INDOT’s Reference Post System

In 1999, the Indiana Department of Transportation decided that it was time to come up with a system that would help better keep track of features along the roads that for which it was responsible. While is would be based, according to INDOT, on the mileage of the road, it was not a milepost system. It was a locator for maintenance items, other than signs, on the state highway system.

RPS 86 on US 40, Marion County, Indiana (Washington Park Cemetery). From Google Maps, snipped 23 December 2020.

There are many parts to the system. The one that most people would have seen, but not really noticed, were the signs that were put up for use with the system. These consisted of small blue signs with a mile number on it, with a smaller sign, if needed, below it with an offset to that mile on it. The signs themselves were barely wider than the post they were on. Very small in relation to most highway signs. Since they are technically only for INDOT use, their size wasn’t a concern. The public wouldn’t notice them, lessening the sign pollution that departments of transportation have been trying to keep under control forever.

RP 88, Offset .88, US 40 bridge of Buck Creek, Cumberland

I really wish I could have had a better snippet for the offset post, but then, the idea was to give the reader the image of what they roughly look like, so the reader would know what to look for.

The RPS manual is very detailed in its information. For instance, the picture to the left is listed as “RP_U_40_Post_86,” meaning “Reference Post, US 40, Post 86.” The one on the right is listed as “CUMBERLAND CORP. LINE BR 4588 O BUCK CREEK,” at least in the 2004 manual.

US 40 is a very prime example of why this system isn’t to be used as a mileage post system. The system was setup prior to the 1 July 1999 decommissioning of US 31, SR 37 and US 40 inside the Interstate 465 loop. What was, in 1999, marked as mile 86 on US 40 is, in 2020, at mile 92.37 on that very same road in 2004. In 2016, the last update from INDOT, it was listed as US 40 mile 65.179. The legal definition of US 40 was lengthened when it was rerouted along the southside of Indianapolis on I-465 in 2004. By a little over six miles. By 2016, the extra mileage along I-465 was removed to show a more accurate road mileage count towards INDOT’s limit of 12,000 miles.

But there is a bit more to the reference post system that comes into play. Each highway listed in the RPS not only includes the complete mileage for the road in Indiana, but they are also listed by the mileage per county, as well. For instance, reference post 86 above is listed as Marion County mile 24.06 in 2004. In the 2016 manual, that mileage is 5.027.

Then, the reference post system records almost everything along the road. This includes EVERY village/town/city street that intersects with the posted road. For instance, near reference post 86 is, in the 2004 manual, “86 + 0.21 24.52 IR 4193 LT (DELBRICK LN).” At reference post location 86.21, 24.52 route miles into Marion County, Delbrick Lane connects to Washington Street (US 40) on the left (north) side of the road. Directions are listed from the increasing number of the reference post. Every street is listed, although almost none of them have a reference post sign.

Also, the corporation limits of towns and cities are listed by the reference post location, although there is no reference post installed most of the time. This even includes old corporation limits. For instance, in the 2016 manual, reference post 85+0.686 is listed as “City or Town Limit – Indianapolis.” Post Road is reference post 86+0.668. Legally, Indianapolis continues for another at least two miles (the sign welcoming one to Indianapolis is west of German Church Road, the county line is another mile east of that, but that is in the town of Cumberland. And even legally, Cumberland is part of Indianapolis. It is as confusing as all get out, but suffice it to say, for the past 50 years, the city limits of Indianapolis have been the county limits of Marion County, with some exceptions. Certainly not Post Road.

But the idea of the legal multiplex of I-465 with almost every INDOT road in Marion County (there are two that don’t mix with I-465: US 136 and SR 135) that brings up another question. What about multiplexes of state roads?

When the system was created in 1999, it was designed with a hierarchy of roads. That hierarchy was interstate, US highway, then state road, in that order. INDOT does not use the term “multiplex” officially. It is called “travel over” in Indiana. The following picture comes from the INDOT RPS guide of 1999 showing how “travel overs” are handled when it comes to marking the mileage of the road.

Indiana Department of Transportation Reference Post System Users Guide, May 1999.

As you can see, near Frankfort, US 421 takes precedence with the little blue signs. SR 39 is junior to SR 38 when it comes to the signs, only due to the fact that 38 is before 39 numerically.

The system underwent some changes between 2004 and 2015. In 2015, it was made perfectly clear that the manual may contain some mistakes, but that every effort was taken to avoid them.

There was also a special note involving US 40 in Vigo County. When US 40 was removed from most of Vigo County, and rerouted along I-70 and SR 46, the RPS system was not changed to reflect that. The section of US 40 that “travels over” SR 46 is still labelled as SR 46. Here is INDOT’s explanation: “US 40 in Vigo County has a special issue that needs to be addressed. Due to relinquishments and creating a travel over for US 40, the alignment does not follow the historic path. US 40 now traverses where SR 46 has traditionally been and SR 46 is considered the Travel Over on US 40. However, the existing reference posts are still for the SR 46 route and are running in a contrary direction to the increasing direction of US 40. Therefore, for the purposes of this book, RP and Offset for the first 3 miles of US are based on the State Log Measure until it reaches the traditional location for US 40 and then jumps to RP 11 + 00 at the intersection of SR 46 and US 40.”

I mentioned above about the original system being put in place prior to the decommissioning of routes in Marion County. It is important to note that there were more routes affected than just those that were moved to I-465. Those routes were US 31, SR 37 and US 40. The mileage on those roads got weird, yes. But there were two others that were affected by the change…and one most people didn’t even realize.

SR 135 was rerouted from Troy Avenue to Thompson Road, cutting two miles out of the official route. This just required moving the little blue signs from north of Thompson Road, and surveying what else would need signs. And what wouldn’t.

The other route affect wasn’t even marked when it was decommissioned. Shadeland Avenue on the east side of Marion County was still legally SR 100 from I-465 to US 40 (Washington Street) until 1 July 1999. For the longest time, the only marker on SR 100 was a smaller blue sign below the reference post signs that read “100.”

INDOT has available on their website the RPS manuals for 2004, 2015 and 2016. Also available is the users guide from 1999. Here are the links for each: Users Guide200420152016

SR 67 in Northeast Marion County

When the Great Renumbering occurred on 1 October 1926, the number 67 was assigned to the Pendleton Pike connecting Indianapolis to Pendleton, through Lawrence and Oaklandon. This would be part of the greater State Road 67 stretching from Vincennes to Muncie…and later to the Ohio State Line. But the route in Indianapolis, and northeast Marion County, would carry the road along Massachusetts Avenue to the city limits, where the name would change to Pendleton Pike.

One of the first changes would involve the adding of US 36 to the same path. Although US 36 is higher in priority, most of the businesses along the old route kept the “67” as part of their names if it included it. As a matter of fact, I find it hard to believe that even today, there are no businesses along that road that include the number “36,” at least as I can recall. But there is a Motel 6t7…with a US route shield shaped sign…as shown to the left.

Changes were being planned for the road in 1933, when it was decided that SR 67 (and as a result, US 36) would be three laned from Indianapolis to Anderson. This would result in a change in the historic path of the Pendleton Pike from northeast of the then town of Lawrence to just south of Pendleton. In Oaklandon, for instance, the old SR 67 followed the current path of Pendleton Pike to what is now Oaklandon Road (formerly Germantown Road, named after the village that is now currently under water in Geist Reservoir at the Marion-Hamilton County line). The road then went north on Germantown (Oaklandon) to Broadway, turning northeast on that street. The old connection between Broadway (old SR 67) and the current Pendleton Pike (US 36/SR 67) still can be seen northeast of Oaklandon.

In 1935, the State Highway Commission decided that the number of miles inside the City of Indianapolis that it had to maintain would best be served if the number was lower. At the time, most of the northern city limit was at 38th Street, the dividing line between the middle tier and northern tier of townships. Where the Pendleton Pike now ends, at 38th Street west of Shadeland, was where the city ended at that point in history.

A bridge contract was let to Edward F. Smith to build a five span, 217 foot long bridge over the Big Four Railroad along 38th Street west of the intersection with SR 67, which was Massachusetts Avenue/Pendleton Pike. The bridge, in 1935, cost $143,825.01. The Indianapolis News of 25 May 1935 states that “Thirty-eighth street, with this and other contemplated improvements, is to become State Road 67. Construction will start in a few days and is scheduled to be completed by November 15.” Plans to move SR 67 to the 38th Street corridor were mentioned in newspapers as far back as June 1933, when plans for a new Fall Creek bridge on 38th Street, near the State Fair Grounds, were in the works.

While construction was going on between Indianapolis and Anderson in 1935, the official detour route had changed in late June. The original detour involved taking US 40 to Greenfield, then north on SR 9 to Pendleton. The new official detour recommended using SR 13 (became SR 37, now Allisonville Road) to SR 32 in Noblesville, then SR 32 to Anderson. This was recommended over the SR 38 route to Pendleton since SR 32 was a hard surface road, and large section of the newly added SR 38 were still gravel.

By 1937, SR 67 would find itself skirting Indianapolis, at least on the north side, along 38th Street. The old SR 67, Massachusetts Avenue, would find itself labelled SR 367. The three lane project between Indianapolis and Anderson would be completed, and Oaklandon would find itself bypassed by one of the two transportation facilities that made it possible. Now, most of what is left of SR 67 on the northeast side of Marion County (Pendleton Pike from I-465 east) is at least five lanes wide…but quite a bit of it is seven.