Running in a southerly direction, it follows the existing north-south line in Hanover's urban area via the Hannover Messe/Laatzen station, which is also served by long-distance trains (primarily during trade fairs), at km 8 towards Rethen.

[11] The highest costs per kilometre were incurred during the construction phase for the sparsely populated but topographically very complex section between Göttingen and the state border north of Kassel.

[21] On 4 August 1969, the head office of Deutsche Bundesbahn issued a first planning order for a new line that would run from Nordstemmen (south of Hanover) via Fulda to Würzburg.

Overcoming the Hessian ridge was planned as the third major climb on the line, in order to then reach Gemünden at an altitude of 150 meters via the Sinn valley.

[25][26] The selected route, which would have been suitable for passenger and freight traffic, emerged as the most favourable solution from the requirement to connect both Kassel and the line to Frankfurt south of Fulda.

In the corridor between Hanover and Gemünden (with a continuation to Würzburg), the two supplementary routes, Hanover–Würzburg and Aschaffenburg–Würzburg were compared to the development of the proposed Autobahn 100 (a northern extension of the .

[38] The distance between the tracks would have been 5.40 meters for this loading gauge, the usable tunnel cross-sectional area above the top edge of the rails should be 103 square metres.

In May 1982, the newly created Federal Railway Board (Bundesbahnvorstand) decided in July 1982 to continue building the lines and bring the commissioning forward to 1991.

Taking into account new planning parameters (250 km/h instead of 300 km/h speed, standard instead of large structural gauge), the economic difference was finally reduced to DM 300 million.

[51] On 26 August 1980, 90 percent of the route was determined in the course of regional planning and the Federal Ministry of Transport gave approval for the last section of the new line between Kassel-Wilhelmshöhe and Burgsinn (near Würzburg).

[57] As late as 1983, the working group of rapid-transit rail opponents and the environmental association tried to prevent the construction of the section between Kassel and Fulda.

[65] On 10 August 1973, the construction of a first, twelve-kilometre section[14] of the Hanover–Gemünden supplementary line began with the symbolic first ramming blow by Federal Transport Minister Lauritz Lauritzen near Laatzen.

Due to objections conveyed in citizens' initiatives and lawsuits, extensive construction work in the northern section between Hanover and Göttingen did not begin until March 1983.

[89] From August 1986, a diverse test program was run with a wide variety of rolling stock in order to gain further knowledge about railway operations at high speeds, which ultimately was used for ICE 1 series trains.

On 3 September, high-speed runs with the ICE predecessor train Intercity Experimental began, which had to be cancelled on the same day after a powered end car derailed in the Burgsinn depot (due to an incorrect points setting).

[93][94] The downpipe toilets, which were still common on the railways at the time—including in IC cars—were open to the outside and would be replaced by closed systems, since the pressure wave could otherwise reverse the flushing process, which only worked with gravity.

[95] On 16 February 1989, the maximum speed allowed for IC trains in the tunnel was increased to 180 km/h (110 mph) (without taking travel times into account), although there were still not enough pressurised cars available.

Thanks to the locally precise measurements, freight trains were now able to use the lines without restrictions up to wind force 10, and beyond that at a maximum speed of 80 kilometres per hour (50 mph).

[97] In 1989, multi-stage test subjects were examined between Fulda and Würzburg, from which pressure comfort criteria for Deutsche Bahn were derived, which in turn found their way into a relevant set of rules by the International Union of Railways (UIC).

[100] Since the Linienzugbeeinflussung (LZB) train control system was not yet available, the maximum speed was 160 km/h (99 mph) until the whole line was commissioned, without any significant gain in travel time.

[121] In October 2019, the section was reopened for heavy traffic between 5 p.m. and 7 a.m.[122] The diversion took place via the Hanoverian Southern Railway along the Leine Valley, which resulted in a travel time extension of 30 to 45 minutes and train cancellations.

The first expert draft published in October 2018 provided for a travel time of exactly 120 minutes for the proposed German clock-face timetable between the stations in Hanover and Würzburg.

[143] The second expert draft submitted in 2019 provided for six trains per hour in each direction south of Fulda to Kalbach; one and a half of them continue towards Munich.

In 1994, reasons given for the actually lower capacity utilisation included the incomplete upgrade of the rest of the network (on which the forecast is based) and the "unsatisfactory development" of rail freight traffic.

Regional traffic only takes place on short sections between the stations and nearby links to the older lines, for example between Ihringshausen and Kassel-Wilhelmshöhe.

[157] While around 20 trains per day and direction operated in the southern section of the line between Mottgers and Würzburg in 2018, the forecast in the Federal Transport Routes Plan 2030 expects up to 74.

At the southern end of the new line, the maximum speed is reduced from 250 to 220 km/h on the Veitshöchheim Main Viaduct, followed by a reduction to 160 km/h in the subsequent Roßberg tunnel.

1 EBO) allowed a maximum line speed for ICE 1 multiple units by a determination of 24 March 1995 of 280 km/h, combined with special safety requirements.

[162] As part of the "Fulda–Burgsinn Mixed traffic" project, a three-week[163] pilot operation starting on 23 November 2009[163] was tested in the 44-kilometre section, under which it is possible to have freight trains run during the day.

With test runs by DB Systemtechnik in December 2022 with a class 403 multiple unit between Würzburg and Fulda, multi-year studies began to increase the maximum speed to 300 km/h (190 mph) in regular operation.