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49 TABLE 42 The National Renewable Energy Laboratory (NREL) KING COUNTY METRO TRANSIT 40-FT BUS SUB-FLEET using Metro Transit's newest low-floor articulated buses, Fleet ID Model Propulsion Year No. conducted a recent evaluation of hybrid technology (32). The 3600 D40LF Diesel 2003 100 buses were identical except for the propulsion system; the test 9000 Phantom 40 Diesel 1999 6 fleet was made up of 20 hybrid articulated buses and the con- 3200 Phantom 40 Diesel 1997 210 trol fleet 20 diesel articulated buses. The test period was 12 months, and the service routes and vehicle-miles of the test and control fleets were similar. A summary of the evaluation ridership Express routes. The average age for the articulated results is given in Table 45. fleet buses is 5.5 years and for the 40-ft fleet buses 8.1 years. The evaluation results show a significant improvement in Maintenance data for 2006 were obtained for both the fuel cost (17 cents per mile) with only a small increase in the articulated and 40-ft fleets. The annual miles traveled per bus maintenance cost of the hybrid propulsion system (1 cent per ranges from 35,000 to 37,000 (see Table 43). mile) when compared with the diesel control fleet. The loss of passenger seats when changing from standard These findings, in combination with the findings in chap- floor to low-floor bus design is apparent in Table 43. For the ter four, indicate that hybrid propulsion technologies offer a seating arrangement chosen by Metro Transit, one low-floor promising approach to overcoming some of the concerns articulated bus is equal to approximately 1.6 low-floor 40-ft expressed with respect to articulated buses, in particular, buses on a passenger seat basis. Comparing the standard floor with respect to the issues of acceleration and fuel economy in models, the factor would be 1.5. The weighted average for all frequent stop-and-go types of operations. sub-fleets is one articulated bus is equal to 1.57 40-ft buses on a seat basis. If one applies those factors to the operational data in Table 43, an operational cost on a passenger seat basis SAFETY ISSUES is obtained and the results are given in Table 44. Safety Considerations Related to Higher Capacity Buses On a seat-mile basis, the articulated fleets are less costly than the 40-ft fleets in both maintenance costs and fuel. Any The operation of HC buses does not appear to create signif- comparisons of the road call experience is complicated be- icant safety concerns. However, two considerations related cause the average age of the total articulated fleet is approx- to safety were identified. The first concerned double-deck imately 2.5 years less than the total 40-ft fleet. buses and the potential safety concern created by the interior TABLE 43 KING COUNTY METRO TRANSIT OPERATIONAL DATA FOR ARTICULATED AND 40-FT BUS SUB-FLEETS Maintenance Cost Miles Between Fuel Economy Fleet ID Propulsion Seats ($/vehicle-mile) Road Calls (mpg) 2600--Articulated Hybrid 58 0.7103 5,628 3.5 2800--Articulated Diesel 58 0.7198 4,424 2.4 2300--Articulated Diesel 64 0.8352 4,123 3.4 Weighted Average 61.2 0.7768 4,763 3.4 3600--40-ft Diesel 35 0.5846 5,069 4.1 9000--40-ft Diesel 42 0.3829 9,552 5.1 3200--40-ft Diesel 42 0.6000 6,494 4.5 Weighted Average 38.9 0.5775 7,539 4.5 Source: King County Metro Transit. TABLE 44 OPERATIONAL DATA COMPARED ON A SEAT-MILE BASIS FOR METRO TRANSIT SUB-FLEETS Maintenance Cost Seat-Miles Between Fuel Economy Fleet ID Propulsion Seats ($/seat-mile) Road Calls (seat-miles/gal.) 2600--Articulated Hybrid 58 0.0122 203 2800--Articulated Diesel 58 0.0124 139 2300--Articulated Diesel 64 0.0130 218 Weighted Average 61.2 0.0126 7,478 207 3600--40-ft Diesel 35 0.0167 143 9000--40-ft Diesel 42 0.0091 214 3200--40-ft Diesel 42 0.0143 189 Weighted Average 38.9 0.0142 7,539 182