TriMet considers BRT

The latest update of TriMet's Transit Improvement Plan contains an intriguing and somewhat surprising item: Bus Rapid Transit (BRT). The Portland region is well-known for its extensive network of MAX light rail lines radiating from downtown, but this marks the first real indication that TriMet is considering another form of high-capacity transit. BRT has the potential in certain corridors to provide a superior form of transit service without the huge capital costs of a full light rail line, and it is encouraging to see TriMet showing some flexibility in their thinking.

So what is Bus Rapid Transit? The term originally referred to the completely grade-separated rail-like systems found in cities like Curitiba and Botage. This "full BRT" is often used in developing countries that need the speed and capacity of a rail line but have difficulty raising the high amounts of capital required. In the US, the availability of federal funds for major rail projects has made full BRT less common. The cost of acquiring the necessary right-of-way is also a major part of the cost of a light rail line, so full BRT may not save as much capital funding as one might expect.

The Seattle region is familiar with a more limited form of BRT in the form of Metro's Rapid Ride and Community Transit's SWIFT. These systems, which TriMet calls "On-Street BRT," usually run buses in mixed traffic like normal, and instead rely on a variety of other mechanisms to make the buses run with more speed and reliability. These tools include: high frequency; off-board payment; real-time arrival signs at stations; wider stop spacing; signal priority; queue jumps and bus-only signals; and many others depending on the project. The rise of On-Street BRT is driven primarily by a new category of federal transportation funding called Very Small Starts. This funding source provides relatively small grants to transit agencies that create such a BRT line, and comes with several requirements. For example, this type of BRT must have its own brand (like RapidRide) with distinctive vehicles, and must have widely spaced "stations" with off-board payment rather than just normal stops.

TriMet is considering "BRT-lite" lines in two major corridors. The first would run downtown Portland east to Gresham via Powell Boulevard. This corridor was identified in the recent Metro  High Capacity Transit (HCT) Plan as a first-tier priority for the region. This BRT line would replace portions of the busy number 9 bus and would provide an excellent parallel route to the existing MAX Blue Line to Gresham farther north. Powell Boulevard is currently very car-focused, so a major transit investment like this could make a huge difference in this corridor.

So why not light rail? One problem is a lack of available right-of-way. While it would be technically possible to put light rail in the center of the roadway like the Yellow Line on Interstate, the reduction in car capacity would be unacceptable on this major arterials. Another related problem is that Powell is a federal highway, so TriMet would be severely constrained in any efforts to remove or change automobile capacity. It is also worth pointing out that this BRT line would be able to bypass the Ross Island Bridge, the worst traffic bottleneck in the corridor, by using the new transit bridge currently under construction.

The other BRT line being considered as a longer-term project would run on I-205, connecting Clackamas Town Center (terminus of the MAX Green Line), Oregon City, Tualatin, and Tigard. This corridor is in the second-priority tier of projects in the HCT Plan. The I-205 BRT line would be a useful crosstown service connecting several suburban employment centers without going through downtown. It would also provide an east-west link between the WES Commuter Rail, the future Southwest Corridor light rail line, and the MAX Green Line. This is another corridor unsuitable for light rail because there is little available right-of-way along the freeway.

-Zef Wagner