The Istanbul Metropolitan Municipality announced Tuesday that the city's taxicabs will now feature roof lamps that change color depending on whether they're carrying passengers or not.

Initially, taxis managed under the municipality's iTaksi application will get the new roof sign, which will turn green when empty, orange when it is reserved or going to pick up a customer and red when it is carrying a passenger. The sensors in the roof lamp will also detect and collect data on outside temperature, humidity, noise, air quality and traffic congestion. The iTaksi app was developed by Turkish engineers as part of the Istanbul Metropolitan Municipality's Directorate of Transportation's strategic plan, which aims to mainstream all types of smart transportation systems using domestic sources. The app monitors, navigates, coordinates taxi stands and ensures the security of both drivers and passengers. It also sets the shortest and most economical route to the destination.

The system has so far been installed in 4,000 cabs in Istanbul, which has some 17,193 taxis in total. The number is expected to increase soon as the municipality is set to hold a bidding on April 12 for the purchase of more iTaksi systems, Chamber of Istanbul Taxi Businesses Deputy Director Veli Yurt told Daily Sabah.

The number of new iTaksi systems to be installed in the city's cabs is not known, but it is intended to ensure more integration with smart systems and raise the quality of cab services in Istanbul.