Single Versus Multiple Vehicle-type Fleet

Introduction
Single Vehicle-type Fleet:
Multiple Vehicle-type Fleet:
System Implications:
Conclusions

Introduction

Given the different network components which together make up the TMP rapid transit network, discussion is warranted as to whether Ottawa should acquire a fleet consisting of a single vehicle-type which can operate over the whole network or a fleet consisting of multiple vehicle-types selected to match different corridor requirements. Based on the eventual size of the rail transit fleet needed to support the TMP rapid transit network, even if a single vehicle-type is adopted, should procurement be restricted to a single supplier to maximize standardization, or expanded to multiple suppliers to increase competition? Key issues to consider include:

• System Implications
• Cost (capital and operating)
• Maintenance
• Operational flexibility
• Compatibility and Future-proofing

Network planning issues will play an influential part determining whether a single or a multiple vehicle-type fleet should be acquired. The TMP rapid transit network is made up of “primary” and “supplementary” corridors, which serve different but overlapping purposes:

• Primary corridors generally serve longer distance commutes from suburbs to downtown or across town. They are primarily fully segregated from other traffic with stations spaced further apart to allow for faster travel times and greater capacity. Vehicles will often be connected into longer trains to provide capacity and minimize operating costs;
• Supplementary corridors provide connections to the primary corridors at key transfer points and support adjacent development along the length of the corridor. They run primarily in partially or un-segregated rights-of-way, with stations spaced closer together. Single vehicles are often used to match capacity to demand but also to respond to limitations on mixed traffic segments of the corridors.

While there are rail vehicles available with the ability to satisfy the different demands and requirements of the primary and secondary rapid transit corridors, the secondary corridors are more likely to impose a greater number of restrictions on other technology decisions (e.g. signalling, power collection) as these corridors will be more closely integrated with their surroundings and there will be the potential for greater interaction between rail vehicles and other travel modes.

Single Vehicle-type Fleet

A fleet made up of a single vehicle-type would be the most straightforward approach and would likely be used in the initial stages of the development of the TMP rapid transit network, while only one or two lines are in operation. If a single vehicle-type fleet is pursued, the vehicle selected must be capable of running on all of the corridor segments that make up the rapid transit network, now and in the future.

Advantages

• Can be planned better
• Training costs are lower
• Problems can be identified and fixed fleet wide
• Better purchasing power for operator
• Known characteristics
• One vehicle type means that knowledge and expertise is focussed on one system

Disadvantages.

• Large retirement costs
• Technology can date
• Kills competition and therefore works against operator in the long term
• Supplier can inflate spare parts costs
• Risk of obsolescence within fleet

Distinction needs to be made between a single vehicle with a “standard” set of technologies (e.g. one power collection system) versus a single vehicle-type which can accommodate multiple technologies (e.g. more than one power collection system). A standard vehicle would likely be cheaper to acquire and operate, while a vehicle incorporating multiple technologies could provide greater operational flexibility and allow for special corridor treatments (e.g. alternate power supply technologies in visually-sensitive areas).

Should a single vehicle-type be preferred, additional consideration needs to be given to whether or not the fleet should be acquired from a single vehicle supplier, or from multiple suppliers. This may limit the ability to provide solutions that require use of proprietary technologies but address issues with respect to competition and retirement costs. This is in essence a similar approach used by OC Transpo with respect to the existing bus fleet, which is made up of vehicles supplied by several different manufacturers. Regardless of whether a single vehicle-type is acquired, the design of the rapid transit system should be able to accommodate a range of vehicle-types, as discussed further below.

Multiple Vehicle-type Fleet

A fleet made up of multiple vehicle-types would be more complex to acquire and operate but may be required, should the City decide that different (non-compatible) technologies are required to operate the primary and secondary rapid transit corridors. If a multiple vehicle-type fleet is pursued, the vehicles selected would only be matched to the specific corridors requirements of the line they would operate over, and could be specialized to take advantage of technology solutions which increase the capacity and speed of the system (e.g. Automatic Train Operation) or address specific issues (e.g. ground level or inductive power collection in visually sensitive areas).

Advantages

• Flexibility in matching demand to the specific corridors for streamlined operation
• Increases competition in manufacturers
• Ensures latest technology is in place
• Major problems don’t ground the whole fleet

Disadvantages

• More training required
• More equipment required for different vehicle types
• Multiple vehicle maintenance and storage facilities may be required
• System sizing based on one type (i.e. newer vehicle may have different power requirements)
• Possible incompatibility of fleet vehicles (including inability to run all vehicles over all tracks)
• Vehicles sizes, performance are different affecting platform lengths, stopping distances and infrastructure
• Requires better specifications and standards to be written
• Knowledge requirements increases with every new vehicle type added

It is noteworthy that development of a multiple vehicle-type fleet is likely to occur over time whether a single vehicle-type is pursued initially or not. The core of the network would likely use one technology, with the subsequent development of secondary corridors using a separate technology.

Some cities, such as San Francisco, have adopted a policy of multi-vehicle fleets to handle the local terrain and market. Cable cars and trolley buses are used for the steep hills; historic PCC streetcars for a scenic waterfront route and to provide local service over the market Street corridor, LRT and metro vehicles for the major routes and a variety of buses for other routes. The variety is part of the attraction to the city and allows for service to match needs to a high degree.

Other cities try to minimize the number of vehicle-types to reduce maintenance issues, provide customers with a few consistent experiences and allow for maximum flexibility to redistribute equipment to respond to changes in demand levels. Cities with subways and commuter rail operations often select one vehicle type for their major systems.

System Implications

Choosing either a single or multiple vehicle-types will have implications to the design of the rapid transit network. Given the range of technology decisions required, it is possible that technologies which are not wholly compatible will be selected, particularly if a multi-vehicle fleet is pursued. For instance, high-floor and low-floor vehicles have different maintenance requirements due to the completely different location of mechanical and electrical components. This would require construction of either two separate heavy maintenance and storage facilities, or the construction of a single larger facility capable of handling both vehicle-types.

Should a multiple vehicle-type fleet be pursued, the design of the rapid transit network infrastructure will be impacted by different vehicle-types that may have differing infrastructure requirements, affecting elements such as:

• Track profile, curve radii, gradients, switch loads and speeds
• Structural clearances
• Crash protection requirements
• Power supply sizing for different electric loads
• Platform width and height

Generally, however, vehicles of the same vehicle-type (e.g. metro, LRT, heavy rail) are compatible with one another in terms of infrastructure requirements.

The importance of maintaining appropriate requirements in the design of the rapid transit network is illustrated by the current issues facing the Toronto Transit Commission with respect to the Scarborough Rapid Transit line in Toronto. The infrastructure of this line was tailored to meet a specific vehicle-type, which is now obsolete. As the current vehicles are nearing the end of their service life, the TTC is faced with either retrofitting this line to accommodate newer (larger) vehicles using the same technology or changing the technology used completely. Either course of action is anticipated to require closure of the line for a considerable amount of time and cost a significant amount of money.

Conclusions

If a single vehicle-type is pursued, the least restrictive (partially or un-segregated) right-of-way in the rapid transit network will therefore govern technology decisions with respect to signalling, power collection and automatic train operation. Acquisition of a single vehicle-type which can accommodate multiple technologies (e.g. in-ground and overhead power collection) to address some of these issues can be pursued but will likely increase vehicle costs and may have some risks associated with vehicle development if off-the-shelf solutions incorporating the multiple technologies required are not readily available.

If multiple vehicle-types are pursued to provide different solutions for the primary and secondary rapid transit corridors, design standards can be tailored to specific technology requirements of each line and the most appropriate vehicle technology applied in each situation. This represents a more complex and potentially costly approach as the needs of different corridor may result in the acquisition of a fleet of incompatible vehicle-types with different operating and maintenance requirements. This is an important question, which must be decided before proceeding with the selection of a preferred technology or technologies.