Google used its cab drivers in Bangalore for the city map-making. The cabbies turned out to be good contributers to the Google maps software, a senior official of Google India said today.

"Cab drivers are the best when it comes to knowing the geography of the city and with a bit training in internet any cab driver can become a good map contributor," Google India's country head (products), Vinay Goel told reporters here.

"In Bangalore, we have our office cab drivers. They drop people in the morning and take them in the evening. They have nothing to do in between. So we give them maps and they work with our people in our lab.

"Many of them have the advantage of knowledge of the city and hence started mapping for us. There are a couple of drivers who contributed heavily to the map-making," Goel said.

To a query on use of cab drivers for the same purpose in other cities, he said it depended on their interest and knowledge in internet. "For other cities we cannot say because we don't know how many of them are trained in internet. We have not reached out to them directly but if they have passion they can participate," he added.

Goel said there are many checks and balances before updating a map. The user group, from which Google accepts suggestions and updates, is carefully scrutinised before their recommendations are accepted, he added.

"Validation of the date is done by a set of moderators. If you are a first time user or editor, the trust in you is very less. So, everything you update does not get published immediately. Over a time, if you have done hundreds of posts and updations, then the trust level goes up," Goel said.

Explaining about maps of boundaries of countries, he said Google will not allow users to change a country's boundaries as the part is not user editable.

Detailing about the maps of Indian cities, Goel said they depend on user groups that give landmark-based information rather than direction-based information for map updation as licensed maps would not necessarily replicate the real picture on the ground.

"In the US and other countries, it is licensed maps we use. But in India, the minute the map is printed, it is out of date. When you look around, new colonies are coming up and new complexes coming up. A road which used to be two-way might have become one-way by tomorrow. So, the driving directions are very difficult and the best thing is to depend on user groups. They take very strong ownership of their neighbourhood," he said.

According to him, Google made 490 changes in its site in 2010 and 510 changes were made in 2009 making an average of 1.5 to 2 changes every week.

"The recent changes in the Google search saves 2-5 seconds time every time one goes for a search," he added.