1 package org.opentrafficsim.road.gtu.generator;
2
3 import org.djunits.value.vdouble.scalar.Length;
4 import org.djunits.value.vdouble.scalar.Speed;
5
6 /**
7 * Extends car-following placement with a first-order bounded acceleration (BA) principle. This principle comes down to
8 * reduction of efficiency by increasing headways, as the generated GTU speed is lower than the desired speed. The increased
9 * headways allow for acceleration to occur, allowing faster flow recovery over time.
10 * <p>
11 * Copyright (c) 2013-2018 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
12 * BSD-style license. See <a href="http://opentrafficsim.org/node/13">OpenTrafficSim License</a>.
13 * <p>
14 * @version $Revision$, $LastChangedDate$, by $Author$, initial version 13 jan. 2018 <br>
15 * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
16 * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
17 * @author <a href="http://www.transport.citg.tudelft.nl">Wouter Schakel</a>
18 */
19 public class CFBARoomChecker extends CFRoomChecker
20 {
21
22 /** {@inheritDoc} */
23 @Override
24 protected double headwayFactor(final Speed desiredSpeed, final Length desiredHeadway, final Speed generationSpeed,
25 final Length generationHeadway, final Length leaderLength)
26 {
27 if (desiredSpeed.eq(generationSpeed))
28 {
29 return 1.0;
30 }
31 // following state at desired speed (capacity)
32 double k0 = 1.0 / (desiredHeadway.si + leaderLength.si);
33 double q0 = k0 * desiredSpeed.si;
34 // actual state
35 double k = 1.0 / (generationHeadway.si + leaderLength.si);
36 double q = k * generationSpeed.si;
37 // recovery flow qr
38 double qr = q; // if already on free flow branch
39 if (k > k0) // on congestion branch
40 {
41 // recovery wave speed assuming theta = 1 / q0 (theoretically sound and tested to be robust)
42 double rho = generationSpeed.si - q0 / k;
43 // recovery free flow state
44 double kr = (q - rho * k) / (desiredSpeed.si - rho);
45 qr = kr * desiredSpeed.si;
46 }
47 // efficiency factor, > 1 is larger headway, so less efficient
48 return q0 / qr;
49 }
50
51 }