Over the past few decades, the need has arisen for multi-lane detection algorithms for use in vehicle safety-related applications. In this paper we propose a new multi-lane detection algorithm that works well in urban situations. This algorithm detects four lane marks, including driving lane marks and adjacent lane marks. Conventional research assumes that lanes are parallel. In contrast, our approach does not require this assumption, thus enabling the algorithm to manage various non-parallel lane situations, such as are found at intersections, in splitting lanes, and in merging lanes. To detect multi-lane marks successfully in the absence of parallelism, we adopt Conditional Random Fields (CRFs), which are strong models for solving multiple association tasks. We show that CRFs are very effective tools for multi-lane detection because they find an optimal association of multiple lane marks in complex and challenging urban road situations. Through simulations, and by using video sequences with 752-480 resolution and Caltech Lane Datasets with runtime rates of 30 fps, we verify that our algorithm successfully detects non-parallel lanes as well as parallel lanes appearing in urban streets.