Sunday, December 16, 2007

Analyzing Purple Line Cost Effectiveness

Table 1

Ridership Estimate
Cost Estimate ($million)
TSM 18000
Low BRT 32000
Med BRT 39500
High BRT 43500
Low LRT 39500
Med LRT 43500
High LRT 45500

TSM = Enhanced-Regular Bus, BRT = Rapid-Bus, LRT = Light-Rail

Table 1 shows the ridership, cost, and cost per rider for enhanced regular-bus service and the various rapid-bus and light-rail Purple Line proposals. Remember that ridership is the number of trips. If we assume that most people make a roundtrip on the Purple Line, then the number of people riding it is only 50% of the numbers here (e.g. a ridership of 40,000 is equivalent to 20,000 people making roundtrips).

Enhanced regular bus is by far the cheapest option. I wonder how many more riders would show up if the enhanced-regular bus option were expanded further. While it would clearly carry fewer people, it would also cost much less than the other options in terms of both total cost and cost per rider. The cost per rider for rapid-bus is around 3 to 5 times higher. The cost per rider of light rail is 5 to 6 times higher.

Table 2
Operating & Maintenance Costs ($million) O&M Costs/Rider
TSM 7 389
Low BRT 9 281
Med BRT 9 228
High BRT 8 184
Low LRT 20 506
Med LRT 18 414
High LRT 17 374

Table 2 shows the operating and maintenance costs for each option. Enhanced-regular bus has the cheapest total costs but it is more expensive per rider than any of the rapid-bus options. However, the difference is small enough that enhanced-regular bus still is more cost efficient. Even after 25 years of operation, enhanced-regular bus would still be more than 50% cheaper after taking into account operating and maintenance costs.

Tables 1 and 2 also make clear that rapid-bus transit is clearly more cost effective than light-rail transit. The initial investment required for every light-rail option is more expensive than every rapid-bus option is terms of cost per rider. The comparison becomes even more favorable to rapid-bus if one takes into account operating and maintenance costs in terms of either total expenditures or cost per rider.

No wonder MTA Project Leader Mike Madden, a promoter of the light-rail system, is now playing down cost effectiveness in terms of choosing a plan to submit to the federal government for funding after having previously emphasized competitiveness. The cost effectiveness numbers favor rapid bus over light rail.

Table 3
Ridership Above TSM Cost Above TSM Marginal Cost/Rider Above TSM
Low BRT 14000 380 27143
Med BRT 21500 595 27674
High BRT 25500 1150 45098
Low LRT 21500 1140 53023
Med LRT 25500 1155 45294
High LRT 27500 1580 57455

As shown in table 3, the various Purple Line alternatives attract around 7000 and 13,750 additional people making roundtrips (the equivalent to the 14,000-27,500 ridership numbers in the table) above TSM/enhanced-regular bus. Table 3 also presents the marginal cost of capturing ridership above enhanced-regular bus service.

Put another way, this is the cost of getting the people who would not ride enhanced-regular buses to get on one of the rapid-bus or light-rail transit options. From this perspective, the cost per rider is far higher than enhanced-regular bus. Attracting the people who would not get on the enhanced-regular bus studied by MTA would cost around 5 to 10 times more per trip than each trip on enhanced-regular bus.

The public could not make these calculations for itself at the recent Purple Line open houses because the ridership for TSM (enhanced-regular bus) was listed as "N/A" (see my photograph taken at the open house from the B-CC High School). I got the 18,000 figure for TSM ridership by asking MTA's ridership expert at the meeting what is TSM and what is the estimated ridership.

Remember that these numbers are from MTA and that the data behind the numbers has yet to be revealed to the public or subject to public scrutiny by either supporters or opponents of the various options.