When much of urban Honolulu was first developed — the on-street and off-street parking facilities, for example — each household had far fewer cars. Nobody would imagine, for example, that residents of Kalihi Valley Homes would have too many cars to be accommodated on site and that they would spill onto neighborhood streets across Likelike Highway.

That is what did happen, though, and it’s why the residents of Kalihi Valley’s Wilson Tract homes turned to city officials for help. The stop-gap solution that is being tested — allowing only tract residents with permits to park on the street — should be considered only short-term relief, however.

The only permanent fix would be an expansion of the parking accommodations on the grounds of Kalihi Valley Homes. The Hawaii Public Housing Authority is the agency that needs to correct the problem.

Under a 30-day pilot project that kicked off Saturday, the city Department of Transportation Services offers free permits for about 230 unmarked stalls in the affected area: Alu, Wilson and Jennie streets, and Alu and Wilson places.

All but 50 of the neighborhood’s 193 households already had their permits by the project launch day. Each household gets up to two hang-tag permits for personal vehicles, with two more available for guests.

On-street parking will be restricted to vehicles with permits from 6 p.m. to 6 a.m. daily.

This is what’s known as an RPZ, which stands for restricted or residential parking zone. Various cities have implemented similar programs as a coping strategy within areas where mixed uses and insufficient parking provisions have led to residents losing the competition for street parking spaces on the public roadways.

Oahu has been anything but immune to this problem; it’s existed for decades in some high-demand areas, such as Waikiki and near the University of Hawaii. Students have scanned Manoa neighborhood streets for free parking rather than buying a stall on campus.

But the concern has spread to many other neighborhoods as well. With families doubling and tripling up in residential areas that abut business districts, the competition for parking can be fierce.

Unfortunately, the precedent such a program as Kalihi Valley’s would set in such a densely populated area as Oahu would be unsustainable.

The problem faced by Wilson Tract residents is understandable. They are unable to find the spaces that customarily were available near their homes; they also assert that crime has increased, along with the crowding, in the area.

Almost certainly, they will embrace the private parking privilege restoring some order, and city officials will be tempted to extend the program indefinitely. One of the temptations: The permits are free for the pilot’s duration, but surely the city is contemplating assessing a fee, creating a new revenue stream.

And that likely will make it all the more difficult to deny petitions from other neighborhoods that want to do the same thing. Adding revenue to the city coffers has been an ongoing pursuit for elected city officials in this era of increasing budgetary pressure.

Wilson Tract may be a contained area, but enabling a long-term RPZ program here would create a slippery slope for other areas to deprive the public of parking for other purposes: stopping at a local business or visiting a park, for example. Even after 6 p.m., this can still be an issue.

Neighborhood board members are working with the Hawaii Public Housing Authority on prospects for allowing more vehicles on-site at Kalihi Valley Homes; that would be a productive path to follow.

As for the residential streets, in Kalihi or any community, they and whatever limited parking they offer are public property. City policy should strive to keep them that way.