 seconds later or 18, 38 and 58 minutes past each hour. These trains will arrive at Lorimer at 28, 48 and 08 past each hour. The Manhattan arrivals at Union Sq permit the Brooklyn bound trains access to the single tube with a 30 second buffer. The Brooklyn arrivals permit the Manhattan bound trains access to the same single tube with a 2 minute buffer. How did it work? On the 15th, the first Manhattan bound train was supposed to arrive at Lorimer at 00:10:00; it actually arrived at 00:06:52. It left Lorimer at 00:07:29 instead of 00:10:30. It arrived at Union Sq at 00:16:52 instead of the scheduled 00:17:30. How did it arrive early at Lorimer? It would appear that the scheduled travel time between stations between Myrtle and Lorimer are padded. The train made up the extra time there. The second Manhattan bound train was supposed to arrive at Lorimer at 00:30:00 and arrived at 00:29:52. It left at Lorimer at 00:30:29 instead of the scheduled 00:30:30. It arrived at Union Sq at 00:38:52 instead of 00:37:30. The train took too long traveling between 3 Av and Union Sq. Its late arrival was enough to make the Brooklyn bound train late. The world caved in on the third Manhattan bound train. It arrived 6 minutes late at Lorimer, 00:56:07 instead of 00:50:00. How? It left Canarsie 4 1/2 minutes late: 00:29:29 instead of 00:25:00. That was the ball game on day 1. The schedule was knocked out in the first inning on day 2 (20190116). The first train arrived 1:05 late at Lorimer because it nearly 2 minutes late leaving Canarsie: 00:06:27 instead of 00:05:00. Not to be outdone, the second train was 3 minutes late leaving Canarsie. The strategy changed on day 3. Manhattan bound trains arrived at Lorimer at 04:30, 24:30 and 44:30 past the hour. They left 30 seconds later and were schedueld to arrive at Union Sq at 15:00, 35:00 and 55:00 past the hour. The Brooklyn bound trains were scheduled to arrive at Union Sq at 15:30, 35:30 and 55:30 past the hour and leave 30 seconds later. These trains were scheduled to arrive at Lorimer at 03:30, 23:30, and 43:30. This provided a 1 minute buffer at Lorimer and 2 minute buffer at Union Sq. Lightning struck again on day 3. The first train was 2 minutes late leaving Canarsie and the second was 3 minutes late. It did not get better on day 4. The Manhattan bound train was only 1:14 late on arriving at Lorimer. It was 1:37 late leaving Lorimer and 2:14 late arriving at Union Sq. This delayed the Brooklyn bound train 2 minutes 7 seconds, even though it was 29 seconds early on its Union Sq arrival. |
|
|
|