Limited parking spaces could cause commuters to think twice about driving to one of Honolulu's planned rail stations for a train ride.

The city forecast that residents and tourists will take more than 95,000 trips a day on Honolulu's planned $5.4 billion rail system. Nearly nine out of every 10 of those trips will be by people arriving at train stations by bus, bicycle or foot. But that will still leave nearly 11,000 trips coming from those who will drive to train stations, according to the city's draft environmental impact study.

Where those drivers will park remains unclear.

The city plans to provide parking for 4,100 autos at four train station park-and-rides located between East Kapolei and Aloha Stadium. Riders commuting from urban Honolulu going west will get no new city-provided transit parking lots under current plans.

For the most part it's not economically feasible for the city to provide parking around stations in urban Honolulu, said city transportation director Wayne Yoshioka. In addition, the city wants to encourage drivers to keep their autos parked at home.

"We're not trying to look for parking right in the corridor because that kind of defeats the purpose," Yoshioka said. "The whole point is to change modes. The hope is that in urban areas we have a lot more (people) walking to transit stations, (and) for some of the suburban riders the hope is they don't drive in — they'll take a feeder bus in."

Deciding how much public parking to provide around train stations requires delicate balancing. If there are too few spaces, or parking is too difficult to find, people may decide not to ride the train.

Honolulu city officials hope to begin construction on the 20-mile East Kapolei to Ala Moana train in December, contingent on federal approval, and launch service in phases between 2013 and late 2018.

Each station will have bike racks, and trains will accommodate bicycles. However, city parking will only be provided at park-and-ride lots in East Kapolei, and at the University of Hawai'i-West O'ahu, Pearl Highlands and Aloha Stadium. Another 1,000 spaces for both bus and train riders will be built near a Middle Street transit center.

Public parking outside of those facilities may be hard to find.

That's because the city last week enacted a new law that establishes a process for creating transit-oriented development zoning regulations around stations. Those rules are partly designed to eliminate or reduce off-street parking within 2,000 feet of stations in an effort to spur residents and others to use mass transit.

WALK, WAIT FOR BUS

The city's goal is to foster transit lifestyles and higher-density developments near train stations. Those who don't live near train stations can take TheBus to one of the stations. There are 3,800 bus stops within a 10-minute walk of 95 percent of O'ahu's urban residents, according to the city.

However, it remains to be seen whether people will leave their autos at home to walk to a bus stop then catch a bus to a train station, said Panos Prevedouros, a UH engineering professor. Train riders will want to be able to park at train stations, he said.

"It's a big convenience," Prevedouros said. "You take your car. You park and you take the rail for the long haul or for the congested part of the haul."

The 4,100 to 5,100 spaces planned for city train stations isn't out of line with the amount of public parking provided at recently opened Mainland train systems. For example, the 10-mile Lynx light rail line in Charlotte, N.C., opened in November 2007 with 5,554 park-and-ride spaces, according to media reports. Phoenix's new 20-mile light rail train launched service in December with about 3,500 park-and-ride spaces.

However, the combined average weekday boardings for both of those systems is about 45,000. That's fewer than half the 95,000 average weekday boardings expected for Honolulu's train in 2030.

Honolulu doesn't need to offer as many spaces as those less-densely populated cities, Yoshioka said.

If the city does not provide adequate parking near stations, demand could spill over into nearby communities. According to the city study, the areas most likely to experience demand for spillover parking include: West Loch, Pearlridge, Iwilei and Ala Moana Center. Those four stations could attract a spillover parking demand of 140 to 370 automobiles each day.

To compound parking concerns, elevated guideway columns and station entrances are expected to eliminate more than 1,000 on-street and off-street parking spaces along the 20-mile route, according to the study.

WORKING IT OUT

Yoshioka said the city will have several strategies for addressing parking problems that may arise once the train begins operations. Those include: