If you want to give a ding-a-ling party in Bochum, Germany, rent a trolley car.

Actually, what the Bochum-Gelsenkirchen Streetcar Company offers are two old trolleycars welded together into one 60-foot-long parlor tram, painted in bright colors and equipped with wall-to-wall carpeting, a stero music system, a bar, cafe tables, couches and a driver.

The party trolley seats 30 guests comfortably or 44 thin people uncomfortably. For 60 Deutsche Mark an hour you can cruise anywhere on the company tracks to see part of the industrial Ruhr valley. You may also park on a siding.

B.Y.O.I.

The Council for International Urban Liaison in Washington thinks the trolleys are an imaginative way to use old streetcars and increase transit revenues.

They are the kind of ideas to save money and improve city living that the council was set up to spread.

(The council was not around when Washington sold its lovely new streetcars to Yugoslavia 20 years ago, or we might be joy riding to Glen Echo.)

Organized with German Marshall Fund State Department and Ford Foundation money to spread ideas that promise to make cities work better, the council publishes a monthly newsletter, Urban Innovations Abroad, that goes to some 5,000 city officials in this country.

Here are some of the innovations editor George G. Wayne has told them about:

Nagoya, Japan, originated sound devices attached to its traffic lights to let blind persons hear when it is safe to walk. The things warble and twitters like birds so they won't get confused with other city noises. Their sound level automatically is adjusted to the prevailing sound level of the street.

Most Japanese traffic lights now burst into bird song when the light changes, making different sounds for north-south and east-west crossings on street corners. Assisted by the Japanese manufacturer, the District of Columbia is now experimenting with the idea on the corner of 12th and C Streets. N.W., which leads to the Internal Revenue Service Building. IRS employs a number of blind people.

But Americans don't get bird songs. They get a single high-pitched note.

Ottawa, Canada, came up with a great idea for handicapped people in wheelchairs: It provides raised garden plots for them to grow flowers and vegetables.

The raised plots are part of Ottawa's allotment garden, provided by the National Capital Commission. Tools and water are supplied. An occupational therapist reported: "The handicapped who are participating in the program are delighted to be involved with the normal community, stimulated by the fresh air, pleasant country smells and companionship

Victoria, Australia, introduced the world's first "granny flats." They are temporary structures, not unlike mobile homes, complete with bathroom, small kitchen, bedroom and living room, that homeowners may put up in their backyard to have granny and or grandpa live close by without sacrificing privacy.

When the old folks leave, so does the "flat." It is permitted only for elderly family members where zoning regulations normally prohibit backyard structures. The exception is allowed to keep families together. The "granny flats" provide "built-in babysitters" and avoid old age homes and other geriatric ghettos. The units are provided and erected for moderate rent by the housing authority.

Cologne, Germany, operate mobile playgrounds. They are called "Juppi" and are converted moving vans, not unlike our mobile libraries. Juppi drives up to parking lots, side streets that can be closed to traffic and vacant market squares in crowded neighborhoods on a regular schedule. Juppi is set up in a jiffy, sporting slides down its roof, jungle gyms, a wading pool (filled from fire hydrants( and all sorts of game and play equipment.

Juppi's drivers are trained youth workers. There are now, three of them operating in Cologne, financed jointly by a voluntary child care organization, a savings bank and a soft drink manufacturer.

Several other West German cities have recently built public school swimming pools with hydraulic floors. The floors are raised and tilted at the touch of a button to create shallow pools for the handicapped as well as tiny tots who are learning to swim. They are lowered within 5 minutes for older kids who want to dive.

The council reports that 10 American communities have already adopted the idea.A moveable floor pool will be used for the next Olympics.

Like the citizens of Georgetown, the citizens of Osaka, Japan, are plagued by airplane noise and let the authorities know about it. Osaka's next airport will therefore be built on a float in the Osaka Bay. It will cost an estimated $5.7 billion, use 5.5 million tons of steel and take three years to build.

If the citizens continue complaining, the 5,000-meter-long airport can just raise anchor and float a bit further out to sea.

Singapore converts one of its biggest daytime downtown parking lots into an outdoor restaurant at night. At 5 p.m. sharp the automobiles must be gone and some 40 food vendors come in with their tables and chairs to feed and entertain crowds until the wee hours of morning. The crowds, presumably, use public transportation.

Our town should adopt the idea and turn the Federal Triangle Grand Plaza into a grand beer garden. The place is now jammed with parked cars during the day and deserted at night. Picnic tables and summer tents could be set up after government workers have evacuated and removed again in the morning before they come back. With Pretzels and enchiladas, beer, wine and soft drinks, ethnic bands and rock, we could have a summer long Oktoberfest .

On Dupont Circle and other city parks, there are often big clusters of kibitzers crowding around the chess tables. Baden-Baden, the famous spa in Germany, has made watching the game more comfortable for players and spectators alike.

Baden-Baden's lush parks have several chess boards for figures you can really see - about the size of a 10-year-old. The giant chess sets have an enchanting Alice-in-Wonderland air about them and attract as many camera bugs as chess fans.

Tel Aviv, Israel, got tired of seeing its parking meters damaged and vandalized. So it introduced "Telpark."

All it takes is for the public to buy books of parking permits in advance. Each permit is good for one hour. It is a piece of cardboard die cut so the user can tear out the name of the month, the day and the hour, and put it on his or her windshield.

If the time indicated on the permit has expired, a policeman or meter maid will ticket the vehicle.

The permits are designed to make counterfeits unprofitable and violations instantly visible.

Tel Aviv citizens like them and so does the city. Telpark saves money for parking meters and their repair and maintenance and has doubled the revenue within a year because everyone has to pay. If a motorist leaves the parking space before his paid time is up, the next one no longer benefits.

George Wynne says he gets hundreds of inquiries a month and ever more ideas are being adopted.