Expressways are controlled-access highways, with crossing traffic limited to overpasses, underpasses, and interchanges. Expressways are limited-access roads, with crossing traffic limited to overpasses, underpasses, and interchanges. Some highways inside Metro Manila have underpasses, tunnels and flyovers. Achieving such free flow requires the construction of many overpasses, underpasses, and ramp systems. The underpasses and overpasses at Placentia, Kraemer, Rose/Tustin and Lakeview are complete. Cumbernauld pioneered designs for underpasses and pedestrian footbridges as well as segregated footpaths. Jinnah-Faisal Avenue Interchange is a combined development of flyovers, underpasses, and roads. All level crossings along the corridor were eliminated with using railway or roadway underpasses. Third are mechanisms to provide safe crossing like overpass, underpasses and escape routes. Some larger roundabouts take foot and bicycle traffic through underpasses or alternate routes. Some lightly used crossings were simply closed, while most were converted into bridges or underpasses. Thus, they are restricted to routes which avoid low bridges and underpasses. Long underpasses may be called tunnels. Localities have tried to limit roadkill by constructing underpasses, highway barriers, and crossing signs. Because it had no intersections, the autobahn required a huge number of bridges and underpasses.