Tatu City’s roads have received high ratings for road quality and performance as part of a rigorous evaluation using the International Roughness Index (IRI). The assessment was conducted in cooperation with the Materials Testing and Research Division (MTRD) of the Ministry of Transport, Infrastructure, Housing, Urban Development and Public Works.
Road roughness is an important pavement characteristic and, through the road user’s perception, may not only be defined by the riding quality, vehicle maintenance and fuel consumption costs, but also by road safety. The World Bank, which brought together several international organisations to develop the IRI as a standard for calibration, has shown that pavements that are built smoother remain smoother over time and provide a longer service life.
“We decided to subject our roads, which are between one and three years old, to IRI’s testing standards prior to handover, to ensure our transport infrastructure provides optimal value for residents and business owners,” said Samuel Gathukia, Head of Construction & Delivery at Tatu City, noting that the roads in Tatu Industrial Park are engineered for heavy vehicles.
The analysis of the roads covered road depressions and surface imperfections. All Tatu City roads, which cover more than 30km within the 5,000-acre Special Economic Zone, received “good” or “excellent” ratings.
At Tatu City, more than 60 companies are operational or under construction, two schools –Crawford International and Nova Pioneer – educate more than 3,000 students daily and 5,000 multi-income homes are completed or under development.
Tatu City is Kenya’s first operational Special Economic Zone, with low corporate taxes and zero-rated VAT and import duties, amongst other benefits. Tatu City’s investment in, and maintenance of, infrastructure – roads, power, water, waste and ICT – is unprecedented by a private developer in East Africa.
The IRI survey exercise was jointly undertaken by MTRD and engineers from Frame Consultants Limited and Stecol Corporation, which is the main civil works contractor at Tatu City.
The IRI is based on the average rectified slope (ARS), which is a filtered ratio of a standard vehicle’s accumulated suspension motion divided by the distance travelled by the vehicle during the measurement. IRI is then equal to ARS multiplied by 1,000. IRI has been widely used to plan for periodic maintenance on paved roads globally.