2015 Indianapolis 500 Pre-Race Strategy Guide

Pit strategy can play a major role in determining who wins a race.  This year, I will analyze yellow flag and pit stop history at each track to see if trends exist in the timing and/or frequency of cautions.  If trends do exist, a clever strategist might be able to gain his/her driver a few extra positions on the track by pitting at the correct time.

Caution Breakdown for Indianapolis 500

Lap	2009	2010	2011	2012	2013	2014
1	Yellow 1	Yellow 1
2	Yellow 1	Yellow 1
3	Yellow 1	Yellow 1
4	Yellow 1	Yellow 1			Yellow 1
5	Yellow 1				Yellow 1
6	Yellow 1				Yellow 1
7
8		Yellow 2
9		Yellow 2
10		Yellow 2
11		Yellow 2
12
13
14				Yellow 1
15				Yellow 1
16				Yellow 1
17				Yellow 1
18
19
20
21	Yellow 2		Yellow 1
22	Yellow 2		Yellow 1
23	Yellow 2		Yellow 1
24	Yellow 2		Yellow 1
25	Yellow 2		Yellow 1
26	Yellow 2		Yellow 1
27	Yellow 2
28			Yellow 2
29			Yellow 2
30			Yellow 2
31			Yellow 2
32			Yellow 2
33
34
35					Yellow 2
36					Yellow 2
37					Yellow 2
38					Yellow 2
39		Yellow 3			Yellow 2
40		Yellow 3			Yellow 2
41		Yellow 3			Yellow 2
42		Yellow 3			Yellow 2
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57	Yellow 3				Yellow 3
58	Yellow 3				Yellow 3
59	Yellow 3				Yellow 3
60	Yellow 3				Yellow 3
61	Yellow 3
62	Yellow 3		Yellow 3
63			Yellow 3
64			Yellow 3
65		Yellow 4	Yellow 3
66		Yellow 4	Yellow 3
67		Yellow 4	Yellow 3
68		Yellow 4	Yellow 3
69		Yellow 4	Yellow 3
70		Yellow 4
71
72
73		Yellow 5
74		Yellow 5
75		Yellow 5
76		Yellow 5
77		Yellow 5
78		Yellow 5
79
80				Yellow 2
81				Yellow 2
82				Yellow 2
83	Yellow 4			Yellow 2
84	Yellow 4			Yellow 2
85	Yellow 4			Yellow 2
86	Yellow 4			Yellow 2
87	Yellow 4
88	Yellow 4
89	Yellow 4
90				Yellow 3
91				Yellow 3
92				Yellow 3
93				Yellow 3
94				Yellow 3
95
96
97
98	Yellow 5
99	Yellow 5
100	Yellow 5
101	Yellow 5		Yellow 4
102	Yellow 5		Yellow 4
103	Yellow 5		Yellow 4
104	Yellow 5		Yellow 4
105	Yellow 5		Yellow 4
106	Yellow 5	Yellow 6	Yellow 4
107	Yellow 5	Yellow 6	Yellow 4
108	Yellow 5	Yellow 6	Yellow 4
109		Yellow 6
110		Yellow 6
111		Yellow 6
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132	Yellow 6
133	Yellow 6
134	Yellow 6
135	Yellow 6
136	Yellow 6
137	Yellow 6
138	Yellow 6
139	Yellow 6
140	Yellow 6
141
142
143
144
145
146				Yellow 4
147				Yellow 4
148		Yellow 7	Yellow 5	Yellow 4
149		Yellow 7	Yellow 5	Yellow 4
150		Yellow 7	Yellow 5	Yellow 4		Yellow 1
151		Yellow 7	Yellow 5	Yellow 4		Yellow 1
152		Yellow 7	Yellow 5			Yellow 1
153		Yellow 7	Yellow 5			Yellow 1
154		Yellow 7	Yellow 5			Yellow 1
155		Yellow 7				Yellow 1
156						Yellow 1
157
158			Yellow 6
159			Yellow 6
160			Yellow 6
161	Yellow 7	Yellow 8	Yellow 6
162	Yellow 7	Yellow 8	Yellow 6
163	Yellow 7	Yellow 8	Yellow 6
164	Yellow 7	Yellow 8	Yellow 6	Yellow 5
165	Yellow 7	Yellow 8		Yellow 5
166	Yellow 7			Yellow 5
167				Yellow 5
168				Yellow 5		Yellow 2
169				Yellow 5		Yellow 2
170				Yellow 5		Yellow 2
171						Yellow 2
172						Yellow 2
173						Yellow 2
174	Yellow 8					Yellow 2
175	Yellow 8
176	Yellow 8					Yellow 3
177	Yellow 8					Yellow 3
178	Yellow 8					Yellow 3
179	Yellow 8					Yellow 3
180	Yellow 8
181	Yellow 8			Yellow 6
182	Yellow 8			Yellow 6
183				Yellow 6
184
185
186
187
188				Yellow 7
189				Yellow 7
190				Yellow 7
191				Yellow 7		Yellow 4
192				Yellow 7		Yellow 5
193				Yellow 7		Yellow 5
194					Yellow 4
195					Yellow 4
196					Yellow 4
197
198					Yellow 5
199					Yellow 5
200		Yellow 9	Yellow 7	Yellow 8	Yellow 5

In addition to being the biggest race of the year, the Indianapolis 500 is also the first oval race of 2015.  This will be our first chance to see how the low-downforce aero kits race.  It's also the first time I've analyzed caution data for an oval race, so I'm hesitant to draw too many conclusions from the data.  That being said, the data from the last 6 races does not indicate that cautions are especially likely to follow immediately after the previous caution.  I'm not comfortable applying that as a rule to all oval races, but it does seem to be the case at the Brickyard.

Cautions per Year

	2009	2010	2011	2012	2013	2014
Total Cautions	8	9	7	8	5	5
Total Caution Laps	61	44	42	39	21	21
Average Caution Length (Laps)	7.6	4.9	6.0	4.9	4.2	4.2
First Caution Lap	1	1	21	14	4	150
Last Restart (Laps Remaining)	18	35	36	7	4	7

Caution Averages 

	2009 to 2011 Avg	2012 to 2014 Avg	2009 to 2014 Avg
Total Cautions	8.0	6.0	7.0
Total Caution Laps	49.0	27.0	38.0
Average Caution Length (Laps)	6.2	4.4	5.3
First Caution Lap	7.7	56.0	31.8
Last Restart (Laps Remaining)	29.7	6.0	17.8

One trend that seems to apply to both 'twisties' (road and street courses) and ovals is that the DW12 has reduced the number of cautions.  Compared to 2009 to 2011, the first 3 years with the DW12 featured a reduction of 2 entire cautions from each race.  Laps run under caution is also down from 49 to 27 during the same time period, a reduction of 45%.

I suspect 2 factors contribute to the reduction in cautions.  First, the DW12 allows drivers to get away with more contact than the IR07 did.  The DW12's sidepods and 'sponsor blocker' are the outermost objects on the side of the chassis, so drivers have a chance of continuing to race despite gentle side to side contact.  This was a rarity with the IR07 because the tires were the outermost objects on the side of that chassis.  Any contact was likely to result in a crash.

The second factor contributing to the reduction in cautions is the way that the DW12 has raced on the Indianapolis oval.  Cars typically make their way around the track in a single file 'drafting train' of 20 or more cars.  Fewer cars get lapped, which reduces the chances for an accident.  Second, drivers don't feel a sense of urgency to make a pass at the first opportunity they have because they know they'll have another passing opportunity soon.  At the same time, the driver being passed doesn't feel like (s)he needs to fight to prevent the pass.  (S)he will probably have a chance to return the favor soon after the pass is safely completed.  This has a calming effect on the field, because drivers can choose safer times to attempt a pass, and give more room to a car making a pass.

One unfortunate trend over the last 6 years has been yellow flags at the end of races.  At the end of the race, the proximity of cars in the 'drafting train' increases the likelihood of a caution.  Drivers know time is running out, so they're willing to attempt riskier passes than they would at the beginning of a race.  Drivers being passed are less likely to leave room for the car attempting the pass.  Because of the increased aggression, 4 out of the last 6 '500s' have ended under yellow.  While I find this problematic, I certainly hope IndyCar resists the urge to use any artificial rules to help a race end under green.  It's the Indianapolis 500, not the Indianapolis 510, 520, or 525.

Lap Number of the Winner's Pit Stops*

Year	2012	2013	2014
Winner	Franchitti	Kanaan	Hunter-Reay
Stop 1	15	29	31
Stop 2	48	58	63
Stop 3	78	90	94
Stop 4	118	121	124
Stop 5	147	153	153
Stop 6	166	178	170
Stop 7	N/A	N/A	192

*Each cell contains the lap number and track condition (green or yellow) for each of the winner's pit stops.

Pit strategy on ovals is significantly different than pit strategy on 'twisties'.  Consider a theoretical 2 car race between Sebastien Bourdais and James Hinchcliffe (#GetWellSoonHinch) where Bourdais is leading but must pit before Hinchcliffe.  On an oval, a green flag pit stop (plus the time it takes to travel down pit road at or below the speed limit) will likely cause Bourdais to go 1 or more laps down to Hinchcliffe, who will pass Bourdais while Bourdais is making his stop.

This is a significant disadvantage for Bourdais.  If a yellow comes out after Bourdais has made his stop, but before Hinchcliffe makes his stop, Bourdais will restart the race behind Hinchcliffe despite the fact that Bourdais was leading before making his stop.  Under the caution, Bourdais will catch up to Hinchcliffe (who must follow the pace car), but will still be one lap down.  Hinchcliffe can make his stop under yellow and catch back up to Bourdais, who cannot pass the pace car.  Bourdais is technically on the lead lap, but he is 99% of a lap behind Hinchcliffe.  Even if Bourdais is allowed to take a wave around (cars between the pace car and the leader pass the pace car and 'get a lap back'), he cannot pass the leader Hinchcliffe before the race resumes.  In this scenario, Hinchcliffe has passed Bourdais using a combination of better fuel mileage, pit strategy, and luck.

The advantage is reversed if the hypothetical race takes place on a 'twisty' where the leader can pit without losing a lap.  Here, Bourdais pits and is passed by Hinchcliffe, but returns to the race on the same lap as Hinchcliffe.  A caution flag allows Bourdais to catch up to Hinchcliffe, who cannot pass the pace car.  At this point, Hinchcliffe must pit under yellow and lose a position to Bourdais but restart the race directly behind him (because Bourdais cannot pass the pace car).  Technically Hinchcliffe can pit soon after the restart, but this leaves him further behind Bourdais because while Hinchcliffe adheres to the pit road speed limit, Bourdais is opening a large gap on Hinchcliffe by driving at race speed.

Since cars want to pit under yellow, the number of pit stops in an oval race can be significantly influenced by the number of yellows.  Strategists may choose to visit pit road under caution if they're near 50% of the way through a fuel run to avoid having to make a green flag pit stop, while other cars who pitted under the yellow don't stop.

Over the last 3 years, the Indianapolis 500 winner has always made at least 6 stops.  Given the reduction in fuel mileage this year, I expect a minimum of 8 pit stops.  That number could easily be 10 or higher if there are more than a handful of cautions.

Oddly, Indianapolis doesn't make the decision to pit under green as easy as other ovals.  Let's return to our 2 car race between Bourdais and Hinchcliffe, this time during the Indianapolis 500 when Bourdais leads by 1 second.  To make this interesting, let's assume each driver runs a 40.5 second lap (a very quick 221MPH according to this sector time sheet from last year's '500') when they don't pit.  Like before, Bourdais must pit before Hinchcliffe.  The chart below contains each driver's lap time, and the gap the leader has on the other car.  All times are in seconds.

Lap	Bourdais Lap Time (s)	Hinchcliffe Lap Time (s)	Gap (s)	Leader
31	40.5	40.5	1	Bourdais
32	65.8	40.5	24.3	Hinchcliffe
33	55.7	40.5	39.5	Hinchcliffe
34	40.5	40.5	39.5	Hinchcliffe

At the end of lap 31, as stipulated, Bourdais leads by 1 second.  Bourdais runs his in-lap (lap when he makes a pit stop) in 65.8 seconds, and his out-lap (lap when Bourdais returns to the track after a pit stop) in 55.7 seconds.  (These in-lap and out-lap times were run by Tony Kanaan on laps 32 and 33 of the 2014 Indianapolis 500, and can be found in the sector time sheet referenced above.  I expect similar in-lap and out-lap times in the 2015 race.)  Laps 32 and 33 are slower than Bourdais' normal speed because Bourdais must run a portion of both laps at or below the pit road speed limit.  Since Hinchcliffe doesn't need to pit yet, he passes Bourdais on lap 32, and builds a gap of 39.5 seconds over Bourdais by the end of lap 33.

The problem for Hinchcliffe here is that Bourdais isn't an entire lap down.  For Hinchcliffe to put Bourdais 1 lap down, he would need a gap of over 40.5 seconds.  Hinchcliffe gained 40.5 seconds over Bourdais, but because he started 1 second behind Bourdais, Hinchcliffe was unable to lap Bourdais.

The key to determine whether the leader is better off pitting under green or yellow is to know how much time (s)he will lose when making a pit stop, commonly referred to as the 'pit stop delta time', or simply 'delta time'.  If the leader's delta time minus his lead over 2nd place is less than the time it takes the 2nd place car to complete a lap, the leader should pit under green.

The implication of this exercise is that Indianapolis 500 leaders may prefer to make their stops under green during the 500, especially if they have a solid pit crew (a low delta time) or the race pace is below 221.  This is the reverse of most other ovals, where the leader prefers to make his/her stops under yellow to avoid going 1 lap down.

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