The following is a resume covering the Northern Pacific Signal Department from its origin to the present time

The following is a resume covering the Northern Pacific Signal Department from its origin to the prese= nt time.

This Department was formally organized in 1909. P= rior to this time, the little signaling that was in existence was under the cont= rol of the Maintenance-of-Way Department and consisted mainly of interlocking plants at crossings of the Northern Pacific and other railroads. These plants were principally of t= he old mechanical type of rather primitive construction. In mo= st instances, each plant was built and owned by the junior road. These early plants were mostly isolated installations, built principally for protection= of the crossing,

In addition to the= above mentioned interlocking plants, there were two short installations of automa= tic block signals between St. Paul and Minneapolis and between Tacoma= and South Tacoma. Also, there was a short signal installation protecting the gauntlet track on the drawbridge over the Red River of the North between Moorhead an= d Fargo.=

In 1909 an all-ele= ctric interlocking plant was installed at the Mississippi Street Yard in St. Paul. This plant served faithfully for many years = in this very busy location. The = old interlocking machine was replaced in 1954.

In 1909 it was pro= posed to construct an interlocking plant to protect our double track main line and the Hinckley Branch of the Great Northern at St. Cloud. as we were the jun= ior road, it was our obligation. The Great Northern desired that we incorporate their junction switches into the plant. This gave the latter road an intere= st in the interlocking plant on an undivided basis,= a new type of interlocking machine called the "American" was selected.<= span style=3D'mso-spacerun:yes'> Only a very few of this type were ever installed in the whole country. It was replaced in 1947 with a new General Railway Signal Company machine.

To protect the sin= gle track gauntlet bridge over the Yellowstone River, just east of Billings, four signals were installed i= n 1910.

In 1910, automatic= block signals of the "Hall K" top post type were installed on the doubl= e track line between Seattle and Tacoma.

In 1910, the double track line between Northtown and St. Cloud was signaled using the General Railway Signal Company Style 2A top of mast signals. The signals were installed and paid for by t= he Northern Pacific. In this territory the northerly track is owned exclusivel= y by the Northern Pacific, while the southerly track is owned by the Great North= ern. These two tracks are used jointly by the two roads as double track. After the signals were installed, = the Great Northern refused to pay for the signals on their track. The ownership remains essentially the same at the present time. Some of the highway protection subsequently installed has been paid for by the two roads on the basis of location of apparatus.

In 1910, General R= ailway Signal Company Style 2A top of mast signals were installed on the double tr= ack between Garrison and Missoula<= /st1:place>.

In 1910, the double track line from Staples to near Dilworth was likewise signaled with the same type of signal, i.e. the General Railway Signal Company Style 2A top of mast signal.

In 1910, a few signals were installed on = the line to Duluth between St. Paul and Maryland Street. Also at this time a short piece of double track between Billings and Laurel<= b> was signaled using the same type= of signals. The mechanical interlocking plant at Laurel was installed at this time.

At this same time,= the first signals on single track were installed between Laurel and Livingston, using the over-lap system of control. This system had the disadvantage that= the same distance had to be maintained between following trains in the same direction as had to be maintained for opposing trains, but protection was provided, however, thus making a start for signaling on single track.<= /o:p>

It should be menti= oned at this point that the signal programs, just previously enumerated, caused changes at a number of foreign owned interlocking plants; due to the fact t= hat the Northern Pacific desired to have continuous automatic signal protection through these plants. These changes consisted primarily of the substitution= of the mechanical top arms of the main line home signals by electrically opera= ted arms.
Also, the approach signals, either of the fixed or wire connected type, ware similarly removed and electri= c top of mast signals were substituted, likewise, electric locks and annunciators ware installed in the interlocking tower= s. The expense of the above changes was borne entirely by the Northern Pacific. Th= ese procedures eventually gave the Northern
Pacific an undivided part ownership in many of the plants originally instal= led by the junior road. This will be elaborated on later -when the subject of Valuation is discussed.

Changes were made = at the following plants: Coon Creek, Elk River, Wadena, Detr= oit Lakes, and Glyndon.=

In 1911, the double track line between Kalama and Vancouver was signaled using the General Railway Signal Company top post signals.

During 1912, the d= ouble track line from Tenino to Kalama was signaled, using the new type of General Railway Signal Company 2A base of m= ast signals. This completed the signal installation on the double track from Te= nino to Vancouver, connecting there with the si= gnals protecting the three drawbridges over the Columbia River, the Oregon Slough, and the Williamette River.

Included in the 19= 12 program was the installation of signals on the double track between <= st1:place w:st=3D"on">St. Cloud and Rice, which was the end of double track at that time.

Also during 1912, a short stretch of single track between Sand Point and Athol, also the single track between Hauser and the end of double track at Ve= lox was installed using the new General Railway Signal Company circuits called = the "A.P. B." system, or the "Absolu= te Permissive Block" system, which includes positive head-on protection between opposing stations, but allows trains to follow one another usually = only one block apart. The success = of this single track system gave the impetus for later installations on single track.

W. RR. & N. crossing at Sp= okane was also installed in 1912. Also in this same year the double track west of= the Spokane yard to Marshall was signaled. At this time, Marshall interlocking plant was install= ed by the Northern Pacific, connecting the track of the S. P. & S. Railway in= to the plant as well as providing interlocking facilities for our Paloose and Lewiston Line. From Marshall plant west to Cheney, A.P.B. signaling was also installed = at this time.

The double track l= ine from Billings to Huntley where the C. B. &= amp; Q. connects with their line from Omaha was signaled in 1923.

In 1913, the single track line between White Bear Lake and West Duluth was signaled with the ne= w A.P.B. circuits and using the new 2A. base of mast signals. A short piec= e of double track between White Bear Lake and <= st1:address w:st=3D"on">Maryland Street, St. Paul, and between West Duluth Jct. and West Duluth was also included in this program.

The line between C= arlton and Superior, which is part double and part single track, was signaled at t= his time in a like manner, as noted before, electric circuits were carried thro= ugh the interlocking plant at Hinckley and to the plant at Carlton.

The 1913 program, included more single track signaling toward the western part of the road, s= uch as the signaling installed this year between Alfalfa and Cle Elum, and another stretch of single track between Les= ter and East Auburn connecting with the signals earlier installed between Seatt= le and Tacoma.

In 1913, a mechani= cal interlocking plant was installed at Staples, controlling the junction of th= e Lake Superior and St. Paul Divisions.

During 1914, anoth= er extensive signal program was undertaken. This included the installation of signals using the A.P.B, single track type of circuits between Paradise and Sand Point, connecting with the previously installed signals between Sand Point and Ath= ol, already noted. It should be mentioned that in the Pa= radise to Sand Point territory, there wa= s about twenty-seven (27) miles of alternate main lines between Kildee and Tr= out Creek that were both signaled for single track operation in both directions, with elaborate signaling at the junctions at both ends of the single tracks. The older line, known as the “White Pine Hill Line” had a very heavy grade just west of the bridge over the Clark's Fork of the Columbia River.&nb= sp; The new line, or low line, had a much better grade. The two lines we= re used for passing trains. The = old line has since been removed. = Also during 1914, the gap between Athol and Hauser was closed. Between these lat= ter points, there was a short stretch of double track, the tracks being widely separated at points. One trac= k did not have a pole line.

To obviate constru= ction of a pole line, a rather unusual type
of polarized motor track relay was used.&n= bsp; This piece of track has since been removed.

Also during 1914, double track signals were installed west from Livingston to the end of doub= le track at Bozeman. The line west from Livingston to the old Bozeman Tunnel is on a very heavy grade to the tunnel where the line then drops down a heavy grade to Bozeman. The down hill signals on both side= s of the tunnel are over-lapped one track circuit, for added protection. This same program was extended west from Bozeman on the si= ngle track as far as Toston.

As indicated in the proceeding paragraph, there is double track on each side of Bozeman Tunnel = with single track through the tunnel. An early type of low voltage switch machine was installed at the ends of double track switches at each end of the tunnel.

During 1914, the s= ingle track line between Pasco and Alfalfa was signaled with the standard A.P.B. circuits and connected into the system at Alfalfa, installed, the previous year.&= nbsp; The short piece of track between Cle Elum and Easton was signal= ed this same year with the standard A.P.B. circuits.

An interesting lit= tle signal installation west of Lo= gan, on the Butte Line, was installed in 19l4 to protect trains when blasting operations were to take place in a mine. Before a blast was touched off, a switch in the mine engine roan was thrown setting a signal at "caution= " in each direction warning trains to stop at a safe point each side of the s= pot where blasting operations might obstruct the track.

When the Puget Sou= nd and Willapa Harbor Railroad (the Milwaukee} was bui= lt, it created two grade crossings with our South Bend Branch at Dryad and Chehali= s, the Milwaukee, being the junior road, built two mechanical interlocking pla= nts and paid for then on the generally recognized basis that the junior road was obligated to interlock. About= 1922, the Milwaukee went to court and won a decision that forced us to assume one-half the construction cost of each plant. Two AFE's were initiated in 192U to prov= ide for these expenditures. Subsequently, the Dryad crossing has been removed and the Chehalis p= lant has been changed to automatic operation.&n= bsp; There has been some confusion in designation between this plant and = the Chehalis Jet. plant on the main line. They are approximately one mile ap= art.

One of the original isolated mechanical interlocking plants mentioned previously had been insta= lled at Fargo at the Milwaukee crossing by the Northern Pacific in spite of the = fact the Milwaukee was the junior road. On January 15, 1915, the old wood tower was destroyed by fire. A new brick tower was built, replacing the old one. In July 1927, the old mechanical p= lant was replaced by an automatic plant. Certain changes in ownership and maintenance obligations were made at this time. The years 1915 and 1916 were very quiet as far as new signal work was concerned. A small installation was made in 1916 at the junction of the main line and the Mandan North Line at Mandan. In 1917 A.C. track circuits were installed on the double tra= ck line between St. Paul and White Bear.

A short explanation probably will be in order. The following will deal with signal work, althou= gh other departments were similarly involved. The valuation date for the North= ern Pacific was set as of June 30, 1917.

The railroad was d= ivided into valuation sections, according to the seven states through which the ro= ad operates. The limits of these sections were usually located at some well defined point, such as head block, end of bridge, etc. Several field partie= s, usually comprising of two men were organized, Mr. S. W. Law, and Mr. Bert <= span class=3DSpellE>Basford worked as one party. Mr. E. J. Ralph, and Mr. Paul Amann comprised a second party and later Mr. Bert Basford, and Mr. A. C. Eastman, a third party. Each party was assigned a motor car. = It was the duty of each to travel over a designated portion of the line and ma= ke written notes and pencil sketches of all signal apparatus, including all ty= pes of signals, counting and listing all different types of relays, battery, terminals, and all associated items, including rubber covered wire of vario= us types and sizes, line wire, bonding, switch boxes and all other apparatus, = and including various types of highway protection, but not the mechanically operated crossing gates.

It was a physical impossibility to do all this work by June 30, 1917, but attempts were made = to include only such work as was in place as of the above date. This work was a Herculean task, between fighting adverse weather conditions, both cold and heat, trains, motor cars of other departments and many = other handicaps. At this time the road was not completely signaled, however, ther= e was a sizeable amount of signal apparatus involved, including many of the old original interlocking plants. Usually the owner of the plant, which included apparatus on both roads, inventoried the plant. This work included branch l= ines as well as main lines.

All the above data= was collected in the Office of the Valuation Engineer, in St. Paul, -where it was all transcribed in proper form. = The following men did preliminary work at this stage of the inventory; <= span style=3D'mso-bidi-font-weight:bold'>Mr. J. Rohner, Mr. F. M. O'Loughlin, Mr. Ralph Thurston, Mr. Bert Ba= sford, Mr. T. C. Rhodes and Mr. A. C. Eastman.

Before it was poss= ible to formulate all this information, the U. S. Government provided a man, to = make a similar inventory. The Northern Pacific furnished a pilot and motor car f= or his use. Mr. Basford of one of the original fie= ld parties acted as pilot and met this man, Mr. J. F. Alexander, in Portland, Oregon. They made a meteoric motor car trip from there to Dul= uth and Superior. Mr. Alexander made his own notes covering the same apparatus as our parties= had previously made. The Northern Pacific was furnished one copy of these notes= .

At this point the onerous task began of making comparisons between the two inventories. Our inventory was called the "Pre-Inventory". Notes were made listing= any discrepancies found. Both omissions and overages were found in comparison w= ith the Government’s notes, but the proper notes were honestly made by the Northern Pacific.

The headquarters o= f the Government, comprising the Western District which included the Northern Pac= ific were located in San Francisco, California<= /st1:State>. Mr. A. C. Eastman, of= one of the field parties, was sent to San Francisco to confer with Mr. Alexander.

The whole comparis= on that had been made in St. Paul was gone ov= er in detail in San Francisco with Mr. Alexander. In some instances, our claims ware allowed and sometime= s we were not as fortunate. All the work with the government there, dealt almost exclusively with quantities.

After the comparis= ons were concluded in San Francisc= o, a large amount of time and energy were expended in trying to arrive at cost figures. We were handicapped by the fact that a large amount of our signals were installed under contract and prices were unavailable.

It was mentioned previously in a number of instances that automatic circuits were installed through a number of interlocking plants wholly owned by another railroad, t= his work being installed and paid for by the Northern Pacific. In each such cas= e a percentage of ownership for each company involved was arrived at by determi= ning the amount contributed by the Northern Pacific against the cost expended by= the road that originally built the plant. The percentages were set forth on a f= orm known as "Form P-72", and signed by an official of each company involved. These percentages of ownership were used by the Government in its computations. Also, these percentages are used as a basis of cost division whenever work is performed by either road regardless of what point in the p= lant the work is performed.

The Government shi= pped its notes and papers from San Francisco to= Washington, D.C. Here the Government applied its own prices on materials and applied its own labor and freight rates agai= nst the materials as collected on its copy of its original field notes. At first, the Government was very reticent about letting representatives of the railroads have access to their pricing sheets, but later on, Mr.= A. C. Eastman of the Northern Pacific was allowed to make copies of all of = the Governments pricing sheets. Complete records were made with the exception of some of the joint and foreign interlocking plants, and were not made on acc= ount of lack of time.

The making of comp= letion reports for signal projects was transferred from the Signal Department to t= he Valuation Department about this time.

The Government fin= ally compiled what is known as the Engineering Report which comprised a summatio= n of all accounts. The Signal Accounts, 15 and 27, as included in the Engineering Report, were accepted by the Northern Pa= cific.

The compilation of= a new form, known as "Form 588" was demanded by the Government.

This form was to c= over all new A. F. E. work performed in the ten and one-half year period subsequ= ent to the date of Valuation, June 30, 1917, to and including December 31, 1927. Approximately about this time, the Government proposed a new method of reporting Signal Completion Reports, using the so-called "Adjustment Units" Two trips to Washington, D«C» were made by Mr. C. A= . Christofferson and Mr. A. C. Eastman in connection with various phases of = the Signal Valuation Program. Ano= ther trip was made by Mr. A. C.= Terrell, Valuation Engineer, and Mr. A. C, Eastman. It was on this last trip that Mr. A. C. Eastman remained and with the collaboration of one of the men, Mr. Hudson, = in Mr. W. M. O'Loughlin's office, the entire inventory of the Northern Pacific signal sys= tem made by the Government was recast into "Adjustment Units", both a= s to quantities and prices. It was on this trip that Mr. A. C. Eastman was affor= ded the opportunity to make copies of the Government's pricing sheets. Mr. W. M= . O’Loughlin, mentioned above, was appointed Sign= al Supervisor of the Eastern District of the Northern Pacific, about 1913. He later resigned and went with the Interstate Commerce Commission with headquarters in Washington, D. C. Later, he was appointed Chief of the Sign= al Valuation Branch of the Interstate Commerce Commission. His warm feeling for the Northern Pacific helped immensely in courtesies extended. Incidentally,= Mr. W, M. O'Loughlin and Mr. F. M. O’Loughlin, who later became Assistant Signal Engineer of the Western District, were brothers.

.Later on, the For= m 588 was extended to includ= e the three year period from January 1, 1928, to January 1, 1930» From ther= e on it is being made on an annual basis.

Now we will retrac= e our steps to the years subsequent to the dull period, during 1915 and 1916,

In 1917, automatic= block signals were installed between Mandan and Dickinson, and between Dickinson and Glendive, these installations were single track signals using the regular A.P.B. circuits, except for the following added feature. Under the standard system= of single track signaling, after the last car of a train has cleared the insul= ated joints in the main line at the end of a siding, whether the train was proceeding down the main lin= e or heading into the siding, the leaving signal will clear. There have been instances at a meet, where the first train was moving slowly, that the engineer of the second train on se= eing the leaving signal start to clear, would speed u= p and side-swipe the last car of the first train.

In the above two installations, circuits were arranged so that the leaving signal would not clear until the tail end of the first train had cleared the fouling point.<= o:p>

In 1917 one of the= old interlocking plants known as Eustis Avenue on Line A between St. Paul and Minneapolis was removed from service.

In 1918, the signal system was made continuous from the vicinity of West Duluth Jet, through the following interlocking plants: the 4= 4^th Avenue plant of the D. W. & P., the Jenswold S= treet plant of the Soo Line, and the Missabe Jet. Plant of the D. M.& N.

In 1918, signals w= ere installed between Missoula and Paradise vi= a St. Regis, this being all single track with the exception of about six miles of double track at the Missoula end. This piece of road is extremely crooked but has a much more favorable grade than via the Evaro Hill Line. It is, incidentally, about thirty mi= les longer.

More work in 1918 included connecting the end of the installation made in 1914 from Toston to Helena, this being single track.

More single track signaling was installed from H= elena west to Garrison, connecting with the old double track signals installed in 1910.

By this time the o= ld end of double track at Rice had been extended west to Gregory. In 1918 signals = were installed on this double track to Little Falls, There is double track betwe= en Easton and Martin at the east portal of Stampede Tunnel, single track throu= gh the two mile long tunnel, then double track from the west portal to Lester. In 1918, when the operation. This was done to allow a passenger train to be operated uphill against the current of traffic, but with signal protection around a slow mo= ving uphill freight train.

In 1915 the double track uphill si= gnals were re-arranged and additional signals added to allow single track operati= on with signal protection on both tracks on both sides of the tunnel.

In 1919, another lar= ge signal program was started, consisting of installation of the usual single track A. P. B. circuits between Glendive and Forsyth, and between Forsyth a= nd Huntley, approximately 212 miles of signaling. It might be well to note that with the exception of connecting in the train order signals, and tying in at Huntley, in the whole 212 miles there was only one crossing bell to interconnect into the new work.

It might be wall t= o cite an occurrence that happened before the completion of the work between Glend= ive and Huntley, just previously mentioned; -

One night about 10= :30, our Train Mo, 3, at that time, a heavy train to the Coast, was stopped by a= red signal at the west end of Myers. The track between layers and Rancher is ve= ry crooked.

The Dispatcher wou= ld not give No. 3 orders to proceed and the Engineer refused to go until the section men were alerted a= nd went ahead of No. 3 with their car. Between the two stations mentioned, they found a large boulder about half the size of a box car which was lodged on = the track. When it rolled down to the track, it had torn down the pole line, causing the red signals. This was an instance where the cost of the whole signal installation paid for itself before the job was entirely completed.<= o:p>

About this time Mr= . Christofferson conceived the idea of the gallon font = lamp for use on the 1st and 2nd subdivisions of the Yello= wstone. This was on account of the very severe weather conditions which at times prevented the Maintainers from properly caring for the small font lamps or eight-day burners. These new = lamps had about a thirty-day capacity. These lamps were purchased on the Glendive to Huntley authority and = were transferred to the Mandan-Glendive territory and the old small lamps used on the Glendive-Huntley territory.

There was not much signal work done in 1920 and 1921. In 1922, another ambitious program again started. This consisted of ty= ing in the end of the old 1910 installation at Dilworth and installing double track signals from that point to the end of double track at Buffalo. From this point, the A.P.B. single track system was extended to the beginn= ing of double track at Bloom. In this stretch from Buffalo to Bloom, there are t= wo alternate main lines, one via the high bridge and the other down into Valley City. Both lines from Peak to Berea, were signaled as single track, thus providing A.P.B. signaling in both directions on both tracks. From Bloom to Jamestown, the signals are arranged for double track operation. From J= amestown west to Eldridge the l= ine is double track and signals were arranged for double track operation. From Eldridge, the standard A.P.B. circuits were installed on the single track to Mandan.

Another link in si= ngle track territory was likewise included in this year's program, the installat= ion of the A.P.B., system of single track signals connecting the end of the signaling at Cheney and extending to the bridge o= ver the Columbia River at Pasco.

In 1922, we undert= ook the relocation of our Line A which passed through the University Campus whe= re the Stadium is now located and then crossed the Mississippi River just nort= h of the present Washington Avenue Bridge. The double track line was moved to a new location just south of the Great Northern tracks in southeast M= inneapolis. Our line now crosses the river on a new bridge. This change in location eliminated the old Univers= ity Avenue mechanical interlocking plant, where our line crossed the Milwaukee near the intersection of U= niversity Avenue and Oak Street S.E. After the new bridg= e was completed, over the river, the old bridge was removed except a portion on the west side which is now use= d by a concrete company for unloading gravel,

A new electric interlocking plant at l8th Avenue S.E. was built at this time giving access= to the Great Northern tracks, and including switches serving the Milwaukee and Great Western roads.=

About 1922, we began to experience trouble w= ith our D. C. track circuits between Garrison and Missoula account electrification of the= Milwaukee Road whose track at points was very close to our tracks. We were forced to insta= ll a.c. track circuits to prevent interference from their 3,000 volt propulsion current. This meant building a separate pole line to carry our 2400 volt A. C. line.

There remained a s= hort piece of track, partly single and partly double, between Little Falls and Staples. Signaling of this track was undertaken in 1924, on the completion = of this work, a gala celebration was instigated at Little Falls, Minnesota, commemorating the completion of the signal system on the Northern Pacific f= rom St. Paul to the Pacific Coast.

Mr. Christofferson, then Signal Engineer, was given the honor of attaching the next to last bla= de, with Mr. C. L. Nichols, General Manager, attaching the last blade, this tak= ing place on September 1, 1924.

In 1922, an order = was issued by the Government ordering all railroads of certain classes to insta= ll "Automatic Train Control" on at least one engine operating divisi= on. The Northern Pacific selected the territory between <= st1:place w:st=3D"on">Mandan and Glendive. Mr. S. B. Ros= encrans was appointed Train Control Engineer. After several experimental attempts, one of which included a trolley-like arrangement on the locomotive, which made contact with an over= head wire, it was decided to use the Sprague Train Control System. This consisted of a

permanent and electromagnet which was placed between the rails at signal locations. When the signal was clear, and the= track relay in advance was de-energized on the approach of a train, the electro-magnet was energized, thus neutralizing the effect of the permanent magnet. A receiver was placed on the locomotive ahead of the front wheels.<= span style=3D'mso-spacerun:yes'> If the signal was at approach, the electro- magnet was not energized and the permanent magnet became effective, thus opening the stick relay circuit through the receiver on the locomotive, and automatically applying the air brakes.= The track magnet was made effective at the approach signal; so that = the train would be brought to a stop before it reached the stop signal. The res= et feature was placed on the locomotive in such a position that it could not be reset until the train came to a complete stop; a forestalling device was installed on the locomotive so that if the engineer was alert, he could forestall a brake application.

The electro-magnets required such a heavy current that it was necessary to install storage batteries. As no charging = line was available, the exi= sting primary battery was used for charging the storage battery. The Government w= as very strict concerning the circuits used and the way the circuits were installed.

On August 12, 1932= , the Northern Pacific was allowed to discontinue operation of the train control system.

Also about 1924, s= everal of the old mechanical interlocking plants were replaced with a newly devised type of automatic interlocking. While this form of interlocking is primarily intended for a straight crossing of two railroads, some rather elaborate circuits were devis= ed for such complicated layouts as at Sauk Centre= and Fergus Falls.

The Northern Pacif= ic has been very successful in the installation of low voltage automatic switch machines at a number of ends of double track as follows; - West Duluth Jct., Gregory, Philbrook, Bloom, Eldridge, Park City, Montana, and Irvin.

In 1927, color lig= ht signals, using a form of the old overlap system were installed on the single track line from Logan to Whitehall and from Butte to Warm Springs. A.C. track circuits were used acc= ount the closeness to the electrified Milwaukee tracks. A.P.B. circuits were not used account p= atent rights, also due to the sparseness of trains. In 1931 the Milwaukee changed their Sappington Interlocking Plant to automatic operation.

In 1927 the instal= lation of the same type of signals and circuits as used on the Butte Line were installed on the single track High Line, or the Evaro<= /span> Hill Line, between DeSmet and Paradise with D.C. track circuits. Also during 1927, the newly constructed double tr= ack Point Defiance line between Ta= coma and Tenino was signaled using the same type of color light signals as previously mentioned but with double track circuits.

In 1930, the old mechanical interlocking plant serving the junction of the Butte and Helena Lines at Garrison was removed and a system of spring switches and two electrically operated switc= hes was installed.

In 1930 the signal system between St. Paul and Minneapolis was modernized, including t= he installation of color light signals with A.C. t= rack circuits.

In 1929, in connec= tion with a line change at Laurel, the old mechanical interlocking plant was removed.

About 1931, throug= h a study of the contract covering Marshall Interlocking Plant, it was discover= ed that this plant should have been installed and paid for by the S.P. & S Railway, account it being the junior road. After various conferenc= es between the two roads, a ruling was made by President Donnelly of the North= ern Pacific that due to the fact that certain switches were included in the pla= nt serving our Paloose Line, that the Northern Pac= ific would assume a proportionate cost. Retroactive billing for maintenance back= to the origin of the plant was made against the S.P.&S. Railway, which was paid by that road.<= span style=3D'mso-spacerun:yes'> An A.F.E. was initiated to cover the change in proportion of ownership and billing the S.P.& S. Railway for i= ts proportion of the original installation cost.

In 1936, the Milwaukee changed= their mechanical interlocking plant at Dempsey (Race Track) to automatic operatio= n.

In 1937, the same = type of color light signals and circuits as were installed between Logan and Butte except for D.C. track circuits w= ere added from Whitehall to Butte and from Warm Springs to Garrison= . This program completed the signaling of the alternate main line between Logan and Garrison.

In 1939, due to an unfortunate occurrence at Ainsworth Jct., where an operator opened the junc= tion switch in the face of a train and sent it down the wrong track where an opposing train was waiting, an electric lock was installed on this switch. = Not long after, the lock was replaced with a switch machine controlled from Pasco. This arran= gement was added to at intervals to the present layout, which now includes the interlocking of the drawbridge over the Snake River<= /st1:place>, and an additional switch machine.

One of the old mechanical interlocking plants, known as St. Anthony Park Tower was located= at the junction of Lines A and Bo The arrangement of switches and signals was = very elaborate, including interlocked switches forming the = wye between Lines A and B. On a very cold night early in 1941, a fire started in the tower, which was destroyed. A new plant was built, eliminating some of = the interlocked switches, the new tower being built somewhat east of the old to= wer, and placed in service late in 1941.

In 1945 the Northe= rn Pacific adopted the system known as "Speed Signaling", replacing = the older "Route Signaling", this system conveys the necessary information to the engineer = as to the speed he may use in handling his train. This necessitated the rearrangement of the signal arms or lights at many interlocking plants and other places.

Over a period of y= ears, we have installed and experimented with various types of snow melters or switch heaters, electric, natural gas, pro= pane gas, and oil.

Several exhaustive studies have been made concerning the installation of Centralized Traffic Control between Gregory, and Staples, Minnesota, but nothing further has been done in this territory. However, studies were made in conn= ection with Centralized Traffic Control installation between Helena and Garrison o= ver the heavy grades at Blossburg. The work was completed in 1948 and= the results have been very gratifying.

In 1916 we install= ed an NX (1) interlocking plant at Laurel. This plant proved very successful. In 1948 another <= span class=3DSpellE>NX plant was installed at Huntley, where the C. B.& Q Railroad enters and leaves our line; this als= o is the beginning of double track west to Laurel. The control machine and certain re= lays were placed in the old two story wooden depot located between the tracks of= the two railroads. The plant was nearing completion and was to be ready for service shortly, when one aftern= oon a fire started, and with a high wind, the entire depot was destroyed in about= 15 minutes. Some of the Signalmen in the construction gang with Mr. C. H. Dunn= as Foreman, had not yet gone home. They made great efforts= to save all the signal apparatus possible and succeeded in getting most everyt= hing out but the control machine, which as fastened to the floor. If there had been several more min= utes, they would have saved it also, but the fire became too intense. The varnish on the blades of the t= rain order signal on the windward side was not scorched, but the rails of the Q track = on the other side were badly warped and could not be used for traffic.

[(1) NX =3D entrance / exit = style of interlocker – Simplified statement - a button is pressed on the track diagram where the train will enter the interlocked section, where it should= exit; and the machine’s logic sets up the route. Jcd]

When the automatic= block signals were originally installed under various programs, with the exceptio= n of the yard at Paradise, it was not the practice to make the signaling complete through the yard, the signals being terminated at each end. During the period about 1950, with= the exception of two short gaps at Mandan and Glendive, the signaling has been completed through the yards. The most noteworthy examples of closing up the gaps in yards are as follows: From the Union Depot at Minneapolis to Northtow= n, Fargo, Jamestown, Dickinson, Miles City, Forsyth, Billings, Livingston, But= te, Missoula, Spokane, Pasco, Yakima, Ellensburg, Tacoma and Seattle,

Since about 194O, a large number of highway crossing protection installations have been made, including many automatic short arm gates on double tracks. Some of the cros= sing protections are rather involved account high and low speed trains, also acc= ount switching moves.

A large number of = spring switch installations have been made. At sidings, the usual layout is to use= the key switch method for clearing the dwarf signal to proceed out from the siding. At yards, the usual m= ethod is that all signals stand normally at stop and clear on approach of a train= .

In 1949, the old H= all signals originally installed in 1910 between Seattle and Tacoma were replaced with G.R.S. Co. Type SA signals In 1954 the old top of mast signals installed in 1911 between Kalama and Vancouver were likewise replaced with Type SA color light signals.

A program was star= ted in December of 1937 relocating signal facilities, Mr. Law and Mr. Eastman did a grea= t deal of planning for the rearrangement and respacing= of signals between Minneapolis and the West Coast to provide more adequate stopping distances. This also involved changes in the lengths of the operating circuits for the various highway protections. Some sidings were lengthened, others were eliminated.<= span style=3D'mso-spacerun:yes'> Later the same rearrangements were= made on the Lake Superior Division.

Over a long period= of years, a great, many miles of rock slide fences have been installed in plac= es where there is danger of slides and falling rocks. These fences have been very effect= ive.

As an added safety feature, when welded rail was placed in the Stampede Tunnel, a coded track circuit was installed, giving continuous= track circuit protection through the length of the tunnel, approximately two miles long.

During 1954 due to= the construction of the McNary Dam by the Federal Government, it became necessary for the Northern Pacific to make extensive changes in the bridge and drawbridge over the Columbia River between Pasco and Kennewick, Each of the stationary spans was raised, all under traffic. The old drawbridge which was of the center pin swing type, was replaced with a lift = span with an opening between centers of the two towers of 317 feet.

Elaborate signalin= g was necessary not only in connection with the bridge but to protect the S.P.&S. Railway connection at the west end of the bridge and connections at the east end of the bridge.

In 1955 the first = car retarder system on the Northern Pacific was installed= and put in operation at Pasco. A large NX type of interlocking is how under construction opposite the Pasco Depot. A few words of explanation of several methods of battery operation that have been used on different signal installations over the years may be given here. With the exception of the track ba= ttery, on the early installations of the G.R.S. Compan= y 2A type of signal, sixteen cells of primary battery connected in series, serve= d to clear the signal, then the same sixteen cells were used to hold the signal = in the approach or clear positions, and in addition, served to operate any line relays involved which were usually of 670 ohms resistance. This method was used for many years. Then the separate line battery method came into use wherein about six, seven or eight cells, conne= cted in series, are used to operate all line relays -which are generally of 136 = ohms resistance. This method keeps the sixteen cells of operating battery entire= ly off the line.

A later developmen= t of the separate line circuit was the use of reversed polarity on the line, i.e= ., with all signals standing clear the positive side of the west bound line batteries were connected to line common and the negative side to the operat= ing side of the circuit, and the negative side of the eastbound line batteries = were connected to line common, with the positive side connected in the conventio= nal manner.

In 1919, another innovation was instigated, the low voltage hold clear coils. With this arrangement, but two coils are used in = the hold clear device. For pickin= g up the hold clear armature, the full sixteen cells of operating battery plus t= he two additional cells are used, then the sixteen cells are disconnected and = the two cells serve the hold clear device. This same method is used in the 1922 installations, to which was added for the first time, approach lighting. A modified method of separate hold clear has been devised for the older signa= ls, to save discarding the old sets of hold clear coils. This is accomplished by running a separate wire to the middle of the sixteen cells of operating battery, picking up on the full sixteen cells and holding on eight cells. <= o:p>

SINGLE TRACK
16 Cells for Operating and Line and Split Hold Clear. (1913 Series)

Whit= e Bear - West Duluth
Carlton - Superior
Laurel - Livingston
paradise - Sand Point
Sand Point - Cheney
Pasco - Ellensburg
Ellensburg - CleElum
Lester - Auburn

16 Cells for Opera= ting, Split Hold Clear = and Separate Line for Relays. (19= 14 Series) =

= Bozeman - Helena
DeSmet - paradise via St. Regis
CleElum - Easton

16 Cells for Opera= ting Only, 2 Cells for Hold Clear and Separate Line Battery: with Reversed .Line. (1919 Series)

Glendive - Huntley=

16 Cells for Operating, 2 Cells for Hold Clear, Separate Line = Battery with Reversed Line, Approach Lighting. (1922 Series)<= /p>

Little Falls - Sta= ples
Dilworth - Jamestown
Jamestown - Mandan
Cheney - Pasco

During the early existence of the Signal Department, the Office of the Signal Engineer was located upstairs over the Local Freight House, located at Fourth and John Streets, St. Paul, This location was about three blocks from the old General Office Building.

Early in 1916, on = the completion of the present General Office Building, 176 East Fifth Street, the Signal Department was moved to its present location on the twelfth floo= r of this building.

A few words might = be said here in connection with the organization of the Signal Department: - The Signal Engineer's Office= has jurisdiction of the entire signal system between St. = Paul and Duluth on the eastern end of the road,= to Seattle, Tacoma and= Portland on the w= estern end of the system. This territory is sub-divided into three districts. The Eastern District covers the area from St. Paul and Duluth to Mandan= , North Dakota, with headquarters at St. Paul, Minnesota. The Central District comprises the territory between = Mandan, North Dakota and P= aradise, Montana, -with headquarters at Livingston, Montana. The Western District covers the balance of the railroad west from Paradise, Montana= , to Seattle, Tacoma and= Portland, Oregon,= with headquarters at Tacoma, Washington.

It might be of int= erest to mention the names of different men who have served as Signal Engineer -<= o:p>

Mr. C. A. Christofferson, the 1st Signal Engineer

Mr. S. W. Law, the= 2nd Signal Engineer

Mr. A. J. Hendry, = the present Signal Engineer

Others who have se= rved in the past; -

Mr. Alf Munthe, Mr. James H. Cormick, Mr. E. J. Ralph, Mr. Wilfred Kearton, Mr. Dick Bozard, Mr. W. M. O'Loughlin, Mr. F. M. O'Loughlin, Mr. A. G. Nutting, Mr. F. L. Eukes, Mr. A. H. Barnes, Mr. E. A. Cuthbertson, Mr. T. C. Hansen, Mr. Anton Bracke, Mr. I. Seeley

Jones, Mr. B. A. <= span class=3DSpellE>Grinde, Mr. Fred Scherfenberg, Mr. E. A. Alien, Mr. W. H. Lindeman, Mr. P. C. = Peters, Mr. Adolph Rudeen, Mr. B. W. Larsen, Mr.= Elmer Slayter, Mr. W. E. Page, Mr. Bert Basford, Mr. Ralph Thurston,= Mr. Paul Amann, Mr. Paul Rohner, Mr. Carl B. Olson, Mr. C. H.Swanson, Mr. F. N. Christofferson, Mr. H. M. Sova, Mrs. Helen Ferron, Mr. T. C. Rhodes, Mr. E. W. = Kaeli, Mr. Alvin Sager, Mr. Thomas Kearton, Mr. Jack Lister, Mr. S. B. Rosencrans, Mr. Adam= Staver, Mr. L. W. Bown, M= r. Harry Renstrom, Mr. R. B. Jackson, Mr. Warren L. Waleen, Mr. C. L. Steinmetz, Miss Sadie Woods, Mr.= -G. H. Davis, Mr. L. E. Harrington, Mr. N. A. Johnson= and Mr. Harley Morrison.

Those who are still serving: - Mr. Evan Wilson, Mr. L. M. Johnson, Mr. S. N. Roden, Mr. J. V. Cih= lar, Mr. C. H. Dunn, Mr. D. E. Peterson= , Mr. Stanley C. Anderson, Mr. J. J. Morrissey, Mr. W. A. Class, Mr. D. A. Harrington, Mr. B. A. Bjorkman, Mr. E. 0. Anderberg, Mr. F. V. Sloop, Mr. M. B. Walker, Mr. Floyd C. Harrington, Mr. J. L. Doroff, Mr. W. B. Olson, Mr. Dwight L. Johnson, Mr. J= . T. Groth, Mr. A. D. Fennell, Mr. R. J. Hagen, Mr. J. R. = Norrbohm, Mr. M. C. Mercer, Mr. A. H. Ohm, Mr. A. J. = Schrumpf, Mr. A. T. Brumfield, Mr. S. C. Sworder, Mr. V. L. Guthrie, Mr. V. G. Jacobson, Mr. R= . W. Larsen, Mr. C. W. Schultz, Mr. = J. L. Elpel, Mr. D. A. Dietrich, Mr. D. B. Sage, Mr. G. L. Flagen, Mr. E. L. Wagnar, J. T. Keough= , Mr.W. C. Wygant, Mr= . M. L. Keough, Mr. Theo. McKenney, Mr. A. D. Macdonald, Mr. E. H. Kleinschmidt, Mr. H.= A. Roloff and Mr. A. C. Eastman.

The above history = of the Signal Department of the Northern Pacific Railway Company was written as of June 30, 1956.

Alden C. Eastma= n <= /span>

Alden C. Eastman