Open Access

Das Bauvertragsrecht ist im Bürgerlichen Gesetzbuch (BGB) im Titel des Werkvertragsrechts in den §§ 631 – 651 BGB enthalten. Aus dem reinen Werkvertrag des BGB heraus war bisher nicht die Möglichkeit gegeben, nachvertragliche Änderungen in den Bauvertrag einfließen zu lassen. Für die notwendige Ausführung vergessener Leistungen wurde unter Beachtung des Konsenzprinzips hilfsweise § 315 BGB „Bestimmung der Leistung durch eine Partei“ in Verbindung mit § 242 BGB „Treu und Glaube“ herangezogen, um einseitig den Leistungserfolg ändern zu können. Eine Konkretisierung, welche Leistungen der Besteller einseitig ändern kann und wie der sich hieraus entstehende Anspruch auf Gegenleistung zu ermitteln ist, fehlte gänzlich. Die bestehenden Regelungen sind daher nicht konkret genug für die heutigen komplexen Bauvorhaben. Mit der Novellierung des Bauvertragsrechts im BGB wurde auch das einseitige Leistungsänderungsrecht und Regelungen für die Ermittlung der Mehr- und Mindervergütung in dem BGB – Bauvertrag aufgenommen. Durch Beschluss des Deutschen Bundestages vom 28. April 2017 ist das neue Bauvertragsrecht eingeführt und wird am 1. Januar 2018 in Kraft treten. Durch diese neuen Regelungen soll „eine interessengerechte und ökonomisch sinnvolle Gestaltung und Abwicklung von Bauverträgen“ (Deutscher Bundestag, 2016, S.2) erzielt werden. Ob die Schnittstelle zwischen Leistungsänderung und Gegenleistung, unter Berücksichtigung baubetriebswirtschaftlicher Aspekte und der Ausgeglichenheit zwischen Leistungsänderung und Gegenleistung mittels der vorgegebenen Maßstäbe überhaupt möglich ist, wurde in der vorliegenden Arbeit untersucht. Hierfür wurde das baubetriebliche System des BGB – Bauvertrags erarbeitet und die Novellierung des Bauvertragsrechts im Hinblick auf die Masterarbeit Torge Meister IV Bereiche des Änderungsrechts (§ 650 b BGB) und der Vergütungsanpassung (§ 650 c BGB) vorgestellt. Basierend auf der Vorstellung des neuen BGB – Bauvertrags sind die Möglichkeiten der Leistungsänderungen in der Schnittstelle zu der Ermittlung der Mehr- oder Mindervergütungen herausgearbeitet worden. Dabei wurde festgestellt, dass neben den beiden Vergütungsermittlungsmethoden des § 650c BGB auch die Möglichkeit der freien Vergütungsermittlung nach § 650 b Abs.1 BGB gegeben ist. Auch wie die Sachverhalte Nachlässe, Mengenänderungen bei Einheitspreisverträgen sowie Bauzeit und die Art der Ausführung bei der Kostenermittlung und der Beauftragung von vergessenen Leistungen zu berücksichtigen sind, ist in die Untersuchung eingeflossen. Trotz der aufgezeigten Lücken des neuen Bauvertragsrechts wurde mittels der Untersuchung der Schnittstelle zwischen den Änderungsverlangen und der Vergütung der vergessenen Leistungen festgestellt, dass grundsätzlich die Umsetzung im baubetrieblichen System möglich ist. Mit den vorgestellten Kalkulationsansätzen in Kombination mit einer Gemeinkostenausgleichsrechnung wird ein Ansatz für die Lösung der fehlenden Ausgeglichenheit zwischen Leistung und Gegenleistung vorgestellt. Darüber hinaus wird herausgearbeitet aus welchen Gründen es bei Bauprojekten, die auf auf dem neuen BGB – Bauvertrag basieren, zu Streit zwischen den Vertragsparteien und damit zu einer Verteuerung und Verzögerung der Bauprojekte kommen wird.

In this dissertation the relation between time headway in car following and the subjective experience of a driver was researched. Three experiments were conducted in a driving simulator. Time headways in a range of 0.5 to 4.0 seconds were investigated at 50km/h, 100km/h, and 150km/h under varied visibility conditions and at differing levels of driver control over the car. The main research questions addressed the possible existence of a threshold effect for the subjective experience of time headways and the influence of vehicle speed, forward visibility, and vehicle control on the position of time headway thresholds. Furthermore, the validity of zero-risk driver behavior models was investigated. Results suggest that a threshold exists for the subjective experience of time headways in car following. This implies that the subjective experience of time headways stays constant for a range of time headways above a critical threshold. The subjective experience of a driver is only influenced by time headway once this critical time headway threshold is passed. Speed does not influence preferred time headway distances in self- and assisted-driving, i.e. time headway thresholds are constant for different speeds. However, in completely automated driving preferred time headways are influenced by vehicle speed. For higher speeds preferred time headways decrease. A reduction of forward visibility leads to a shift in preferred time headways towards larger time headways. Results of this dissertation give credence to zero-risk models of driver behavior.

Micro- and small enterprises are of great importance for the economic growth in developing countries, as they contribute to employment creation and innovation. In light of their economic relevance, several approaches to support micro- and small enterprises have emerged, including building human capital through business trainings. However, the effects of existing business trainings on entrepreneurial success have so far been limited. One promising alternative training approach that has emerged in the last years is personal initiative training, which teaches self-starting, future-oriented, and persistent entrepreneurial behavior. This dissertation helps to improve the understanding of personal initiative training by shedding light on the mechanisms through which it affects business success, on supporting factors, and on its long-term impacts. Chapter 1 provides an overview on the topic of personal initiative training for entrepreneurs in developing countries. Chapter 2 introduces personal initiative training and other proactive behavior trainings in various contexts of work, including entrepreneurship. The chapter presents action regulation theory and the theory on personal initiative as the theoretical foundation of the training. In addition, the chapter provides insights into training and evaluation methods and makes recommendations for the successful implementation of personal initiative training. Chapter 3 offers a first answer to the question how personal initiative after training can be maintained over time. The chapter introduces training participants´ need for cognition as beneficial factor for post-training personal initiative maintenance. Chapter 4 explains how action regulation trainings like personal initiative training contribute to poverty reduction in developing countries by supporting entrepreneurial success. Chapter 5 enlarges upon the topic of personal initiative training for entrepreneurial success in developing countries. The chapter focuses on how personal initiative training supports female entrepreneurs in developing countries by helping them to overcome the uncertainty involved in entrepreneurial actions. Chapter 6 summarizes the overall findings and illustrates the theoretical and practical implications that result from this dissertation. In sum, this dissertation makes a contribution to the better understanding of personal initiative training and its effects on entrepreneurship in developing countries and thereby helps to create effective interventions to combat poverty in developing countries.

The dissertation project focuses on empirically investigating consumers´ attitudes, motiva-tions and purchasing decisions regarding sustainable products. The focus on this micro per-spective, however, does not reflect consumers´ roles within the transformation towards sus-tainable consumption. Therefore, the present framework paper puts the included papers into a greater context and evaluates the findings on a meta-level by applying an enhanced transition management theory. The analysis underlines that consumers´ limited personal capabilities are an underlying reason for unsustainable practices. Therefore, the active engagement not only of consumers, but also of companies is required if the transformation is to be successful. If companies actively support consumers in making sustainable choices, consumers can engage in sustainable consumption with only low cognitive efforts. On this basis, genuine sustainable choices are enabled. The dissertation provides practical implications by highlighting potential measures which will help to promote sustainable products from niches to mainstream. In sum, the dissertation project enhances academic understanding of consumers´ sustainable purchas-ing behavior and reveals the potential of integrating such insights into the management of transformations towards sustainable consumption.

In 2013, the European Commission adopted the so called ´Entrepreneurship 2020 Action Plan´ to ease the creation of new ventures and to support the takeover of existing firms. The goal is to create a supportive environment for entrepreneurs to thrive and grow (European Commission 2013). This shows that the European Union puts its efforts to support small firms as they are seen as means for Europe´s sustainable economic growth. However, the successful processes of growth and investment are complex and depend on different determinants. The present thesis focuses on the firm level and analyzes in three independent articles: how small firms invest over time, how new ventures grow and which variables influence growth, how small firms grow after business takeover and which variables influence growth. The framework that connects these articles forms the content-related focus on the early stage of development of small firms and the methodological and analytical approaches that comply with up-to-date and adequate statistical analysis techniques. Supported by an extensive dataset, which is the foundation of all three articles, it is possible to investigate empirically different open research questions using bivariate and multivariate analysis techniques. Thus, this thesis also serves the research needs for more multivariate analyses for small firms, for which so far mainly cross-sectional studies have been conducted.