Junction design rules for urban traffic networks

Transcription

1 Junction design rules for urban traffic networks Erwin Bezembinder European Transport Conference Frankfurt, 1 October 2014

2 Involved Erwin Bezembinder Luc Wismans Eric van Berkum

3 Junction design challenge Road planners frequently face the challenge to determine: What is the best junction design given a particular traffic demand?

4 Junction design challenge Design manuals provide guidelines for the assessment of different junction designs However, most guidelines refer to specialised software in which the performances of different design alternatives can be modelled This is not feasible for planning purposes Junction design rules are needed Only a very limited amount of rules exist Lack of rules largely explained by lack of data Alternatively, data can be modelled

5 Junction design rule Demand flows Junction design rule Optimal design(s)/ Ranking

6 Determine junction design rules for Isolated junctions Single objective Isolated junctions Multiple objectives Junctions in a network Single objective Junctions in a network Multiple objectives

7 Data set Junction design rules Modelling framework Data generation Data analysis Junction model HCM 2010 Effect model Volume weighted average control delay Rule prediction method Decision tree methods Generation method 24 junction designs 1 million demand conf. Selection method One optimal solution by size category

8 Junction designs AWSC (1), TWSC (5), Signalised (10), Roundabout (8) TW4 SIG7 RA7

9 Junction model HCM 2010 Example of a roundabout resulting in 16.6 s/veh control delay

10 Data generation: base set Nr Demand configuration Junction design Size category Delay (s) 1 DC1 AW DC1 TW DC1 TW DC1 TW DC2 AW DC2 TW DC2 TW DC2 TW3 2 21

11 Data generation: training set Nr Demand configuration Size category Optimal junction design 2 DC1 1 TW DC1 2 TW DC2 1 TW DC2 2 TW3 21 Delay (s) 38 demand variables: 12 turning volumes, 16 combined volumes, 10 combined percentages

12 Decision trees Classification technique Advantages, such as: Numerical and categorical data White box model Easy to understand and interpret Perform well with large datasets Statistical validation Rules can be derived Root, nodes, branches and leafs Example: Apply a signal control? Yes Rural Total volume <=1250 pcu/h Area Urban Speed limit 30 km/h 50 km/h >1250 pcu/h No No Yes

13 Decision tree methods Algorithms to induce decision trees from a given dataset No algorithm is the best for all domains No examples for predicting junction design We use CHAID, C(A)RT and QUEST Options concerning splitting, stop and pruning criteria 7 alternative methods

14 Evaluation Test different methods, data set sizes, validation methods Evaluate prediction accuracy CHAID CHAID ECHAID ECHAID CRT CRT QUEST Cases Pearson Likelih. Pearson Likelih. Gini Twoing - All All 500, % 85.9% 85.8% 85.9% 85.7% 87.3% 84.4% Classified by main type Modelled by size category AW 688 TW 81,659 SIG 163,380 RA 254,273 All 500, , , , , , % 39.9% 36.6% 38.3% 45.1% 51.2% 32.6% 86.2% 86.4% 86.1% 86.1% 85.0% 86.8% 81.4% 85.1% 85.1% 85.0% 85.4% 84.9% 87.2% 85.4% 96.2% 96.1% 96.2% 96.0% 95.6% 96.3% 94.9% 90.7% 90.7% 90.6% 90.7% 90.2% 91.6% 89.3% 89.6% 89.7% 89.7% 89.8% 91.9% 91.8% 89.6% 71.6% 71.5% 71.3% 71.2% 76.4% 76.9% 67.6% 88.5% 88.5% 88.5% 88.5% 89.9% 90.0% 86.6% 91.6% 91.7% 91.7% 91.7% 93.3% 93.4% 91.6% 87.7% 87.9% 87.8% 87.9% 89.1% 89.3% 86.6%

15 Evaluation Importance of independent variables Example for size category 3 Variable % 1 Through volume 100.0% 2 Major through & left volume 97.1% 3 Major through & minor left volume 79.8% 4 Major through volume 77.4% 5 EB through volume 56.0% 6 Through percentage 51.8% 7 EB left volume 44.0% 8 WB through volume 29.1% 9 Minor through volume 28.1% 10 Major left volume 28.0%

16 Evaluation

17 Further research Existing rules Bicycle effects Isolated junctions Single objective Isolated junctions Multiple objectives Air quality Noise Safety Network related design rules Junctions in a network Single objective Junctions in a network Multiple objectives Fast alternative for multi-objective optimisation

18 Network example 1 network 3 junctions 2 junction designs Priority junction Roundabout 1 OD-matrix

19 Voertuigverliesuren (h) Network example RRR RRV RVR RVV VRR VRV VVR VVV Oplossingssets Kruispunt Wegvak

20 Questions and discussion