Diverging Diamond Interchange: Implementering i Danmark

Student thesis: Master thesis (including HD thesis)

  • Thomas Nissen
  • Charlotte Østergaard Pedersen
4. term, Transport Engineering, Master (Master Programme)
Road network worldwide often experience unwanted situations like congestion, on a daily basis. Statistics indicates that the future will bring even more traffic, than what is experienced today. The increase in traffic is currently causing traffic problems, which may only increase with time unless action is taken. To improve traffic operations a new type of interchange between arterial roads and motorways was developed in the US in the 00s. The interchange is now know as a Diverging Diamond Interchange (DDI). The DDI has been analysed and tested. Since 2009, 64 interchanges have been built – a number, which is increasing rapidly. The interchange has become so popular due to the increase in traffic operations, traffic safety and the relatively low cost associated with the rebuild from a conventional diamond to a diverging diamond interchange.

The object of this report is to analyse the diverging diamond interchange with the view of implementing this design as a part of the Danish road network.

This report consists of two parts – a litterateur study and an analysis. The litterateur study is based on American research and analyses. The focus includes the design of the DDI, and how geometrics can improve traffic safety, the driving experience, assure speed doesn’t exceed the limit and the correct signage. Furthermore the study includes traffic safety, the development in conflict points and collisions, the actual and the experienced traffic safety and considerations about having pedestrians as a part of the interchange. At last the development of operational performance is studied and the possibilities of simulating the DDI in a microscopic simulation.

The second part consists of a microscopic simulation of two common Danish interchanges compared with the DDI. The simulated Danish interchanges are respectively a conventional signalised diamond interchange and an interchange with two roundabouts. The interchanges are compared based on travel time, congestion and queue lengths. Simulations are based on seven different scenarios, which all aims to challenge different aspects of the interchanges. There are e.g. two scenarios, which include vulnerable road users to determine their best possible location in a DDI.

There are four locations in Denmark where a rebuild from the current interchange into a DDI is possible according to the current traffic flow. However there are 17 interchanges with less traffic, which may benefit of being rebuild into a DDI. Therefore a simpler version of the DDI with only one lane in each direction is analysed according to on travel time, congestion and queue lengths as well.

Based on the litterateur study and the simulations it can be concluded that a diverging diamond interchange is highly recommended as a new interchange design in Denmark. However it is recommended to locate vulnerable road users in a separate crossing or locate them on the outside of the interchange and make them give way to vehicles.
Publication date7 Jun 2016
Number of pages156
ID: 234893724