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Road Worrier: New life for an old rail transit idea

Triangle Transit displayed this full-scale mockup of a diesel multiple unit railcar in 2005 to promote its plan for a 28-mile regional transit line, which was shelved in 2006.
Triangle Transit displayed this full-scale mockup of a diesel multiple unit railcar in 2005 to promote its plan for a 28-mile regional transit line, which was shelved in 2006. NEWS & OBSERVER FILE PHOTO

Fifteen years after it was endorsed in the Triangle’s first, failed transit plan, an odd-duck sort of train has found new life as the vehicle most likely to bring rail transit service – some day – to Wake County.

The dismally named diesel multiple unit, or DMU, can share standard-gauge tracks with Amtrak and freight trains. It doesn’t need a locomotive. Each rail car is powered by its own diesel engine, much like the ones that are found in tractor-trailer trucks.

Credit Jarrett Walker, an Oregon consultant guiding Wake through its latest round of transit hoping, with the DMU’s resurrection here.

Last week, Walker helped the latest citizen advisory committee conclude that DMUs are less expensive and in some ways more flexible than light rail for providing high-volume, high-frequency service between Research Triangle Park and downtown Raleigh. These self-propelled rail cars may also prove a better choice than locomotive commuter trains for rush-hour transit in Durham County as well as in Wake.

“It really is a very nice alternative,” Wake County Commissioner Sig Hutchinson said. “The price is more reasonable than the light rail, and I think it can give us greater coverage than the commuter rail.”

DMUs were featured in a planned 28-mile rail transit line for Durham and Wake counties that died in 2006. The Federal Transit Administration concluded that it was too expensive and would attract too few riders.

That wasn’t so long ago, but it seems like ages. The Triangle Transit Authority has changed its name twice since 2006 – and staffers still struggle with their new identity, Go Triangle, when they answer the phone.

And Wake is developing its second transit plan since then. The last plan called for light rail from Morrisville to downtown and North Raleigh – plus a separate commuter-rail line, with locomotives pulling standard train cars, from Durham through RTP to Garner.

The new idea is that diesel multiple units can provide service every 15 minutes from RTP to downtown, and pointing north from downtown to Highwoods.

“It’s the best case we can put forward for rail,” said Tim Gardiner, a county transportation planner overseeing the new Wake transit plan. “There is a lot of potential for this technology with the network we have.”

He said the same trains could be extended in future years to run every 30 minutes during weekday rush hour – north to Wake Forest, east to Garner and Clayton, and west to Durham, where a planned light-rail line will connect to UNC-Chapel Hill.

If the county commissioners settle on a transit plan this year, they could schedule a referendum in 2016 on a half-cent sales tax that would help pay for transit improvements. Planners would like to have the trains running by 2026 – if the county decides to include trains.

Wake’s transit committee will deliver four different transit scenarios – two with trains and two without – for public comment on May 11.

Two versions will feature beefed-up bus networks designed around a bus rapid transit spine – with buses that travel faster than automobile traffic, in vehicles that are like train cars on rubber tires. The other two will build this spine with DMU rail service. Walker calls this “rail rapid transit.”

Light rail vs. DMU

Light rail’s lighter trains use narrower rails that, for safety reasons, must be built farther away from freight tracks. That means more land acquisition and bridge construction would be needed than for DMU trains. And light rail trains are powered by electricity, adding the expense of overhead power lines.

Light-rail trains can squeeze through downtown streets, unlike DMUs. But DMUs are getting the nod here for the same reason they were favored by Triangle Transit, aka Go Triangle, in 2000.

They can use existing railroad corridors, mostly the N.C. Railroad combined with some CSX tracks. The tracks run through most of the Triangle’s major employment and activity hubs, from Duke University and downtown Durham through RTP, the State Fairgrounds, N.C. State University and downtown Raleigh.

DMU trains are doing urban and suburban transit duty in Oregon, Colorado, Texas, south Florida and southern California. Walker says they could be a good fit for Wake and the Triangle.

“Because they are cheaper than electric light rail, and easier to phase in, I expect DMUs to be increasingly popular in cases like yours where a primary demand corridor follows an existing heavy railway line – and where the relatively low density suggests the value of something that can be phased in ... as demand grows,” Walker said by email.

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