Zagreb bypass
Zagreb bypass is a U-shaped motorway partially encircling Zagreb, Croatia. The largest part by far, between Jankomir and Ivanja Reka interchanges, was built between 1977 and 1979, while the Ivanja Reka – Sveta Helena section was built between 1996 and 1999. The bypass is long, tracing around the city from the northwestern suburb of Zaprešić to Sveta Helena in the northeast. The bypass crosses the Sava River twice and comprises a bridge across the Sava-Odra floodwater overflow canal. As the busiest sections between Jankomir and Buzin interchanges carry traffic volume of approximately 45,000 AADT, it is the most heavily used motorway sector in Croatia.
Zagreb bypass is not designated as a separate motorway with a distinct motorway number, rather it consists of sections of three motorways:
| Motorway | Sections |
| Zaprešić – Jankomir | |
| Jankomir - Lučko - Buzin - Kosnica - Ivanja Reka | |
| Ivanja Reka - Kraljevečki Novaki - Popovec - Sveta Helena |
Those motorway sections are concurrent with sections of the D1 and D3 state roads as well as European routes E59, E65, E70 and E71.
The bypass currently comprises four traffic lanes along its entire length, with an emergency lane in each direction. In its current form, the Zagreb bypass has a small number of interchanges spaced widely apart. For example, the current Zaprešić interchange extends a trip from Zaprešić to Zagreb via the bypass by. The last new interchange was built in 2007–2008 at Kosnica in the southeast, to connect the Homeland Bridge and Zagreb via Radnička cesta.
There are two rest areas along the bypass: Lučko rest area is located between Jankomir and Lučko interchanges comprising famous Plitvice Motel, well known for its pedestrian bridge across the bypass, while Sesvete rest area is located between Popovec and Sveta Helena interchanges. A new rest area is planned between Jakuševec and Kosnica interchanges.
Future expansion
A proposal has been made in 2007 for a new interchange near Zaprešić, one that would reduce traveling time between the cities.As a part of the A11 motorway construction works, a new Jakuševec interchange was built east of the Buzin interchange. The Buzin interchange in turn is planned to be abolished, in favor of another new interchange, Sveta Klara, further to the west.
A long-term plan exists to build a new outer bypass road around Zagreb. The outer bypass would be a part of the tolled motorway network thus permitting vehicles not to stop at two toll plazas near Zagreb as they enter and leave the present bypass, decreasing congestion on the inner bypass motorway. 2009–2012 motorway and road construction plan entails funds for development of design documents for the outer bypass motorway and specifies its route: It is to be a long motorway originating from the A2 motorway Luka interchange, connecting the A3 motorway Gradina interchange near Samobor, the A1 motorway Horvati interchange, the A11 motorway Mraclin interchange, once again the A3 motorway Ivanić Grad interchange and finally the A4 motorway Zelina interchange. A total of 14 interchanges are planned on the new bypass, including the ones connecting it to the other motorways already specified, connecting the outer bypass to all major roads intersected.
Because of the Medvednica Mountain north of Zagreb, the present bypass is U-shaped, leaving the city without a northern bypass that would connect the A2 and A4 highways. A northern branch of the bypass was planned and designed to bridge the gap. It was planned to connect the Zaprešić interchange with the Popovec interchange. The route would have required a number of long tunnels and viaducts making it expensive. According to the general design alternative in a study executed by the Faculty of Architecture and Institut IGH, the route would comprise 15 tunnels. The tunnels longer than 500 m would be: Ivanec Tunnel, Borčec Tunnel, Pantovčak Tunnel, Dotrščina Tunnel, Remete 1 Tunnel, Čuguvec Tunnel and Novaki Tunnel. The construction works were planned in stages with an additional 5–10 km long tunnel built subsequently through Medvednica Mountain to connect Zagreb and Hrvatsko zagorje directly. However, as of September 2011, all such plans were cancelled as unfeasible.