The Miami-Dade Expressway Authority (MDX) in South Florida, US, is offering $412m in bonds for sale to convert its roads to electronic tolling.

Funds secured through the bond sale will be used for current and future construction projects by the authority as it expects to increase traffic on MDX toll roads.

The agency currently generates annual revenues of around $109m from toll collection, but expects $125m next year and $150m by 2014.

The agency plans to undertake reconstruction of existing highways, expansion works and other lengthening works.