A well-known challenge in planning is for the professionals involved to handle multiple sources ofknowledge and to influence decision-making as a result. This challenge is the main focus of this research and in order to explore it I have directed attention to the integration of knowledge pertaining to landscape in practices of transport planning. In particular, this re­search considers the professionals who contribute to such integration. The aim is to develop and refine our understanding of the challenges and opportunities professionals face when integrating knowledge oflandscape into the practices oftransport planning. A second aim is to contribute to an ongoing discussion within the field of planning theory that addresses the use ofknowledge and the logics underlying practices oftransport planning. At the centre of analysis are the professionals taking part in transport planning and their reflections on their own professional practice. Their perspectives are analysed in relation to the procedural and institutional aspects of their practice and in relation to previous research conceming professional knowledge, within the fields of planning, practice and organisations studies. Findings are presented in three separate studies that focus on different groups of planning professionals working in different parts of Swedish transport planning practice. Study I, investigates strategic planning performed at Regional Development Councils. Study Il sets eyes on the processes of förmal planning and design at the Swedish Transport Ad­ministration (STA) and Study III focuses on planning and design practices taking place at consultancy companies commissioned by the STA. Study IV differs from the other three, as it is primarily a theoretical discussion focusing on the knowledge oflandscapes. Study IV ad­dresses critical issues and challenges regarding the formation ofknowledge about landscapes in spatial planning contexts, based on published landscape research and planning theory.

This research provides situated accounts of professionals' reflections of their own roles, tasks, and practices. The main contribution lies in the details and nuances of their descrip­tions as these deepen our understanding of the complexity of landscape consideration and knowledge integration in transport planning. Participating professionals elucidate essential aspects of challenges in integrating knowledge of landscapes and additionally outline ways to make the interrelation of different types ofknowledge possible. Professionals' discussions provide insights into their perceived opportunities to influence planning decisions and ways they try to safeguard landscapes (rnitigate negative effects and create positive effects) in the layout and design of transport structures.

The study explores enablers and barriers of collaborative planning and design work in transport infrastructure planning projects, drawing upon five cases of projects in Sweden. The study apply a set of theoretical lenses complied of previous research focusing professional knowledge and co-production in planning and design practices, and research revolving around the concept of boundary objects in studies of collaborative work. The study provides insights into the mechanisms of practitioners' learning across professional boundaries: what they learn from each other, how they learn, and how the learning facilitates collaborative work. The results show that disciplinary barriers can be bridged through both individual efforts and project management strategies.

This study shed light a set of enablers on individual level including; 1) a capacity to change focus between solving tasks within the remit of one's own discipline and jointly solving tasks together with professionals representing other disciplines; 2) curiosity and interest other professional perspectives; 3) willingness to learn from other professionals; and 4) motivation to engage in cross-disciplinary design processes. Project management is proposed to enable collaboration by; 1) opening up discussions about reasons and motives for collaborative work; 2) opening up discussions about strategies for collaborative processes; 3) promoting and facilitating learning processes among project participants, 4) coordinating meetings and activities for collaboration, and 5) facilitating deliberative dialogues at project meetings in which different types of knowledge can be put forth and interrelated.

Knowledge about landscapes is highly complex and it is important to clarify how that complexity is reflected in the knowledge claims that feed into a particular planning process. Thus, this paper addresses critical issues and challenges regarding the formation of knowledge about landscapes in spatial planning contexts, based on published landscape research and planning theory. The analysis is rooted in planning theorists’ discussion of various types of knowledge claims involved in spatial planning practices. Thinking in terms of knowledge, and discussing both the character of knowledge production and types of knowledge claims that will be included, is a useful approach for choosing and developing assessment methods. To aid such approaches, two key aspects of formation of knowledge about landscapes are addressed here. One is the trans-disciplinary challenge of capturing landscapes as a whole. The other is the normative element of knowledge pertaining to landscapes, including diverging moral and ethical perspectives.